15th International
Symposium on Insect-Plant
Relationships
17-22 August 2014
University of Neuchâtel
Switzerland
SIP 15
ABSTRACT BOOK
SPONSORS AND PARTNERS
SIP 15
SIP 15
CONTENTS
Table of Contents
Impressum
4
Map
5
General Information
6
Programme Schedule
11
List of Posters
17
Abstracts of Talks
23
Keynote
25
Multitrophic Interactions 1
26
Pollination
36
Belowground Interactions
46
Plant Domestication and Application
53
Plant Volatiles
59
Metabolomics and Molecular Mechanisms
66
Phylogenetics and Co-Evolution
76
Multitrophic Interactions 2
87
Abstracts of Posters
Multitrophic Interactions
95
97
Pollination
130
Belowground Interactions
136
Plant Domestication and Application
143
Plant Volatiles
151
Metabolomics and Molecular Mechanisms
166
Phylogenetics and Co-Evolution
184
Addendum
195
Participant List
199
3
IMPRESSUM
Impressum
Organizing Committee
Institute of Biology
University of Neuchâtel
Ted Turlings
Betty Benrey
Sandrine Gouinguené
Thomas Degen
Layout Abstract Book
Scientific Visualization Thomas Degen
www.thomas-degen.ch
[email protected]
4
SIP 15
SIP 15
MAP
Map
Rue des Parcs
Place de
la Gare
Bo
ine
-Ho
Rue Jehanne-de chberg
- Go
det
Rue du C
hât
eau
Rue
de
l'Hôp
e
ue d
Aven
5
Avenue
la
de
pital
l'Hô
Lac
du
urg
Faubo
ier-Mars
du Prem
Place Avenue
du Port
rg
Faubou
ital
3
Gare
Ga
re
Chauss
ée
de
la
Rue de l'Ecluse
Quai Philippe
Rue des Fahys
Rue des Sablons
Port
de la
Ville
Rue
de
la
dière
Mala
2
Rue de la Pierre-à-Mazel
4
1
de
Belle
vaux
e du
nu
Ave
Ro
u te
des
Fala
ise
Mail
s
Port du
Nid du Crô
Place du
12 septembre
Aula des Jeunes-Rives (meeting site)
Restaurant Le Romarin (lunches)
Faculty of Sciences (lab tour)
Shopping centre Maladière
Harbour (banquet)
Train Station
Auditorium
Registration
desk
Faculty of
Humanities
Cafeteria
Poster Session
5
GENERAL
GeneralINFORMATION
Information
SIP 15
Congress venue and access
from Geneva airport
The easiest way to reach Neuchâtel from Geneva airport is by train (1hr 20min). The station is
located directly in the airport and a train leaves for Neuchâtel every hour. For schedules, please
check directly on the SBB/CFF website (SBB/CFF is the Swiss national train company).
from Zurich airport
The easiest way to reach Neuchâtel from Zurich airport is by train (1hr 50min). The station is
located directly in the airport and a train leaves for Neuchâtel every hour. For schedules, please
check directly on the SBB/CFF website (SBB/CFF is the Swiss national train company). We
advice you not to take the train via Bern.
from Basel-Mulhouse airport
Basel-Mulhouse EuroAirport is not linked directly to the railway system, but there are connections
by public transport (shuttle bus, line 50, duration of ride 20 min) to the Basel railway station.
Train Basel-Neuchâtel (direct connection, 1hr 30min). For schedules, please check directly on
the SBB/CFF website (SBB/CFF is the Swiss national train company).
by train
Neuchâtel is easily reachable by train from anywhere in Europe. For more information and
detailed schedules, please check the SBB/CFF website.
by car
Coming by car to Neuchâtel is easy. The city is directly connected to the national highway
network. At the border, you will have to purchase a highway sticker (40 CHF).
Registration
Sunday 17 August: The registration desk will be open from 13:00 to 17:00. The registration
desk is located in the hall of the main Aula of the Faculty of Humanities (1 on the map). For late
arrivals, the desk will be open also on Monday morning.
Upon arrival, the participants will receive a meeting welcome package including a short program,
badge, maps and touristic information.
6
SIP 15
GENERAL INFORMATION
Talks and Posters
All talks will be presented in the Aula des Jeunes Rives (Auditorium). Contributions should be
submitted and uploaded in an electronic format at least the day before the scheduled presentation.
There will be a PC and Mac to transfer and preview the presentation at the upload desk. Such a
preceding test is strongly recommended, especially if the presentation contains video clips. Due
to the dense programme schedule, talks that do not respect the presentation time will be stopped
according to the schedule.
Posters will be displayed in two rooms in a neighbouring building (see map). On Thurday
evening, a prize of 500 CHF each will be awarded to three posters from students.
Internet access
The participants can use the Wi-Fi connections by selecting the network UNINE-PUBLIC and
typing a valid e-mail address in the grey login section (as a guest).
Système d'authentification du réseau de l'Université de
Neuchâtel
Login pour Utilisateurs
Utilisateur
Mot de passe
Conseil important: dès à présent, utilisez le réseau WiFi sécurisé et
fiable "unine" au lieu de "public-unine".
Manuels de configuration pour Windows 7 et Vista, Windows XP, Mac.
Login pour les utilisateurs enregistrés à l'UniNE:
Donnez votre nom d'Utilisateur et mot de passe du domaine UNINE.CH
Log in
Login pour Invités
Votre adresse de courrier
électronique
Log in
Invités / Guests:
Accès réservé aux invités de l'UniNE et aux lecteurs de la Bibliothèque
Publique et Universitaire.
Donnez une adresse de messagerie valide.
Pour les utilisateurs d'autres Universités et Hautes écoles en Suisse:
Démarrez votre client VPN pour vous connecter à votre campus et Internet.
Friday August 8, 2014
Commercial Internet Access:
Please use the network "PWLAN".
Accès Internet Commercial:
Veuillez s-v-p utiliser le réseau "PWLAN".
Kommerzieller Internetzugriff:
Bitte das Netzwerk "PWLAN" verwenden.
Lien sur Conditions d'utilisation et aide / Link for Conditions of use and help
En cas de problème: [email protected] ou 032 718 20 10
7
GENERAL INFORMATION
SIP 15
Meals
All lunches will be served in the restaurant le Romarin (2 on the map, 10 minutes walk from
the congress site). Coffee breaks will be held at the cafeteria. Participants will receive further
information about restaurants included in the meeting welcome package. For any further needs,
a nearby shopping mall (Maladière, located at the football stadium, 4 on the map) can be reached
within 2 minutes by foot from the congress site.
Opening Hours
Shops/shopping
Monday – Friday: 8:30 – 19:00, Saturday: 8:30 – 18:00
Late night shopping: Thursday, 8:30 – 20:00
Many stores are closed on Monday morning; smaller shops are closed from 12:00 – 13:30
Banks and currency exchange
Monday – Friday: 9:00 - 12:15 / 13:45 – 17:00
Saturday: closed
Public authorities and offices
Monday – Friday: 8:30 – 12:00 / 13:30 – 17:00
Saturday: closed
Phone Calls
The international code for Switzerland is +41. Example: 41 (0) 32 718 31 76. When calling
internally, the number will include the “0”. Example: 032 718 31 76.
Important Phone Numbers
Emergency calls
117 Police
118 Fire
144 Ambulance
1414 Swiss heli rescue
8
SIP 15
GENERAL INFORMATION
Public Transport
Train
Switzerland has a very dense railway network. Tickets can be purchased in the train stations or
online (http://www.sbb.ch/en/home.html), but no longer in the trains. For Neuchâtel, the services
can be found at: www.cff.ch/gare-services/am-bahnhof/gare/autres-gares/neuchatel.html
Local buses
Neuchâtel and the surrounding villages are also well connected by the urban bus system. Tickets
can be purchased from the machines at the bus stops or in the Bureau commercial, Place Pury:
www.transn.ch, [email protected]
You can find timetables and maps of the lines and bus stops at:
www.transn.ch/fr/reseau-horaires/reseau-transn.html
Taxis
• City Taxis: +41 (0) 32 733 33 33; free call: 0800 80 33 33
• Taxis Arto : Rue de l’Ecluse 56, 2000 Neuchâtel, +41 (0) 32 725 7777, [email protected]
• Taxicab: +41 (0) 32 724 12 12; office: +41(0) 76 491 25 06
• Taxicool: +41 (0) 32 544 46 46 / +41 (0) 32 721 10 10
Car Rental
• Europcar: Rue des Poudrières 10, 2000 Neuchâtel, phone: +41 (0) 32 724 96 96
• Avis: Wabernstrasse 41, 3007 Bern, phone: +41 (0)31 378 15 15
• Hertz: Chemin du Pré Neuf, 1400 Yverdon-les-Bains, phone : +41 (0)24 445 22 60
Dining in Neuchâtel
There are more than 20 restaurants in the City centre of Neuchâtel, please check
www.tripadvisor.com/Restaurants-g188066-Neuchatel.html
We will provide a list with a map in your welcoming package.
Touristic Information
More touristic information can be obtained from Tourisme neuchâtelois, Hôtel des Postes,
2001 Neuchâtel, +41 (0)32 889 68 90, [email protected], www.neuchateltourisme.ch
9
GENERAL INFORMATION
SIP 15
Neuchâtel
geography
The city is located on the northwestern shore of the Lake of Neuchâtel and at the foothills of the
Jura mountains, with the nearby Chaumont (1100 m above sea level) worth an excursion that, on
a sunny day, can offer an amazing view of the Bernese Alps, the Mont Blanc and three Jura lakes.
population
The city of Neuchâtel counts around 33’000 inhabitants, almost third of which are are resident
foreign nationals. The majority of the population (ca. 80%) speaks French as their first language.
history
In 1814 Neuchâtel became the capital of the 21st canton of Switzerland, but also remained
a Prussian principality. It took a bloodless revolution in the decades following for Neuchâtel
to shake off its princely past and declare itself on 1 March 1848 a republic within the Swiss
Confederation.
economy
Renowned for its watch industry, Neuchâtel has been able to position itself as the heart of microtechnology and high-tech industry. The canton has also a wine-growing region along the Lake
Neuchâtel shore. The Val-de-Travers is famous as the birthplace of absinthe, which has now been
re-legalized in Switzerland.
museums
www.museum-neuchatel.ch (natural history) www.latenium.ch (archeology)
www.men.ch (ethnography) www.mahn.ch (art and history)
www.can.ch (contemporary art) www.cdn.ch (centre dürrenmatt)
10
Programme Schedule
PROGRAMME
SCHEDULE
SIP 15
PROGRAMME SCHEDULE
Sunday, 17 August 2014
10:00
–20:00
Arrival of participants
free visit Botanical Garden
13:00
–17:00
Registration (SIP 15 conference site)
Setting up of posters
PLENARY LECTURE
16:00
Betty Benrey
Ted Turlings
Welcome
16:15
Sharon Strauss
Apparency revisited
17:00
Welcome reception
11
PROGRAMME SCHEDULE
SIP 15
Monday, 18 August 2014
8:50
Chair:
Gwen Shlichta
MULTITROPHIC INTERACTIONS 1
9:00
Martin Heil
Successful teamwork: Cooperation as a strategy in plant defence
9:35
Tobias Lortzing
Paid in blood – Ant-attracting wound secretions of Solanum dulcamara
provide indirect defense against herbivory
9:20
9:50
10:05
10:20
Enric Frago
Andrew Gherlenda
Andrew George
Stephenson
10:50
Fanny Vogelweith
11:05
Johan A. Stenberg
11:20
Yin-Quan Liu
11:35
Karen Muller
11:50
Arjen Biere
12:05
13:30
Insect symbionts: a hidden trophic level in insect-plant interactions
Is the response of insect herbivores to elevated CO2 and temperature
universally predictable for different host tree species?
Impact of Solanum carolinense trichomes on larval growth, integrity of
the peritrophic membrane, and the immune system of Manduca sexta
tea/coffee break
Which processes shape grapevine moth immune response against
parasitism?
Sex-biased predation in dioecious willow: the long reach of plant
genes
Effects of a begomovirus on the tritrophic interaction of tomato, white­
fly Bemisia tabaci and its parasitoid Eretmocerus hayati
Male larval nutrition on different grape varieties affects adult repro­
ductive success in wild European grapevine moth (Lobesia botrana)
Effects of plant microbial symbionts on aboveground plant-insect
interactions in Plantago lanceolata
lunch at Le Romarin / dessert and coffee at the conference site
Poster session
Chair:
Christophe Praz
15:30
Florian Schiestl*
Floral signals in the context of pollination and herbivory
16:05
Angela Köhler
‘Toxic nectar’: harmful and beneficial effects of nicotine on an important
pollinator, the African honey bee
15:50
Daniel Gervasi
16:20
Mascha Bischoff
16:35
Paulo MiletPinheiro
16:50
17:20
Martine Hossaert
17:40
Vincent Trunz
18:10
Dani LucasBarbosa*
17:55
18:25
12
information
Holly Summers
Rayko Halitschke
* EuroVOL participant
POLLINATION
Impact of changing pollinator environments on the evolution of plants
No pollinator is an island – the role of context and previous experience
in floral reproductive isolation
Sexual deception or rendezvous attraction? Deconstructing the floral
mimicry of Cephalanthera rubra (Orchidaceae)
tea/coffee break
Lord of the dance: chemical mediators and specific pollination
interactions
Pollen secondary metabolites influence bee-flower relationships
Nitrogenous aldoximes produced by a night-blooming flower influence
hawkmoth feeding behavior
Integrating Plant-Pollinator and Plant-Herbivore Interactions
Herbivore-pollinator interactions in wild Solanum
SIP 15
PROGRAMME SCHEDULE
Tuesday, 19 August 2014
8:50
Chair:
Ted Turlings
9:00
Roxina Soler
9:20
Scott Johnson
9:35
Ivan Hiltpold
9:50
Christelle Robert
10:10
10:25
Meret Huber
information
BELOWGROUND INTERACTIONS
Plant-mediated interactions between insects across above-below­
ground domains: ecology, mechanisms and utilization
The missing half: can we predict how climate change will affect below­
ground insect-plant interactions?
Induced fitness cost: a consequence of root indirect defences in
western corn rootworm population showing resistance to Bt-toxins
Plant secondary metabolite hijacking by a specialist root herbivore
Root herbivory drives the evolution of defensive latex secondary
metabolites in nature
tea/coffee break
10:55
Michael Rostás
11:10
Shai Morin
Chair:
Betty Benrey
11:25
Yolanda Chen
Crop domestication and naturally selected species interactions
12:00
Gwen Shlichta
Contrasting effects of plant domestication on herbivore interactions:
The case of wild and cultivated lima beans
11:45
Kirsten Leiss
12:15
13:30
Toby Bruce
16:05
Karen Kloth
Chair:
Ivan Hiltpold
16:20
Eric Schmelz
16:40
16:55
Martín Aluja
Feng Zhu
17:25
Sergio Rasmann
18:00
Tuuli-Marjaana
Koski
17:40
18:15
18:30
Inoculation of tomato plants with rhizobacteria enhances the perfor­
mance of the phloem-feeding insect Bemisia tabaci
PLANT DOMESTICATION AND APPLICATION
Host plant resistance to Western flower thrips in cultivated, biofortified
and wild carrots
lunch at Le Romarin / dessert and coffee at the conference site
15:30
15:50
Aboveground endophyte affects root volatile emission and host plant
selection of a belowground insect
Peter Anderson*
Foteini
Paschalidou*
Sara Hermann
* EuroVOL participant
Poster session
The call of the wild: tracking an indirect defence trait in maize
Costs of extreme apple domestication and the value of old cultivars
under global climate change
High-throughput phenotyping of plant resistance to aphids by auto­
mated video tracking
PLANT VOLATILES
Plant volatiles: getting a biochemical grasp on specificity
Plant volatile mediated interactions in food webs up to the fourth
trophic level
tea/coffee break
The effect of ecological gradients on plant volatile emissions
Effect of experience to plant cues on host plant choice of a moth
Volatile organic compounds from insect-defoliated trees as possible
foraging cues for insectivorous birds
Effects of insect herbivore eggs on interactions of plants with their
insect community
Prey perception of predation risk: volatile chemical cues mediate nonconsumptive effects of a predator on a herbivorous insect
13
PROGRAMME SCHEDULE
SIP 15
Wednesday, 20 August 2014
8:50
Chair:
Matthias Erb
information
METABOLOMICS AND MOLECULAR MECHANISMS
9:00
Gaétan Glauser
Metabolomics for studying plant-insect interactions: help or hype?
9:35
Christelle Bonnet*
9:50
Duy Nguyen
Impact of (a)biotic pretreatments on Pieris brassicae feeding re­
sponses in Brassica nigra
9:20
10:05
10:20
10:50
11:10
11:25
Caroline Müller
Peter Klinkhamer
Philippe
Reymond*
Suzanne Kos
Vinzenz Handrick
11:40
Osnat Malka
11:55
Michele Bandoly
12:10
12:40
Specificity of metabolic plant responses to salicylic and jasmonic acid
and impacts on chewing and sucking herbivores
Water stresses affect herbivore-induced defense responses in
Solanum dulcamara
Metabolomics of different leaf cell types and interacting effects of
secondary metabolites on toxicity to Spodoptera
tea/coffee break
Role of Arabidopsis bHLH transcription factors MYC2, MYC3 and
MYC4 in defense against herbivory
Unravelling host plant resistance in chrysanthemum using NMR
Benzoxazinoids: Biosynthesis and function of major defense com­
pounds in maize
Disarming the glucosinolate-myrosinase complex by sulfatase in
Bemisia tabaci
Insect eggs predict future attack and prime induced plant defence
business meeting
packet lunch
FREE AFTERNOON
* EuroVOL participant
14
SIP 15
PROGRAMME SCHEDULE
Thursday, 21 August 2014
8:50
Chair:
Sergio Rasmann
9:00
Nadir Alvarez
9:20
Tobias Züst
9:35
Martin Steinbauer
9:50
Georg Petschenka
10:05
Jared Gregory Ali
10:20
10:50
Susanne Dobler
11:10
Jeffrey Ahern
11:25
Franziska Beran
11:40
Nina Fatouros*
11:55
Corinna Krempl
12:10
Thure Pavlo
Hauser
12:25
13:30
information
PHYLOGENETICS AND COEVOLUTION
Processes from patterns – can co-evolutionary diversification be
tested in a phylogenetic framework?
Prevalence of growth-defense trade-offs in two major defense traits of
the common milkweed Asclepias syriaca L.
An Australian contribution to the coevolution of red leaf colour
hypothesis – courtesy of eucalypts and eucalypt-feeding psylloids
Evolution of cardenolide resistance and sequestration in milkweed
butterflies (Lepidoptera, Danaini)
Aphids suck and monarchs rule: asymmetry of plant-mediated inter­
actions between specialist aphids and caterpillars on two milkweeds
tea/coffee break
Convergent adaptive evolution – how insects master the challenge of
cardenolide-containing host plants
Macroevolutionary patterns of plant phenolic metabolites in the
Onagraceae
Phyllotreta flea beetles utilize host plant defense compounds to create
their own glucosinolate-myrosinase system
Synergism between direct and indirect defence controls herbivore
eggs on a wild crucifer
Adaptation of generalist herbivores to Gossypol, a cotton secondary
metabolite
Constraints to the evolution of both insect and pathogen resistance in
two chemotypes of a wild crucifer
lunch at Le Romarin / desert and coffee at the conference site
Poster session
Chair:
Angela Köhler
15:30
Erik Poelman*
Multi species multi trophic interactions
16:05
Jeltje Stam
16:20
Grit Kunert
Order of arrival of early season herbivores affect the subsequent
insect community
15:50
16:35
Aino Kalske
17:05
Ilka Vosteen
17:20
Tiantian Lin
17:35
Paul Ode
17:50
Stefan Pentzold
18:45
–24:00
MULTITROPHIC INTERACTIONS 2
Inbreeding in a plant-herbivore interaction: effects on herbivore perfor­
mance, preference and third-trophic level interactions
What does the aphid feeding behaviour tells us about plant factors
important for pea aphid host race maintenance?
tea/coffee
The role of hoverfly – plant species interaction in maintenance of pea
aphid host races
The EICA and SDH hypothesis revisited: A competition experiment
between invasive and native Jacobaea vulgaris under specialist or
generalist herbivore attack
Parasitism increases plant investment in chemical defences against
herbivores
Insect counter-adaptations to plant cyanogenic glucosides
Boat tour, Gala dinner, poster awards and Jazz band Cocinando
* EuroVOL participant
15
PROGRAMME SCHEDULE
Friday, 22 August 2014
Departure
9:00
–17:30
16
EuroVOL FINAL MEETING
SIP 15
SIP 15
ListOF
of POSTERS
Posters
LIST
LIST OF POSTERS
17
LIST OF POSTERS
SIP 15
MULTITROPHIC INTERACTIONS
P1
Hiroshi Abe
Analyses of interaction among Arabidopsis, thrips, and tospovirus
P3
Daniel Anstett
P4
Agnès Ardanuy
Genetically based latitudinal patterns in physical, chemical and life
history defence traits in the native plant Oenothera biennis
P5
Pasquale Cascone*
P6
Antonino Cusumano*
P7
Antonino Cusumano*
P8
Sandra Elisa da Silva
P9
Marjolein De Rijk
P2
P10
Benedicte
Albrectsen*
Micky Eubanks
P11
Minghui Fei
P12
Marian Giertych
P14
Johnattan Hernandez
Cumplido
P13
P15
Aidan Hall
Anne-Violette Lavoir
P16
Jenny Lazebnik
P17
Yehua Li
P18
Dani Lucas-Barbosa*
P19
Xoaquín Moreira
P20
Kim Karlsson Moritz
P22
Helga Pankoke
P21
Colin Orians
* EuroVOL participant
18
Genetic basis of endophyte community on aspen (Populus tremula)
is altered after introduction of a specialist beetle (Chrysomela
tremula)
A trophic chain as indicator of potential GM maize impacts:
disentangling the effects of ambiental variation
Does non-host damage affect Diaeretiella rapae behaviour towards
HIPV from Brassica nigra
The role of dual herbivore attack on plant VOC emission and egg
parasitoid recruitment
Effect of dual biotic stress on plant volatile synomones used by egg
parasitoids
Aphids and caterpillars damaging the same plant: olfactory response
of four aphidophagous insects to induced volatiles
Parasitoid foraging in multi-herbivore communities
Escape and radiate: have orchids escaped herbivory or insect
ecologists?
Quantitative and qualitative constraints on development and survival
of a gregarious insect herbivore and its endoparasitoid
Oak leaves – gall wasp. Conflict or cooperation?
Characterisation of the parasitoid complex and of its inhibition during
a psyllid outbreak in an Australian native eucalypt woodland
Effects of early season defense induction in Lima bean plants on
late season tritrophic interactions on bean seeds
Nitrogen and water availability to tomato plants triggers bottom-up
effects on the leafminer Tuta absoluta
How do potatoes deal with biotic stress? Unravelling a tripartite
interaction between a plant, a pathogen and a herbivore
Consequences of intra-specific variation in aphid-induced plant
responses on herbivore and carnivore community composition
Caught between parasitoids and predators – survival of specialist
herbivore on leaves and flowers of mustard plants
Latitudinal variation in herbivory: Influences of climatic drivers,
herbivore identity and natural enemies
Plant sex effects on tritrophic interactions
Do herbivore-induced allocation shifts explain contrasting impacts of
two invasive herbivores?
Impact of leaf defences of Plantago lanceolata on performance,
nutrient utilization, and feeding behaviour of a polyphagous
caterpillar
SIP 15
LIST OF POSTERS
MULTITROPHIC INTERACTIONS
P23
Martín Pareja
P24
Carlos PascacioVillafán
P25
Mathilde Poyet
P26
James Ryalls
P27
Diego Silva
P28
Jirislav Skuhrovec
P30
Jörg Stephan
P31
Xianqin Wei
P32
Hao Xu
P33
Zhaonan Yu
P29
Michael Stastny
Sequential damage by two aphid species on the same plant en­
hances attraction of an aphid natural enemy
Food quality mediates fitness correlates of a potentially invasive
insect pest: effects of plant phenolics and nutrients on Anastrepha
ludens (Diptera: Tephritidae)
Drosophila suzukii atropine consumption a prevention against
parasitoids ?
Global climate change and aboveground-belowground interactions
in Lucerne
Response of the zoophytophagous predators Macrolophus pyg­
maeus and Nesidiocoris tenuis to volatiles of uninfested plants and
of plants infested by conspecifics
Harmonia axyridis and coccinellids in central Europe
Phenotypic divergence in an invasive plant: potential for adaptation
to insect biocontrol?
Predator hunting mode and habitat domain of two predators sharing
a leaf beetle
The role of pyrrolizidine alkaloids on the performance of generalist
and specialist invertebrate herbivores in Jacobaea species
Synergistic roles of plant volatiles and sex pheromones in mate
finding by parasitoids
ZJU-93 induces susceptibility in rice to brown planthopper Nilapar­
vata lugens (Stål)
POLLINATION
P34
Gaylord Desurmont
P35
Daniel Gervasi
P37
Martin Steinbauer
P38
Timothy Sutton
P36
P39
Paulo Milet-Pinheiro
Martin von Arx
The interplay between pollinator attraction and indirect defense:
the impact of Brassica rapa floral volatiles on herbivore-induced
volatiles and attractiveness to natural enemies
Impact of changing pollinator environments on the evolution of plants
Floral scents in Catasetum: do scent patterns predict pollinating
orchid bee genera?
Thermogenesis and the chemical ecology of pollination in endemic
Australian Araceae
Vulnerability of a fig – pollinator system to climate change
Diversity and distribution of microbial communities in floral nectar in
two typical plants of the Sonoran Desert
BELOWGROUND INTERACTIONS
P40
Kirk Barnett
P41
Alison Bennett
P42
Ines Cambra
Australian grassland responses to root herbivory and extreme
rainfall
Do genotypic and species level variation matter in abovebelowground interactions?
Digesting the indigestible
19
LIST OF POSTERS
SIP 15
BELOWGROUND INTERACTIONS
P43
Raquel CamposHerrera
P44
Sarah Facey
P45
Geoffrey Jaffuel
P46
Shuhang Wang
Measuring entomopathogenic nematode soil food webs in Swiss
wheat-maize agroecosystem for developing root-herbivores sustain­
able biocontrol
Testing the interactive effects of elevated temperature and CO2 on
an above-/belowground herbivore system
The natural occurrence of entomopathogenic nematodes in Swiss
agricultural soils is not affected by management practices
Breeding for resistance to root flies (Delia radicum) in cabbage,
Brassica oleracea – resistance screens among wild Brassica species
PLANT DOMESTICATION AND APPLICATION
P47
Maximilien Cuny
P48
Toby Bruce
P50
Mickaël Gaillard
P52
Iris Guedes Paiva
P53
Liora Shaltiel-Harpaz
P54
Adrianna
Szczepaniec
P49
P51
Frauke Fedderwitz
Larissa Guillén
Bean domestication and intraspecific competition interact to in­
fluence performance in a bruchid beetle
Aphid resistance in Solanum stoloniferum, a wild species of potato
Effects of methyl jasmonate treatment of conifer seedlings on pine
weevil feeding
Non-specialized insect pests benefit from maize domestication
Effect of mango breeding on laticiferous duct density and sap content/
pressure and its consequences on infestation by two polyphagous
fruit flies (Diptera: Tephritidae)
Floral resources provided by Tagetes erecta as a strategy for en­
hancing natural enemy activity in organic lettuce
The use of resistant pear accessions as inter-stock in order to reduce
susceptibility to pear psylla Cacopsylla bidens (Šulc) in commercial
pear trees
Neonicotinoid insecticides alter induced defenses and increase sus­
ceptibility to spider mites in crop plants
PLANT VOLATILES
Carlos BustosSegura
Terpene composition of leaves, stem and headspace in the Austral­
ian tea tree
P57
Holger Danner*
P58
Emma Despland
Exotic herbivores modify the protective perfume of Brassica rapa
plants
P59
Sylvia Drok
P60
Franziska Eberl
P61
Kamal Gupta
P62
Sandra Irmisch
P55
P56
Xavier Chiriboga
* EuroVOL participant
20
The diffusion of the herbivore-induced root signal (E)-β-caryophyllene
depends on soil texture and humidity
What is the role of monoterpenes in white spruce - spruce budworm
interactions?
Egg deposition alters volatile emission of Nicotiana attenuata in
response to herbivore feeding
Volatile emission in black poplar (Populus nigra) after pathogen and
herbivore attack
An assessment of juvenile hormone mimicking activity of plant
volatiles on red cotton bug, Dysdercus koenigii
The production of volatile aldoximes and nitriles: putative key players
in the direct and indirect defense of poplar
SIP 15
LIST OF POSTERS
PLANT VOLATILES
Diego Martins
Magalhães
Boll weevil uses homoterpenes to identify cotton phenological stages
P65
Goddy Prinsloo
P66
Melanie Senning*
Potential use of Tulbaghia leaf extracts in integrated control of wheat
aphids
P67
Sybille Unsicker
P68
Xianqin Wei
P69
Berhane T.
Weldegergis
P63
P64
Camille Ponzio*
Foraging behavior of three parasitoid species during dual herbivore
attack to plants; does herbivore density matter?
Molecular and metabolic bases of volatile isoprenoid-induced
resistance to abiotic stresses (MOMEVIP): challenging Arabidopsis
wild type and MVA pathway mutant plants with climate scenarios
Volatile emission in poplar: temporal dynamics and the role of minor
compounds in attracting herbivore enemies
Exogenous application of methyl jasmonate changes concentration
and composition of individual pyrrolizidine alkaloids in Jacobaea
plants
Insect behaviour toward plants under biotic and abiotic stresses
METABOLOMICS AND MOLECULAR MECHANISMS
P70
Jacqueline Bede
P71
Onno Calf
P72
Daniel Geuss
P73
Olivier Hilfiker
P75
Anneke Kroes
P77
Jie Li
P79
Mirka Macel
P81
Karina MedinaJiménez
Transcriptome analysis of Physalis philadelphica (husk tomato)
response to herbivory
P83
Stefano Papazian*
P84
Ana Pineda
Plant defense under multiple stress conditions: linking metabolomics
and volatiles (META-VOC)
P74
P76
P78
P80
P82
Ghazanfar Khan
Jiancai Li
Daniel Maag
Ricardo Machado
Caroline Müller
* EuroVOL participant
Protein post-translational modification in response to caterpillar
herbivory
The consequences of natural variation in Bittersweet’s defences to
mollusc herbivores
Direct defence responses in Solanum dulcamara after insect egg
deposition
Oviposition by Pieris brassicae induces SAR in Arabidopsis thaliana
Jasmonate signaling is involved in shoot growth reduction and
induced defense during phosphate starvation in Arabidopsis
Plant defense in response to multiple insect attack
OsHI-MAPK1 is a key factor regulating rice induced defense and
senescence
Feeding by whiteflies induce the production of glucosinolates
3-β-D-glucopyranosyl-6-methoxy-2-benzoxazolinone – a novel
detoxification product of maize benzoxazinoid derivatives in
Spodoptera spp.
Admixture in invasive plants: the effects on chemistry and herbivory
Auxin as an herbivory-induced signal in Nicotiana attenuata
Plant metal hyperaccumulation acts as efficient defence against
specialist and generalist herbivores
Plant-mediated effects of several water stress intensities on a leafchewer and a phloem feeder
21
LIST OF POSTERS
SIP 15
METABOLOMICS AND MOLECULAR MECHANISMS
P85
Manus Thoen
Induced plant defenses upon thrips infestation in Arabidopsis
P87
Wenfeng Ye
A novel EF-hand protein secreted from salivary glands of the rice
brown planthopper Nilaparvata lugens functions as an effector for
defense responses in rice
P86
Meng Ye
OsHI-LRR2, a novel leucine-rich repeat receptor-like kinase, plays
important roles in herbivore-induced defense responses in rice
PHYLOGENETICS AND COEVOLUTION
P88
Jacqueline Bede
The Aulacoscelidinae beetles and their Cycad hosts
P90
Eva Castells
P91
Érika Castro
Rapid evolution of Senecio pterophorus in response to climate but
not to herbivore release
P92
Aidan Hall
P93
Franziska Heidemann
P94
Marco Herde
P95
Shai Morin
P96
Jirislav Skuhrovec
P97
Martin Steinbauer
P98
Timothy Sutton
P89
Jacqueline Bede
Defensive toxins of neotropical Chrysomeline beetles better reflect
phylogenetic origin than host plant associations
Evolutionary aspects of cyanogenic glucoside biosynthesis in butter­
flies and moths and their food plants
Coevolution between bacterial endosymbionts and their psyllid
hosts of the Cardiaspina genus (Hemiptera: Psyllidae)
Molecular evolution of flavin-dependent monooxygenases adapted
for the detoxification of plant pyrrolizidine alkaloids in Lepidoptera
Host plant-specific remodeling of midgut physiology in the generalist
insect herbivore Trichoplusia ni
The evolutionary relationship between constitutive and induced de­
toxification resistance in generalist herbivores
Plant-herbivore interactions in diploid and tetraploid cytotypes of
Centaurea phrygia
Molecular phylogeny for the Australian jumping plant lice and lerp
insects (Hemiptera: Psylloidea) reveals host specificity
Contrasting dispersal and inbreeding in a fig-pollinating wasp and
its parasitoid
ADDENDUM PHYLOGENETICS AND COEVOLUTION
P99
Peter Roessingh
The sensory basis of host shifts in phytophagous insects
ADDENDUM PLANT VOLATILES
P100
P101
22
James Blande
Juergen Gross
Malicious signals – when plants should not eavesdrop
Plant volatile emission is affected by different virulent AP phyto­
plasma strains
SIP 15
Abstracts ofTALKS
Talks
ABSTRACTS
ABSTRACTS OF TALKS
23
ABSTRACTS TALKS
24
SIP 15
SIP 15
Keynote
KEYNOTE
Apparency revisited
Strauss SY
Department of Ecology and Evolution, University of California Davis, USA
[email protected]
The idea of plant ‘apparency’ to herbivores is almost 40 years old, and the importance of
apparency as a selective force on plant defense remains hotly debated. Apparency is a trait that is
hard to define; it depends both on the eye, nose or antennae of the herbivore beholder, as well as
on the community context in which a plant occurs. Apparency, as originally framed, is also often
confounded with plant life-history, with perennial plants always falling under the ‘apparent’
categorization. Here I discuss one aspect of apparency, the occupancy of sparsely vegetated or
‘bare’ habitats. First, I review how bare habitats may select for increased investment in defense
in a number of plant and animal species. Second, I discuss how, in several species of native
northern California mustards, we find evidence that occupying bare habitats may make plants
more apparent to herbivores. We show this vulnerability using both descriptive and experimental
approaches. Apparency in bare habitats may have shaped the evolution of several plant traits,
including leaf pigmentation and egg mimicry. Apparency may also increase vulnerability of
herbivores in barer habitats, and plant relationships with pollinators.
Third, using a phylogenetic approach in this Streptanthoid mustard clade, we show that
occupancy of barer habitats has strong phylogenetic signal, more so than occupancy of particular
soil types, suggesting that adaptation to barer habitats is not a labile trait. In contrast, glucosinolate
profiles of these species are more labile than occupancy of bare habitats. Some glucosinolate
fractions, however, may be correlated with habitat bareness.
The concept of apparency may still have some usefulness in understanding plant-herbivore
relationships, but perhaps requires modifications on how we define apparency.
17.8.2014 16:00–17:00
invited talk
25
Multitrophic Interactions
1
MULTITROPHIC
INTERACTIONS
SIP 15
Successful teamwork:
Cooperation as a strategy in plant defence
Heil M
Departamento de Ingeniería Genética, CINVESTAV-Irapuato, Km. 9.6 Libramiento Norte,
36821 Irapuato, Guanajuato, México
[email protected]
Mutualisms are commonly threatened by parasites and cheaters: species that exploit the hostderived resources without providing an adequate service. Here, I summarize mechanisms for
the stabilization of obligate defensive ant-plant mutualisms: a commonly used model system for
the research into horizontally transmitted mutualisms. Host plants exert partner choice and can
sanction non-defending ants by shedding the domatia that serve as nesting space or ceasing the
production of ant rewards. Hosts can also restrict the exploitation of the ant rewards by means of
specific biochemical traits that decrease their quality for non-adapted generalist exploiters and,
thus, convert them into exclusive rewards1. Reward provisioning can even shift the competitive
balance between mutualists and exploiters in favour of the mutualists2. In turn, plant–ants show
adaptations in their colony structure3,4 and changes in their digestive capacities5 that enhance
their efficiency in the use of the host-derived resources. Founding queens use plant odours for
host choice behaviour, and ants not supplied with adequate amounts of EFN decrease their
defensive service and thereby exert partner sanctions6. Theoretical models and empirical research
into mutualisms usually focus on actions that are taken by the host. Using ant-plants as model
systems, we are now discovering the importance of contributions that come from the symbiont.
This discovery indicates the potential for multiple reciprocal interactions between phenotypically
plastic hosts and symbionts, which contribute significantly to what is still considered a miracle:
the stability of mutualisms in the presence of exploiters.
1 Orona-Tamayo D et al. 2013. Exclusive rewards in mutualisms: ant proteases and plant protease inhibitors create
a lock-key system to protect Acacia food bodies from exploitation. Mol. Ecol. 22: 4087-4100.
2 Heil M et al. 2009. Divergent investment strategies of Acacia myrmecophytes and the coexistence of mutualists
and exploiters. Proc. Natl. Acad. Sci. U.S.A. 106: 18091–18096.
3 Kautz S et al. 2012. Host use by competing acacia-ants: Mutualists monopolize while parasites share hosts.
PLOS ONE 7: e37691.
4 Kautz S, Pauls SU, Ballhorn DJ, Heil M 2009. Polygynous supercolonies of the acacia-ant Pseudomyrmex peperi,
an inferior colony founder. Mol. Ecol. 18: 5180-5194.
5 Heil M, Barajas-Barron A, Orona-Tamayo D, Wielsch N, Svatos A. 2014. Partner manipulation stabilises a
horizontally transmitted mutualism. Ecol. Lett. 17: 185-192.
6 González-Teuber M, Silva-Bueno JC, Boland W, Heil M 2012. Increased host investment in extrafloral nectar
(EFN) improves the efficiency of a mutualistic defensive service. PLoS ONE 7: e46598.
26
invited talk
18.8.2014 9:00–9:20
SIP 15
MULTITROPHIC INTERACTIONS
Insect symbionts:
a hidden trophic level in insect-plant interactions
Frago E 1, van Veen FJF 2, Dicke M 1, Godfray HCJ 3
1 Laboratory of Entomology, Wageningen University, Droevendaalsesteeg 1, Building 107,
6708 PB Wageningen, The Netherlands
2 Centre for Ecology and Conservation, College of Life and Environmental Sciences,
University of Exeter, Cornwall Campus, TR10 9FE, United Kingdom
3 University of Oxford, Department of Zoology, The Tinbergen Building, South Parks Road,
Oxford, OX1 3PS, United Kingdom
[email protected]
Recent evidence suggests that insect symbionts may be more important hidden-players in insectplant interactions than is currently realised. In the last decade, it has become apparent that
facultative symbionts (i.e. not required for host survival) can be important mediators of direct
and indirect interactions between insects, their host plants and their natural enemies1. The pea
aphid (Acyrthosiphon pisum) is the main model organism for studying the role of facultative
symbionts in insect-plant interactions2. In this species facultative symbionts provide their hosts
with several services. Hamiltonella defensa, for example, protects aphids from parasitic wasps,
an effect that has been extensively studied in the laboratory. The role of this bacteria in a wider
community context, however, remains relatively unexplored. In a series of field experiments, we
address costs, benefits and trophic web consequences of pea aphid infection with H. defensa.
We found that costs in terms of reduced population growth were higher than the potential
benefits obtained through reduced mortality due to parasitoids. We also show that this protective
symbiont increases species link and diversity in the trophic web of associated parasitoids and
hyperparasitoids. We also predicted that effects in the trophic web would indirectly affect other
insect species (aphids in particular) through shared natural enemies (i.e. apparent competition).
In particular, we expected plots with aphids infected with a protective symbiont to represent
an enemy-free space leading to an increase in the number of aphids naturally colonising them;
an effect that we did not find to be very strong. Our results suggest insect symbionts can be an
important hidden trophic level in plant-based insect communities.
1 Frago E, Dicke M, Godfray HCJ 2013. Insect symbionts as hidden players in insect-plant interactions. Trends in
Ecology & Evolution 27: 705-711.
2 Oliver KM, Degnan PH, Burke GR, Moran NA 2010. Facultative symbionts in aphids and the horizontal transfer
of ecologically important traits. Annual Review of Entomology 55: 247-66.
18.8.2014 9:20–9:35
talk
27
MULTITROPHIC INTERACTIONS
SIP 15
Paid in blood – Ant-attracting wound secretions of Solanum
dulcamara provide indirect defense against herbivory
Lortzing T 1, Calf O 2, Geuß D 1, Böhlke M 1, van Dam NM 2,3, Steppuhn A 1
1 Freie Universität Berlin, Dahlem Centre of Plant Sciences (DCPS), Molecular Ecology
Group, Haderslebener Str. 9, 12163 Berlin, Germany
2 Radbound University, Institute of Water and Wetland Research, Heyendaalseweg 135,
6525 AJ Nijmegen, the Netherlands
3 German Centre for Integrative Biodiversity Research (iDiv), Deutscher Platz 5e,
04103 Leipzig, Germany
[email protected]
[email protected]
Many plants secrete extrafloral nectar (EFN) to attract ants that in turn reduce herbivore load. This
EFN secretion is often induced by herbivore feeding and usually involves specialized secretory
tissues, i.e., extrafloral nectaries. Here, we report herbivore-induced sugar secretions that act as
indirect defense in a plant lacking nectaries. We discovered that Bittersweet nightshade (Solanum
dulcamara) secretes sucrose-rich droplets at the edges of wounds caused by herbivore feeding.
In laboratory trials, ants collected these secretions, foraged longer on herbivore-damaged leaves,
and visited even undamaged leaves of herbivore-damaged plants in greater numbers. When
we applied sucrose droplets to leaves of S. dulcamara in a natural population, we successfully
increased ant abundance. As a result, sugar-augmented plants suffered less feeding damage than
neighboring control plants. We observed slugs (Arion spp) as well as slug feeding patterns on the
experimental plants in the field. When keeping Arion spp slugs with S. dulcamara plants in cages
that were either accessible to ants or not, we found that ants killed slugs and significantly reduced
weight of the survivors. Furthermore, ant attendance correlated negatively with the amount of
leaf damage in both this laboratory- and the field trial. Thus, S. dulcamara´s secretions from
wounds in response to herbivory increase ant attendance that functions as an indirect defense.
This mechanism acts in a very similar manner as EFN that is secreted from more or less complex
morphological structures. Since this phenomenon effectively facilitates an induced indirect
defense, it may represent an evolutionary basal form of EFN.
28
talk
18.8.2014 9:35–9:50
SIP 15
MULTITROPHIC INTERACTIONS
Is the response of insect herbivores to elevated CO2 and
temperature universally predictable for different host tree
species?
Gherlenda A 1, Haigh AM 2, Moore BD 1, Johnson SN 1, Riegler M 1
1 Hawkesbury Institute for the Environment, University of Western Sydney, Locked bag 1797,
Penrith, NSW, 2751, Australia
2 School of Science and Health, University of Western Sydney, Penrith, Australia
[email protected]
Elevated atmospheric CO2 concentrations (eCO2) are expected to reduce the palatability and
quality of eucalypt leaves to herbivorous insects via the dilution of essential elements, such as
nitrogen (bound in amino acids and proteins) while increasing leaf defence compounds. This
decrease in leaf nutritional quality may lead to longer developmental times, reduced survival and
a decrease in immune-competence, thus increasing the susceptibility to pathogens, parasites or
parasitoids. However, elevated temperature (eT) in combination with eCO2 may ameliorate these
foliar chemistry changes, and thus reduce the impact on insect performance. The Eucalyptus
genus contains over 700 species with varying foliar chemistry that can display species specific
responses to eCO2 and eT which may shift the outcomes of insect-plant interactions. The objectives
of this study were: (1) to assess how plant-mediated effects via changes in leaf chemistry of two
different eucalypt species as a result of varying CO2 concentrations and temperature impacted
larval developmental time, survival, leaf consumption and pupal weights; (2) determine whether
changes in the leaf beetle-eucalypt interaction were consistent across both eucalypt species;
(3) to assess whether the immune response of larvae was altered as a result of varying [CO2]
and temperature conditions. The study used two eucalypts with differing but overlapping home
ranges; Eucalyptus tereticornis and Eucalyptus robusta, grown in a glasshouse in a multifactorial design for eight months. Larvae of Paropsis atomaria, a common eucalypt leaf beetle,
were placed onto each tree and monitored for the entire larval development to adulthood.
To assess the immune response the final instar was used and larvae challenged with a nylon
monofilament. eCO2 reduced foliar nitrogen, phosphorous and moisture content while total nonstructural carbohydrates and leaf mass per area increased. eT had no effect on foliar chemistry.
Insect developmental time increased as a result of eCO2, while eT reduced developmental
time. At eCO2 survival of P. atomaria larvae was increased when feeding on E. robusta while
it decreased when feeding on E. tereticornis. This suggests idiosyncratic responses of insect
herbivores as a result of plant-mediated responses to eCO2. The immune response of P. atomaria
larvae on E. tereticornis at eCO2 decreased in phenoloxidase activity, encapsulation response
and haemolymph protein content, indicating larvae may be more vulnerable against a parasitoid
or pathogen attack. However, encapsulation response increased at eCO2. Our study shows that it
may not be appropriate to assume that measured responses of herbivorous insects are universal
across their entire host range and that the diversity of host plant interactions may allow insect
herbivores to adapt to climate change.
18.8.2014 9:50–10:05
talk
29
MULTITROPHIC INTERACTIONS
SIP 15
Impact of Solanum carolinense trichomes on larval growth,
integrity of the peritrophic membrane, and the immune system
of Manduca sexta
Kariyat RR 1,2, Serpi MA 3, De Moraes CM 1,2, Mescher MC 1,2, Cox-Foster D 1,
Stephenson AG 3
1 Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
2 Department of Environmental Systems Science, ETH Zurich 8092, Zurich Switzerland
3 Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
[email protected]
Previous studies have shown that inbred horsenettle plants produce fewer stellate trichomes
constitutively than outbred plants and that the ability to induce additional trichomes upon
herbivore damage is compromised in inbred plants. Consequently, we examined the effects
of trichomes on the foliar consumption rate and growth rate of Manduca sexta larvae and we
examined the impacts of foliar trichomes on the peritrophic membrane of larvae after consuming
horsenettle leaves. We found that first instar larvae took longer to take their first bite and grew
more slowly on the leaves of outbred plants that had higher trichome density. In a series of
experiments in which larvae were given leaf discs in which the trichomes had been removed
(shaved off) or unshaved we found that there was no difference in the consumption or growth
rates of larvae on shaved leaf discs of inbred and outbred plants; that larvae consumed more and
grew faster on shaved leaf discs compared to unshaved discs and on unshaved inbred leaf discs
compared to unshaved outbred leaf discs. When we added the shaved trichomes to artificial diet,
we found that larval mortality was greater and growth rates were reduced on diet containing the
shaved trichomes. Light microscopy and SEM studies revealed that foliar trichomes remained
intact when moving through the gut and damaged the peritrophic membrane of 3rd instar larvae.
This damage could potentially alter digestion, nutrient absorption, and expose the larvae to
pathogenic microbes in the gut. This is one of the few studies to unambiguously demonstrate
that non-glandular trichomes function to deter chewing insects. Finally, we intend to report
on a series of ongoing studies that examine the effects of foliar trichomes and damage to the
peritrophic membrane on the immune system of the larvae.
30
talk
18.8.2014 10:05–10:20
SIP 15
MULTITROPHIC INTERACTIONS
Which processes shape grapevine moth immune response
against parasitism?
Vogelweith F 1,2, Thiéry D 2, Moret Y 1, Moreau J 1
1 UMR 6282 Biogéosciences équipe Ecologie Evolutive – Dijon, France
2 UMR INRA-ENITAB 1065 Santé et Agroecologie du Vignoble, INRA, Institut des Sciences
de la Vigne et du Vin – Centre de Recherches INRA de Bordeaux-Aquitaine, France
[email protected]
Identification of the selective forces shaping immune traits of organisms in natural conditions
is a central question in the field of ecological immunology. The immune response is expected
to be the evolutionary response to selective pressure from parasites and pathogens. While
laboratory studies support this view, few have investigated variation in immune defence in
natural populations and identified the putative causal factors of such variation.
Here, I will present data showing significant geographical co-variation between levels
of innate immune defences of the phytophagous moth, Lobesia botrana, and their infection
prevalence by parasitoids among natural populations. I examine the potential causes of covariation by testing two non-exclusive hypotheses. The first hypothesis is that such covariation
between immune defences and prevalence of infection by parasitoids results from a plastic
enhancement of immune defences in L. botrana in response to cues indicating the abundance of
parasitoids in the environment. As immune defence is costly to maintain and use, the immune
system may unsurprisingly exhibit plastic responses to perceived environmental threats,
in the same way that phenotypic defences respond to environmental challenges. The second
hypothesis proposes that the co-variation between immune defences and prevalence of infection
by parasitoids corresponds to local optimal investments to the immune system driven by costs
arising from the allocation of resources to immune functions and the benefits arising from higher
defence to parasitoid attacks.
Our results appear to refute the first hypothesis in which moth larvae would be able to
adjust their immunity in response to the presence of parasitoids in the environment, but support
the second hypothesis in which levels of investment to immune functions is shaped by the costs
of immunity and the benefits of immunocompetence against parasitoids.
18.8.2014 10:50–11:05
talk
31
MULTITROPHIC INTERACTIONS
SIP 15
Sex-biased predation in dioecious willow:
the long reach of plant genes
Kabir MdF 1, Moritz KK 1, Stenberg JA 2
Department of Ecology, Swedish University of Agricultural Sciences, P.O. Box 7044, 75007
Uppsala, Sweden
[email protected]
The extended phenotype of plants involves direct effects on herbivory and herbivore dynamics,
but little is known about its effect on predators and predator-herbivore interactions. Here we
take a holistic approach to simultaneously study plant genetic effects on herbivore and predator
preference, performance, as well as population densities and predation pressure in the field. In
dioecious Salix cinerea (grey willow) we found that male plants were of higher food quality than
females for an omnivorous predator (Anthocoris nemorum, common flower bug), while plant
quality for its herbivorous prey (Phratora vulgatissima, blue willow beetle) was not sex-biased.
The herbivore showed an adaptive behaviour, strongly preferring the host-plant sex (females) that
was suboptimal for the predator, which in turn followed its prey to female plants, leading to sexbiased predation. These findings elucidate a mechanism behind plant-genetic effects on predatorherbivore dynamics, and can be utilized in breeding for improved biocontrol of herbivores.
32
talk
18.8.2014 11:05–11:20
SIP 15
MULTITROPHIC INTERACTIONS
Effects of a begomovirus on the tritrophic interaction of tomato,
whitefly Bemisia tabaci and its parasitoid Eretmocerus hayati
Liu YQ 1, Pan D 1,2, Yan TT 1, Zhang Z 1, Liu SS 1 and Li YX 2
1 Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, China
2 Department of Entomology, College of Plant Protection, Nanjing Agricultural University,
Nanjing 210095, China
[email protected]
Plant viruses can manipulate the morphology and physiology of host plants and thereby may
affect the behavior of insect vectors and parasitoids. Begomoviruses are important plant viruses
exclusively transmitted by the whitefly Bemisia tabaci. However, the impact of begomoviruses
has been rarely considered in the research of plant-whitefly-parasitoid interactions. In this study,
we tested the effects of Tomato yellow leaf curl virus (TYLCV) on the olfactory responses and
the foraging performance of the whitefly, B. tabaci, and its parasitoid, Eretmocerus hayati. When
tomato plants were infected by either the whitefly or the virus alone, the whitefly showed no
preference between infected and uninfected plants whereas the parasitoid preferred the infected
plants. When plants were co-infected by the whitefly and the virus, the whitefly preferred the
co-infected plants to whitefly-infected plants but showed no preference between co-infected and
virus-infected plants; however, the parasitoid preferred the co-infected plants to virus-infected
plants but showed no preference between co-infected and whitefly-infected plants. The host
handling time and patch residence time of the parasitoid on TYLCV-infected plants were ca. 2- and
1.5-fold that on uninfected plants, respectively, although the parasitism rates, emergence rates
and developmental duration from egg to adult of the parasitoid were similar on virus-infected
and uninfected plants. We further compared volatiles and leaf trichome density between virusinfected and uninfected plants and attempted to infer their association with changes of insect
behavior.
Key words: Tomato yellow leaf curl virus; patch residence time; olfactory response; plant-virusvector-natural enemy interaction
Acknowledgements: This study was financially supported by the National Basic Research
Program of China (2013CB127604).
18.8.2014 11:20–11:35
talk
33
MULTITROPHIC INTERACTIONS
SIP 15
Male larval nutrition on different grape varieties affects adult
reproductive success in wild European grapevine moth
(Lobesia botrana)
Muller K 1, Thiéry D 2, Moret Y 1, Moreau J 1
1 Université de Bourgogne, Equipe Ecologie Evolutive, UMR 6282 Biogéosciences,
6 Bd Gabriel, 21000 Dijon, France
2 INRA UMR 1065 Santé et Agroecologie du Vignoble, Institut des Science de la Vigne et du
Vin, Ave E. Bourleaux, 33883 Villenave d’Ornon Cedex, France
[email protected]
The abundance of phytophagous insects is determined by numerous interacting biotic and abiotic
factors. In capital-breeding phytophagous insects, larval food quality is a key determinant of adult
fitness. Moreover, in Lepidoptera, males transfer to females a spermatophore containing sperm
and accessory gland secretions that could be reinvested into female reproduction. Curiously,
if the effect of host plant quality on female reproductive success is well-established, only few
studies attempted to determine such effect on male sexual quality and the subsequent implications
it might have on female reproduction. In this study, we used the European grapevine moth
(Lobesia botrana), a major grapevine pest to investigate how male larval nutrition on different
grape varieties influences male reproductive success and how it affects female reproduction.
Specifically, we examined the effect of male larval nutrition on their mating success by scoring
individual motivation to mate, male spermatophore size and amount of sperm, and finally female
fecundity and fertility. A strong effect of male larval nutrition was found on spermatophore
size and amount of fertilizing sperm produced by males. These male performances had strong
repercussions on the female reproductive output. Indeed, females mated with males producing
the biggest spermatophore and the more fertilizing sperm were the most fecund and fertile.
Finally, females seemed able to recognize males of different quality during the precopulatory
phase and to motivate their mating behaviour accordingly. The present results suggest that male
nutritional quality could have strong implications in population dynamics.
34
talk
18.8.2014 11:35–11:50
SIP 15
MULTITROPHIC INTERACTIONS
Effects of plant microbial symbionts on aboveground plant-insect
interactions in Plantago lanceolata
Biere A
Dept. Terrestrial Ecology, Netherlands Institute of Ecology, NIOO-KNAW, Droevendaalsesteeg 10, 6708 PB Wageningen, The Netherlands
[email protected]
It is increasingly recognized that plant-insect interactions are strongly affected by “hidden”
microbial players, including both insect and plant symbionts1. The effects of such microbial
symbionts on plant-insect interactions are far-reaching, impacting e.g. host specialization, plantinsect dynamics, and insect community structure2. Prominent amongst the plant-associated
symbionts are arbuscular mycorrhizal fungi. They can affect insect performance by altering plant
nutritional status, plant tolerance to abiotic and biotic stress, and by inducing or priming plants
for direct and indirect defense against insect herbivores3.
We studied effects of the arbuscular mycorrhizal fungus Funneliformis mosseae on leaf
chemistry and direct and indirect defense of two plant genotypes of ribwort plantain, Plantago
lanceolata, against the generalist noctuid Spodoptera exigua under high and low soil phosphorus
conditions. In this system, higher leaf C/N and C/P ratios result in lower efficiency of conversion
of ingested food (ECI) of S. exigua caterpillars, that they partly compensate by increasing their
relative consumption rate (RCR), while higher levels of leaf iridoid glycosides (important defense
metabolites in P. lanceolata) result in lower caterpillar RCR and relative growth rate.
Effects of mycorrhizae on leaf chemistry depended on plant genotype and soil phosphorus
conditions. We found no evidence for mycorrhizal priming of direct defenses; under conditions
where inducing herbivores reduced the consumption rate of later arriving herbivores, the
mycorrhiza tended to weaken rather than strengthen the plant’s induced response. The mycorrhiza
also decreased the attractiveness of S. exigua-damaged plants for its parasitoid Microplitis
mediator, in accordance with observed mycorrhiza-mediated reductions in green leaf and
terpenoid volatiles in this system. Interestingly, while the mycorrhiza consistently increased leaf
N and P in the two plant genotypes, its effect on defense metabolites strongly differed between
the plant genotypes. In the absence of the mycorrhiza, one of the plant genotypes produced twofold higher levels of IG defense metabolites, but in its presence, the difference was annihilated.
This illustrates the role of microbial symbionts in modulating intraspecific variation in direct
plant defense and in shaping plant defense phenotypes.
1 Biere A, Bennett AE 2013. Three-way interactions between plants, microbes and insects. Funct. Ecol. 27: 567573.
2 Frago E, Dicke M, Godfray HCJ 2012. Insect symbionts as hidden players in insect-plant interactions. Trends
Ecol. Evol. 27: 705-711.
3 Pozo MJ, Azcón-Aguilar C 2007. Unraveling mycorrhiza-induced resistance. Curr. Opin. Plant Biol. 10: 393398.
18.8.2014 11:50–12:05
talk
35
Pollination
POLLINATION
SIP 15
Floral signals in the context of pollination and herbivory
Schiestl FP
Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, 8008 Zürich
[email protected]
The interactions of plants with their pollinators represents a key mutualism for ecosystem
functioning as well as for human nutrition. For maintaining interactions with pollinators, plants
have evolved floral signals, such as color and fragrance, which advertise rewards such as nectar.
Although floral signals are key traits for reproductive success and reproductive isolation, little is
known about the evolutionary process that shape their properties and variability. In my talk I will
discuss functions of floral signals for pollinator attraction as well as alteration of floral signalling
after herbivore attack. In will focus on Brassica rapa which has a generalised pollination system.
In a study on functional significance of floral signals for pollinator attraction, we found that flower
size and one floral scent compound, phenylacetaldehyde were associated with reward status of a
plant and can thus act as honest signals for pollinators. Bumble bees were shown to learn and use
honest signals when visiting flowers. After herbivore attack, emission of phenylacetaldehyde as
well as other aromatic floral volatiles were found to be strongly reduced. Flowers of herbivoreattacked plants were less attractive than control plants in dual choice assays with bumble bees.
To compensate for this, plants produced more early flowers and thus did not suffer any reduced
seed set. Reduced floral scent was found, however, to increase the attractiveness of plants for
parasitoids and thus improve the indirect defence of the plant. These results show that floral
signals have multiple functions and can be emitted in a plastic way to optimise the interaction of
a plant with multiple interacting organisms.
36
invited talk
18.8.2014 15:30–15:50
SIP 15
POLLINATION
Impact of Changing Pollinator Environments on the Evolution
of Plants
Gervasi DDL, Schiestl FP
Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, 8008 Zürich,
Switzerland
[email protected]
Selection mediated through pollinators played a key role in floral adaptation and reproductive
isolation of plants. Although the importance of pollinator-driven selection on plant evolution
cannot be neglected, it has never been demonstrated in an experimental approach where
the pollinator environment has been manipulated. Thus the details of these processes still
remain little understood. The aim of this study is to investigate pollinator-driven selection by
experimentally changing the pollinator environments. Specifically we investigate the effects of
different pollinators on the evolution of floral traits and plant reproductive success over several
generations. We use Brassica rapa (Wisconsin rapid cycling) as model plant with its generalized
pollination system and short generation time. As pollinators we use the bumblebee, Bombus
terrestris, and the hoverfly, Episyrphus balteatus. In our study we found that bumblebees and
hoverflies differ in the selection they impose on floral traits. The strength of selection on the
floral traits also varies significantly between the two pollinators, which lay the foundation for
divergent evolution in the plants. We observed strong positive selection on plant height and
flower number in bumblebees over several generations while hoverflies imposed no selection
on these traits. In terms of evolutionary response we observed in bumblebee-visited plants an
increase in plant height and flower number after 5 generations. Additionally the reproductive
success of the plants differed significantly; bumblebee pollinated plants had a significantly
higher reproductive success than hoverfly pollinated plants. After 5 generations only hoverfly
pollinated plants showed a significant increase in reproductive success indicating adaptations
to this type of pollinators have evolved. This study thus shows for the first time the effects of
changing pollinators on plant evolution in an experimental approach over several generations.
18.8.2014 15:50–16:05
talk
37
SIP 15
POLLINATION
‘Toxic nectar’: harmful and beneficial effects of nicotine
on an important pollinator, the African honey bee
Köhler A 1,2, Pirk CWW 1, Nicolson SW 1
1 Dept. Zoology & Entomology, University of Pretoria, Pretoria 0002, South Africa
2 Present address: Lab. Fundamental and Applied Research in Chemical Ecology, University
of Neuchâtel, 2000 Neuchâtel, Switzerland
[email protected]
The presence of secondary metabolites (SM) in floral nectar seems paradoxical, in view of the
reward function of nectar, and little is known of their role in mediating interactions between
plants and their pollinators. Nectar SM may have multiple ecological functions, including
protection from microbial infection and unwanted flower visitors. Nicotine, best known from
the Solanaceae, is highly toxic to most herbivores, and its presence in nectar may have adverse
effects on pollinators. We examined the effects of nectar nicotine on honey bee (Apis mellifera
scutellata) foraging choices and longevity, using preference tests on free-flying bees and feeding
assays on caged worker groups in the laboratory. We showed that the dose-dependent deterrent
effect of nicotine is stronger in more dilute nectars. Nicotine may act as partial repellent that
keeps pollinators moving between plants and ensures outcrossing. Plants with nectar SM may be
more attractive to pollinators when flowering in isolation or secreting concentrated nectar, and
pollinators can avoid intoxication by foraging on multiple nectar sources. We found that caged
honey bee groups tolerate naturally occurring nectar nicotine concentrations (≤30 µM) in 0.63 M
sucrose, but survival decreased on high dietary nicotine (300 µM). Honey bees injected with
E. coli lipopolysaccharides showed even lower survival when fed nicotine, suggesting that the
combined effect of immune challenges and dietary toxins can be detrimental to colony fitness.
However, antimicrobial properties of this alkaloid may also be beneficial to honey bees: weak
workers (possibly affected by a bacterial brood disease) and workers infested with parasitic
Varroa destructor mites (known to transmit viral diseases) demonstrated prolonged survival on
nicotine diets. A possible exploitation of nectar SM for therapeutic purposes may help to explain
the role of these compounds in mediating plant-pollinator interactions.
38
talk
18.8.2014 16:05–16:20
SIP 15
POLLINATION
No pollinator is an island – the role of context and previous
experience in floral reproductive isolation
Bischoff M 1,2,3, Campbell DR 2,3, Jϋrgens A 4, Raguso RA 1
1 Department of Neurobiology & Behavior, Cornell University, Ithaca, NY 14853 USA
2 Department of Ecology & Evolutionary Biology, University of California, Irvine, CA 92697 USA
3 Rocky Mountain Biological Laboratory, Crested Butte, CO 81224 USA
4 School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg 3209, South Africa
[email protected]
The remarkable diversity of flowers in the angiosperms is widely recognised to arise from biotic
pollination, although interactions with antagonists or abiotic stress factors may also shape floral
evolution. Pollinator behaviour is thought to be among the key factors mediating reproductive
isolation and thus speciation in flowering plants. Pollinators respond to floral features such
as flower morphology, colour and scent. To date, the role of floral scent mediating pollinator
behaviour in the wild has rarely been investigated. Moreover, very little is known on the
priming effect of previous experience with flowers during foraging and the role of context in the
presentation of multimodal floral signals to pollinators.
We carried out both field experiments with free-flying, wild hawkmoths and flight cage
experiments with naïve, lab-reared hawkmoths of the species Hyles lineata that visit flowers
of two species of Ipomopsis in the Rocky Mountains, USA. We investigated attraction to and
probing of flowers in response to the hawkmoth attractant indole, a common floral volatile
emitted by I. tenuituba but not its close relative I. aggregata. This difference in floral bouquet
is consistent with other differences between the species, e.g. I. tenuituba has narrower pale pink
flowers, whereas I. aggregata flowers are wider and vividly red. These traits are often associated
with hawkmoth and hummingbird pollination, respectively. The effect of indole was tested both
alone and in combination with floral colour differences. Our results show that indole attracts
wild hawkmoths to Ipomopsis flowers. However, it does not significantly influence the rate at
which those attracted moths probe flowers. In contrast, white flower colour did not suffice to
attract hawkmoths in the field, yet more of the attracted moths probed flowers. Thus, both scent
(indole) and high visual contrast (white colour), in that order, are required for H. lineata to find
and feed from I. tenuituba flowers at dusk. Lab experiments with naïve hawkmoths revealed
that preference for indole-scented flowers is innate. However, prior experience with I. tenuituba
flowers could overcome initial rejection of I. aggregata flowers in the lab. In the wild, preference
based on scent and colour broke down in the presence of a concentrated indole plume enveloping
flowers of both species in mixed arrays. The responses of foraging H. lineata moths were contextdependent both in lab and field settings.
Our findings contribute to explain geographical variation in the hybridisation rate of the
two species of Ipomopsis, revealing an intricate network of factors governing pollinator foraging
and thus pollinator-mediated reproductive isolation. The formation of hybrid bridges in other
hawkmoth-pollinated plants may potentially follow similar patterns. The significance of prior
foraging experience indicates considerable plasticity of pollinator behaviour, thus highlighting
the importance of individual pollinator choice.
18.8.2014 16:20–16:35
talk
39
SIP 15
POLLINATION
Sexual deception or rendezvous attraction? Deconstructing the
floral mimicry of Cephalanthera rubra (Orchidaceae)
Milet-Pinheiro P 1, Dötterl S 2, Ayasse M 1
1 Institute of Experimental Ecology, University of Ulm, Germany
2 Department of Organismic Biology, University of Salzburg, Austria
[email protected]
The rewardless flowers of the European orchid Cephalanthera rubra are believed to mimic
Campanula flowers and thereby attract Campanula-pollen specialist bees of Chelostoma rapunculi
as pollinator. Since, however, only males of this bee are described to visit flowers of Ce. rubra in
the nature, sexual deception or rendezvous attraction are possible alternatives. Here, we aimed to
clarify the pollination mechanism involved in this system by using a multidisciplinary approach
that included bioassays, colorimetric measurement of flowers, chemical and electrophysiological
analyses. The bioassays performed in an experimental flight cage evidenced that 1) pentane
extracts of Ch. rapunculi virgin females but not of Ce. rubra flowers elicit more copulation
attempts by males than pentane controls, 2) olfactory and visual floral cues of Ca. trachelium
and Ce. rubra are equally attractive to flower-naive male and female bees of Ch. rapunculi
when tested against each other, and 3) both male and female flower-naive bees of Ch. rapunculi
visit and pollinate flowers of Ce. rubra. Color measurements indicate a high similarity among
flowers of Campanula (14 spp.) and Ce. rubra. A comparative analysis did not reveal chemical
similarity between extracts of Ch. rapunculi virgin females and those of Ce. rubra flowers.
Furthermore, we found several compounds in females extracts triggering antennal responses in
Ch. rapunculi males, but did not in flower extracts. Finally, the analyses of headspace samples
of virgin females revealed no volatile compound, whereas those of Ce. rubra flowers revealed
a scent bouquet composed of eight compounds, including (E)-conophthorin. This compound,
rarely found as floral scent constituent but quite common among Campanula species, is known
to be involved (together with other spiroacetals) in recognition of Campanula host flowers by
Ch. rapunculi. Our results comprehensively show that Ce. rubra is not pollinated by sexual
deception, and that flowers mimic visual and olfactory floral cues of Campanula to attract
pollinators by means of rendezvous. However, we also found some evidence of food deception
in this system, since females of Ch. rapunculi also pollinate flowers of Ce. rubra in the flight
cage. Future investigations are necessary to clarify why only males have been observed visiting
flowers of Ce. rubra in the nature.
Key words: floral mimicry, olfactory cues, oligolectic bees, pollination, visual cues
40
talk
18.8.2014 16:35–16:50
SIP 15
POLLINATION
Lord of the dance:
chemical mediators and specific pollination interactions
Hossaert-McKey M, Schatz B, Kjellberg F, Proffit M
CEFE UMR 5175, CNRS, University of Montpellier, University Paul-Valery, EPHE, 1919 route
de Mende, 34293 Montpellier, France
[email protected]
Chemical mediation plays a major role in mediating interactions between plant and animal partners
in specific pollination systems. Thanks to quantitative and qualitative variations in volatile
organic compounds, the complexity and diversity of floral scents offer a virtually infinite number
of combinations. These olfactory signals are crucial cues for maintaining the high specificity
of partner encounter in many interactions. First, unique combinations of chemical compounds
emitted by flowers provide the templates for fine-tuned recognition, which is required for the
specificity of interactions and can even lead to odor-mediated reproductive isolation. Second,
fine-tuned timing of interactions is also required, and this aspect of chemical mediation has
been much less studied. Success of both plant and animal partners requires tight coordination
and synchronization between the plant’s phenology and the visits of pollinators. Changes in
the chemical composition of compounds emitted by the plant can advertise the precise stage of
receptivity—often associated with rewards—signaling thereby the optimal time for visits of the
specific pollinator.
We will examine chemical mediation in different pollination systems, ranging from
complex signals to very specific ‘private channels’. We will document the proximate mechanisms
in chemical mediation of specific plant-pollinator interactions, and show how they are coupled to
the selective forces driving these interactions.
18.8.2014 17:20–17:40
invited talk
41
SIP 15
POLLINATION
Pollen secondary metabolites influence bee-flower relationships
Trunz V, Glauser G, Lucchetti M, Praz C
Université de Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel
[email protected]
The evolutionary significance of plant secondary metabolites in pollen and nectar remains
unclear. Their presence in these floral rewards may be a consequence of their accumulation
in other plant tissues; alternatively, their presence could be adaptive and may mediate plantpollinator interactions. While nectar secondary metabolites have received much attention, little
research has been done on pollen secondary compounds. Unlike nectar, pollen has a dual role
as a vector of gametes and a reward to pollinators. In this study, we surveyed the presence of
pyrrolizidine alkaloids (PAs) in the floral parts within the plant family Boraginaceae. We asked
whether PA concentrations in the pollen were correlated with the presence of PAs in the corolla.
In addition, we tested the effect of pollen PAs on the fitness and development of bees, which
are the main pollinators of Boraginaceae. Of the 17 species of Boraginaceae surveyed, nine
exhibited low to high concentrations of PAs in the pollen, while the other eight had no PAs in
the pollen. Pollen PA concentration was not linked with the PA concentration in the corolla. The
pollen of one species, Echium vulgare, contained three different alkaloids in high concentrations
and in a distinct ratio compared to other plant parts. Plants entirely relying on pollen-collecting
bees for their pollination (e.g. species of Onosma) tended to have low PAs in the pollen, whereas
plants visited by a diverse array of nectar-foraging insects (e.g. Echium) often exhibited high PA
concentrations in the pollen. To test the effect of PAs on the fitness of pollinators, we isolated the
three PAs present in the pollen of Echium vulgare. We performed bioassays with the larvae of
three species of solitary bees, Osmia cornuta, O. bicornis and Chelostoma rapunculi. Previous
studies have shown that O. bicornis and C. rapunculi could not develop on pure Echium pollen
provisions, possibly due to high PA concentrations. We supplemented the natural pollen provisions
of each species with the same concentrations of PAs found in pure provisions of Echium vulgare.
Survival did not differ between controls and PAs-supplemented diets in O. cornuta. In contrast,
survival was significantly lower in the PAs-supplemented provisions than in the control in
O. bicornis and C. rapunculi. Taken together, these results strongly suggest that the presence of
PAs in pollen does not merely reflect PA concentrations in other floral tissues but is most likely
an adaptive trait. Moreover, pollen PAs affect the survival of solitary bee larvae and thus may
play an important role in mediating bee-flower relationships.
42
talk
18.8.2014 17:40–17:55
SIP 15
POLLINATION
Nitrogenous aldoximes produced by a night-blooming flower
influence hawkmoth feeding behavior
Summers HE 1, Broadhead GT 2, Raguso RA 2
1 Institute of Plant Sciences, University of Bern, 21 Altenbergrain, 3013 Bern
2 Department of Neurobiology and Behavior, Mudd Hall 215 Tower Rd, Cornell University,
Ithaca, NY 14853
[email protected]
The Yellow Evening Primrose, Oenothera flava (Onagraceae), is a night blooming, hawkmoth
pollinated angiosperm common throughout western North America. Each flower is open for a
single evening and wilts by the following morning. The showier of the two extant subspecies,
O. flava ssp. taraxacoides, has the longest floral tube in North America (up to 25 cm) and a broad
corolla that emits copious amounts of volatile compounds within the first 30-90 minutes postanthesis. The more widespread subspecies, O. flava ssp. flava, produces shorter flowers (~6 cm),
with smaller, weakly scented corollas.
The floral bouquets of both subspecies are dominated by the amino acid derivatives
2-methylbutylaldoxime (2-MBA) and 3-methylbutylaldoxime (3-MBA). These compounds
are most well studied in other species as early intermediates formed during biosynthesis of
cyanogenic glycosides and glucosinolates. However, 2-MBA and 3-MBA are also found in the
floral headspace of a number of unrelated, hawkmoth-pollinated night-blooming angiosperms
including members of Orchidaceae (orchids), Caprifoliaceae (honeysuckle) and Zingiberaceae
(wild ginger). Both this distribution in unrelated taxa and the timing of aldoxime production in
the petals of O. flava, suggests a role for in these compounds in pollination.
We tested whether these compounds influence visitation by the hawkmoth pollinator
Hyles lineata to artificial flowers in a still flight chamber. The application of synthetic 3-MBA
to artificial flowers increased Hyles feeding responses, while application of 2-MBA or a 1:1
mixture of the two aldoximes did not. Additionally, Hyles feeding responses to masked, scented
flowers and to unscented artificial flowers demonstrated a synergistic interaction between
visual and olfactory signals. These experiments demonstrate the importance of this aldoxime in
elicitation of hawkmoth feeding and open up promising new research directions in the evolution
of mechanisms of plant/pollinator interactions.
18.8.2014 17:55–18:10
talk
43
SIP 15
POLLINATION
Integrating plant-pollinator and plant-herbivore interactions
Lucas-Barbosa D
Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands
[email protected]
Plants are under natural selection to maximize fitness, and most flowering plants rely on insect
pollinators for reproduction. However, to be able to reproduce plants need to survive the battle
against insect herbivores. Plants must, therefore, balance the investments in defences against
herbivores with investments in growth/reproduction, and these aspects have been expected to
trade-off. A trade-off between plant defence and reproduction is expected when: 1) resources
that are allocated to reproduction cannot be allocated to defence and vice versa; 2) the attraction
of carnivorous insects - so called indirect defence - can conflict with attraction of pollinators
that mediate reproduction. However, despite this potential trade-off plant reproduction and plant
defence have typically been investigated in isolation. In fact, induced plant defences cannot
be fully understood when disconnected from plant-pollinator interactions because selection on
defensive traits against herbivores implies a plant fitness benefit. Here, I explore the fitness
consequences of induced responses of plants to herbivores in the context of plant-mediated
interactions with carnivorous and pollinating insects.
Upon exposure to herbivores, black mustard plants (Brassica nigra) reallocate resources
and the induced production of plant secondary metabolites into reproductive tissues. Mustard
plants speed up reproduction in response to butterfly egg deposition, and compensate for
herbivory in terms of seed production. During this talk, the underlying mechanisms will be
addressed, including interactions with day and night pollinators and selfing upon induction by
herbivores. The main message of this study is that interactions with both pollinators and the
natural enemies of herbivores are essential in determining plant fitness.
44
talk
18.8.2014 18:10–18:25
SIP 15
POLLINATION
Herbivore-pollinator interactions in wild Solanum
Halitschke R, Kessler A
Ecology & Evolutionary Biology, Cornell University, Corson Hall, Ithaca, NY 14853, USA
[email protected]
Recently the interactions between herbivory and pollination and the associated plant metabolic
processes have received increased attention. Studies have shown ecological costs of induced
defences to herbivory mediated by a pollination limitation in damaged plants1. Additionally,
plant mating strategy has been shown to have dramatic consequences for the expression of
defensive traits, and herbivory increases the fitness costs due to inbreeding depression2. Together
these results suggest that plant mating systems and associated floral characters, and defense
strategy, including constitutive and inducible production of defensive secondary metabolites, are
not evolving independently.
We characterize the pattern of induced responses to herbivory and floral traits involved
in pollinator attraction in wild Solanum (Solanaceae) species and compare the observed
pattern in the context of mating system evolution. Self-compatibility has evolved several times
independently in the genus Solanum and we will discuss results of our comparative approach as
well as manipulative field experiments to address the biochemical mechanisms and ecological
function underlying the observed pattern.
1 Kessler A, Halitschke R, Poveda K. 2011. Herbivore-mediated pollinator limitation: negative impacts of induced
volatiles on plant-pollinator interactions. Ecology 92:1769-1780.
2 Campbell SA, Thaler JS, Kessler A. 2013. Plant chemistry underlies herbivore-mediated inbreeding depression
in nature. Ecology Letters 16:252-260.
18.8.2014 18:25–18:40
talk
45
Belowground Interactions
BELOWGROUND
INTERACTIONS
SIP 15
Plant-mediated interactions between insects across abovebelowground domains: ecology, mechanisms and utilization
Soler R
Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
[email protected]
Ecologists have a long-standing interest in understanding the assembly and functioning of
terrestrial communities, and the discovery of phytochemicals mediating complex interactions
between plants and insects has played a central role in this quest. Plant-insect interactions were
initially studied on relatively simplified aboveground systems of individual plant-herbivoreparasitoid species. The field is rapidly moving, and now multiple root- and shoot-associated
organisms have entered the picture because they were shown to induce changes in plant chemistry
and defence signalling and so affect plant-herbivore-parasitoid trophic chains. I will discuss a
number of case studies where soil-dwelling organisms are revealed as important hidden players in
aboveground systems, elucidating exciting interactions that span several trophic levels. I would
finally like to brain storm about opportunities for this type of ecological work to make an impact
on applied areas in agriculture. The vast field of plant-insect research is not only of fundamental
interest but also of socio-economic importance for the design and development of pest control
practices, with great possibilities of spill over into sustainable plant production systems.
46
invited talk
19.8.2014 9:00–9:20
SIP 15
BELOWGROUND INTERACTIONS
The missing half: can we predict how climate change will affect
belowground insect-plant interactions?
Johnson SN
Hawkesbury Institute for the Environment, University of Western Sydney, Australia
[email protected]
Understanding how global climate change affects insect-plant interactions has become a major
focus of research for scientists around the world. This has been driven by a range of topical
issues, ranging from conservation objectives to achieving food security1. Predicted increases
in the concentration of atmospheric CO2 is a major driver of climate change, and numerous
studies catalogue how elevated atmospheric CO2 concentrations ([eCO2]) modifies insect-plant
interactions2. There is one remarkable omission in this growing field however; belowground insectplant interactions. Only a handful of studies have examined how [eCO2] affects belowground
insect-plant interactions3, despite >50% of net primary productivity being allocated to the roots
in most plants. Moreover, belowground insect-plant interactions are pivotal in many ecosystems,
with root herbivores being influential drivers of other trophic groups4, 5. Here I present several
examples of how [eCO2] shape belowground herbivore interactions, significantly moderating
the overall response of plants to [eCO2]. In particular, many studies show that eucalypts show
consistent responses to [eCO2] (increases in biomass, specific leaf mass and C:N ratio). When
subject to brief periods of root herbivory, however, all of these effects were either negated or
reversed. This potentially occurred because root herbivory impaired root function and reduced
photosynthetic rates, so observed responses of eucalypts to [eCO2] no longer took place. In a
subsequent study, we found that [eCO2] caused an increase in C:N ratios in the roots of a C3
grass, but not in a C4 grass. This change triggered compensatory feeding by root herbivores on
the C3 grass, resulting in these herbivores consuming 118% more root tissue and making the C3
grass particularly vulnerable to attack. I conclude by identifying key differences and similarities
between how above- and belowground insect herbivores will be affected by atmospheric and
climatic change.
1 Gregory PJ, Johnson SN, Newton AC, Ingram JSI 2009. Integrating pests and pathogens into the climate change/
food security debate. Journal of Experimental Botany 60: 2827–38.
2 Robinson EA, Ryan GD, Newman JA 2012. A meta-analytical review of the effects of elevated CO2 on plantarthropod interactions highlights the importance of interacting environmental and biological variables. New
Phytologist 194: 321–36.
3 Staley JT, Johnson SN 2008. Climate change impacts on root herbivores. Root feeders: an ecosystem perspective.
Wallingford, UK: CABI: 192–213.
4 Johnson SN, Mitchell C, Thompson J, Karley AJ 2013. Downstairs drivers - root herbivores shape communities
of aboveground herbivores and natural enemies via plant nutrients. Journal of Animal Ecology 82: 1021–30.
5 Johnson SN, Clark KE, Hartley SE, Jones TH, McKenzie SW, Koricheva J 2012. Aboveground-belowground
herbivore interactions: a meta-analysis. Ecology 93: 2208–15.
19.8.2014 9:20–9:35
talk
47
BELOWGROUND INTERACTIONS
SIP 15
Induced fitness cost:
a consequence of root indirect defences in western corn
rootworm population showing resistance to Bt-toxins
Hiltpold I 1, Hibbard BE 2
1 Division of Plant Sciences, University of Missouri, 205 Curtis Hall, Columbia, MO 65211,
USA
2 USDA-ARS, Plant-Genetic Unit, University of Missouri, 205 Curtis Hall, Columbia, MO
65211, USA
[email protected]
Resistance management has become a pivotal component of long-term insect pest control.
The commercialization of genetically engineered plants producing Bt-toxins resulted in high
selective pressure on many insect pests. Products targeting the western corn rootworm (WCR)
Diabrotica virgifera virgifera, a major root pest on maize, produce levels Bt-toxins which cannot
be considered high dose and Bt-resistant WCR have evolved in the field, in part, due to the
lack of a high dose. As Bt-maize plants attacked by resistant WCR suffer more damage, it is
likely that inducible plant defenses are elicited to a greater extent in these roots, resulting in the
emission of volatiles that recruit entomopathogenic nematodes. These nematodes quickly kill
the insect pest and effectively reduce root damage when used in combination with appropriate
maize cultivars. In the laboratory, Bt-roots of particular cultivars induced with Bt-resistant WCR
larvae recruited entomopathogenic nematodes. In the field, significantly less damage by Btresitant WCR was measured on those plants than on Bt-cultivars emitting an inaccurate blend or
inappropriate doses of volatiles. This induced fitness cost to Bt-resistance offers additional and
sustainable approaches to resistance management plans. These results underline the importance
of understanding root-mediated interactions and their potential in the development of sustainable
agroecosystems.
48
talk
19.8.2014 9:35–9:50
SIP 15
BELOWGROUND INTERACTIONS
Plant secondary metabolite hijacking
by a specialist root herbivore
Robert CAM
Biotic Interaction Section, Institute of Plant Science, University of Bern, Switzerland
[email protected]
Secondary metabolites are essential for plant resistance against herbivores. Yet, little is known
about their influence on herbivore foraging patterns and their impact on below ground feeders.
To address this gap of knowledge, we explored the role of the major root secondary metabolites
of maize, 1,3-benzoxazin-4-ones (BXs) in the interaction between the plant and the larvae of
the specialized root feeder Diabrotica virgifera virgifera. Using BX-deficient indole mutants
and chemical complementation, we found that D. virgifera is able to tolerate high levels of
BXs in its diet. Furthermore, we discovered that the root-feeder uses differences in BX blends
between different root types to locate the most nutritious tissues1. As a result, BX-guided
foraging increases D. v. virgifera fitness and leads to crown root pruning, a typical D. virgifera
associated damage phenotype in the field. To identify which BXs are used by D. virgifera to
forage optimally, we conducted behavioral assays with different BX mutants that are deficient in
a subset of root BXs. These experiments demonstrate that only a few specific BXs are necessary
and sufficient for D. virgifera to orient itself within the root system. As a next step, we are
now studying the mechanisms that allow D. virgifera to tolerate BXs. Preliminary experiments
suggest that D. virgifera stabilizes BXs through re-glycosilation, similar to what has been
described for leaf-feeding insects2. The identification of the corresponding D. virgifera glycosyl
transferases through RNAi-mediated knockdown is currently in process and will allow us to
investigate whether the insect’s capacity to detoxify BXs also determines its feeding preference
via a digestive behavioral feedback loop.
1 Robert CAM., Veyrat N, Glauser G, Marti G, Doyen GR, Villard N, Gaillard MDP, Köllner TG, Giron D, Body
M, Babst BA, Ferrieri RA, Turlings TCJ, Erb M 2012. A specialist root herbivore exploits defensive metabolites
to locate nutritious tissues. Ecology Letters 15(1): 55-64.
2 Glauser G, Marti G, Villard N, Doyen GA, Wolfender JL, Turlings TCJ, Erb M 2011. Induction and detoxification
of maize 1,4-benzoxazin-3-ones by insect herbivores. The Plant Journal 68(5): 901-911.
19.8.2014 9:50–10:10
invited talk
49
BELOWGROUND INTERACTIONS
SIP 15
Root herbivory drives the evolution of defensive latex secondary
metabolites in nature
Huber M 1, Reichelt M 1, Triebwasser-Freese D 1,2, Schulze-Gronover C 3,
Gershenzon J 1, Erb M 2
1 Department of Biochemistry, Max-Planck Institute for Chemical Ecology, Hans-Knöll
Strasse 8, D-07745 Jena
2 Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013 Bern
3 Frauenhofer Institute for Molecular Biology and Applied Ecology, Schlossplatz 8, D-48143
Münster
[email protected]
Roots produce an enormous diversity of secondary compounds with potential activity against
below ground herbivores. Yet, evidence that root feeding insects can drive the evolution of
defensive metabolites in nature is lacking. We studied the interaction of the common dandelion
(Taraxacum sect. Ruderalia) and its native root herbivore, the white grub Melolontha melolontha,
by i) measuring the abundance of defensive secondary metabolites in dandelion populations under
different root herbivore pressure in nature and ii) testing the observed patterns under controlled
conditions in the glasshouse and a common garden. We found that taraxinic acid glucoside
(TA-G), a sesquiterpene lactone glucoside, is highly enriched in the dandelion latex. Natural
dandelion populations growing under high M. melolontha density in the field produced more
TA-G than local and regional controls under low root herbivore pressure. The concentration of
TA-G was positively correlated to plant performance and negatively correlated with larval growth
under controlled conditions. Transcriptome analyses have led to the identification of candidate
genes that code for a key step in the production of TA-G, and we are currently producing RNA
interference (RNAi) lines with reduced TA-G levels to confirm its function as a root herbivore
resistance factor. Taken together, our results provide first evidence that a native root herbivore
has the potential to drive the evolution of defensive metabolites in nature.
50
talk
19.8.2014 10:10–10:25
SIP 15
BELOWGROUND INTERACTIONS
Aboveground endophyte affects root volatile emission
and host plant selection of a belowground insect
Rostás M 1, Cripps MG 2,3, Silcock P 4
1 Bio-Protection Research Centre, Lincoln University, Lincoln 7647, New Zealand
2 Department of Agriculture and Life Science, Lincoln University, Lincoln 7647, New Zealand
3 AgResearch Ltd, Private Bag 4749, Christchurch 8140, New Zealand
4 Department of Food Science, Otago University, Dunedin, New Zealand
[email protected]
Plants emit specific blends of volatile organic compounds (VOCs) into the environment that
serve as multitrophic, multifunctional signals. Fungi colonizing aboveground or belowground
plant structures are known to modify such VOC patterns and may thus alter the information
content for aboveground insects. Whether aboveground microbes can affect the emission of root
volatiles that play a role in the foraging decisions of belowground herbivores remains unresolved.
The endophytic fungus Neotyphodium uncinatum colonizes the aerial parts of the grass
hybrid Festuca pratensis x Lolium perenne and is responsible for the presence of insect-toxic loline
alkaloids in the roots. We investigated whether N. uncinatum affects the host location behaviour
of the root feeding beetle Costelytra zealandica by carrying out belowground olfactometer
experiments to assess the gustatory and olfactory choices of the larvae. Root volatiles of infected
and uninfected plants were analysed by gas chromatography-mass spectrometry and protontransfer-reaction mass spectrometry.
Grubs of C. zealandica were more attracted by roots from uninfected than from endophyteharbouring grasses. Likewise, larvae showed a clear feeding preference for uninfected plants.
This correlated with lower root VOC production in endophyte-infected grasses but higher carbon
dioxide emission.
Our results demonstrate that soil insects can use root volatiles to assess host plant quality
and conclude that endophytic fungi colonizing aboveground parts may influence the behaviour
of belowground herbivores.
19.8.2014 10:55–11:10
talk
51
BELOWGROUND INTERACTIONS
SIP 15
Inoculation of tomato plants with rhizobacteria enhances the
performance of the phloem-feeding insect Bemisia tabaci
Morin S 1, Shavit R 1,2, Ofek-Lalzar M 3, Burdman S 2
1 Department of Entomology, the Hebrew University of Jerusalem, P.O. Box 12, Rehovot
76100, Israel
2 Department of Plant Pathology and Microbiology, the Hebrew University of Jerusalem, P.O.
Box 12, Rehovot 76100, Israel
3 Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization of
Israel, P.O. Box 6, Bet Dagan 50250, Israel
[email protected]
In their natural environment, plants experience multiple biotic interactions and respond to this
complexity in an integrated manner. Therefore, plant responses to herbivory are flexible and
depend on the context and complexity in which they occur. For example, plant growth promoting
rizhobacteria (PGPR) can enhance plant growth and induce resistance against microbial pathogens
and herbivorous insects by a phenomenon termed induced systemic resistance (ISR).
In the present study, we investigated the effect of tomato (Solanum lycopersicum) preinoculation with the PGPR Pseudomonas fluorescens WCS417r, on the performance of the
generalist phloem-feeding insect Bemisia tabaci. Based on the ability of P. fluorescens WCS417r
to prime for ISR against generalists chewing insects and necrotrophic pathogens, we hypothesized
that pre-inoculated plants will strongly resist B. tabaci infestation. In contrast, we discovered
that the pre-inoculation treatment increased the tomato plant suitability for B. tabaci which was
emphasized both by faster developmental rate and higher survivability of nymph stages on preinoculated plants.
Our molecular and chemical analyses suggested that the phenomenon is likely to be related
to: (I) the ability of the bacteria to reduce the activity of the plant induced defense systems;
(II) a possible manipulation by P. fluorescens of the plant quality (in terms of suitability for
B. tabaci) through an indirect effect on the rhizosphere bacterial community. The contribution of
our study to the pattern proposed for other belowground rhizobacteria and mycorrhizal fungi and
aboveground generalist phloem-feeders will be discussed.
52
talk
19.8.2014 11:10–11:25
SIP 15
Plant
Domestication and&Application
PLANT
DOMESTICATION
APPLICATION
Crop domestication and naturally selected species interactions
Chen YH 1, Gols R 2, Benrey B 3
1 Department of Plant and Soil Sciences, University of Vermont, Burlington, VT, USA
2 Laboratory of Entomology, Wageningen University, 6708PB Wageningen, The Netherlands
3 Institute of Biology, Laboratory of Evolutionary Entomology, Université de Neuchâtel,
Switzerland
[email protected]
Crop domestication is the process of artificially selecting plants to increase their suitability to
human tastes and cultivated growing conditions. We review the increasing evidence that crop
domestication can profoundly alter interactions among plants, herbivores, and their natural
enemies1. We stress that the effects of crop domestication will be most detectable for species
interactions in the geographical ranges where these crops originate, where they are sympatric with
the ancestral plant and share the associated arthropod community. In general, crop domestication
has consistently reduced chemical resistance against herbivorous insects, increasing herbivore
and natural enemy performance on crop plants. We also review possible responses by which
insect herbivores and natural enemies may interact with the artificially-increased variation caused
by crop domestication, such responses may help structure general expectations on how specific
traits may influence species interactions. Overall, we find that more studies are needed in order
to predict how selection on morphological and resistance traits during domestication may affect
species interactions across multiple scales in agroecosystems and natural ecosystems.
1 Chen YH, Gols R, Benrey B. In Review. Crop domestication and naturally selected species interactions. Annual
Review of Entomology.
19.8.2014 11:25–11:45
invited talk
53
PLANT DOMESTICATION & APPLICATION
SIP 15
Host plant resistance to Western flower thrips
in cultivated, biofortified and wild carrots
Leiss KA 1, Rahkmawati R 1,2, Klinkhamer PGL 1
1 Plant Ecology and Phytochemistry, Institute of Biology, Leiden University, The Netherlands
2 Sebelas Maret University, Surakarta, Indonesia
[email protected]
Domestication of plants and selection for agronomic traits may reduce plant secondary defence
metabolites relative to their ancestors. Carrot (Daucus carota L.) is an economically important
vegetable. Recently, carrot developed as a functional food with additional health-promoting
functions. Biofortified carrots contain increased concentrations of chlorogenic acid as an
antioxidant. Chlorogenic acid is involved in host plant resistance to Western Flower Thrips
(Frankliniella occidentalis), one of the key agri- and horticultural pests worldwide1. We, therefore,
investigated whether cultivated carrot is more vulnerable to herbivore attack compared to wild
carrots. We subjected a set of 14 biofortified, cultivated and wild carrots to thrips infestation.
We compared morphological traits and the metabolomic profiles of leaves of the three most
resistant and susceptible carrots using nuclear magnetic resonance spectroscopy (NMR)2. In
contrast to our expectation, wild carrots were not more resistant to thrips than cultivated ones.
Biofortified carrots were not resistant to thrips. Plant size, leaf area and number of leaf hairs did
not differ between resistant and susceptible carrots, while their leaf metabolomic profiles were
significantly different. The leaves of resistant carrots contained higher amounts of the flavanoid
luteolin, the phenylpropanoid sinapic acid and the amino acid β-alanine. The negative effect
of these compounds on thrips was confirmed using in-vitro bioassays. We then investigated
potential synergistic effects of these compounds on thrips mortality and oviposition using single
compounds as well as compound mixtures at a 1:1 ratio in a range of 6 to 150% of the plant
concentration. All single compounds and mixtures at 100 and 150% significantly increased
thrips mortality compared to the control. Compared to the single compounds the mixture of
sinapic acid and alanine at 150% resulted in a higher thrips mortality while the mixture of alanine
and luteoline at 100 and 150% resulted in a lower thrips mortality. Independent of mortality,
oviposition was significantly inhibited by all compounds at all concentrations. The mixture of all
three compounds at plant concentration caused the strongest effect. Our results demonstrate that
wild carrots do not seem to be necessary to improve herbivore resistance aboveground. Instead
the natural variation of metabolites present in cultivated carrots can be used. This is especially
promising in view of the candidate compounds we identified since they do not only confer a
negative effect on thrips but as antioxidants also play an important role in the improvement of
human health.
1 Leiss, KA, Maltese F, Choi YH, Verpoorte R, Klinkhamer PGL 2009. Identification of chlorogenic acid as a
resistance factor for thrips in chrysanthemum. Plant Physiology 150:1567-157.
2 Leiss KA, Cristofori G, van Steenis R, Verpoorte R, Klinkhamer PGL 2013. An eco-metabolomic study of host
plant resistance to Western flower thrips in cultivated, biofortified and wild carrots. Phytochemistry 93:63-70.
54
talk
19.8.2014 11:45–12:00
SIP 15
PLANT DOMESTICATION & APPLICATION
Contrasting effects of plant domestication on herbivore
interactions: The case of wild and cultivated lima beans
Shlichta JG, Cuny MAC, Glauser G, Hernández-Cumplido J, Benrey B
Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
[email protected]
We examined the effects of domestication of lima bean (Phaseolus lunatus) on its chemical
defenses against leaf- and seed-feeding insects. Based on previous studies with other Phaseolus
species and existing evidence for a decrease in secondary defense metabolites in cultivated
plants, we hypothesized that herbivores will prefer and perform better on cultivated lima
bean varieties than on their wild counterparts. Further, we predicted that in the field cultivated
varieties suffer greater damage due to lower concentrations of cyanogenic glycosides (CNGs).
To test these hypotheses we exposed plants and seeds from three cultivated varieties and three
wild populations of P. lunatus to the leaf herbivore, Spodoptera exigua, and the seed predator,
Zabrotes subfasciatus. The objectives were to 1) determine the concentrations of CNGs in
cultivated varieties and wild populations, 2) determine the preference and performance of both
herbivores when exposed to leaves and seeds from wild and cultivated plants and 3) to determine
whether cultivated varieties suffer greater damage in the field than wild plants.
Concentrations of CNGs were highly variable in the leaves, but no significant differences
were found between wild and cultivated plants. In contrast, seeds from the cultivated plants
had significantly lower concentrations of CNGs. Seeds from wild populations had up to 20
times the CNG concentration compared to seeds from the wild populations. The preference
and performance of larvae of S. exigua was not correlated with plant domestication status, or
with concentrations of CNGs. However, beetles laid more eggs and had higher performance
on cultivated varieties than seeds from wild populations. The results from our field studies
showed no significant difference on leaf and seed damage between cultivated varieties and wild
populations. Our results indicate that domestication of P. lunatus has altered the concentration of
CNGs only in the seeds and not in the leaves. This results on differential effects on the herbivores
that attack these two plant structures. The contrasting effect of domestication on different plant
tissues can be explained by the fact that bean plants have been selected for human consumption
of the seeds.
19.8.2014 12:00–12:15
talk
55
PLANT DOMESTICATION & APPLICATION
SIP 15
The call of the wild: tracking an indirect defence trait in maize
Bruce TJA 1, Pickett JA 1, Odeny DA 2, Paliwal R 2, Mutyambai DM 3, Tamiru A 3,
Midega CAO 3, Khan ZR 3, Buckler E 4
1 Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
2 ICRISAT, P.O. Box 39063, Nairobi, Kenya
3 icipe, P.O. Box 30, Mbita, Kenya
4 Cornell University, Ithaca, NY 14853, USA
[email protected]
Our cultivated crop plants were domesticated from wild ancestor species which had evolved
adaptations that allowed them to survive in their natural habitats where they were exposed to
attacking organisms. These plants were then selected for yield and quality by humans over
thousands of years and in recent decades plant breeding trials have usually been conducted in
the background of a robust pesticide programme. High yielding varieties (HYVs) have been
developed but to obtain the high yield these elite varieties often require high levels of inputs.
On-farm yields are often lower and more variable than in breeding trials and for low input,
smallholder farms the ‘yield gap’ can be substantial. Part of this may be due to the vulnerability
of many HYVs to attack by pests when not protected by pesticides. Selection for yield and
quality in a pesticide treated background can lead to inadvertent loss of natural plant defence
traits.
We discovered that certain farmer selected varieties of maize have a valuable defence
trait that was not present in the initial sample of commercial hybrid maize we tested (1): They
release odours (herbivore induced plant volatiles, HIPVs) to attract natural enemies after the
stemborer herbivore lays her eggs on the plant. Both egg (Trichogramma bournieri) and larval
(Cotesia sesamiae) parasitoids are attracted to HIPVs such as (E)-4,8-Dimethyl-1,3,7-nonatriene
when Chilo partellus lays eggs on maize lines with the trait. The “SCPRID Smart Cereals”
project aims to develop molecular markers for genes underpinning this HIPV production to
improve resistance to stemborers. For this, we have grown many different lines of maize and
sorghum. Volatile profiles are compared between plants with and without stemborer pest eggs
and semiochemicals identified. Lines that show induction of semiochemicals after stemborer
oviposition are being tested in bioassays with stemborer parasitoids. Genome-wide association
studies will be used to detect allele variants associated with the trait. SNP molecular markers
associated with HIPV emission will be defined and used to screen germplasm. We have found
genotypic variation in the indirect plant defence trait: it is more prevalent in wild and landrace
maize lines than in elite hybrid maize lines. Certain improved maize lines with the trait have
now been identified and links between this phenotype and the genotype are being explored.
Identification of molecular markers will allow breeders to efficiently select and introgress this
indirect defence trait into improved lines of maize.
1 Tamiru A, Bruce TJA, Woodcock CM, Caulfield JC, Midega CAO, Ogol CKPO, Mayon P, Birkett MA, Pickett
JA, Khan ZR 2011. Maize landraces recruit egg and larval parasitoids in response to egg deposition by a herbivore.
Ecology Letters 14: 1075-1083.
56
invited talk
19.8.2014 15:30–15:50
SIP 15
PLANT DOMESTICATION & APPLICATION
Costs of extreme apple domestication and the value
of old cultivars under global climate change
Aluja M 1, Birke A 1, Ceymann M, Guillén L 1, Arrigoni E 2, Baumgartner D 2,
Pascacio-Villafán C 1, Samietz J 2
1 Instituto de Ecología, A.C., Apartado Postal 63, 91000 Xalapa, Veracruz, México
2 Agroscope Changins-Wädenswil ACW, Schloss 1, CH-8820 Wädenswil, Switzerland
[email protected]
Extreme apple domestication aimed at increasing human palatability, is well exemplified by
the cultivar ‘Golden Delicious’ in which selection processes, oversimplifying matters, resulted
in a tradeoff between low phenolic compound content and reduced resistance to insects and
pathogens.
We present expanded data and photographs related to a recently published study carried
out in Switzerland and México1, encompassing 18 apple cultivars significantly varying in
total content of phenolic compounds and also exhibiting variability in phenol type. We used
the Mexican Fruit Fly, Anastrepha ludens (Diptera: Tephritidae) as a model as it is a highly
polyphagous herbivorous insect currently expanding its geographical range as a result of global
climate change. In Mexico, it is slowly moving from tropical and subtropical lowlands to more
temperate regions in the highlands were apples are grown. In Switzerland and elsewhere in
European, Asian and North American apple-growing regions, it is a potentially invasive species
representing a severe menace to commercial and backyard apple orchards.
Our data conclusively show that old apple cultivars containing high levels of phenolic
compounds, both in Switzerland (e.g., ‘Grauer Hordapfel’, ‘Engishofer’) and Mexico (e.g., ‘San
Juanera’) are totally resistant to the attack by A. ludens, whereas extremely selected, highly
palatable cultivars such as ‘Golden’ or ‘Gala’, are severely attacked (i.e., up to 1000 A. ludens
pupae per 25 fruit were collected). Resistant cultivars that yielded a few pupae, caused significant
damage to both larvae and pupae (i.e., tissue burnings, malformations), inhibited complete
metamorphosis, and depressed the immune system of the herbivore.
We discuss our results in terms of environmental resilience under global climate change
scenarios and in light of their relevance with respect to protecting locally-grown apple cultivars
as sources of genes for breeding programs directed at restoring the ability of crops to defend
themselves against pests and diseases.
1 Aluja M, Birke A, Ceymann M, Guillén L, Arrigoni E, Baumgartner D, Pascacio-Villafán C, Samietz J 2014.
Agroecosystem resilience to an invasive insect species that could expand its geographical range in response to
global climate change. Agriculture, Ecosystems & Environment 186: 54-63.
19.8.2014 15:50–16:05
talk
57
PLANT DOMESTICATION & APPLICATION
SIP 15
High-throughput phenotyping of plant resistance to aphids
by automated video tracking
Kloth KJ 1,2,3, ten Broeke CJM 1, Thoen MPM 1,2,3, Hanhart-van den Brink M 1,
Wiegers GL 1,3, Krips OE 4, Noldus LPJJ 4, Dicke M 1, Jongsma MA 3
1 Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH Wageningen,
The Netherlands
2 Laboratory of Plant Physiology, Wageningen University, P.O. Box 658, 6700 AR
Wageningen, The Netherlands
3 Plant Research International, Wageningen University and Research Center, P.O. Box 619,
6700 AP Wageningen, The Netherlands
4 Noldus Information Technology bv, P.O. Box 268, 6700 AG Wageningen, The Netherlands
[email protected]
To study quantitative genetics of plant resistance to herbivorous insects, large plant panels need
to be screened to cover numerous polymorphisms. The amount of work, space, and plant material
involved in measuring plant resistance to insects is often a limiting factor. We have developed a
high-throughput platform for automated video tracking of aphid feeding behaviour. Timing and
duration of plant penetrations by the aphid’s piercing-sucking mouthparts were estimated by
body-movement analysis. Each aphid was introduced in an arena with a leaf disc and 20 arenas
were measured simultaneously. The platform was benchmarked against Electrical Penetration
Graph (EPG) recording, using susceptible and resistant plant lines of lettuce, Lactuca sativa,
and Arabidopsis thaliana and two aphid species, the generalist Myzus persicae and the specialist
aphid Nasonovia ribisnigri. Automated video tracking data confirmed the resistance effects that
were found with EPG recording in both lettuce and Arabidopsis. The use of leaf discs partially
attenuated the effects in video assays, but sufficiently replicated experiments delivered similar
outcomes as EPG. In view of reduced manual exercises and the possibility to screen up to 100
aphids simultaneously, this platform can serve as a first screening method in quantification of
plant resistance to piercing-sucking insects.
58
talk
19.8.2014 16:05–16:20
SIP 15
PlantVOLATILES
Volatiles
PLANT
Plant volatiles: getting a biochemical grasp on specificity
Schmelz EA, Huffaker A
University of California San Diego, Division of Biological Sciences, Section of Cell and
Developmental Biology, Muir Biology (M2B), 9500 Gilman Drive, La Jolla, CA 92093-0116
[email protected]
Over 20 years ago a series of behavioral and biochemical discoveries invigorated the mechanistic
investigation of plant-insect interactions. We now appreciate the wide spread existence of
herbivore-induced volatiles mediating the recruitment of natural enemies and the importance
of both jasmonate and peptide-based plant signals regulating these inducible defenses. Plant
responses to insect herbivory, by even neonates, is often amplified by the presence of specific
herbivore-associated elicitors that yield a mixture of anti-insect and antimicrobial defenses. The
presence or absence of insect elicitors can be empirically demonstrated to quantitatively mediate
the magnitude of volatiles emitted. However, significant questions remain. “How specific are
induced plant volatiles and other responses to herbivore and pathogen elicitation?”. Using
maize (Zea mays) as a model, we consider the transcriptional activation and pharmacological
activity of the Plant Elicitor Peptide family (ZmPeps) with regards to the activation of antipathogen and anti-insect defenses including volatile terpenes. Pathogen regulated ZmPROPEP
genes encode ZmPeps that pharmacologically produce weaker volatile emission than respective
ZmPROPEP transcripts (and predicted ZmPeps) which accumulate after application of insect
oral secretions. The analysis of different tissue types creates an additional layer of complexity
in the search for specific plant responses. In contrast to widely examined leaf responses, stem
herbivory by the European corn borer (Ostrinia nubilalis) results in a rapid and transient burst
of indole production followed by the accumulation of non-volatile diterpenoid phytoalexins,
termed kauralexins. Maize leaves also produce kauralexins during pathogen attack yet even
intense skeletonization by Lepidoptera fails to trigger this defense. Maize volatile terpenes and
acidic terpenoid phytoalexins represent useful biochemical markers to understand the basis of
plant tissue response specificity at the level of signaling.
19.8.2014 16:20–16:40
invited talk
59
SIP 15
PLANT VOLATILES
Plant volatile mediated interactions in food webs
up to the fourth trophic level
Zhu F 1, Weldegergis BT 1, Harvey JA 2, Dicke M 1, Poelman EH 1
1 Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands
2 Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW),
Wageningen, The Netherlands
[email protected]
Herbivore-induced plant volatile (HIPVs) mediated plant-insects interactions have been
extensively studied within three trophic levels during the last decade. However, food webs
generally include four or more trophic levels. Hyperparasitoids are parasitic wasps attacking
larvae and cocoons of primary parasitoids, which are considered as biological control agents.
Our previous study revealed that, similar to primary parasitoids, hyperparasitoids use HIPVs to
locate their parasitoid hosts. Since hyperparasitoids may find their parasitoid host developing
in different herbivores, the identity of herbivores is likely contributing to plant-hyperparasitoid
interactions. In the current study, we addressed the questions: 1) whether the hyperparasitoids
respond to HIPVs emitted by wild Brassica oleracea plants, 2) whether herbivore identity and
parasitism influence plant responses to herbivore infestation, and 3) whether hyperparasitoids
can discriminate HIPVs induced by different parasitized caterpillars and use them as foraging
cues under field conditions. We found that hyperparasitoids are able to respond to HIPVs
released by wild Brassica oleracea under both lab and field conditions. In addition, we observed
higher attraction of hyperparasitoids by HIPVs when plants were infested with parasitized
caterpillars. However, the herbivore identity did not affect the attractiveness of hyperparasitoids.
Our metabolomics and transcriptomics on herbivore induced plants revealed that both herbivore
identity and parasitism affect plant responses to herbivory. Therefore, our results suggest
parasitism plays a major role in HIPVs-mediated plant-hyperparasitoid interactions.
60
talk
19.8.2014 16:40–16:55
SIP 15
PLANT VOLATILES
The effect of ecological gradients on plant volatile emissions
Rasmann S
Ecology and Evolutionary Biology, University of California, Irvine, CA, USA
[email protected]
Syndromes of plant defences against herbivores are driven by the influence of community
responses, inherited functional traits, abiotic conditions, and the geographical and historical
contingencies affecting the community. Therefore, a better understanding of which factors affect
plant defences requires the use of more holistic approaches. I use elevation gradients as natural
experiments to test classic hypotheses of plant defences theories across and within species.
Recently acquired data is showing that lower direct and indirect levels of plant defences are
correlated with lower herbivore pressure and decreased predator abundance at high elevation.
Additionally, using comparative phylogenetic approach, I will explore which abiotic factors
better explain variation in leaf volatile production along elevation gradients.
19.8.2014 17:25–17:40
talk
61
PLANT VOLATILES
SIP 15
Effect of experience to plant cues on host plant choice of a moth
Anderson P
Chemical Ecology, Swedish University of Agricultural Sciences, Box 102, S-230-53 Alnarp,
Sweden
[email protected]
Selection of a suitable host plant is essential for the fitness of herbivorous insects and plant
volatiles play an important role during this choice. As many habitats can show large spatial
and temporal variability in plant availability, herbivores need to adapt by showing behavioural
plasticity when choosing a host plant. Prior experience with a host plant can be a valuable way
to assess host-plant quality and can therefore influence host plant preference.
We investigated the effect of experience with plant cues, both during the larval and adult
stage, on the host-choice of the multivoltine polyphagous moth Spodoptera littoralis. Therefore,
we tested the response of females and males after experience with a host plant. We found that
the host plant species experienced by the larvae was generally elevated to the most preferred
plant in both sexes, without otherwise affecting the overall preference hierarchy1. Furthermore,
we demonstrate that mating experience on a plant also changes plant preference in subsequent
reproductive behaviours, while a mere exposure to the plant, alone or in combination with the
sex pheromone, did not. When combining mating and larval experiences, we found that both
affect innate plant preference and that this modulation occurs in parallel. Lastly we find that
larval feeding experience is associated with plant odour and that the response to odours depends
on food quality.
Thus, we show that plant preference in a polyphagous insect is guided by innate preferences,
that are modulated by experience with plant cues and these modulation can happen at multiple
occasions during their whole lifetime.
1 Thöming G, Larsson MC, Hansson BS, Anderson P 2013. Comparison of plant preference hierarchies of male
and female moths and the impact of larval rearing hosts. Ecology 94: 1744-1752.
62
invited talk
19.8.2014 17:40–18:00
SIP 15
PLANT VOLATILES
Volatile organic compounds from insect-defoliated trees as
possible foraging cues for insectivorous birds
Koski T-M 1, Laaksonen T 1, Mäntylä E 1 , Ruuskanen S 1, Li T 2, Girón-Calva PS 2,
Huttunen L 1, Blande JD 2, Holopainen JK 2, Klemola T 1
1 Section of Ecology, Department of Biology, University of Turku, FI-20014, Finland
2 Department of Environmental Science, University of Eastern Finland, Kuopio Campus, P.O.
Box 1627, FI-70211 Kuopio, Finland
[email protected]
As a result of insect-defoliation, plants release volatile organic compounds (VOCs) that are
known to attract natural enemies, e.g. invertebrate predators and parasitoids, of these herbivores.
In addition to this, insectivorous birds are attracted to insect-defoliated trees even when they do
not see the damages or the herbivores. There are, however, only few studies that have examined
the mechanism behind this foraging behaviour. The most obvious possibilities are that birds
can either scent the odour of VOCs, or use some visual cues from the damaged plants, or
combine the use of both of these sensory cues. We tested the alternative that olfactory cues from
defoliated trees attract insectivorous birds by using VOC solutions and larval defoliation in three
experimental setups.
In the first experiment, two VOC blends (terpenes and green leaf volatiles in hexane
solutions) simulating volatile emissions after insect-defoliation were applied to plastic trees.
Pure hexane was used as control solution. In the second experiment, the same VOC blends,
together with plasticine larvae as artificial prey for birds, were applied to natural trees in the
field. In the third experiment, birch saplings experienced either larvae defoliation (chewed by
autumnal moth, Epirrita autumnata) or were left intact controls. The damaged branches were
removed and other possible visual cues were minimized by covering the saplings with black
mesh bags. In each experiment, the potential preference of the birds towards the olfactory cues
was measured either as the first choice, the total number of visits, or the total number of pecked
artificial larvae. Our results do not support the olfactory cue hypothesis, as birds did not show
any preferences either towards artificial or natural trees with VOC-supplements or towards the
herbivory treatment in hidden saplings. This indicates that olfactory cues may not be necessary in
the attraction of birds to herbivore-damaged trees, contradicting with some other recent findings.
19.8.2014 18:00–18:15
talk
63
SIP 15
PLANT VOLATILES
Effects of insect herbivore eggs on interactions of plants with
their insect community
Paschalidou FG, Gols R, van Loon JJA, Dicke M, Fatouros NF
Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH Wageningen, the
Netherlands
[email protected]
Herbivory induces direct and indirect plant responses that affect the dynamics and structure of
herbivore and carnivore communities. Plants can respond to initial attack by herbivorous insects,
namely egg deposition, by activating direct and indirect plant defences. We tested whether plants
exposed to egg deposition activate direct defences against subsequent herbivory and whether
these defences influence the attraction of natural enemies. Plant-mediated effects of herbivore
egg deposition on subsequently feeding lepidopteran larvae were tested in the annual Black
Mustard. Effects on caterpillar performance as well as on plant height and flowering rate were
measured. Caterpillars that developed on plants that had been previously infested with eggs
gained less mass compared to caterpillars that developed on egg-free plants. Moreover, plants
exposed to butterfly eggs showed accelerated plant growth and flowering compared to eggfree plants. Subsequently, we investigated whether these effects could also cascade to the third
trophic level by studying the preference and performance of a specialist larval endoparasitoid.
The wasps showed a stronger attraction to volatiles induced by early host stages on plants
previously infested with eggs compared to plants not been exposed to eggs. This preference was
positively correlated with parasitoid fitness benefits. For this annual crucifer, the retardation of
caterpillar growth in response to butterfly egg deposition in combination with enhanced growth
and flowering is likely to result in reproductive assurance, after being exposed to eggs from
an herbivore whose larvae are florivorous. Additionally, attraction of parasitoids mediated by
volatiles (that indicate upcoming herbivory) acts in concert with direct plant responses against
the herbivore and results in fitness benefits for the parasitoid.
64
talk
19.8.2014 18:15–18:30
SIP 15
PLANT VOLATILES
Prey Perception of Predation Risk:
volatile chemical cues mediate non-consumptive effects
of a predator on a herbivorous insect
Hermann SL, Thaler JS
Department of Entomology, Cornell University, Ithaca NY 14853 United States
[email protected]
Predators can affect prey in two ways – by reducing their density (consumptive effects) or
by changing their behavior, physiology or other phenotypic traits (non-consumptive effects).
Understanding the cues and sensory modalities prey use to detect predators is critical for
predicting the strength of non-consumptive effects and the outcome of predator-prey encounters.
While predator-associated cues have been well studied in aquatic systems, less is known about
how terrestrial prey, particularly insect larvae, detect their predators. We evaluated how Colorado
potato beetle (Leptinotarsa decemlineata) larvae perceive predation risk by isolating cues from
its stink bug predator, the spined soldier bug (Podisus maculiventris). When exposed to male
“risk” predators that were surgically manipulated so they could hunt but not kill, beetles reduced
feeding 29% compared to controls. Exposure to risk females caused an intermediate response.
Beetles ate 24% less on leaves pre-exposed to predators compared to leaves never exposed
to predators, indicating that tactile and visual cues are not required for the prey’s response.
Volatile cues from male predators reduced feeding by 16% compared to controls, whereas larvae
exposed to odors from female predators did not impact beetle feeding. Finally, visual cues from
the predator did not affect beetle feeding. These results demonstrate that volatile cues explain
the net effect of predation risk from male predators on prey feeding and that these cues are sex
specific. Because multiple cues appear to be involved in prey perception of risk, and because
male and female predators have differential effects, beetle larvae likely experience tremendous
variation in the information about risk from their local environment.
19.8.2014 18:30–18:45
talk
65
Metabolomics&and
Molecular Mechanisms
METABOLOMICS
MOLECULAR
MECHANISMS
SIP 15
Metabolomics for studying plant-insect interactions:
help or hype?
Glauser G
Neuchâtel Platform of Analytical Chemistry, University of Neuchâtel, Avenue de Bellevaux 51,
2000 Neuchâtel, Switzerland
[email protected]
Metabolomics is the last-born of the “omics” sciences and is increasingly used to understand
metabolic responses to various biological stimuli. In contrast to targeted analytical approaches that
measure only a limited number of selected compounds, metabolomics aims at profiling the global
metabolite composition of biological organisms in a hypothesis-free manner. It therefore has a
great potential for revealing as yet unknown chemicals involved in plant-insect interactions. Yet,
plant biologists may encounter a number of obstacles when running metabolomic experiments.
First, users of metabolomic techniques are seldom experts in all the methodologies needed to
address their question and have thus to rely on analytical chemists who may not possess the
biological background necessary for a full understanding of the underlying biological processes,
possibly leading to communication issues and reducing the chances of a successful outcome.
This issue is even amplified by the fact that metabolomics is the analytically most challenging
technique of the “omics” and still presents certain limitations as no single method is able to
capture entire plant metabolomes. Second, once a selected approach has revealed statistically
significant markers of potential biological interest, their identification and integration to other
functional genomics data (from genes to biological activity/phenotype) still will have to be
achieved. This represents a complex task that requires again interdisciplinary expertise as well
as extensive resources and labour time. As a result, the utilisation of metabolomics is often
restricted to the assessment of global metabolic alterations following given stimuli by means of
statistical representations.
I will present the benefits and limitations of metabolomics for studying plant-insect
interactions and will illustrate this with a biological study performed on maize leaves attacked
by caterpillars of the genus Spodoptera. Using LC-MS-based untargeted metabolomics, we have
shown that herbivory causes extensive metabolic reprogramming of primary and secondary
metabolites including amino acids, tyramine and tryptamine derivatives, lysophospholipids,
flavonoids and benzoxazinone glycosides. The latter were found to play an essential role in the
induced resistance of maize, which prompted us to conduct an in-depth study of their metabolic
fate at the plant-insect interface. This finally led to the discovery of a novel breakdown product
of benzoxazinones, 3-β-D-glucopyranosyl-6-methoxy-2-benzoxazolinone (MBOA-N-Glc),
produced by Spodoptera as a detoxification mechanism. Taken together, this work underlines
the importance of using metabolomics in combination with subsequent targeted analyses and
appropriate bioassays in order to elucidate the specific biochemical strategies that plants and
insects use against each other.
66
invited talk
20.8.2014 9:00–9:20
SIP 15
METABOLOMICS & MOLECULAR MECHANISMS
Specificity of metabolic plant responses to salicylic and jasmonic
acid and impacts on chewing and sucking herbivores
Schweiger R 1, Heise A-M 1, Persicke M 2, Müller C 1
1 Chemical Ecology, Bielefeld University, Universitätsstr. 25, D-33615 Bielefeld, Germany
2 Center for Biotechnology, Bielefeld University, D-33615 Bielefeld, Germany
[email protected]
The phytohormones jasmonic acid (JA) and salicylic acid (SA) mediate induced plant responses
to various challenges. Their corresponding signaling pathways interact in a complex manner,
whereby negative cross-talk has been mainly demonstrated using gene expression studies. Using
a comprehensive metabolomics approach by combining untargeted metabolic fingerprinting
with metabolite profiling of leaf tissues and phloem exudates, we compared the responses of
Plantago lanceolata (Plantaginaceae) plants induced either by JA or SA or by the combination of
both to disentangle the interaction pattern between the pathways. We uncovered highly specific
induction patterns, indicating points of divergence, convergence, positive crosstalk and mutual
antagonism between both signaling pathways. Additionally, the consequences of these patterns
were tested on the survival of herbivores in bioassays. Sucking and chewing herbivores suffered
from single phytohormone applications, whereas the combined JA + SA treatment attenuated the
negative effects. The treatment-specific effects on herbivores may be explained by the fine-tuned
induction patterns of metabolites and mutual versus antagonistic interactions between the JA
and SA pathways1. The pathway interactions allow the plant to trigger and modulate appropriate
defences when attacked by different antagonists.
1 Schweiger R, Heise A-M, Persicke M, Müller C 2014. Interactions between the jasmonic and salicylic acid
pathway modulate the plant metabolome and affect herbivores of different feeding types. Plant, Cell and
Environment doi: 10.1111/pce.12257
20.8.2014 9:20–9:35
talk
67
METABOLOMICS & MOLECULAR MECHANISMS
SIP 15
Impact of (a)biotic pretreatments on Pieris brassicae feeding
responses in Brassica nigra
Bonnet C, Lassueur S, Reymond P
Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland
[email protected]
In nature, plants are always the target of numerous attackers such as herbivores and pathogens
and, at the same time, exposed to many environmental changes. Currently, studies are focused
on single (a)biotic stress responses and it is not well known how plants react to a combination of
stresses at the molecular level. For example, in response to single attacks in Arabidopsis thaliana,
jasmonic acid (JA) and ethylene (ET) signaling pathways are triggered after herbivorous and
necrotroph challenge whereas the salicylic acid (SA) pathway is triggered after biotroph invasion.
It is also known that these different pathways can interact with each other, a phenomenon
named crosstalk, to create a flexible defense response to encountered stresses. Moreover, plants
are known to emit biogenic organic compounds (BVOCs) into the atmosphere for their own
protection against herbivores by attracting parasitoids. We performed whole-genome analyses of
the black mustard, Brassica nigra, to test the effect of different pretreatments on further responses
to Pieris brassicae insect feeding. Our results show that plants pretreated by P. brassicae eggs
before larval feeding modulated pathway crosstalk differently than in Arabidopsis and that
the transcription profile was different from that of larval feeding. This combination of stresses
appears thus to be like a new pathosystem. On the contrary, ozone pretreatment followed by
P. brassicae feeding displayed a transcription profile that was very similar to the profile observed
during larval feeding alone. In this case, ozone pretreatment seems thus to have no effect on the
molecular response to P. brassicae feeding. Finally, a transcriptome analysis of genes involved
in BVOCs biosynthesis showed no evidence for expression changes in response to single or dual
stress. BVOCs biosynthesis and emission appears thus to be regulated posttranscriptionally.
68
talk
20.8.2014 9:35–9:50
SIP 15
METABOLOMICS & MOLECULAR MECHANISMS
Water stresses affect herbivore-induced defense responses
in Solanum dulcamara
Nguyen D 1, Rieu I 2, Mariani C 2, van Dam NM 1
1 Department of Ecogenomics, Radboud University Nijmegen, PO Box 9010, 6500 GL
Nijmegen, The Netherlands
2 Department of Molecular Plant Physiology, Radboud University Nijmegen, PO Box 9010,
6500 GL Nijmegen, The Netherlands
[email protected]
Studies have shown that abiotic stress factors have strong impacts on herbivore-induced plant
responses, which are largely regulated by phytohormones. Understanding interactions between
the molecular responses to these multiple stressors would provide essential insights into
mechanisms of plant adaptation to the changing environment. In this study, we investigated the
responses of Solanum dulcamara plants under combined stresses of drought / waterlogging and
insect herbivory by Spodoptera exigua. Our results show that S. dulcamara plants accumulated
abscisic acid (ABA) and salicylic acid (SA) under drought stress. Insect herbivory had a synergistic
effect on the induction of ABA but reduced SA accumulation. Moreover, damage by S. exigua
as well as drought stress led to a significant induction of jasmonic acid (JA) and its amino acid
conjugate JA-Isoleucine (JA-Ile). By contrast, no accumulation of JA or JA-Ile was found in the
waterlogged treatments. These hormonal patterns are supported by RNA sequencing analysis of
the plants under the single and double stresses. There is an extensive overlap in gene expression
profiles due to drought and insect herbivory, which is not observed under waterlogged conditions.
Gene set enrichment analysis showed that both drought and herbivory induced many processes
associated with defenses against insects, such as protease inhibitor activity, alkaloid biosynthesis
and regulation of defense responses. Enzyme assays of a candidate defense, protease inhibitors,
confirmed these findings and explained why S. exigua performed better on waterlogged plants
than drought-stressed plants. Our study suggests that drought stress induces many defense
responses and possibly primes the plants to be more resistant against insects, whereas plants
under waterlogged conditions may become more susceptible to insect herbivory.
20.8.2014 9:50–10:05
talk
69
METABOLOMICS & MOLECULAR MECHANISMS
SIP 15
Metabolomics of different leaf cell types and interacting effects of
secondary metabolites on toxicity to Spodoptera
Klinkhamer PGL 1, Leiss KA 1, Nuringtyas TR 2
1 Plant Ecology and Phytochemistry, Institute of Biology, Leiden University, 6333 BE, The
Netherlands
2 Faculty of Biology, Gadjah Mada University, 55281 Yogyakarta, Indonesia
[email protected]
Plants produce a staggering diversity of secondary metabolites. Within individual plants inter cell
variability may be especially pronounced in secondary metabolites interacting with the plant’s
environment. Most metabolomic analyses have focused on plant parts such as roots or shoots
rather than on detecting metabolite accumulation in specific cell types. We, therefore, studied the
inter cell variation of leaf cell metabolites in two genotypes of Jacobaea hybrids. Jacobaea species
are known for their pyrrolizidine alkaloids (PAs). PAs act as constitutive defence compounds
against large grazers and a variety of insect herbivores. We excised epidermis, palisade and
spongy mesophyll cells using laser microdissection and subjected these cells to cryogenic nuclear
magnetic resonance spectroscopy. PLS-DA showed a clear separation of the metabolomes of
the different cell layers with the same pattern for both genotypes. Epidermis cells were rich
in metabolites involved in environmental interactions: chlorogenic acid (CGA), kaempferol
glucoside and cholin. Mesophyll cells accumulated metabolites for energy generation: fructose
and malate. PAs accumulated in the palisade while their precursor, threonine, was concentrated
in the spongy cells. To explain this distinct distribution of secondary metabolites over different
cell layers we studied the interacting effects of PAs and CGA on toxicity to Spodoptera cell lines.
The PAs jacobine and erucifoline were highly toxic while senecionine showed only a modest
level of toxicity. CGA was also toxic to the Spodoptera cell lines. When jacobine or erucifoline
were given in combination with CGA, the mixture showed only very low levels of toxicity. This
strong antagonistic effect can result from the formation of molecular complexes between CGA
and the PAs. Accumulation of PAs and CGA in different cell layers may prevent this type of
antagonistic interactions. An additional advantage of PA accumulation in the mesophyll rather
than in the epidermis cells can be that it reduces the PAs on the leaf surface that are used as host
cues by specialist herbivores. Cell compartmentalization of metabolites in leaves is important
for plant defence and as such emphasizes the significance of studying single cell metabolomes
to understand plant ecology.
70
talk
20.8.2014 10:05–10:20
SIP 15
METABOLOMICS & MOLECULAR MECHANISMS
Role of Arabidopsis bHLH transcription factors
MYC2, MYC3 and MYC4 in defense against herbivory
Reymond P
Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland
[email protected]
Arabidopsis thaliana plants respond to herbivory by constitutive and inducible production of
toxic metabolites such as glucosinolates (GS). We previously showed that MYC2, MYC3, and
MYC4 bHLH transcription factors additively control jasmonate-related defense responses. In
addition, we identified other transcription factors that play a significant role in insect defense.
Here we discovered that the triple mutant myc2myc3myc4 has a highly reduced expression of
GS biosynthesis genes and is almost completely devoid of GS. Consequently, myc2myc3myc4 is
more susceptible to the generalist herbivore Spodoptera littoralis but not to the specialist Pieris
brassicae. Moreover, S. littoralis shows and altered feeding behaviour on the mutant. At the
cellular level, we present evidence that MYC2 binds to the promoter of several GS biosynthesis
genes in vivo and that MYC2/MYC3/MYC4 interact directly with six MYB transcription factors.
This specific MYC-MYB interaction plays a crucial role in the regulation of defence secondary
metabolite production and underlines the importance of GS in shaping plant interactions with
herbivores.
1 Schweizer F, Fernández-Calvo P, Zander M, Diez-Diaz M, Fonseca S, Glauser G, Lewsey MG, Ecker JR, Solano
R, Reymond P 2013. Arabidopsis bHLH transcription factors MYC2, MYC3 and MYC4 regulate glucosinolate
biosynthesis, insect performance and feeding behavior. Plant Cell 25: 3117-3132.
2 Schweizer F, Bodenhausen N, Lassueur S, Masclaux F, Reymond P 2013. Differential contribution of transcription
factors to Arabidopsis thaliana defence against Spodoptera littoralis. Frontiers in Plant Science 4:13.
20.8.2014 10:50–11:10
invited talk
71
METABOLOMICS & MOLECULAR MECHANISMS
SIP 15
Unravelling host plant resistance in chrysanthemum using NMR
Kos SP 1, Choi YH 1,2, Klinkhamer PGL 1, Leiss KA 1
1 Plant Ecology and Phytochemistry, Institute of Biology, Leiden University, The Netherlands
2 Natural Products Lab, Institute of Biology, Leiden University, The Netherlands
[email protected]
Nuclear magnetic resonance (NMR) spectroscopy is a metabolomic technique used to characterize
and compare metabolomes. It permits the simultaneous detection of a wide range of compounds
which a priori might be unknown. NMR is a valuable tool to investigate host plant resistance
and its potential to facilitate resistance breeding1. To control pests the use of host plant resistance
forms an important alternative to the use of pesticides which leads to resistance, health, and
environment related problems.
In this study, we use NMR to investigate host plant resistance of chrysanthemum
(Chrysanthemum x morifolium Ramat) to its main pest western flower thrips (WFT) (Frankliniella
occidentalis (Pergande)). Chrysanthemum is, after rose, the most important ornamental grown in
the Netherlands, but inadequate pest control leads to substantial damage. Considerable variation
in resistance to WFT exists among chrysanthemum cultivars, but the mechanism behind this is
largely unknown.
We first quantified variation in WFT resistance in a greenhouse bioassay testing a broad
range of chrysanthemum types from commercial germplasm provided by Dutch breeding
companies. Twelve chrysanthemum cultivars, showing extreme WFT resistance or susceptibility,
were chosen based on the results of this large scale bioassay. With these cultivars small scale
WFT choice and non-choice bioassays and a reproduction test were performed. The results of
the whole plant choice and non-choice bioassays were highly correlated. In addition, both these
bioassays were correlated with the results of the leaf reproduction bioassay. Besides, the influence
of morphological plant characteristics, such as dry weight, leaf toughness etc. were examined,
but none of these traits was related to WFT resistance. These results suggested that resistance of
chrysanthemum to WFT was chemically based. Therefore, we compared the 1H NMR profiles of
the 12 thrips resistant and susceptible chrysanthemum varieties using PLS-DA. The profiles were
clearly separated based on their metabolites. The signals contributing most to this separation
were identified and, subsequently, quantified. The WFT resistant cultivars contained significantly
higher concentrations of the WFT resistance related metabolites.
Using an NMR approach we were able to indentify metabolites related to WFT resistance
in chrysanthemum. This opens the way to investigate the use of NMR profiles as predictors for
WFT resistance to facilitate resistance breeding by replacing time consuming and costly in-vivo
resistance bioassays.
1 Leiss KA, Choi YH, Verpoorte R, Klinkhamer PGL 2011. An overview of NMR-based metabolomics to identify
secondary plant compounds involved in host plant resistance. Phytochemistry Reviews 10: 205-216.
72
talk
20.8.2014 11:10–11:25
SIP 15
METABOLOMICS & MOLECULAR MECHANISMS
Benzoxazinoids:
Biosynthesis and function of major defense compounds in maize
Handrick V 1, Meihls LN 2, Glauser G 3, Gershenzon J 1, Jander G 4, Erb M 5,
Köllner TG 1
1 Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena, Germany
2 Agricultural Research Service, Kerrville, Texas
3 Institute of Biology, University of Neuchâtel, Switzerland
4 Boyce Thompson Institute for Plant Research, Ithaca, New York
5 Institute of Plant Sciences, University of Bern, Switzerland
[email protected]
Benzoxazinoids (BXDs) are major defense compounds in grasses and have been shown
to protect against fungi, aphids, and caterpillars. The biosynthesis of benzoxazinoids is well
established leading to DIMBOA-Glc (2-(2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one)-βD-glucopyranose, compound 1). However, several grass species like maize or wheat contain
other BXDs such as HDMBOA-Glc (2) and DIM2BOA-Glc (3) whose biosynthesis and impact
on plant defense are unknown. We aim to identify the enzymes involved in the biosynthesis of
2 and 3 in maize using modern genetic approaches and use the information to investigate their
ecological function.
A quantitative trait locus (QTL) mapping of the content of 2 in a set of diverse maize lines
revealed a QTL on maize chromosome 1. This locus comprises three O-methyltransferase genes
(OMT) which were designated as Bx10a, Bx10b, and Bx10c. Overexpression in Escherichia
coli and subsequent enzyme assays with purified recombinant proteins showed that BX10a-c
were able to convert 1 to 2. A natural transposon insertion in Bx10c in some of the tested maize
lines was found to correlate with decreased formation of 2 and an increase in maize leaf aphid
(Rhopalosiphum maidis) susceptibility. Although 2 was more toxic to R. maidis than 1 in vitro,
the increase in 2 upon methylation of 1 was associated with decreased resistance to aphids in vivo
due to reduced callose deposition. The QTL mapping of 3 formation revealed two loci containing
a 2-oxoglutarat-dependent dioxygenase (2ODD) and an O-methyltransferase, respectively.
Recombinant 2ODD catalyzed the oxidation of 1 in vitro, resulting in TRIMBOA-Glc, a precursor
of 3. The characterization of the putative O-methyltransferase is currently underway. Using the
approach of QTL mapping we have tracked enzymes involved in the biosynthesis of 2 and 3.
This has enabled us to study the role of these benzoxazinoids in plant insect interactions from a
new perspective.
20.8.2014 11:25–11:40
talk
73
METABOLOMICS & MOLECULAR MECHANISMS
SIP 15
Disarming the glucosinolate-myrosinase complex by sulfatase
in Bemisia tabaci
Malka O 1, Vassao D 2, Gershenzon J 2, Morin S 1
1 Department of Entomology, the Hebrew University of Jerusalem, P.O. Box 12, Rehovot
76100, Israel
2 Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745 Jena, Germany
[email protected]
Like other plants in the Brassicaceae, Brussels sprouts plants (Brassica oleracea) produce
secondary metabolites, including glucosinolates, which have a defensive function against
herbivores. Upon cellular disruption, glucosinolates are hydrolyzed to various bioactive
breakdown products by the endogenous enzyme myrosinase. These include isothiocyanates,
nitriles, thiocyanates, oxazolidine-2-thiones and epithionitriles which are likely to be toxic to
the phloem-feeding whitefly, Bemisia tabaci, a severe agricultural pest of Brassicaceae crops.
Different enzymatic mechanisms have been described for the detoxification of glucosinolates
by herbivores. The diamondback moth, and larvae and adults of the desert locust possess a
glucosinolate sulfatase that hydrolyzes glucosinolates to their corresponding desulfated forms.
These are no longer susceptible to cleavage by myrosinase, thus eliminating the formation of
toxic glucosinolate hydrolysis products.
To get an overview of the glucosinolate metabolism in Bemisia tabaci, adults were allowed
to feed on artificial diet containing glucosinolates, on Brussels sprouts and Arabidopsis thaliana
plants and their honeydew was analyzed for the presence of possible metabolites, including
glucosinolates with modified side chains, desulfoglucosinolates, and various hydrolysis products
found in the plant. We found that Bemisia tabaci, like larvae of the diamondback moth and
the desert locust, possess a glucosinolate sulfatase that metabolizes glucosinolates to their
corresponding desulfated forms. These are no longer susceptible to cleavage by myrosinase,
thus eliminating the formation of toxic glucosinolate hydrolysis products.
The presence of an active glucosinolate sulfatase system capable of hydrolyzing
glucosinolates in a generalist phloem-feeder might indicate a necessity to detoxify these
compounds. As these herbivores may feed in a way that avoids bringing glucosinolates from
the phloem sap into contact with myrosinase enzyme, it might reflect adaptation to “multi attack
conditions” in which other herbivores/nectrotrophic pathogens co-occur on the Brassicaceae
host plant.
74
talk
20.8.2014 11:40–11:55
SIP 15
METABOLOMICS & MOLECULAR MECHANISMS
Insect eggs predict future attack and
prime induced plant defence
Bandoly M, Hilker M, Steppuhn A
Freie Universität Berlin, Haderslebener Str. 9, Dahlem Centre of Plant Sciences, 12163 Berlin,
Germany
[email protected]
Plant defence reactions are multifarious like the variety of herbivore attackers. An increased
plant defence response against herbivory upon a first stimulus linked to stress has been termed
as priming1. Insect egg deposition predicts future larval attack and could serve as such a first
stimulus. Earlier studies reported an increased plant resistance against larvae upon insect egg
deposition2,3. It still remains unclear, whether such effects are due to egg-induced responses
active against larvae or an egg-priming of feeding-induced responses. We investigated whether
the egg deposition of the generalist Spodoptera exigua primes the subsequent larval induced
defence of Nicotiana attenuata. We conducted greenhouse experiments and (i) compared larval
performance on prior egg-laden and egg-free plants, (ii) measured chemical defence parameters,
among others production of caffeoylputrescin (CP) and trypsin protease inhibitors (TPI), of
feeding-damaged egg-laden and egg-free plants (iii) and tested for an egg-priming effect against
larvae on CP-deficient (silenced NaMyb8 gene) and TPI-deficient (silenced NaPI gene) plants.
(i) The generalist suffered higher mortality, gained less weight and developed more slowly on
prior egg-laden compared to egg-free plants. (ii) The eggs per se did not induce a change in
the production of secondary plant metabolites but after larval damage the feeding induced CP
concentration and TPI activity was higher in prior egg-laden than egg-free plants. (iii) This effect
of prior egg-laden plants on S. exigua larvae was absent on CP-deficient plants but present in
TPI-deficient plants. Hence, priming of anti-herbivore plant defence by prior egg deposition
was based on a MYB8 mediated defence trait, but probably not on TPI production. Our results
demonstrate that insect egg deposition warns tobacco plants of future herbivory and primes
feeding induced defence responses.
1 Prime-A-Plant Group: Conrath U, Beckers GJM, Flors V, García-Agustín P, Jakab G, Mauch F, Newman MA,
Pieterse CM, Poinssot B, Pozo MJ, Pugin A, Schaffrath U, Ton J, Wendehenne D, Zimmerli L, Mauch-Mani B
2006. Priming: Getting ready for battle. Molecular Plant-Microbe Interactions 19, 1062-1071.
2 Beyaert I, Köpke D, Stiller J, Hammerbacher A, Yoneya K, Schmidt A, Gershenzon J, Hilker M 2011. Can insect
egg deposition ‘warn’ a plant of future feeding damage by herbivorous larvae? Proceedings of the Royal Society
Biological Sciences 279, 101-108.
3 Geiselhardt S, Yoneya K, Blenn B, Drechsler N, Gershenzon J, Kunze R, Hilker M 2013. Egg laying of cabbage
white butterfly (Pieris brassicae) on Arabidopsis thaliana affects subsequent performance of the larvae.
PLoS One 8.
20.8.2014 11:55–12:10
talk
75
Phylogenetics and
Co-Evolution
PHYLOGENETICS
& CO-EVOLUTION
SIP 15
Processes from patterns – can co-evolutionary diversification
be tested in a phylogenetic framework?
Alvarez N
Department of Ecology and Evolution (DEE), University of Lausanne, Switzerland
[email protected]
Since the seminal paper by Ehrlich and Raven in the early 60’s, coevolution is seen as a major driver
of species diversification. In particular, the vast species diversity found nowadays in angiosperms
and insects is often explained by coevolution. Because macro-evolutionary processes can hardly
be tested experimentally, research has focused on tracking spatial and temporal congruence in
phylogenetic splits across interacting lineages to show evidence for codiversification. However,
other processes may produce patterns erroneously attributed to coevolution. Among them are
shared biogeographical events among interacting lineages and unilateral adaptive processes (or
phylogenetic tracking). Here we review classical and more recent case studies from the literature
on comparative phylogeny of plants and associated insects to examine if the coevolutionary
component stands firm for explaining congruent phylogenies.
76
invited talk
21.8.2014 9:00–9:20
SIP 15
PHYLOGENETICS & CO-EVOLUTION
Prevalence of growth-defense trade-offs in two major defense
traits of the common milkweed Asclepias syriaca L.
Züst T 1, Agrawal AA 1
Ecology and Evolutionary Biology, Cornell University, 215 Tower Road, Ithaca, NY, 14853,
USA
[email protected]
Theories of coevolution nearly always assume trade-offs between plant defense and fitness
as a limitation on runaway selection. However, even though defensive plant traits are now
mostly acknowledged to carry a cost, these costs continue to be difficult to detect and trade-offs
with plant fitness often remain elusive. The common milkweed Asclepias syriaca employs an
arsenal of defensive traits against a variety of herbivores. The most prominent of these traits are
cardenolides and sticky latex, both of which have no known function in primary metabolism and
therefore likely represent a costly investment by the plant.
Allocation costs, which are the reduction in plant growth and reproduction as a consequence
of the allocation of limited resources to defensive traits, are most likely to be detected at low
resource availability. Accordingly, we grew 24 genotypes of A. syriaca with a priori knowledge
of defense trait expression in a nitrogen fertilizer-addition experiment. We measured plant size
repeatedly over the course of six weeks, and then measured concentration and diversity of
cardenolides in shoots and roots, latex exudation from shoots, and final shoot and root biomass.
From the repeated measures of plant size we estimated parameters of plant growth and related
these to the biomass measures at final harvest and the quantities of defensive traits.
In both the low and high fertilization treatment, genetic correlations between shoot
cardenolide concentrations and shoot mass were strongly negative, while root cardenolide
concentrations varied independently of root mass. Plant genotypes did not differ in the diversity
of compounds, and the 18 individual cardenolide peaks identified by HPLC were present in the
majority of plants. Interestingly, cardenolide profiles were more divergent between root and
shoot tissue, with the most abundant cardenolide compound in shoots being completely absent in
roots, and conversely, the most abundant cardenolide compound in roots being present in shoots
in only marginal concentrations.
Plants receiving low fertilization generally grew slower and decreased cardenolide
production, resulting in lower total concentrations overall. However, genotypes responded
differently to low fertilization, ranging from strongly decreasing to increasing concentrations.
Changes in genotype-specific cardenolide production in response to fertilization were reflected
in corresponding changes in plant growth rate. Even though cardenolides are carbon-based
molecules and would be expected to be largely independent of nitrogen fertilization, these results
are clear evidence that cardenolide accumulation is associated with growth costs in milkweed.
In contrast, latex exudation was positively correlated with both final biomass and growth rate,
which may be an indication that this trait is more dependent on general plant vigour.
21.8.2014 9:20–9:35
talk
77
PHYLOGENETICS & CO-EVOLUTION
SIP 15
An Australian contribution to the coevolution
of red leaf colour hypothesis –
courtesy of eucalypts and eucalypt-feeding psylloids
Steinbauer MJ, Farnier K
Department of Zoology, La Trobe University, Melbourne, Victoria 3086, Australia
[email protected]
Autumnal leaf colour and its relevance to insect herbivores has been much discussed since the
proposition of a coevolutionary association in 20001. Archetti’s hypothesis proposes that the red
autumnal leaves of deciduous species are a warning to insect herbivores that leaves are chemically
defended, have lower nutritional quality and/or are about to be abscised. Nevertheless, a number
of questions about the red as a warning signal to insect herbivores hypothesis remain2. Some
of these questions reflect their origin in studies of plants in which anthocyanin (red pigment)
synthesis is always associated with leaf senescence and others the paucity of information about
colour vision in insect herbivores.
In eucalypts (Myrtaceae), anthocyanin accumulation occurs in young, expanding foliage
as well as in stressed or old, senescing leaves3. Research on species of psylloid in the genus
Cardiaspina (mature leaf specialists) has shown how anthocyanin accumulation is initiated
by nymphal feeding (induces premature leaf senescence) and moderated by the severity of
photoinhibition leaves experience4. Adults of one Cardiaspina species aggregate above chlorotic
and anthocyanic lesions caused by the feeding of conspecific nymphs. This may indicate an
advantage in Cardiaspina adults locating areas of mobilised amino nitrogen5. Research on adults
of Anoeconeossa bundoorensis (young leaf specialist) and Glycaspis brimblecombei (young leaf
specialist) has found that both are positively attracted to long wavelength (red) stimuli6.
The ability of some psylloids to perceive red provides a biological mechanism by which
they may discriminate between young and old leaves or between leaves on the basis of their
physiology. We present data on foliar quality (amino nitrogen : phenolics) relative to ontogenetic
and reflectance properties to consider the ability of visual cues to provide honest signals about
host suitability to psylloids. We discuss the possible implications of psyllid host specificity
mediated by visual cues.
1 Archetti M 2000. The origin of autumn colours by coevolution. Journal of Theroretical Biology 205: 625-630.
2 Archetti M et al. 2009. Unravelling the evolution of autumn colours: an interdisciplinary approach. Trends in
Ecology and Evolution 24: 166-173.
3 Close DC, Beadle CL 2003. The ecophysiology of foliar anthocyanin. Botanical Review 69: 149-161.
4 Steinbauer MJ et al. (in review) Nutritional enhancement of leaves by a psyllid through senescence-like processes:
insect manipulation or plant defence? Functional Ecology.
5 Holopainen JK, Semiz G, Blande JD 2009. Life-history strategies affect aphid preference for yellowing leaves.
Biology Letters 5: 603-605.
6 Farnier K, Dyer AG, Steinbauer MJ (in review) Colour preferences of psyllids exhibit species-specific differences
and indicate perception of long wavelength (red) stimuli. Journal of Experimental Biology.
78
talk
21.8.2014 9:35–9:50
SIP 15
PHYLOGENETICS & CO-EVOLUTION
Evolution of cardenolide resistance and sequestration in
milkweed butterflies (Lepidoptera, Danaini)
Petschenka G, Agrawal AA
Ecology and Evolutionary Biology, Corson Hall, Cornell University, Ithaca, New York 14853,
USA
[email protected]
In a co-evolutionary scenario, plants produce toxins to ward of attacking insect herbivores which
in turn evolve counterstrategies to resist these toxins. Moreover, some herbivores even make
use of plant toxins which they sequester and use as a defense against their own predators. Here,
we aim to understand the ecological and mechanistic significance of insect adaptations to plant
toxins in an evolutionary framework. Specifically, we tested if insect physiological adaptations
are necessary to tolerate dietary toxins, or alternatively, whether these adaptations are primarily
associated with sequestration. We studied the milkweed butterflies (Lepidoptera, Danaini), a
model system for comparative analysis of adaptation to plant defense and sequestration. Milkweed
butterflies cope with dietary cardenolides, plant toxins that specifically inhibit the ubiquitous
cation transporter Na+/K+-ATPase. Recently, it was shown that danaine Na+/K+-ATPases have
three levels of cardenolide resistance and that this resistance evolved in a stepwise manner. We
used three species of milkweed butterflies (Euploea core, Danaus gilippus, and D. plexippus)
representing the three stages of Na+/K+-ATPase resistance to cardenolides, and fed them eight
species of Asclepias that dramatically vary in cardenolide levels. We found that caterpillar
performance was not quantitatively associated with host plant cardenolides and that Na+/K+ATPase resistance did not impact performance, even for the most toxic plants. Nonetheless, the
butterfly species strongly differ in the amount of sequestered cardenolides (E. core: low to none,
D. gilippus: intermediate, D. plexippus: highest) and this pattern paralleled the three stages of
Na+/K+-ATPase resistance to cardenolides. In addition to HPLC analysis of leaves and caterpillar
haemolymph to investigate cardenolide pharmacokinetics, we pharmacologically assessed the
impact of sequestered cardenolides by in vitro application of haemolymph on butterfly Na+/
K+-ATPase. This pharmacodynamic approach allows testing for quantitative relationships
between the amount of sequestered cardenolides and the potential toxic burden for the animal.
We found an overall correlation between the amount of cardenolides stored and the impact on
Na+/K+-ATPase. Moreover, we found that the pharmacological potential of the haemolymph
of the three species strongly differed which is in agreement with the three levels of Na+/K+ATPase resistance. Accordingly, the progressive three stages of Na+/K+-ATPase resistance to
cardenolides in the milkweed butterflies correspond to sequestration, but not dietary tolerance.
21.8.2014 9:50–10:05
talk
79
PHYLOGENETICS & CO-EVOLUTION
SIP 15
Aphids suck and monarchs rule:
asymmetry of plant-mediated interactions between
specialist aphids and caterpillars on two milkweeds
Ali JG 1, Agrawal AA 2
1 Department of Entomology, Michigan State University, East Lansing, MI 48824
2 Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853
[email protected]
Plant-mediated interactions between co-occurring herbivores play an important role in insect
herbivore communities. Although induced resistance pathways associated with jasmonic
acid and salicylic acid are often implicated in such plant-mediated interactions, there are few
examples from non-model systems involving specialized herbivores that regularly interact in
nature. Here, we tested reciprocal impacts between co-occurring specialist herbivores from
two feeding guilds, monarch caterpillars Danaus plexippus and oleander aphids Aphis nerii, on
two co-occurring and closely related, but defensively contrasting milkweeds, Asclepias syriaca
and A. tuberosa. Larvae grew 38% faster on aphid-infested A. syriaca compared to controls.
Reciprocally, aphid growth was >50% lower on caterpillar-damaged A. syriaca compared to
controls. While caterpillar feeding on A. syriaca induced a jasmonate burst and higher defensive
end products (cardenolides and latex), this induction was substantially attenuated in the presence
of aphids. We found a negative correlation between jasmonic acid and salicylic acid only
on A. syriaca infested by both caterpillars and aphids. Asclepias tuberosa displayed distinct
hormonal dynamics and lacked induction of defensive end products. Accordingly, we found
no evidence for plant-mediated interactions between monarchs and aphids on A. tuberosa.
Thus, A. syriaca has specific responses to each herbivore, but if challenged simultaneously, the
outcome is asymmetric: monarchs benefit from defence attenuation by aphids, while aphids are
impaired by monarch feeding. Our results suggest phytohormonal trade-offs induced by two
feeding guilds can differ between closely related plant species, and our notion of trade-offs in
defence based on phytohormonal pathways would improve with further comparative designs
from both model and non-model systems.
1 Ali JG, Agrawal AA 2014. Asymmetry of plant-mediated interactions between specialist aphids and caterpillars
on two milkweeds. Functional Ecology DOI: 10.1111/1365-2435.12271
80
talk
21.8.2014 10:05–10:20
SIP 15
PHYLOGENETICS & CO-EVOLUTION
Convergent adaptive evolution – how insects master the
challenge of cardenolide-containing host plants
Dobler S 1, Dalla S 1, Wagschal V 1, Petschenka G 1,2
1 Biocenter Grindel and Zoological Museum, Hamburg University, Martin-Luther King Pl. 3,
20146 Hamburg, Germany
2 present address: Department of Ecology and Evolutionary Biology, Corson Hall, Cornell
University, Ithaca, NY 14853, USA
[email protected]
Over a hundred insect species are known to feed on cardenolide containing plants despite
their toxic secondary compounds. Cardenolides gain their toxicity by blocking a ubiquitous
transmembrane carrier in animals, the Na,K-ATPase, which is amongst others essential for
establishing membrane potentials and generating action potentials. Nevertheless, many of the
specialized insects on cardenolide plants sequester large amounts of the toxins in their bodies
without suffering ill effects. We here investigate whether the adaptations to cardenolides are
based on a single physiological mechanism or whether several strategies have evolved in different
insect groups to avoid the noxious effects of a potent toxin.
We combined sequencing of Na,K-ATPase α-subunit genes to screen for amino acid
substitutions combined with heterologous expression of genetically engineered Na,K-ATPase
genes and in vitro enzyme assays to uncover substitutions that lower sensitivity to cardenolides.
This approach revealed in representatives of five insect orders (Heteroptera, Caelifera,
Coleoptera, Lepidoptera and Diptera) convergently evolved amino acid replacements that
increase the enzyme’s resistance to cardenolides. Within a single family, the Chrysomelidae,
we can even trace four independent origins of identical substitutions. This striking convergence
of adaptations at the molecular level is, however, not the only solution to avoiding cardenolide
toxicity. Efficient carrier mechanisms that block the uptake in the hemolymph or restrict access
to the nervous tissue are two alternative routes to avoid toxic effects of dietary cardenolides.
20.8.2014 10:50–11:10
invited talk
81
PHYLOGENETICS & CO-EVOLUTION
SIP 15
Macroevolutionary Patterns of Plant Phenolic Metabolites
in the Onagraceae
Ahern JR 3, Anstett DN 2,3, Johnson MTJ 2,3, Salminen J-P 1
1 Laboratory of Organic Chemistry and Chemical Biology, Department of Chemistry,
University of Turku, FI-20014 Turku, Finland
2 Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON,
M5S 3B2, Canada
3 Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6,
Canada
[email protected]
Plant species vary greatly in their allocation to different plant defenses, but existing theory has
struggled to explain this variation. To examine the macroevolution of plant defenses, we have
employed comparative analyses of the phenolic chemistry of different species in the evening
primrose family (Onagraceae). Using 26 Oenothera (Onagraceae) species, we have found
evidence that secondary chemistry has evolved rapidly during the diversification of Oenothera1.
This evolution has been marked by allocation tradeoffs between traits, some of which are related
to herbivore performance. Additionally, the repeated loss of sex via permanent translocation
heterozygosity (PTH) appears to have constrained the evolution of plant secondary chemistry,
which may help to explain variation in defense among plants.
Ongoing work has expanded sampling to over 80 species in the Onagraceae, with tissue
from leaves, flowers, and fruits. Using UPLC-tandem mass spectroscopy, we have detected
dozens of phenolic compounds, including ellagitannins, gallyl glucoses, caffeic acid derivatives,
proanothcyaninidins, and various flavonoid glycosides. The concentration and composition of
phenolics varied dramatically between species and tissues. The Phylogenetic patterns of phenolic
metabolism, and correlations with functional assays of phenolic bioactivity will be discussed.
1 Johnson MT, Ives AR, Ahern JA, Salminen J-P 2014. Macroevolution of Plant Defenses Against Herbivores in
the Evening Primroses. New Phytologist DOI: 10.1111/nph.12763
82
talk
21.8.2014 11:10–11:25
SIP 15
PHYLOGENETICS & CO-EVOLUTION
Phyllotreta flea beetles utilize host plant defense compounds to
create their own glucosinolate-myrosinase system
Beran F 1, Pauchet Y 1, Kunert G 1, Reichelt M 1, Wielsch N 1, Vogel H 1, Svatoš A 1,
Srinivasan R 2, Hansson BS 1, Gershenzon J 1, Heckel DG 1
1 Max Planck Institute for Chemical Ecology, Hans-Knoell-Strasse 8, D-07745 Jena, Germany
2 AVRDC-The World Vegetable Center, 60 Yi-min Liao, Shanhua, Tainan 74151, Taiwan
[email protected]
Glucosinolates are characteristic secondary metabolites in plants of the order Brassicales which
form an activated defense system against herbivores together with the enzyme myrosinase.
Tissue damage brings these two components together and leads to the formation of bioactive
isothiocyanates which repel and/or harm non-adapted herbivores. Different strategies for
detoxification of glucosinolates and their hydrolysis products have been identified in Lepidoptera,
Hemiptera, and Hymenoptera; however, how crucifer-feeding leaf beetles cope with this plant
defense is not known.
We focus on the striped flea beetle, Phyllotreta striolata, a devastating pest species of
Brassica crops in Southeast Asia and North America. In previous studies we found that P. striolata
adults are able to emit volatile alkenyl isothiocyanates. We hypothesized that this specialist
sequesters host plant glucosinolates and hydrolyzes them using a beetle myrosinase to release
isothiocyanates. To test this, we performed feeding assays with host plants differing in their
glucosinolate profile. The accumulation of plant glucosinolates in P. striolata adults was traced
using HPLC. We found that the beetles selectively sequestered mainly alkenyl glucosinolates
up to 1.75% of their body weight, but only low amounts of aromatic and indolic glucosinolates.
The presence of a beetle myrosinase was verified and the enzyme was partially purified. By
combining proteomics and transcriptomics we were able to clone and heterologously express
a gene responsible for the myrosinase activity in P. striolata belonging to glucoside hydrolase
family 1. The major substrates of the heterologously expressed beetle myrosinase were aliphatic
glucosinolates which were hydrolyzed with at least 4-fold higher efficiency than aromatic and
indolic glucosinolates. These results indicate that P. striolata efficiently prevent glucosinolate
hydrolysis by the plant myrosinase during feeding while possibly using controlled release of
isothiocyanates for their own defense.
21.8.2014 11:25–11:40
talk
83
PHYLOGENETICS & CO-EVOLUTION
SIP 15
Synergism between direct and indirect defence controls
herbivore eggs on a wild crucifer
Fatouros NE 1, Pineda A 1, Verbaarschot P 1, Shimwela MM 2, Figueroa Candia IA 3,
Huigens ME 1,4, Bukovinszky T 5
1 Laboratory of Entomology, Wageningen University, Droevendaalsesteeg 1, 6708 PB
Wageningen, The Netherlands
2 University of Florida, Plant Pathology Department, PO Box 110680, Gainesville, FL, USA
3 Dutch Butterfly Conservation, Mennonietenweg 10, 6702 AD Wageningen, The Netherlands
4 Fundación PROINPA, Av. Elias Meneces Km 4, El Paso, Cochabamba, Bolivia
5 Resource Ecology Group, Wageningen University, Droevendaalsesteeg 3a, 6708 PB,
Wageningen, The Netherlands
[email protected]
Prominent theories on the evolution of plant defences against herbivores predict a conflict
between direct (anti-herbivore traits) and indirect defences (attraction of carnivores) when
carnivore fitness is reduced.
Some plant species can respond to herbivore egg deposition by exhibiting a hypersensitive
response (HR)-like necrosis that kills herbivore eggs. We studied a black mustard population and
how this lethal direct trait affects preferences and/or performances of abundant cabbage white
butterflies, and their natural enemies, tiny egg parasitoid wasps.
Within the studied black mustard population, we observe natural variation in expression
of HR induced by cabbage white eggs. Butterfly eggs inducing HR-like necrosis suffer higher
parasitism rates and increased mortalities than eggs that do not induce the lethal trait. Surprisingly,
HR does not negatively affect survival of egg parasitoids. Moreover, we reveal that wasps are
attracted to volatiles of egg-induced plants expressing HR and show genotypic variation therein.
We conclude that in a system where plants deploy potentially lethal direct defences, such
defences may still act with indirect defences in a synergistic manner to reduce herbivore pressure.
Future studies investigating phenotypic variation in direct plant defences between populations
that differ in herbivore pressures should shed more light on how directional selection of plant
defence traits may shape multitrophic interactions.
84
talk
21.8.2014 11:40–11:55
SIP 15
PHYLOGENETICS & CO-EVOLUTION
Adaptation of generalist herbivores to Gossypol,
a cotton secondary metabolite
Krempl C, Joussen N, Heidel-Fischer H, Reichelt M, Heckel DG, Vogel H
Max Planck Institute for Chemical Ecology, Hans-Knöll Str. 8, 07745 Jena, Germany
[email protected]
The cotton bollworm Helicoverpa armigera and the tobacco budworm Heliothis virescens are
polyphagous insects and important pests on a number of economically important crop plants.
Most generalist herbivores, including H. armigera and H. virescens, are confronted with a large
variety of plant secondary metabolites which they need to detoxify to ensure successful growth
and development. The major defence compound of one of their host plants, cotton, is gossypol,
a sesquiterpene dimer that is toxic to most organisms. Although gossypol has been extensively
studied in mammals for its antifertility, antitumor, antiparasitic, and antiviral activities, very little
is known about gossypol detoxification mechanisms in cotton-feeding insects. We investigate the
mechanisms that enable Heliothine moth species to feed on cotton plants and, furthermore, we
aim to identify gossypol metabolites.
Our hypothesis is that gossypol is detoxified by larvae via an enzymatic reaction, to
reduce its toxicity. To test potential candidate enzymes for their ability to detoxify gossypol,
we expressed candidate P450 genes in insect cell lines and performed metabolism studies.
Furthermore, we detected glycosylated gossypol metabolites in the faeces of larvae fed on
gossypol diet using HPLC and LC/MS. Feeding studies with artificial diet containing gossypol
showed species-specific differences in larval development. Microarray hybridizations allowed
the identification of tissue-specific and/or species-specific transcripts responding to gossypol
supporting the findings of the feeding studies. The microarray data furthermore revealed UDPglycosyltransferases (UGTs) to be induced in gossypol fed larvae, reinforcing our HPLC and LC/
MS analysis. Ongoing heterologous expression of candidate UGTs are aiming to identify enzymes
that produce the glycosylated metabolite, a potentially crucial step in gossypol detoxification in
generalist herbivores.
Gossypol 21.8.2014 11:55–12:10
talk
85
PHYLOGENETICS & CO-EVOLUTION
SIP 15
Constraints to the evolution of both insect and pathogen
resistance in two chemotypes of a wild crucifer
Hauser TP, Christensen S, Heimes C, Kuzina V, van Mölken T
Dept of Plant and Environmental Sciences, University of Copenhagen, Denmark
[email protected]
Plants are often attacked by a multitude of herbivores and pathogens. Evolution of resistances to
these may be constrained by several historical, ecological, genetic, physiological and biochemical
factors.
Barbarea vulgaris is shortlived crucifer, which is diverged into two chemotypes that differ in
a saponin-based resistance towards some insect species and a resistance to an oomycete pathogen
Albugo sp., which causes white blister rust. The two plant types have different geographical
distributions but co-occur in Scandinavia and Finland, where most populations are either insect
or pathogen resistant, even though dually resistant plants seemingly would be at an advantage.
A proximate reason for why we find few dually resistant plants could be that the resistances
are functionally exclusive, due to e.g. mutually antagonistic resistance pathways. However, the
insect and pathogen resistances are not correlated in advanced hybrids between the two plant
types, showing that they are not functionally coupled. Instead, the different associations of
resistances in the plant types seem to caused by historical divergence.
The two plant types are strongly differentiated genetically and separated by a strong sexual
hybridisation barrier, which lower the probability of resistance transfer between the plant types.
The saponin biosynthesis of B. vulgaris involves on at least four regulatory and coding genes,
and combinations of these may be needed for synthesis of the resistance-conferring saponins;
this will further decrease the probability of transfer of this resistance to the other plant type.
A recent field experiment with F3 hybrids between the two plant types indicate that
insect-resistant plants are not more fit than susceptible plants; in contrast, pathogen resistance
substantially improves plant fitness. Thus, the benefit of being insect resistant may be conditional,
which would further decrease the probability of introgression of the insect resistance into the
susceptible plant type. Possibly, the resistance has evolved under different conditions in another
parts of the distribution range.
Our results suggest that present plant defense against antagonists may sometimes be
strongly affected and constrained by historical patterns of population divergence and resistances.
However, surprisingly few have studied this possibility.
86
talk
21.8.2014 12:10–12:25
SIP 15
Multitrophic Interactions
2
MULTITROPHIC
INTERACTIONS
Multi species multi trophic interactions
Poelman EH
Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH Wageningen, The
Netherlands
[email protected]
Plant-insect interactions typically take place in complex settings of interactions between
multiple trophic levels as well as multiple species in each trophic level. We have learned that,
when considering the full community in which plant-insect interactions are played out, many of
the assumptions in these interactions are fundamentally affected by complexity. Induced plant
resistance to herbivores may at the same time mean induced susceptibility to other herbivores,
or indirect resistance by recruiting natural enemies may control some herbivores, but the odours
emitted may have negative side-effects that include attraction of the fourth trophic level. When
considering the full community that plants and insects are part of it proves to be difficult to
predict the fitness outcome of an (induced) trait and hence coin it induced direct or indirect
defence. Similarly, species in the second or higher trophic level may behave differently in simple
pair-wise interactions than in species rich assemblies. One such an example is the host location
behaviour by parasitoids. Apparently neutral non-host herbivores that share the food plant may
strongly impact on parasitoid host location by altering plant volatile emission or by their own
infochemicals.
Several studies have identified that parasitoids that search for hosts may be negatively
affected in the efficiency of host location by non-host presence. Parasitoids may not always be
able to discriminate host infested from non-host infested plants and the encounters with nonhosts on the food plant may cause parasitoids to give up searching for their host on that plant.
My own studies show that presence of non-host herbivores may also affect extrinsic competition
interactions between parasitoid species that share a host herbivore, because parasitoid species
may deal differently with non-host presence. Moreover, non-host herbivores may alter the
realized niche that each parasitoid species establishes when searching for two host species.
21.8.2014 15:30–15:50
invited talk
87
MULTITROPHIC INTERACTIONS
SIP 15
Inbreeding in a plant-herbivore interaction: effects on herbivore
performance, preference and third-trophic level interactions
Kalske A 1, Muola A 1, Mutikainen P 2, Leimu R 3
1 Section of Ecology, University of Turku, Turku, Finland
2 Institute of Integrative Biology, ETH-Zürich, Zürich, Switzerland
3 Department of Plant Sciences, University of Oxford, Oxford, UK
[email protected]
Plants defend themselves against insect herbivores directly with secondary chemical compounds
or physical defenses and indirectly by attracting natural enemies of the herbivores. Inbreeding
resulting from self-fertilization or mating between related individuals often causes inbreeding
depression, i.e., reduction in performance due to inbreeding. Inbreeding can alter herbivore
fecundity and performance as well as composition of plant secondary chemicals and emissions
of volatile compounds in plants and can thus affect interactions between plants and herbivores as
well as with natural enemies of the herbivores.
We studied how inbreeding of both a long lived plant (Vincetoxicum hirundinaria) and
its specialist herbivore (Abrostola asclepiadis) affect herbivore preference and performance and
plant resistance to herbivores via direct and indirect defences. In a feeding assay with inbred
and outbred lines of V. hirundinaria, and A. asclepiadis, we discovered that plant inbreeding
increased inbreeding depression in herbivore performance in some populations. In addition,
inbreeding depression in plant resistance was substantial when herbivores were outbred, but
diminished when herbivores were inbred. We also conducted a preference test where female
moths were allowed to oviposit on inbred and outbred plants, and discovered that herbivores
preferred outbred plants. This was unexpected as inbred plants are of higher nutritional quality to
the herbivore larvae. Finally, we examined the interactions with natural enemies of the herbivore
eggs in a field experiment with inbred and outbred plants that bore inbred or outbred moth eggs.
We discovered that the herbivore eggs were predated to the same degree on both inbred and
outbred plants. However, eggs of the outbred herbivores were more likely to be destroyed by
predators or parasitoids, because they are likely to be of higher quality for the enemies.
Our results suggest that when herbivores are inbred, herbivore-induced selection against
self-fertilization in plants may diminish. Interestingly, even though inbred plants have been
observed to attract fewer natural enemies of the herbivores when damaged, we did not find a
corresponding effect of plant inbreeding in this study. We demonstrate that direction and strength
of inbreeding depression in plants and herbivores can vary among different life stages of the
herbivore (i.e. from adult to egg to larvae). Furthermore, the strength of inbreeding depression of
the herbivores can be reduced when the interactions with the natural enemies of the herbivores
are considered.
88
talk
21.8.2014 15:50–16:05
SIP 15
MULTITROPHIC INTERACTIONS
Order of arrival of early season herbivores affect the subsequent
insect community
Stam JM, Dicke M, Poelman EH
Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH Wageningen, The
Netherlands
[email protected]
Defending against herbivorous attackers is an ongoing battle for plants. Throughout the season
plants have to cope with multiple insect herbivores, each herbivore with its own way of feeding.
Insects from these different feeding guilds, and at different times in the season, force the plant to
have a defence strategy that can cope with the insect community as a whole. In this community
perspective, plant defensive responses are constrained by the multidimensional effect of their
response to a single attacker. Not only the initial herbivore attackers are affected by the plant
defence, but also subsequent herbivores that arrive next on the attacked plants. Subsequent
herbivores might on their turn also affect plant defence and subsequent new arriving insects of
multiple trophic levels, thus creating a cascading effect of plant defences on the whole insect
community, throughout the season. The way in which the whole insect community is shaped by
the order of arrival of early season herbivores is however largely unknown.
Here we investigated how order of arrival of two early season herbivores affected the
development of the insect community. The insect community on two populations of wild
cabbage plants were weekly monitored from June to early October 2012 after placing at end May
herbivores of either the leaf-chewing, the phloem-feeding or both feeding guilds on the plants.
In the treatments with both feeding guilds present, the two insect species where either placed
simultaneously, first the phloem-feeder, or first the leaf-chewer on the plant, to investigate effects
of order of early-season herbivore arrival.
The order of early-season herbivore arrival affected the subsequent insect community later
in the season. These effects on the insect community were influenced by both herbivore feeding
guild and plant population, showing that plant defence changes depending on both insect and
plant identity.
In conclusion, ‘who comes first’ is an important factor determining plant defence strategies
and in shaping the insect community on a focal plant.
21.8.2014 16:05–16:20
talk
89
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SIP 15
What does the aphid feeding behaviour tells us about plant
factors important for pea aphid host race maintenance?
Kunert G, Schwarzkopf A, Gershenzon J
Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany
[email protected]
The pea aphid (Acyrthosiphon pisum HARRIS), a legume specialist, encompasses at least 11
genetically distinct sympatric host races. Each host race shows a preference for a certain legume
species but all can feed and live on the universal host plant Vicia faba. Until now it is not
known which factors are responsible for the maintenance of the different pea aphid host races.
To localize plant factors responsible for a compatible plant – aphid interaction we focused on the
intimate interaction between the aphid and its potential host plants and investigated the feeding
behaviour of six pea aphid clones from three host races on four legume species. The location of
plant factors influencing penetration and feeding was determined using the electrical penetration
graph (EPG) technique. Therefore, aphid and plant were introduced into an electrical circuit with
the EPG device, resulting in voltage fluctuations as soon as the aphid penetrates the plant and the
electrical circuit is closed. The voltage fluctuations give information about the aphid behaviour
and localization of the aphid stylet in the plant. The most important plant factors influencing
aphid penetration and feeding behaviour were localized in the epidermis and sieve elements.
Repetitive puncturing of sieve elements is an important prerequisite for phloem feeding,
but in most cases this behaviour does not lead to feeding on non-hosts. We also investigated
whether prior feeding experience of two pea aphid clones of the Medicago race affects their
ability to use their native and universal host plants. Feeding experience on the rearing plant
significantly affected the overall ability to feed on the test plant. The proportion of individuals
able to establish feeding on a host was much higher for aphids that had already had experience
on the same host. Prior experience facilitated penetration of the epidermis and mesophyll, and
feeding on the sieve elements. Experience effects manifested in the sieve elements were most
crucial for aphids trying to feed on M. sativa. Both experienced and inexperienced individuals
carried out cycles of repeated sieve element punctures, but these were followed by feeding most
often in experienced individuals. By conditioning future acceptance of the same host, feeding
experience will reinforce separation of the different pea aphid host races on various legumes and
thus maintain their differences.
90
talk
21.8.2014 16:20–16:35
SIP 15
MULTITROPHIC INTERACTIONS
The role of hoverfly – plant species interaction in maintenance of
pea aphid host races
Vosteen I, Gershenzon J, Kunert G
Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany
[email protected]
Herbivorous insects are the most diverse group of multicellular organisms inhabiting our world.
One process that may have contributed to this enormous biodiversity is ecological speciation via
continuous host plant switches. We use the pea aphid (Acyrthosiphon pisum) complex as a model
system to study this process. The pea aphid complex consist of at least 11 genetically distinct
host races which are native to specific host plants of the legume family, but can all develop on
the universal host plant Vicia faba. The factors that gave rise to and maintain these host races are
not yet known, but natural enemies might have played a role. If enemies prefer certain plants for
prey searching or oviposition, aphids might have a higher fitness on other (enemy free) plants,
this could help maintain the different pea aphid host races. The attractiveness of a certain plant
for natural enemies might depend on its architecture, volatile profile and chemical composition
which may alter the nutritional value and toxin content of aphids, thereby influencing natural
enemy performance.
We tested for the existence of enemy free space by exposing three pea aphid host races
feeding either on their respective native host plants, Medicago sativa, Trifolium pratense, or
Pisum sativum, or on the universal host plant to natural predator populations in the field. For two
aphid host races we found a strong oviposition preference of hoverflies (Episyrphus balteatus)
for the universal host plant V. faba instead of the native hosts. Since hoverfly larvae are important
aphid predators we conclude that they may have selected for these two pea aphid host races to
use host plants other than V. faba. We have also investigated which factors may have created
the observed hoverfly oviposition pattern. The varying amount of honeydew produced by the
different aphid races living on different host plants seems to play a crucial role.
21.8.2014 17:05–17:20
talk
91
MULTITROPHIC INTERACTIONS
SIP 15
The EICA and SDH hypothesis revisited:
A competition experiment between invasive and native
Jacobaea vulgaris under specialist or generalist herbivore attack
Lin T, Klinkhamer PGL, Vrieling K
Institute of Biology, Section Plant Ecology and Phytochemistry, Leiden University, PO Box
9505, 2300 RA Leiden, The Netherlands
[email protected]
Theories predict that invasive plants show a higher competitive ability than native species which
is believed to contribute to their invasion success. The Evolution of Increased Competitive
Ability (EICA) hypothesis and the Shifting Defense Hypothesis (SDH) suggest that the competi­
tive ability of invasive plants has increased because the absence of natural specialist herbivores
has led to an evolutionary shift in allocation from defense to growth. As an extension, the SDH
predicts that plants from the invasive range under generalist herbivore pressure will outcompete
plants from the native range. We tested these two hypotheses with a competition experiment
between invasive and native genotypes from the same species under two different herbivore
treatments: herbivory by the generalist herbivore Mamestra brassicae or herbivory by the
specialist herbivore Tyria jacobaeae and a control treatment without herbivores. Our results
showed that in accordance with both hypotheses, invasive J. vulgaris had better competitive
ability than native genotypes in the treatment without herbivores. In the herbivore treatments,
the invasive genotypes of J. vulgaris were more resistant to M. brassicae but more susceptible
to T. jacobaeae compared to native genotypes. Therefore the competitive ability of invasive
genotypes was significantly increased by the generalist M. brassicae while it was reduced by the
specialist T. jacobaeae. Our results fully support the EICA hypothesis. However, since the EICA
hypothesis ignores the effect of generalist herbivores, the effects of generalist and specialist
herbivores on competing J. vulgaris in this study are fully inline with the more comprehensive
predictions of the SDH hypothesis. The results indicated that an evolutionary shift has occurred
in the invasive J. vulgaris genotypes which are better competitors than native J. vulgaris in the
absence of specialist herbivores and in the presence of generalist herbivores.
92
talk
21.8.2014 17:20–17:35
SIP 15
MULTITROPHIC INTERACTIONS
Parasitism increases plant investment in chemical defences
against herbivores
Ode PJ 1, Gols R 2, Harvey JA 3
1 Graduate Degree Program in Ecology and Dept. of Bioagricultural Sciences, Colorado State
University, Fort Collins, CO 80523-1177, USA
2 Laboratory of Entomology, Dept. of Plant Sciences, Wageningen University,
The Netherlands
3 Dept. of Multitrophic Interactions, Netherlands Institute of Ecology, Center for Terrestrial
Ecology, Wageningen, The Netherlands
[email protected]
Plant defensive chemistry is widely recognized to have negative effects on parasitoids largely
through its negative effects on host (herbivore) quality. In some cases, plant defence chemistry
has been shown to have negative effects on parasitoids when these natural enemies directly
encounter unmetabolized plant toxins when feeding upon their insect hosts. To our knowledge,
this paper presents the first known example of how parasitoids can induce increased level of
plant chemical defence against herbivory.
In this study, we compared the glucosinolate profiles produced by three populations of wild
cabbage (Brassica oleraceae) plants and one cultivated variety in a common garden. Plants were
randomly assigned to one of three treatments: no herbivory, or herbivory by unparasitized larvae,
or herbivory by parasitized larvae (parasitized by the polyembryonic parasitoid Copidosoma
floridanum). Plants fed upon by parasitized cabbage loopers (Trichoplusia ni) produced higher
levels of two glucosinolates (glucobrassicin and neoglucobrassicin) than plants fed upon by
unparasitized herbivores. Unattacked plants produce the lowest levels of these glucosinolates.
Cabbage loopers parasitized by C. floridanum consume 50% more plant tissue than unparasitized
cabbage loopers. Interestingly, glucobrassicin and neoglucobrassicin, along with sinigrin and
4-hydroxyglucobrassicin, are negatively correlated with total clutch size and survivorship of the
parasitoid. So, from the perspective of the plant, at least in this tritrophic system, the enemy of
my enemy is still my enemy!
21.8.2014 17:35–17:50
talk
93
MULTITROPHIC INTERACTIONS
SIP 15
Insect counter-adaptations to plant cyanogenic glucosides
Pentzold S 1, Zagrobelny M 1, Kroymann J 2,3, Olsen CE 1, Møller BL 1, Bak S 1
1 Department of Plant and Environmental Sciences, University of Copenhagen, Denmark
2 Max Planck Institute for Chemical Ecology, Jena, Germany
3 Laboratoire d’Ecologie, Systématique et Evolution, Université Paris-Sud/CNRS, Paris,
France
[email protected]
Cyanogenic glucosides (CNglcs) are widespread phytoanticipins that release toxic hydrogen
cyanide by specific β-glucosidases after tissue damage. Specialist herbivores such as Zygaena
filipendulae often possess various counter-adaptations to overcome and sequester intact CNglcs1,
e.g. a minimal disruptive feeding mode, an alkaline gut lumen and digestive β-glucosidases
lacking activity towards CNglcs2,3. In contrast, generalist herbivores may suffer from the toxic
hydrolysis products of CNglcs4.
We analysed performance and metabolism of insect herbivores from different orders,
feeding modes and niche specialisations by rearing them on plants with different CNglcprofiles. Generalist Spodoptera littoralis larvae were reared on Lotus japonicus mutant plants
either containing or lacking the CNglcs linamarin and lotaustralin. Surprisingly, larval and
pupal performance on either plant type did not differ significantly. In contrast to sequestering
Z. filipendulae, frass of S. littoralis larvae contained large amounts of intact CNglcs, which
when macerated, released hydrogen cyanide. This shows that plant β-glucosidase activity is
inhibited specifically during plant material passage through the S. littoralis digestive system.
Leaf-snipping as minimal disruptive feeding mode, an alkaline gut inhibiting plant β-glucosidase
activity and digestive insect β-glucosidases lacking activity on linamarin and lotaustralin are key
adaptations in S. littoralis.
Moreover, lepidopteran species such as Mamestra brassicae, Spodoptera exigua, Plutella
xylostella, Pieris rapae and Pieris brassicae as well as the hemipteran species Lipaphis erysimi
and Myzus persicae were reared on transgenic Arabidopsis thaliana plants producing the
CNglc dhurrin. These lepidopteran species excreted intact dhurrin efficiently and avoided toxic
hydrolysis, probably by an alkaline gut and leaf-snipping. The hemipterans avoided accumulation
of dhurrin in their body, probably by their piercing-sucking feeding mode.
Our study highlights the importance of excretion efficiency, an alkaline gut and minimal
disruptive feeding modes, which enable specialist and generalist herbivores from different insect
orders to overcome CNglc-based plant defence.
1 Zagrobelny M, Olsen CE, Pentzold S, Fürstenberg-Hägg J, Jørgensen K, Bak S, Møller BL, Motawie MS 2014.
Sequestration, tissue distribution and developmental transmission of cyanogenic glucosides in a specialist insect
herbivore. Insect Biochemistry and Molecular Biology 44: 44-53.
2 Pentzold S, Zagrobelny M, Roelsgaard PS, Møller BL, Bak S 2014. The multiple strategies of an insect herbivore
to overcome plant cyanogenic glucoside defence. PLoS ONE 9: e91337.
3 Pentzold S, Zagrobelny M, Rook F, Bak S 2014. How insects overcome two-component plant chemical defence:
plant β-glucosidases as the main target for herbivore adaptation. Biological Reviews (doi:10.1111/brv.12066).
4 Gleadow RM, Møller BL 2014. Cyanogenic glycosides: synthesis, physiology, and phenotypic plasticity. Annual
Review of Plant Biology 65: 24.1–24.31.
94
talk
21.8.2014 17:50–18:05
SIP 15
Abstracts ofPOSTERS
Posters
ABSTRACTS
ABSTRACTS OF POSTERS
ABSTRACTS POSTERS
SIP 15
SIP 15
Multitrophic Interactions
MULTITROPHIC
INTERACTIONS
Analyses of interaction among Arabidopsis, thrips, and
tospovirus
Abe H 1, Tomitaka Y 2, Sakurai T, Seo S 2, Kugimiya S 3, Shimoda T 4, Tsuda S,
Kobayashi M 1
1 Experimental Plant Division, RIKEN BioResource Center, Tsukuba 305-0074, Japan
2 National Institute of Agrobiological Sciences, Tsukuba 305-8666, Japan
3 National Institute for Agro-Environmental Sciences, Tsukuba 305-8604, Japan
4 National Agricultural Research Center, Tsukuba 305-8666, Japan
[email protected]
The western flower thrips (Frankliniella occidentalis) is a polyphagous herbivore that causes
serious damage to many plants. In addition to causing feeding damage, it is also a vector
insect that transmits tospoviruses such as Tomato spotted wilt virus (TSWV). We previously
reported that thrips feeding on plants induces a jasmonate (JA)-regulated plant defense, which
negatively affects both the performance and preference of the thrips. Here we report that TSWV
infection allows thrips to feed heavily and multiply on Arabidopsis plants. TSWV infection
elevated SA contents and induced SA-regulated gene expression in the plants. On the other
hand, TSWV infection decreased the level of JA-regulated gene expression induced by thrips
feeding. Importantly, we also demonstrated that thrips significantly preferred TSWV-infected
plants to uninfected plants. In JA-insensitive coi1-1 mutants, however, thrips did not show a
preference for TSWV-infected plants. In addition, SA application to wild-type plants increased
their attractiveness to thrips. Our results suggest that TSWV infection suppresses the antiherbivore response in plants and attracts its vector, thrips, to virus-infected plants. We also report
the possible function of volatile compounds for thrips preference.
1 Abe et al. 2009. Jasmonate-dependent plant defense restricts thrips performance and preference. BMC Plant
Biology 9, 97.
2 Abe et al. 2012. Antagonistic plant defense system regulated by phytohormones assists interactions among vector
insect, thrips, and a tospovirus. Plant and Cell Physiology 53, 204-212.
P1
poster
97
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SIP 15
Genetic basis of endophyte community on aspen (Populus
tremula) is altered after introduction of a specialist beetle
(Chrysomela tremula)
Albrectsen BR, Siddique A, Guo-Decker VH
Department of Plant Physiology, Umeå University, 90183 Umeå, Sweden
[email protected]
Endophytic fungi are abundant symptomless colonizers of plant tissues, and their ecological
functions are still largely unknown. Recent studies suggest that endophytes may interact with
herbivores and other consumers for example through the production of toxic compounds or
by competing for the same substrate. Dynamic community interactions of this kind may be of
particular importance for the health of long lived species – like trees, that co-evolve at asymmetric
time scales relative to their antagonists. The asymmetric generation time is a constraint to the
evolution of new resistance strategies for the long lived host and a balanced arms race is unlikely
to happen. Association with microbial body guards, that have similar generation time as the
potential antagonists, might enable a tree to keep its resistance potential working, although its
defense package is not fully updated to meet the latest version of the pest.
Resistance properties in trees could thus potentially be shaped by the presence of
endophytic fungi. We isolated endophytes from leaves of eight genotypes of Eurasian aspen
(Populus tremula): control plants without beetles and treated plants that had been subjected to
damage by the leaf beetle Chrysomela tremula. The diversity and composition of fungal morphs
varied according to aspen genotype and chemotype1, and new fungi were introduced in the beetle
treated plants, which both increased diversity of the fungi and led to interactions between fungal
morphs. Sequencing of the fungi presently takes place to identify the involved fungi.
1 Abreu IN, Ahnlund M, Moritz T, Albrectsen BR 2011. UHPLC-ESI/TOFMS Determination of Salicylate-like
Phenolic Gycosides in Populus tremula Leaves. Journal of Chemical Ecology 37(8): 857–870.
98
poster
P2
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MULTITROPHIC INTERACTIONS
Genetically based latitudinal patterns in physical, chemical and
life history defence traits in the native plant Oenothera biennis
Anstett DN 1,2, Ahern JR 3, Salminen JP 3, Johnson MTJ 1,2
1 Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S
3B2, Canada
2 Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6,
Canada
3 Laboratory of Organic Chemistry and Chemical Biology, Department of Chemistry,
University of Turku, FI-20014 Turku, Finland
[email protected]
The observation that herbivory and plant defenses increase towards the equator has long been
viewed as a well-supported pattern called the Latitudinal Herbivory Defense Hypothesis (LHDH).
Recent studies call this hypothesis into question, which suggests alternative hypotheses might
explain biogeographic patterns of herbivory and plant defense in nature. Here we test LHDH
by growing Oenothera biennis plants from 150 populations in a common garden to examine if
genetically based latitudinal gradients are present in life history traits (bolt date, flowering time
and growth rate), physiological traits (SLA, % water content), and physical resistance traits
(trichomes, leaf toughness). We also examined latitudinal patterns in total phenolics, oxidative
capacity, and concentrations of over 100 individual ellagitannin and flavonoid glycoside, and
condensed tannin compounds present in Oenothera biennis. To our knowledge this is the largest
chemical data set to date used to test geographical variation in plant defensive chemistry.
Multiple traits show clear genetically based clines associated with latitude, but there
is no consistent increase in levels of physical or chemical resistance traits at lower latitudes.
Trichome number, bolt date, and flowering date were higher in populations from lower latitudes,
and % water content and leaf toughness showed no latitudinal pattern. The concentration of
secondary metabolites was related to latitude, but the direction and strength of these patterns
varied according to plant tissue. Oxidative capacity of phenolics in leaves and fruits was greatest
in higher latitude populations, but the opposite pattern was observed for fruits. Total phenolics
increased at lower latitudes in fruit tissues, but showed no association with latitude in flower and
leaf tissues. These mixed results support our previous research from natural populations which
showed that the relationship between herbivory pressure and latitude varied between positive
and negative depending on the plant tissue. Overall, our findings suggest that there is no clear
latitudinal pattern in defence traits. Instead, the assumptions of the hypothesis may hold true or
not, depending on the specific tissue examined.
P3
poster
99
MULTITROPHIC INTERACTIONS
SIP 15
A trophic chain as indicator of potential GM maize impacts:
disentangling the effects of ambiental variation
Ardanuy A, Albajes R
Universitat de Lleida, Agrotecnio Center, Rovira Roure 191, E-25198 Lleida, Spain
[email protected]
Tritrophic interactions can be used to monitor environmental change as multispecies assemblage
indicators. The choice of indicator or surrogate species and its characteristics has been widely
discussed topic in Genetically Modified (GM) crops field monitoring trials. An indicator species
or assemblage to be used in a monitoring program must (i) be relevant of the function to protect
(ii) have a proved capacity to detect differences between GM crop and its isogenic counterpart,
and also (iii) have a known baseline ambiental variation (temporal, spatial). We present the
leafhopper Zyginidia scutellaris as our candidate herbivore indicator of GM maize impacts. It
is the most abundant herbivore in maize fields throughout the season and probably it is the base
to build an indicator maize trophic web together with the main predator genus Orius spp. Both
species display good statistical power for detecting GM effects in Mediterranean conditions.
In this work we assessed how indicator populations respond to the ambiental variation both in
time and space. During three years we monitored in three agricultural regions the abundance of
Z. scutellaris and Orius spp. in commercial 5-7 maize fields (study sites per region and year) on
their population peak. Our results show that the variation in maize populations of Z. scutellaris
due to region is greater than the year-to-year variation. And that the year-to-year variation is
region dependent, meaning that for its nature a region may sustain more/less stable populations
over the seasons. Also, the recruitment of Orius spp. to maize fields differs between the three
study regions. Hence, these results point to the existence of a landscape mediated effect on the
indicator populations. To check this hypothesis the last two years of the study we characterized
the agricultural cover surrounding maize fields (0.5 and 1 km radius ) in two of the study regions
to determine the effect of landscape composition and configuration on the indicator species. Our
results show that the landscape variables that explain the species abundance are edge density
(kilometers of edge/ total area, positively correlated with abundance) and the proportion of semi
natural habitat present in the landscape (negatively correlated with the abundance) for both our
study species. This results will allow us to design an appropriate monitoring and surveillance
plan to ensure the detection of the possible negative impacts of growing new GM maize varieties
on the maize epigeal food web.
100
poster
P4
SIP 15
MULTITROPHIC INTERACTIONS
Does non-host damage affect Diaeretiella rapae behaviour
towards HIPV from Brassica nigra
Cascone P 1, Ponzio C 2, Gols R 2, Guerrieri E 1, Dicke M 2
1 National Research Council, the Institute for Plant Protection (IPP-CNR) - Via Università 100,
80055 Portici, Italy
2 Laboratory of Entomology, Wageningen University, P.O. Box 8031, NL-6700 EH
Wageningen, The Netherlands
[email protected]
Plants emit large amounts of compounds into the atmosphere called biogenic volatile compounds
(BVOC’s) in order to interact with the surrounding environment comprising the associated
community members such as other plants and animals. Plants are able to modulate their
BVOC production in response to different stimuli, such as biotic and abiotic stresses. In recent
years it has been demonstrated how their release specifically changes (quantitatively and/or
qualitatively) following different biotic stresses and this affects the response of higher trophic
levels. For instance, volatiles induced by herbivorous insects (while feeding or ovipositing on
the host plant) are exploited by their natural enemies, both predators and parasitoids, to locate
their victims, a mechanism referred to as indirect plant defence. However, in nature plants suffer
multiple stresses at the same time and this opens a virtually unexplored field of investigation. We
aimed at understanding how multiple stresses can affect the response of a natural enemy. The
multitrophic system studied was constituted by Brassica nigra (plant), the aphid Brevicoryne
brassicae (as representative of phloem suckers), the lepidopteran herbivore Pieris brassicae
(as representative of plant chewers) and Diaeretiella rapae, an endoparasitoid of B. brassicae.
We aimed at understanding if and how the behavioural response of the aphid parasitoid changes
when a plant is attacked simultaneously by its host (the aphid) and by the non-host (eggs laid
by butterflies and feeding caterpillars). Sap feeders and chewers are known to activate different
signal-transduction pathways in the plant leading to the production/release of different blends of
volatiles. The simultaneous attack by aphids and caterpillars could in fact disrupt the response of
the aphid parasitoid. However, we found that the presence of P. brassicae on an aphid-infested
plant did not affect the behavioural response of D. rapae. Indeed, more than the presence of a
non-host, it is the aphid host’s density that plays a role in the attractiveness of B. nigra plants
towards D. rapae.
P5
poster
P5
101
MULTITROPHIC INTERACTIONS
SIP 15
The role of dual herbivore attack on plant VOC emission and
egg parasitoid recruitment
Cusumano A 1,2, Ponzio C 2, Gols R 2, Weldegergis BT 2, Colazza S 1, Fatouros NE 2,
Dicke M 2
1 Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo viale delle
Scienze, 90128 Palermo, Italy
2 Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH Wageningen,
The Netherlands
[email protected]
Studies on semiochemical communication have demonstrated that egg parasitoids are able to
exploit volatile synomones emitted by plants in response to egg deposition of herbivorous hosts.
However, such studies have largely focused on single tri-trophic systems involving a plant,
an insect herbivore and its insect natural enemy. This simple approach overlooked that plants
growing in natural conditions are normally under multiple attacks by several species of insect
herbivores that could disrupt the attraction of the herbivores’ enemies as a result of modifications
of the induced volatile blend. In tri-trophic systems, it has been shown that the egg parasitoid
Trichogramma brassicae (Bezdenko) is able to locate its host Pieris brassicae L. by exploiting egg
deposition induced synomones emitted by Brassica nigra L. plants. In the Netherlands, B. nigra
plants can often be attacked by the non-host Brevicoryne brassicae L. and dual infestation by
P. brassicae and B. brassicae is common under field conditions. Dual trophic stresses can vary
in terms of herbivore density and localization (local stress = dual infestation on the same leaf;
systemic stress = dual infestation on different leaves). In this study we investigated if non-host
infestation can interfere with plant emission of egg deposition induced synomones and parasitoid
recruitment. Results indicated that T. brassicae attraction toward volatiles of B. nigra plants
attacked by the host P. brassicae and non-host is not only affected by the presence of the nonhosts, but also density and the stress localization of the non-host played a role.
102
poster
P6
SIP 15
MULTITROPHIC INTERACTIONS
Effect of dual biotic stress on plant volatile synomones
used by egg parasitoids
Moujahed R 1, Cusumano A 1, Salerno G 2, Frati F 2, Conti E 2, Peri E 1, Colazza S 1
1 Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo viale delle
Scienze, 90128 Palermo, Italy
2 Dipartimento di Scienze Agrarie e Ambientali, Università degli Studi di Perugia, Borgo XX
Giugno 74, 06121 Perugia, Italy
[email protected]
Studies on semiochemical communication have demonstrated that broad bean plant, Vicia faba,
emits volatile synomones induced by feeding and oviposition activities of the southern green
stink bug, Nezara viridula, which recruit the egg parasitoid Trissolcus basalis. However plants
growing in agro-ecosystems can be attacked by several herbivore species that could affect both
above and belowground plant tissues with possible consequences for parasitoid recruitment.
For example, broad bean plants can also be attacked by the leaf weevil, Sitona lineatus, and
simultaneous attacks by the southern green stink bug and the leaf weevil can occur in agroecosystems. The purpose of this work was to investigate the effects of dual biotic stresses, the
host N. viridula and the non-host S. lineatus, on V. faba volatile synomones that recruit T. basalis.
The response of wasp females to V. faba volatiles was investigated in a Y-tube olfactometer
testing the following treatments: (1) plant damaged by N. viridula feeding and oviposition; (2)
plant damaged by S. lineatus feeding; (3) plant mechanically damaged to resemble S. lineatus
feeding; (4) plants damaged by N. viridula feeding and oviposition and by mechanical damages;
(5) plants damaged by N. viridula feeding and oviposition and by S. lineatus feeding; (6); healthy
plants. Volatile organic compounds emitted from tested plants were also chemically analyzed
by Gas Chromatography – Mass Spectrometry (GC-MS). The results showed that dual biotic
stresses affect V. faba volatile synomones decreasing their attractiveness towards T. basalis.
Chemical analysis indicated qualitative differences between volatiles emitted by V. faba plants in
response to N. viridula feeding and oviposition and volatile emitted as consequence of dual insect
infestation. The ecological consequences of these results in terms of multi-trophic interactions
are discussed.
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Aphids and caterpillars damaging the same plant: olfactory
response of four aphidophagous insects to induced volatiles
França JF 1*, da Silva SEB 1*, Pareja M 2
1 Programa de Pós-Graduação em Entomologia, Universidade Federal de Lavras, Campus
Universitário, Caixa Postal 3037, CEP37200-000, Lavras, MG, Brazil
2 Departamento de Entomologia, Universidade Federal de Lavras, Campus Universitário,
Caixa Postal 3037, CEP37200-000, Lavras, MG, Brazil
* These authors contributed equally and should be considered joint first authors
[email protected]
Plants damaged by herbivores emit blends of volatile organic compounds (VOCs) that attract
the herbivore´s natural enemies. Until recently most work has focussed on systems involving
one plant, one herbivore and one natural enemy. In nature, plants can be simultaneously attacked
by several herbivore species, which can induce different defence responses in plants. These
defence responses can interact in complex ways, possibly affecting the attraction of natural
enemies of herbivores. The aim of our study was to understand how four different aphid
natural enemies respond to VOCs induced by aphids and how this is affected when the plant is
simultaneously damaged by a chewing herbivore. We used a model system based on Brassica
juncea (Brassicaceae), the aphid Myzus persicae (Hemiptera: Aphididae) and Plutella xylostella
(Lepidoptera: Plutellidae). We tested the response of three aphid predators - Ceraeochrysa
cubana, Chrysoperla externa (Neuroptera: Chrysopidae) and Cycloneda sanguinea (Coleoptera:
Coccinellidae) and the parasitoid Aphidius colemani (Hymenoptera: Braconidae) to odours of
B. juncea in a Y-tube olfactometer. The lacewing C. cubana did not respond to undamaged B.
juncea or to M. persicae-damaged B. juncea, while the ladybird C. sanguinea responded to
undamaged B. juncea but not to M. persicae-damaged plants. Therefore no further tests were
carried out with these two species. The lacewing C. externa showed a response to M. persicaedamaged plants but not to P. xylostella-damaged plants. When damaged simultaneously by
both M. persicae and P. xylostella, C. externa preferred the plant with multiple damage over
undamaged plants and over M. persicae-damaged plants. The parasitoid A. colemani responded
to M. persicae-damaged plants and plants damaged by the non-host P. xylostella. When damaged
by both M. persicae and P. xylostella, B. juncea attracted more parasitoids than undamaged plants,
but was not more attractive than M. persicae-damaged plants. Contrary to expectations, multiple
herbivory on B. juncea did not interfere with attraction of neither A. colemani nor C. externa,
being equally attractive to A. colemani and more attractive to C. externa than M. persicaedamaged plants. A. colemani responded to P. xylostella-damaged plants, demonstrating a lack
of specificity in responses to VOCs that is uncommon among aphid parasitoids. The other two
aphid predators showed no responses to induced B. juncea VOCs, highlighting how different
natural enemies can have different responses to herbivore damage. Further studies are being
carried out to characterise the VOC blend induced by the different types of damage on B. juncea.
Financial support: Fapemig (project CRA APQ 04256/10), CAPES
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Parasitoid foraging in multi-herbivore communities
De Rijk M 1, Engel B 2, Dicke M 1, Poelman EH 1
1 Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH, Wageningen,
The Netherlands
2 Department of Mathematical and Statistical Methods, Wageningen University, P.O. Box 100,
6700 AC, Wageningen, The Netherlands
[email protected]
Parasitic wasps, or parasitoids, are dependent on hosts for the development of their offspring.
Parasitoid eggs are laid in or on the host and the emerged parasitoid larvae use the host as their
food source. To find the host, female parasitoids use information from the environment. First,
to find the plant the herbivore host is feeding from, the parasitoid utilizes plant volatiles emitted
by the plant in response to herbivore feeding. Second, after finding the right plant, the parasitoid
uses host kairomones (e.g. frass, oral secretions) to locate the host on that plant. A natural or
agricultural environment normally consists of more than one plant individual or species and
more than one herbivore species. The parasitoid therefore is faced with a diverse environment
and consequently with a high information input both on plant volatile as on herbivore kairomone
level. Part of this information is produced by the presence of herbivores that are not suitable as
a host. These so-called non-host herbivores can alter plant volatiles and can produce distracting
kairomones. Different non-host herbivore characteristics (e.g. feeding guild, developmental
stage) and other herbivore factors (e.g. herbivore position on the plant, order of herbivore
arrival) could be of importance. This study aimed to elucidate the influence non-hosts have on
the foraging behaviour of a parasitoid. We used three experimental set-ups to study parasitoid
flight response towards the plant, parasitoid behaviour on the plant and the total parasitization
efficiency of the parasitoid.
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Escape and radiate:
have orchids escaped herbivory or insect ecologists?
Eubanks MD
Department of Entomology, TAMU 2475, Texas A&M University, College Station TX 77845
USA
[email protected]
Orchidaceae is the most species rich plant family on the planet. There are more than 25,000
species of orchids in over 800 genera. Orchids are cosmopolitan and live in habitats ranging from
tropical forests to grasslands. Orchids are renowned for their spectacular floral diversity and
intricate adaptation to pollinators. Adaptations unique to orchids include pollinia (tightly packed
masses of pollen that can be transported as a unit) and deceptive mating (orchid flowers mimic
other flowers, pollinator food, pollinator mates, etc.). Although evolutionary biologists have
long thought that there is a link between orchid pollination and orchid diversity, the distinction
between cause and effect has been debated. The most recent analyses of orchid diversification
and pollinator specialization suggest that diversification in orchids is the , not the consequence
of floral/pollinator specialization.
I propose that orchids have escaped from insect herbivory and that this has contributed
significantly to their diversification. I conduced extensive literature searches to test this hypothesis.
There is little evidence that insect herbivory is widespread or important in orchids or that there
are large radiations of insect herbivores associated with orchids. The lack of information about
orchids and insect herbivory strongly suggests that insect herbivory in orchids is relatively rare.
The key innovation associated with escape from insect herbivory could be novel allelochemistry,
novel orchid life histories that result in unpredictable and patchy local abundance, a combination
of orchid traits, or the relatively recent diversification of orchids (~ 50 Ma).
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Quantitative and qualitative constraints on development and
survival of a gregarious insect herbivore and its endoparasitoid
Fei M 1, Harvey JA 1,2 , Zhu F 3 , Malcicka M 2, Gols R 3
1 Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW),
Wageningen, The Netherlands
2 VU University Amsterdam, Department of Ecological Sciences, Amsterdam, The
Netherlands
3 Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands
[email protected]
Understanding the adaptive and evolutionary significance of group feeding (favoring this strategy
over a solitary lifestyle) in the Lepidoptera has attracted considerable discussion over many
years. Despite the obvious advantages of living in a group, there are many possible drawbacks
as well. One of them is that there is an increase in the level of intraspecific competition for
potentially limiting food resources. Variation in the spatial and temporal distribution of food
resources has thus long been considered as a factor affecting the efficacy of insect populations,
and in particular species in the Lepidoptera. Although some gregarious species attack plants (e.g.
trees) containing excess resources that can support hundreds, if not thousands of conspecifics
(effectively many broods), other species are specialists that attack short-lived ephemeral plant
species (weedy plants) with limited available biomass. In this situation, a single plant is incapable
of supporting the development (to adult) of a single brood. In these species, late-instar larvae
must usually disperse to find new food plants once their natal plant is exhausted.
To investigate the importance of sufficient food resources for survival of a gregarious
insect herbivore and its endoparasitoid wasp, we studied a naturally occurring wild species of
cruciferous plant in Holland, the black mustard Brassica nigra, the large cabbage white butterfly,
Pieris brassicae, and its gregarious endoparasitoid wasp, Cotesia glomerata. By periodically
starving healthy and parasitized caterpillars during their final (=5th) instar, we were able to
determine the critical point at which feeding is necessary to allow pupation or the successful
development of the parasitoids to egression. Survival to pupation in the herbivore and adult
emergence in the parasitoid increased with duration of food access. Moreover, the longer those
herbivores were allowed to feed, the larger were the adult parasitoids that emerged from them. By
contrast, development time was extended with increasing food access. In a semi-field experiment,
we released 25 parasitized and 25 unparasitized caterpillars on mustard plants placed singly or in
groups of 5 or 8 plants in open tents in natural vegetation. Two mustard plants were also placed
approximately 1.5 metres away in the corner of each tent. The number of caterpillars on the focal
plant(s) as well as on the corner plants was monitored daily from the third instar. When there
were 8 plants grouped together, most P. brassicae caterpillars remained on the plants until late in
the final instar, as there was sufficient plant biomass to sustain them. However, the caterpillars
completely defoliated single plants and were forced to search for the corner plants; whereas
some were able to locate them many were not. When there were 5 plants together, the duration
of caterpillar residency was intermediate. Survival in each cohort was independent of parasitism
treatment.
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Oak leaves – gall wasp. Conflict or cooperation?
Giertych MJ 1,2, Karolewski P 1
1 Polish Academy of Sciences, Institute of Dendrology; Parkowa 5, 62-035 Kórnik; Poland
2 University of Zielona Góra, Faculty of Biological Sciences, PL 65-516 Zielona Góra, Poland
[email protected]
Relations between gall-forming insects and plants are examples of the perfect obligatory
dependence of the insect on the plant. The insect, using yet unrecognized molecular mechanisms,
forces the plant to produce the gall, which provides shelter and an optimum food supply.
The presence of galls on leaves, especially as large as the gall of Cynips quercusfolii may be
detrimental to the plant. It remains an open question if this relationship benefits in any way the
plant. It is suggested that the presence of galls prolongs the leaf lifespan and reduces infestation
leaf by fungal pathogens1. We decided to test the hypothesis that the presence of galls on the
leaf can be beneficial to the plant. The aim of the study was to answer a few questions: Is the
photosynthetic activity of leaves with galls of C. quercusfolii limited? Does cutting the vein near
the galls reduce their development? Is it so that the presence of galls prolongs leaf lifespan? Does
the presence of galls reduce other damages caused by herbivore insects and fungal pathogens or
is this connected with changes of defense metabolites?
The study was conducted in Poland on two species of oak Quercus robur and Q. petraea
and the gall wasps from Cynipidae with particular focus on C. quercusfolii. We studied the effect
of mechanical damage of leaf veins on the growth of galls and the effect of galls on the efficiency
of the photosystem II. We analyzed leaf lifespan and the effect of occurrence of the galls of
Neuroterus and Cynips on other damages and on the presence of pathogens.
It was found that damage of the veins on both sides of galls restricts their growth, but the
gall supplied sufficient materials necessary for the completion of the development of the insects.
The survival rate in the variant of cut vein on both sides of the galls was 13.6% with an overall
average survival of about 27%. Leaf fragments partially cut off from the main vein by the presence
of the galls showed a few percent only but a significant decrease in the activity of photosystem
II. In these fragments, in both studied oak species we also found a significant increase of both
total soluble phenols and condensed tannins. We found no effect of galls C. quercusfolii on the
leaf lifespan. We have not found the presence of galls to cause an increase in the level of defense
metabolites in tissues of leaves, except for part of lamina lying between the gall and the edge of
the leaves. Also, there was no significant effect of the presence of Cynipidae galls on the degree
of damage to oak lamina caused by other insects. In contrast, the fungal pathogen (powdery
mildew) was significantly less on the leaves with galls.
The presence of individual galls on the leaves has little effect on the metabolism of the
leaf and is limited to a small fragment of the leaf blade. Beneficial for plants is the reduction of
infection by powdery mildew of leaves on which galls occur.
1 Stone GN, Schönrogge K, Atkinson RJ, Bellido D, Pujade-Villar J 2002. The population biology of oak gall wasp
(Hymenoptera: Cynipidae). Annual Review of Entomology 47: 633-668.
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Characterisation of the parasitoid complex
and of its inhibition during a psyllid outbreak
in an Australian native eucalypt woodland
Hall A, Cook J, Johnson S, Riegler M
Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797,
Penrith NSW 2751, Australia
[email protected]
Psyllids, also known as jumping plant-lice, are tiny sap-feeding insects belonging to the
hemipteran suborder Sternorrhyncha. Outbreaks of eucalypt psyllids regularly occur in Australian
woodlands, and the efficacy of their top-down control has been debated. The principal natural
enemies of psyllids are encyrtid parasitic wasps mainly belonging to the genus Psyllaephagus.
While parasitoids have been used effectively in biological control of Australian psyllids that have
invaded eucalypt plantations overseas, they have never been described to successfully regulate
native outbreaks. Perhaps the most likely reason for this is that, as the parasitoids are introduced
overseas, their own natural enemies, such as hyperparasitoids, do not occur in the invasive range.
The critically endangered Cumberland Plain Woodland (CPW) of Western Sydney,
Australia has recently experienced massive infestations by a psyllid species belonging to the
lace lerp genus of Cardiaspina (Hemiptera: Psyllidae). This psyllid outbreak, with a particular
focus on its parasitoid antagonists, has been surveyed over a 12 month period from 2013 to 2013.
This study aimed to assess the extent to which parasitism was able to regulate this outbreak and
to assess factors, such as climate, hyperparasitism and density dependence, that may have played
a role in preventing parasitism from regulating the outbreak.
Three encyrtid morphospecies were identified, two of which belong to the Psyllaephagus
genus. Molecular characterisation of mitochondrial and nuclear DNA markers confirmed three
distinct clades and will be used to recognise the parasitoids and hyperparasitoids and thus
facilitate the study of their ecological role. Although parasitism rates reached up to 40%, leaf
availability and not parasitism appeared to regulate this psyllid outbreak.
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Effects of early season defense induction in Lima bean plants
on late season tritrophic interactions on bean seeds
Hernandez-Cumplido J 1, Heil M 2, Benrey B 1
1 Laboratory of Evolutionary Entomology, Institute of Biology, University of Neuchâtel
(UNINE), Emile Argand 11, 2009 Neuchâtel, Switzerland.
2 Departamento de Ingeniería Genética, CINVESTAV Irapuato. Km. 9.6 Libramiento Norte,
Carretera Irapuato-León, 36821 Irapuato, Guanajuato, México
[email protected]
Herbivory-induced defense responses in plants typically involve the jasmonic acid pathway. The
consequences of the biochemical changes caused by the responses may linger on over time and
can affect insects that attack the plants later on during the season. These indirect, plant-mediated
interactions between insects have been well-documented for herbivores that feed on the same
plant tissues, as well as for interactions between below- and aboveground herbivores. Virtually
nothing is known about the effects of early season herbivore-induced defenses in the vegetative
plant tissues on the performance of herbivores that later feed on the plants’ reproductive parts. To
obtain such information we conducted a field study with Lima bean plants in its natural habitat
near the Mexican pacific coast. Plants were grown from seeds obtained from four populations
that differ in their levels of cyanogenic glucocides, and natural insect infestation rates. Potted
plants were first placed in large tents to prevent herbivory until they were three weeks old, after
which they were transplanted into a common garden arrangement. They were then either left
untreated, or they were damaged in the leaves and treated with jasmonic acid (JA). Towards
the end of the season, a subset of these plants were damaged in the pods and again treated with
JA to simulate herbivore attack. We measured effects of these treatments on plant performance
and on the incidence of infestation by bruchid beetles that oviposit on ripe bean seeds, as well
as the performance of parasitoids that attack the bruchid larvae. In laboratory assays it was
further confirmed that the hormone treatments significantly reduced the quality of the seeds as a
resource for beetle development.
Keywords: sequential herbivory, induced plant defense, host plant-mediated interactions,
parasitoids, beans
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Nitrogen and water availability to tomato plants triggers bottomup effects on the leafminer Tuta absoluta
Han P 1, Lavoir A-V 1,2, Le Bot J 3, Amiens-Deneux E 1, Desneux N 1
1 French National Institute for Agricultural Research (INRA), UMR1355, 400 Route des
Chappes, 06903, Sophia-Antipolis, France
2 University of Nice Sophia-Antipolis (UNS), UMR1355, 400 Route des Chappes, 06903,
Sophia-Antipolis, France
3 French National Institute for Agricultural Research (INRA), UR1115 PSH (Plantes et
Systemes de culture Horticoles), 84000 Avignon, France
[email protected]
[email protected]
This study examined the effects of various levels of nitrogen inputs (optimal, insufficient and
excessive) and water inputs (optimal, low drought and high drought) to tomato plants (Solanum
lycopersicum) on survival and development of an invasive tomato leafminer, Tuta absoluta
(Meytick) (Lepidoptera: Gelechiidae). Plant growth i.e. plant height and the number of nodes
declined under insufficient or excessive nitrogen treatment. Compared to optimal N, insufficient
N treatment decreased leaf N content and increased the carbon/nitrogen ratio (C/N) whereas
an excess of N had no effect on both leaf N content and leaf C/N ratio. Sub-optimal nitrogen
supplies, water treatments and their interactions, significantly reduced the leafminer survival
rate and slowed down its development. Together with the findings from three recent companion
studies, we assumed that a combination of changes in nutritional value and chemical defense
could explain these observed effects. Furthermore, our findings supported both the ‘‘Plant vigor
hypothesis’’ and the ‘‘Nitrogen limitation hypothesis’’.
Published in Scientific Report 2014: DOI: 10.1038/srep04455
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How do potatoes deal with biotic stress?
Unravelling a tripartite interaction between
a plant, a pathogen and a herbivore
Lazebnik J, Dicke M, van Loon JJA
Wageningen University
[email protected]
Plants are faced with a variety of different biotic stressors. Understanding how plants integrate
their responses to multiple stresses can provide valuable insights into ecological interactions
between members of the plant-associated community. Pathogenesis-related genes are known to
be involved in responses to biotrophic pathogen infection, as well as in responses to herbivory
by aphids. In this study, using RT qPCR we quantified the expression of the PR1 gene, a well
known gene up-regulated downstream of the salicylic acid pathway; and PAL, up-regulated
downstream. In order to understand the effects of resistance to the hemibiotrophic pathogen
Phytophthora infestans in a tripartite interaction, susceptible and genetically modified pathogenresistant potatoes (Solanum tuberosum) were subjected to aphid and P. infestans treatments,
and monitored for the expression of PR1, 48 hours after pathogen infection. Gene expression
was quantified in plants in response to attack by P. infestans in the initial (biotrophic) phase
of infection, in the presence or absence of aphid herbivory by Myzus persicae. Based on a
preliminary study, we expect that aphid infestation alone on susceptible plants will induce a
higher expression of PR1 than pathogen infection alone, and that the combination of the two
stresses is primarily mediated by which of these is first introduced and the intensity of infection
or herbivory. We found that upstream of the SA pathway, susceptible and resistant plants respond
differently to pathogen infection. Within susceptible potatoes, expression of PR1 is higher in
all treatments compared to control, dual attack showing highest expression (possibly additive).
In resistant potatoes, expression of PR1 does not change with pathogen infection, yet increases
for treatments with aphids. This is the first study of this kind unravelling the effects of multiple
stresses on potato plants, by measuring gene expression of specific stress-response genes in
potato.
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Consequences of intra-specific variation in aphid-induced plant
responses on herbivore and carnivore community composition
Li Y, Stam J, Dicke M, Poelman E, Gols R
Laboratory of Entomology, Wageningen University, P.O. Box 8031, NL-6700 EH Wageningen,
The Netherlands
[email protected]
Early season herbivory has been shown to have community-wide effects throughout the season1.
In a laboratory study, we have demonstrated that whether the performance of chewing herbivores
and their parasitoids is affected by previous infestation with a phloem-feeding aphid depends
on the identity of the leaf chewing insects2. However, it is unknown how early season aphidinfestation influences the biodiversity and abundance of herbivores and their natural enemies
during the growing season under field conditions. Carnivore performance and community
composition are affected by plant volatiles, host density, as well as host/prey quality in terms
of their nutritional value mediated by the host plants. Plant genotypes are known to harbour
different insect communities. Both constitutive and inducible plant defensive traits could drive
community dynamics. Previous studies have suggested that induced plant responses override
constitutive resistance in cabbage cultivars3. However, the induced responses of cultivated
plants may not necessarily reflect those of wild conspecific species that have evolved under the
process of natural selection. Here, we used wild cabbage populations (Brassica oleracea) that
differ in both constitutive and inducible defensive chemistry4. In a common garden experiment,
we investigated the effect of intra-specific variation in aphid-induced (Brevicoryne brassicae)
plant responses on herbivore and carnivore community composition. In addition, we monitored
parasitism dynamics of one common crucifer specialist Plutella xylostella in more details.
1 Poelman EH, Broekgaarden C, Van Loon JJ, Dicke M 2008. Early season herbivore differentially affects plant
defence responses to subsequently colonizing herbivores and their abundance in the field. Molecular Ecology 17:
3352-3365.
2 Li Y, Dicke M, Harvey J, Gols R 2014. Intra-specific variation in wild Brassica oleracea for aphid-induced plant
responses and consequences for caterpillar-parasitoid interactions. Oecologia 174: 853-862.
3 Poelman EH, Van Loon JJA, Van Dam NM, Vet LEM, Dicke M 2010. Herbivore-induced plant responses
in Brassica oleracea prevail over effects of constitutive resistance and result in enhanced herbivore attack.
Ecological Entomology 35: 240-247.
4 Gols R, Wagenaar R, Bukovinszky T, van Dam NM, Dicke M, Bullock JM, Harvey JA 2008. Genetic variation
in defense chemistry in wild cabbages affects herbivores and their endoparasitoids. Ecology 89: 1616-1626.
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Caught between Parasitoids and Predators – Survival of
Specialist Herbivore on Leaves and Flowers of Mustard Plants
Lucas-Barbosa D 1, Poelman EH 1, Aartsma Y 1, Snoeren TAL 1,2, van Loon JJA 1,
Dicke, M 1
1 Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands
2 Present address: Nickerson-Zwaan BV, PO Box 28, 4920 AA Made, The Netherlands
[email protected]
The survival of insect herbivores is typically constrained by food choice and predation risk. In
this study, we explored whether movement from leaves to flowers increases survival chances
of herbivores that prefer to feed on floral tissues. Combining field and greenhouse experiments,
we investigated whether flowering influences the behaviour of Pieris brassicae butterflies and
caterpillars and, consequently, herbivore survival in the field. In this context, we investigated
also if flowers of Brassica nigra can provide caterpillars refuge from the specialist parasitoid
Cotesia glomerata and from predatory social wasps.
By moving to flowers, caterpillars escaped from the parasitoid. Flowers are nutritionally
superior when compared with leaves and caterpillars develop faster when feeding on flowers.
However, late-stage caterpillars can be intensively preyed upon by social wasps, irrespective of
whether they feed on leaves or flowers. We conclude that flower preference by P. brassicae is
more likely driven by nutritional advantages and reduced parasitism on flowers, than by risks of
being caught by generalist predators.
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Latitudinal variation in herbivory: influences of climatic drivers,
herbivore identity and natural enemies
Moreira X 1,2, Abdala-Roberts L 2, Parra-Tabla V 3, Mooney KA 2
1 Institute of Biology, Laboratory of Evolutive Entomology, University of Neuchâtel, Rue EmileArgand 11, 2000 Neuchâtel, Switzerland
2 Department of Ecology and Evolutionary Biology, University of California, Irvine, California,
USA 92697
3 Departamento de Ecología Tropical, Campus de Ciencias Biológicas y Agropecuarias,
Universidad Autónoma de Yucatán, Apartado Postal 4-116, Itzimná, 97000 Mérida, Yucatán,
México
[email protected]
Although a number of investigations have concluded that lower latitudes are associated with
increases in herbivore abundance and plant damage, the generality of this pattern is still under
debate. Multiple factors, typically unaccounted for, may explain the lack of consistency in latitudeherbivory relationships. For instance, latitudinal variation in herbivore pressure may be shaped
entirely or not by climatic variables, or vary among herbivore guilds and herbivore species’ lifehistory traits. Additionally, the strength of top-down effects from natural enemies on herbivores
might also vary geographically and influence latitude-herbivory patterns. Here, we carried out
a field study where we investigated the concurrent effects of latitude and climate on herbivory
by a seed-eating caterpillar and leaf chewers, as well as parasitism associated to the former
across 30 populations of the perennial herb Ruellia nudiflora (Acanthaceae). These populations
were distributed along a 5° latitudinal gradient extending from northern Yucatan (Mexico) to
southern Belize (range in mean annual precipitation from 700 to 2900 mm, temperature from
24 to 26°C, and two-fold seasonality in precipitation), representing one-third of the species’
latitudinal distribution (14°N to 29°N) and the entirety and one-third of the precipitation and
temperature gradient of this species’ distribution (respectively). We found opposing latitudinal
gradients of seed herbivory and leaf herbivory, and this difference appeared to be mediated by
contrasting effects of climate on each guild. Specifically, simple regressions showed that whereas
seed herbivory increased at higher latitudes, with colder temperatures and drier conditions, leaf
herbivory increased toward the equator and with wetter conditions. Multiple regression showed
that latitudinal variation in seed herbivory was driven predominantly by variation in temperature
whereas latitudinal variation in leaf herbivory was unexplained by the climatic correlates of
latitude. Parasitism did not exhibit variation with latitude or climatic factors. Overall, these
findings underscore that the factors driving latitudinal clines in herbivory vary even among
herbivore species coexisting on the same host plant, and more generally that clinal patterns in
interaction strength may attenuate at higher trophic levels.
Keywords: diet breadth, feeding guild, herbivory, latitude, Lepidoptera, parasitism, precipitation,
Ruellia nudiflora, temperature, Yucatan Peninsula
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Plant sex effects on tritrophic interactions
Moritz KK 1, Björkman C 1, Parachnowitsch A 2, Tiitto RJ 3, Stenberg JA 1
1 Department of Ecology, Swedish University of Agricultural Sciences, Ulls väg 16, 756 51
Uppsala, Sweden
2 Department of Plant Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen
18D, 752 36 Uppsala, Sweden
3 Natural Product Research Laboratory, Department of Biology, University of Eastern Finland,
P.O.Box 111, 80101 Joensuu, Finland
[email protected]
Effects of plant sex on insect herbivory dioecious plants are well-studied, with a most common
finding of sex-biased herbivory, mostly toward male plants. However, plant sex effects on insects
at higher trophic levels, such as omnivorous predators, are poorly understood. Herbivores may
heavily impact a plant population or the yield in an agricultural system, while their predators
may reduce herbivory by suppressing the herbivore population. Thus, we investigate the effects
that plant sex has on a herbivore and its natural enemies.
The dioecious willow Salix viminalis is grown as a bioenergy crop in a number of European
countries including Sweden. Salix viminalis is susceptible to herbivory by Phratora vulgatissima,
the blue willow leaf beetle. We study S. viminalis, P. vulgatissima and two omnivorous predator
species with potential to suppress the herbivory exerted by P. vulgatissima.
Through field-based experiments we investigate whether male or female S. viminalis host
higher abundances of these herbivorous and omnivorous insects in an agricultural landscape.
Merely quantifying abundances would not explain the mechanisms behind the differences
observed, so we also perform experiments in controlled laboratory environments where we
test whether plant sex affects traits related to survival, consumption rates, development and
preferences.
Among those findings were that one omnivore had a higher survival through the nymphal
stages and higher chance to reach adulthood on female plants while no difference was found
for P. vulgatissima consumption rate, development time or body size. We also demonstrate how
concentrations of phenolic leaf compounds and volatile organic compounds in S. viminalis differ
between male and female plants and correlate to the results found in performance-related traits
and differences in abundances in the field experiment.
By compiling information of abundances and single traits, we want to help advancing
our knowledge of effects of sex in dioecious plants on insects at different trophic levels. The
results can be applied to field plantations of S. viminalis in order to promote natural enemies of
P. vulgatissima, by choosing to use the plant sex on which higher predation occurs.
116
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Do herbivore-induced allocation shifts explain contrasting
impacts of two invasive herbivores?
Orians CM 1, Gomez S 1.2, Soltis N 1, Gonda-King L 2, Preisser EL 2
1 Department of Biology, Tufts University, Medford, MA, USA
2 Department of Biological Sciences, University of Rhode Island, Kingston, RI, USA
[email protected]
Eastern hemlock (Tsuga canadensis), a foundation tree species native to the east coast of North
America, is being largely decimated by the invasive hemlock woolly adelgid (Adelges tsugae).
It is known that adelgid infestation decreases both needle production and photosynthesis1.
Interestingly, the negative effects on the host are reduced in the presence of a second invasive
hemipteran, the elongate hemlock scale2, (Fiorinia externa), which only kills severely stressed
trees3. In order to understand why these two herbivores from the same feeding guild have such
different impacts on their host we examined whole-plant allocation of carbon, nitrogen and
biomass, and sugar and protein content in response to individual attacks.
Young potted plants were labeled with 13CO2 (one pulse) and 15NH415NO3 (applied every
third day) to assess herbivore-induced shifts in resource allocation. After ~8 weeks (scale) and 12
weeks (adelgid) of insect feeding, plants were harvested and divided into different tissues: roots,
main stem, old branches, old needles, new branches and new needles. Biomass, C and N (labeled
and non-labeled), sugars and protein concentration were quantified.
Adelgid feeding altered whole-plant biomass and resource allocation. Adelgid-infested
plants had reduced biomass in young needles and increased biomass in old needles compared
to control plants. Overall, the effects of adelgid feeding was dependent on initial plant size
with the negative effects of aldegid being much stronger on smaller plants. Old needles (where
the adelgid was actively feeding) had also higher absolute accumulation of 15N, in contrast to
a reduction observed in newly produced needles. This suggests that adelgid feeding induces
allocation shifts diverting nitrogen away from growth. Adelgid feeding also induced a shift in
carbon allocation patterns. The observed increase in C allocation to stems and roots in adelgid
infested plants compared to controls further suggests a prioritization away from new growth
production. In contrast, scale feeding only marginally significantly decreased biomass and did
not affect resource allocation patterns. Scale feeding did slightly increase 15N(at-%) in root, stem
and marginally significant in new needles. These results highlight the more negative effects of
the adelgid might be explained by significant and rapid alterations in resource allocation patterns
which might be due to a combination of host manipulation by the insect and maladaptation by
the host. Overall changes in protein and starch were less striking and only significant for HWA
treated plants.
1 Gonda-King L, Gómez, S, Martin JL, Orians CM, Preisser EL 2014. Tree responses to an invasive sap-feeding
insect. Plant Ecology DOI 10.1007/s11258-014-0298-y.
2 Preisser EL, Elkinton JS 2008. Exploitative competition between invasive herbivores benefits a native host plant.
Ecology 89: 2671–2677.
3 McClure MS. 1980. Foliar nitrogen: a basis for host suitability for elongate hemlock scale, Fiorinia externa
(Homoptera: Diaspididae). Ecology 61: 72–79.
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Impact of leaf defences of Plantago lanceolata on performance,
nutrient utilization, and feeding behaviour
of a polyphagous caterpillar
Pankoke H, Gehring R, Müller C
Department of Chemical Ecology, Faculty of Biology, Bielefeld University,
Universitätsstraße 25, 33615 Bielefeld, Germany
[email protected]
Insects that are unadapted to iridoid glycosides often suffer from reduced growth rates, retarded
development or higher mortality1. Pharmacological approaches revealed that iridoid aglycones
denature and crosslink proteins after hydrolysis by β-glucosidases2,3. To test the hypothesis that
leaf β-glucosidases and iridoid glycosides form a dual defense system in plants, we used the model
organism Plantago lanceolata. To analyze the impact of functional plant β-glucosidases and leaf
age dependent concentrations of defense compounds on performance and nutrient utilization of
a polyphagous Lepidopteran species, young or mature freeze-dried leaves were incorporated into
artificial diets or given freshly to the larvae. We analyzed caterpillar performance over a period
of ten days, and determined the carbon and nitrogen content of the diets and feces. Furthermore,
dual choice feeding assays were performed to disentangle physiological effects from deterrent
effects of iridoid glycosides.
Caterpillars performed better on artificial diets than on fresh leaves, indicating that
functional plant enzymes interfered with caterpillar development. Moreover, larval growth
differed on artificial or fresh young leaf diets in comparison to mature leaf diets, suggesting
that leaf age dependent concentrations of defense compounds also affected insect performance.
On artificial diets, larval weight gain correlated positively to the amount of nitrogen that larvae
ingested. Yet, this correlation was not significant, when larvae fed fresh leaves. Shifts in the C/N
ratio indicated that only larvae fed fresh young leaves excreted more nitrogen relative to carbon,
while larvae on the other diets excreted more carbon relative to nitrogen. Our results thus suggest
that high β-glucosidase activities and high concentrations of defense compounds in fresh young
leaves3 confer resistance to P. lanceolata against unadapted herbivores.
Besides the physiological impact of leaf defense compounds on caterpillar performance,
reduced consumption rates of the larvae could be related to the deterrent effect of polar defense
compounds such as the iridoid glycoside catalpol. We thus conclude that P. lanceolata has a dual
defense system consisting of plant β-glucosidases and iridoid glycosides that besides effectively
mediating consumption rates reduces the nutrient utilization of unadapted herbivores in vivo.
1 Dobler S, Petschenka G, Pankoke H 2011. Coping with toxic plant compounds – The insect’s perspective on
iridoid glycosides and cardenolides. Phytochemistry 72: 1593-1604.
2 Konno K, Hirayama C, Yasui H, Nakamura, M 1999. Enzymatic activation of oleuropein: a protein crosslinker
used as a chemical defense in the privet tree. PNAS 96: 9159-9164.
3 Pankoke H, Buschmann T, Müller 2013. Role of plant β-glucosidases in the dual defense system of iridoid
glycosides and their hydrolyzing enzymes in Plantago lanceolata and Plantago major. Phytochemistry 94:
99‑107.
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Sequential damage by two aphid species on the same plant
enhances attraction of an aphid natural enemy
Oliveira MS 1, Pareja M 2
1 Programa de Pós-Graduação em Entomologia, Universidade Federal de Lavras, Campus
Universitário, Caixa Postal 3037, CEP37200-000, Lavras, MG, Brazil
2 Departamento de Entomologia, Universidade Federal de Lavras, Campus Universitário,
Caixa Postal 3037, CEP37200-000, Lavras, MG, Brazil
[email protected]
When damaged by herbivores, plants activate specific defence responses that cause changes in the
plants’ volatile organic compound (VOC) profile. These changes can be specific to each herbivore
species, and natural enemies can use these VOCs to find plants attacked by their preferred prey.
In nature plants are attacked by a suite of herbivores simultaneously or in sequence. The aim of
our study was to understand how an aphid natural enemy responds to plants damaged by two
aphid species either individually, simultaneously or in sequence. We used the model system
based on sweet pepper, Capsicum annuum (Solanaceae), the two aphids Myzus persicae and
Aphis gossypii (Hemiptera: Aphididae) and the aphid predator Cycloneda sanguinea (Coleoptera:
Coccinellidae). We tested the response of C. sanguinea in a Y-tube olfactometer to different
combinations of damage to sweet pepper. C. sanguinea did not show a response to undamaged
sweet pepper, but preferred sweet pepper damaged by either aphid individually over undamaged
plants. When plants damaged by M. persicae were compared to plants damaged by A. gossypii,
C. sanguinea did not show a preference for either plant. C. sanguinea responded equally to plants
damaged by a single aphid and plants damaged simultaneously by both aphid species. When the
plant was damaged sequentially, C. sanguinea preferred plants damaged by A. gossypii followed
by M. persicae compared to plants damaged only by A. gossypii, but it did not show a preference
for any of the other sequential damage combinations over plants with single-species damage.
We can conclude that multiple-species damage did not interfere with attraction of C. sanguinea
to induced VOCs. Furthermore we observed that, in one case, attraction of C. sanguinea was
enhanced when plants were sequentially damaged by the two species compared to single-species
damage. Being a generalist aphid predator, C. sanguinea is likely to be responding to general
aphid-induced VOCs, whose emission might be enhanced when more than one species attacks
the plant. To elucidate this, the VOC profile of sweet pepper is being characterised. Aphids might
therefore be exposed to greater predation risk when feeding on plants previously damaged by
another aphid species. Further studies with more specialised aphid natural enemies are needed
to determine if host range affects these responses to plants damaged by several aphid species.
Financial support: Fapemig (project CRA APQ 04256/10), CAPES (studentship to MSO)
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Food quality mediates fitness correlates of a potentially invasive
insect pest: effects of plant phenolics and nutrients
on Anastrepha ludens (Diptera: Tephritidae)
Pascacio-Villafán C 1, Williams T 1, Sivisnki J 2, Birke A 1, Aluja M 1
1 Red de Manejo Biorracional de Plagas y Vectores, Instituto de Ecología, A.C. (INECOL),
Xalapa, Veracruz, Mexico
2 Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, U.S.A.
[email protected]
The Mexican fruit fly, Anastrepha ludens (Loew), is a tropical polyphagous pest of fruiting
crops that could potentially invade temperate areas under current global climate change. Recent
work suggests that the expansion of A. ludens to novel hosts could be hindered by the presence
of phenolic compounds mixtures in potential host fruit. We have been investigating the effects
of a variety of flavonoids and phenolic acids on diverse indicators of A. ludens fitness, using
an artificial diet treated with mixtures of such compounds. Phenolics such as (+)-catechin,
chlorogenic acid or p-coumaric acid, alone or in combinations, can influence larval weight
and development time of A. ludens, and are presumably acting like antinutritive/antidigestive
compounds. Given that interactions between phenolics and nutrients are likely, we suspect that
the effects of the phenolics we tested may have been damped by the super-optimal nutrient
content of the artificial diet.
With this in mind, we modified the nutritional content of an artificial diet of A. ludens by
varying the proportion of ingredients source of protein and carbohydrate. We tested 17 replicated
artificial diets with varying proportions of dried yeast and sugar, and examined the survival,
development time, pupal weight, sex ratio and resistance to starvation of A. ludens reared on
them. Polynomial models were fitted to the data, and validation experiments were conducted to
assess the predictive capabilities of the models. With the exception of sex ratio, all the response
variables evaluated were significantly affected by dried yeast and sugar mixtures in the diet. No
survival was observed in diets with high carbohydrate content (sugar proportion ranging from 88
to 100%). A trade-off between larval development time and the resistance of adults to starvation
was observed, with larvae developing faster and adults living shorter periods when larvae fed on
diets with high protein content. Overall, the models proved useful for predicting the response of
A. ludens to varying proportions of nutrients in its diet.
These results contribute to further understanding of the factors that influence the distribution
of among host plant. Ongoing work is exploring the interactions between phenolic compounds
and nutrient levels in the diet, and the effect of phenolics mixtures on higher trophic levels,
namely parasitoids.
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Drosophila suzukii atropine consumption a prevention
against parasitoids?
Poyet M 1,2, Eslin P 2, Gibert P 2
1 Laboratoire de Biométrie et Biologie Evolutive, UMR CNRS 5558, Université Lyon 1,
F-69622, Villeurbanne cedex, France
2 Laboratoire de Bio-écologie des Insectes Phytophages et Entomophages, FRE-CNRS 3498
EDYSAN, Université de Picardie Jules Verne, F-80037, Amiens cedex, France
[email protected]
Interactions between phytophagous and entomophagous insects can be influenced by the first
trophic level: the herbivore’ host plant. For instance, many studies have shown the role of plant
chemistry on the host location and acceptance behavior of natural enemies of insect herbivores.
This kind of effect is often positive for the parasitoid by increasing its foraging success and
efficiency1. However, an increasing number of studies have shown a negative impact of host
plant chemistry on parasitoid fitness2. This impact can be either direct when the developing
parasitoid meets the plant toxin in this host, or indirect when the parasitoid fitness suffers due to
host quality.
Drosophila suzukii is a successful invasive species native from Asia that has been rapidly
spreading in Europe and the United States since 2008. Unlike most other Drosophila species that
lay eggs on rotting fruit, D. suzukii infests fresh fruits before maturity. Our previous work has
highlighted the great polyphagia of D. suzukii against a wide range of wild plants, some of them
known for their high levels of alkaloids and their entomotoxic properties. Atropa belladonna in
particular is known for its high content of atropine (a tropanique alkaloid). Besides, we found
that D. suzukii is particularly resistant to Europeans larval endoparasitoid, while pupal parasitoids
development is possible3.
The objective of this study is to investigate the possible effects of atropine consumption
by D. suzukii on its interaction with several parasitoid species. Three parasitoids were used:
two European parasitoids, a larval parasitoid (Leptopilina heterotoma) and a pupal parasitoid
(Trichopria drosophilae) and larval Japanese parasitoid (Asobara japonica) a sympatric enemy
of D. suzukii. Our results show that the development on a medium supplemented with atropine
allows D. suzukii to increase its resistance against all parasitoids and has a negative effect on the
fitness of the parasitoids.
1 Ode PJ 2006. Plant chemistry and natural enemy fitness: effects on herbivore and natural enemy interactions.
Annual Review of Entomology 51: 163–185.
2 Singer MS, Mace KC, Bernays EA 2009. Self-medication as adaptive plasticity: increased ingestion of plant
toxins by parasitized caterpillars. PLOS ONE 4 : e4796.
3 Chabert S, Allemand R, Poyet M, Eslin P, Gibert P 2012. Ability of European parasitoids (Hymenoptera) to
control a new invasive Asiatic pest, Drosophila suzukii. Biological control 63: 40-47.
P25
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Global Climate Change and Aboveground-Belowground
Interactions in Lucerne
Ryalls JMW, Riegler M, Moore BD, Johnson SN
Hawkesbury Institute for the Environment, University of Western Sydney, Australia
[email protected]
Interactions between above- and belowground herbivores have been prominent in the field of
aboveground-belowground ecology from the outset, although little is known about how climate
change affects these organisms when they share the same plant. Additionally, the interactive
effects of multiple factors associated with climate change such as elevated temperature (eT) and
elevated atmospheric carbon dioxide (eCO2) are untested. We investigated how lucerne (Medicago
sativa) root damage by biotic agents (e.g. nodule herbivory by the lucerne weevil, Sitona
discoideus) and abiotic means (e.g. simulated herbivory) affected the pea aphid (Acyrthosiphon
pisum) under eT and eCO2. Sitona discoideus larvae, which feed on root nodules housing N2fixing rhizobial bacteria, are significant pests of lucerne. Root damage had a weak negative effect
on aphid performance, potentially due to impairment of nitrogen acquisition because nodules
were damaged. eT severely reduced root nodulation by 43%, whereas eCO2 promoted nodulation
by 56%, but only at aT. Effects of eT and eCO2 on root nodulation were mirrored by weevil
development success; eT and eCO2 reduced and increased weevil emergence, respectively. These
results demonstrate that eT can negate the effects of eCO2 on lucerne nodulation and herbivory
belowground, an important consideration for determining future outcomes of climate change.
122
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MULTITROPHIC INTERACTIONS
Response of the zoophytophagous predators
Macrolophus pygmaeus and Nesidiocoris tenuis to volatiles
of uninfested plants and of plants infested by conspecifics
Silva DB 1, van Loon JJA. 2, Bueno VHP 1, van Lenteren JC 2
1 Department of Entomology, Federal University of Lavras, Brazil
2 Laboratory of Entomology, Wageningen University, The Netherlands
[email protected]
Plants are faced with a tradeoff between on the one hand growth, development and reproduction
and on the other hand defense against environmental stresses. They have evolved a high
diversity of constitutive and induced responses to attack, including the systemic emission of
herbivore-induced plant volatiles (HIPVs). An unresolved question is whether the composition
of the volatile blends induced by zoophytophagous predators species is attractive to their
conspecifics and if the volatiles differ consistently enough to indicate not only that the plants are
infested by predators, but also the identity of the predator species. Feeding on tomato plants by
zoophytophagous Miridae (Hemiptera) may cause the development of necrotic rings on the stems.
The objective of our study was to investigate the orientation mechanisms used by two important
mirid predators (Macrolophus pygmaeus Rambour and Nesidiocoris tenuis (Reuter)) in finding
their conspecifics and whether they cause damage to tomato plants. In Y-tube olfactometer
experiments, the behavioral responses of naïve female predators were tested to volatiles emitted
by uninfested tomato plants, and herbivore-induced plant volatiles (HIPVs) from tomato plants
infested with N. tenuis and M. pygmaeus. N. tenuis females were only attracted by plants infested
by M. pygmaeus (P = 0.050). M. pygmaeus was only attracted to tomato plants infested by
conspecifics (P = 0.043). The number of necrotic rings on the stem was recorded after 10 days of
the predators’ release in the cages, the number of necrotic rings was much higher after feeding by
N. tenuis reaching around 19.5 per plant, whereas the average number of necrotic rings made by
M. pygmaeus was 2.4 per plant. Further studies will be conducted with the objective to identify
the compounds released from the tomato plants infested by these predators and and to possibly
identify the implications for biological control of herbivorous insects on tomato.
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Harmonia axyridis and coccinellids in central Europe
Honek A 1, Martinkova Z 2, Skuhrovec J 2
1 Department of Entomology, Crop Research Institute, Prague, Czech Republic
2 Department of Plant Ecology and Weed Science, Crop Research Institute, Prague, Czech
Republic
[email protected]
Harmonia axyridis is an invasive coccinellid species recently spreading in Europe. After
colonizing a new territory it quickly becomes dominant species of coccinellid community. It
decreases abundance of native species apparently because of intraguild predation. We tested this
prediction in central Europe two years after arrival of H. axyridis.
In this poster we address three theses: (a) In 2008, two years after its arrival, H. axyridis
became dominant at some habitats; (b) other coccinellid species became rare already before the
arrival of H. axyridis; and (c) H. axyridis in fact influenced little the domestic aphidophagous
coccinellid species.
In central Europe abundance of H. axyridis varied according to habitats with a tendency
to prefer trees. Herbaceous stands were occupied when aphids were abundant. Coccinellid
species (including dominant Coccinella septempunctata and Adalia bipunctata) became less
abundant since 1990s. Changes in agriculture practices and land use may contribute to this
trend. In particular years before arrival of H. axyridis diversity of coccinellid community (N of
species, Shannon index H) was positively correlated with total coccinellid abundance. After its
arrival in 2008, H. axyridis slightly increased diversity of coccinellid community because overal
abundance of native coccinellids was low.
Two years after its introduction, Harmonia axyridis became dominant species on trees but
remained less abundant on wild herbs and crops. Abundance of many species of coccinellids
decreased already before the arrival of H. axyridis. Immediately after its arrival H. axyridids
did not negatively influence diversity of coccinellid communities and decrease abundance of
particular domestic species.
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Phenotypic divergence in an invasive plant:
potential for adaptation to insect biocontrol?
Stastny M, Sargent R
Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada
[email protected]
A key hypothesis to explain the success of invasive plants invokes their release from natural
enemies, giving them an ecological advantage over their competitors in the new range, and
potentially leading to evolutionary changes, such as the relaxation of defences against herbivores.
However, renewed selection pressures in this unique ecological context may arise when the
interactions with their natural enemies are re-established through biological control. We have
investigated phenotypic divergence and the potential for rapid adaptation to a specialist insect
herbivore in a widespread wetland invasive species, purple loosestrife (Lythrum salicaria).
We studied plant growth and responses to herbivory in 17 Lythrum populations from eastern
Ontario, Canada, some of which have been exposed to the Chrysomelid leaf beetle, Galerucella
calmariensis, since its release in the region as a biocontrol agent (early 1990s), while others
have been exposed to it for a shorter period of time, or have not yet come in contact with
this herbivore. In a two-year common garden and in complementary greenhouse studies, we
examined their growth traits, phenology, resistance, regrowth ability, and reproduction, under
varying intensity of Galerucella herbivory. Our study revealed substantial among-population
variation in plant growth and responses to herbivory, and the strength of selection on plant traits
due to herbivory, partly mediated through phenology. These differences highlight the potential
for evolutionary changes due to selection imposed by specialist herbivory. However, the overall
differences among the populations with versus without a recent history of Galerucella were
relatively minor, suggesting that little adaptation or genotype sorting has occurred since the
release of biocontrol. We examine the possibility of further phenotypic divergence among the
populations in the context of biocontrol.
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Predator hunting mode and habitat domain of two predators
sharing a leaf beetle
Stephan JG, Stenberg JA, Björkman C
Swedish University of Agricultural Sciences, Department of Ecology, Ulls väg 16,
75651 Uppsala, Sweden
[email protected]
Predators drive food web dynamics and structures communities that mostly consist of several
predators and the questions are if and how they interact and what are the consequences for a shared
prey. Hunting mode and habitat domain of predators are identified to shape these consequences
for that prey and the interactions among predators. The here utilized willow - leaf beetle omnivorous bug system is well-known with the blue willow leaf beetle (Phratora vulgatissima)
preferentially feeding in the shoot canopy but migrating to the lower shoot part for oviposition.
Among the most important predators in natural systems and willow short rotation coppies are
two Heteroptera with different foraging behaviors: Orthotylus marginalis that shows a `find and
stay´ hunting mode while Anthocoris nemorum shows a `run and eat´ behavior. The herbivores
and one omnivorous (A. nemorum) host acceptance and performance depend on the Salix species
making different Salix species differently suitable. Here we investigated if egg survivals within
larger herbivore clutches, that are generally believed to have higher single egg survival compared
to small clutches due to the dilution effect, depend on the predator behavior. We also investigated
the habitat domain of both predators to further shed light on the fact that both predators do not
interact negatively. We pinned differently sized egg clutches on four different Salix genotypes
on different vertical positions on plant shoots, released either of the predators and measured
the proportion of surviving eggs within a clutch. We found that bigger herbivore egg clutches
are only advantageous if confronted with the mobile A. nemorum and not if confronted with a
predator that finds and consumes all eggs immediately. Both predators showed different habitat
domains: A. nemorum preferred to hunt in the plant canopy, while O. marginalis consumed more
eggs in the lower plant part. The bottom-up effect of plant genotype on the predation was only
relevant for A. nemorum that consumed slightly more eggs on a genotype that offers suboptimal
plant food. The results show that predator behavior is important for the reproductive success of
the leaf beetle and that one behavior selects for larger clutches while the other does not. Both
predators seemed to share the plant shoots which could, in addition to the different foraging
modes, further explain the neutral interspecific relationship.
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The role of pyrrolizidine alkaloids on the performance
of generalist and specialist invertebrate herbivores
in Jacobaea species
Wei X 1, Vrieling K 1, Mulder PPJ 2, Klinkhamer PGL 1
1 Plant Ecology & Phytochemistry, Institute of Biology, Leiden University, Sylviusweg 72,
P.O. Box 9505, 2300 RA, Leiden, The Netherlands
2 RIKILT-Wageningen UR, Wageningen University and Research Center, P.O. Box 230,
6700 AE, Wageningen, The Netherlands
[email protected]
Plants produce a diversity of secondary metabolites (SMs) to protect themselves from specialist
and generalist herbivores. Generalist herbivores are reported to be deterred by SMs while
specialist herbivores are thought to be adapted to SMs and even sequester them for their own
defense. They can use SMs as host plant recognition, feeding and oviposition cues. Plants are
assumed to face an evolutionary dilemma from contrasting effects of generalist and specialist
herbivores on SMs. To test this hypothesis, two bioassays were performed with a series of
F2 hybrids from Jacobaea species segregating for their pyrrolizidine alkaloids (PAs), using a
specialist herbivore flea beetle (Longitarsus jacobaeae) and a common generalist herbivore slug
(Deroceras invadens). The hybrids were derived from a cross between Jacobaea vulgaris and
Jacobaea aquatica. Our study demonstrated that slug feeding damage was negatively correlated
with the concentration of total PAs and that of senecionine-like PAs while the flea beetle showed
no correlation between feeding damage and PAs. There was negative correlation between slug
and flea beetle feeding damage. In addition, flea beetle feeding was positively correlated with
leaf fresh weight. Therefore, we concluded that the slug, a generalist herbivore was deterred by
senecionine-like PAs while the flea beetle, a specialist herbivore was adapted to PAs in its host
plant. We will compare our data with previous herbivores tested in the same system with the
same set of genotypes and give an overview for the interactions between herbivores and PAs in
Jacobaea plants.
P31
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127
MULTITROPHIC INTERACTIONS
SIP 15
Synergistic roles of plant volatiles and sex pheromones
in mate finding by parasitoids
Xu H, Desurmont G, Laplanche D, Degen T, Turlings T
Laboratory of Fundamental and Applied Research in Chemical Ecology (FARCE), Institute of
Biology, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland
[email protected]
Plant volatiles are important foraging cues for many adult insects. This is particularly true for
parasitoids, which are known to locate their herbivorous hosts with the use of plant volatiles that
are specifically released upon herbivory. Mate finding in parasitoids is assumed to be mainly based
on sex pheromones. Here, we tested whether herbivore-induced plant volatiles (HIPVs) may also
be used for mate finding in parasitoids, as is the case for several herbivorous insects, in particular
beetles. Odour-mediated foraging behaviour of two braconid wasps, Cotesia glomerata (L.) and
Microplitis mediator (Haliday), was studied in six-arm olfactometers. Females and males of
both species were strongly attracted by HIPVs, independent of whether they were virgin or not.
Volatiles from undamaged plants also attracted males of both species, as well as mated females of
C. glomerata. Virgin females and unmated males of M. mediator do not seem to use volatilizing
pheromones to attract each other, except in the presence plant volatiles. In this species the release
of pheromones by virgin females appears to be triggered upon the detection of plant volatiles,
either from plants damaged by the hosts or from intact plants. Virgin females of C. glomerata
consistently release a sex pheromone, but this is only attractive to males at relatively short range,
whereas plant volatiles are attractive at longer distances. To our knowledge, ours is the first
study to specifically investigate plant volatiles and sex pheromones in mate finding strategies of
parasitoids. We conclude that both cues work in synergy and that plant volatiles are used by both
parasitoid species as cues to locate mates, especially at relatively long distances.
128
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P32
SIP 15
MULTITROPHIC INTERACTIONS
ZJU-93 induces susceptibility in rice to brown planthopper
Nilaparvata lugens (Stål)
Yu ZN, Wang WW, Lou YG
National Key Laboratory of Rice Biology, Institute of Insect Science, Zhejiang University,
Hangzhou 310029, China
[email protected]
Synthetic chemical elicitors of plant defense have been touted as a powerful means for sustainable
crop protection. To discover these chemical elicitors, we screened a number of compounds using
an established high-throughput chemical genetics screening system, and finally we identified ZJU93 as a potential elicitor. By combining chemical and transcriptional analysis, and bioassay, we
revealed that ZJU-93 could enhance transcript levels of defense-related genes, such as OsMPK3,
OsWRKY70, OsHI-LOX and OsHI-ACS, and concentrations of jasmonic acid and ethylene in rice
plants. On the other hand, ZJU-93 reduced the transcript levels of OsHI-ICS, a gene encoding
a key enzyme in the production of salicylic acid (SA), and repressed the biosynthesis of SA
and H2O2. The decreased SA and H2O2 pathways increased susceptibility of rice to the brown
planthopper (BPH) Nilaparvata lugens (Stål): adult BPH females preferred to lay more eggs on
plants treated with ZJU-93 over control plants, and the hatchability and developmental duration
of eggs on plants treated with ZJU-93 was higher and shorter, respectively, than those on control
plants. ZJU-93 had no direct influence on the behavior and performance of BPH. These results
suggest that ZJU-93 was a potential chemical elicitor, which may be applied in the management
of BPH as a component of push-pull strategy.
P33
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129
Pollination
POLLINATION
SIP 15
The interplay between pollinator attraction and indirect defense:
the impact of Brassica rapa floral volatiles on herbivore-induced
volatiles and attractiveness to natural enemies
Desurmont GA, Turlings TCJ
University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
[email protected]
The role of plant ontogeny on investment in direct defense against herbivores is well accepted,
but how the transition from the vegetative to the reproductive stage affects indirect defense (i.e.
attraction of the natural enemies of plant attackers) has been little explored. Here, we combined
behavioral bioassays in olfactometers and chemical analyses to determine whether the presence
of floral volatiles of Brassica rapa plants affects attraction of two natural enemies: Cotesia
glomerata and Hyposoter ebeninus, larval parasitoids of the herbivore Pieris brassicae.
Pieris-infested plants were always more attractive to parasitoids than control plants,
independently of plant developmental stage. The relative attractiveness of Pieris-infested plants
depended on the developmental stage of B. rapa: Pieris-infested plants were more attractive at
the pre-flowering stage than at the vegetative stage, and more attractive at the vegetative stage
than at the flowering stage. Chemical analyses revealed that herbivore-induced leaf volatiles are
strongly reduced in flowering plants. The direct addition of synthetic floral volatiles decreased
the attractiveness of vegetative B. rapa plants to parasitoids, showing a direct interference effect.
Our results show that putative indirect defense traits are affected by plant development,
and are reduced during B. rapa reproductive stage. The effects of ontogenetic shifts in resource
allocation on the behavior of members of the third trophic level need to be explored further and
generalized to different classes of natural enemies.
130
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P34
SIP 15
POLLINATION
Impact of Changing Pollinator Environments on the Evolution
of Plants
Gervasi DDL, Schiestl FP
Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, 8008 Zürich,
Switzerland
[email protected]
Selection mediated through pollinators played a key role in floral adaptation and reproductive
isolation of plants. Although the importance of pollinator-driven selection on plant evolution
cannot be neglected, it has never been demonstrated in an experimental approach where
the pollinator environment has been manipulated. Thus the details of these processes still
remain little understood. The aim of this study is to investigate pollinator-driven selection by
experimentally changing the pollinator environments. Specifically we investigate the effects of
different pollinators on the evolution of floral traits and plant reproductive success over several
generations. We use Brassica rapa (Wisconsin rapid cycling) as model plant with its generalized
pollination system and short generation time. As pollinators we use the bumblebee, Bombus
terrestris, and the hoverfly, Episyrphus balteatus. In our study we found that bumblebees and
hoverflies differ in the selection they impose on floral traits. The strength of selection on the
floral traits also varies significantly between the two pollinators, which lay the foundation for
divergent evolution in the plants. We observed strong positive selection on plant height and
flower number in bumblebees over several generations while hoverflies imposed no selection
on these traits. In terms of evolutionary response we observed in bumblebee-visited plants an
increase in plant height and flower number after 5 generations. Additionally the reproductive
success of the plants differed significantly; bumblebee pollinated plants had a significantly
higher reproductive success than hoverfly pollinated plants. After 5 generations only hoverfly
pollinated plants showed a significant increase in reproductive success indicating adaptations
to this type of pollinators have evolved. This study thus shows for the first time the effects of
changing pollinators on plant evolution in an experimental approach over several generations.
sentation
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131
POLLINATION
SIP 15
Floral scents in Catasetum: do scent patterns predict pollinating
orchid bee genera?
Milet-Pinheiro P 1, Kaiser R, Navarro DMAF 2, Dötterl S 3, Gerlach G 4
1 Institute of Experimental Ecology, University of Ulm, Germany
2 Departamento de Química Fundamental, Federal University of Pernambuco, Brazil
3 Department of Organismic Biology, University of Salzburg, Austria
4 Botanischer Garten München-Nymphenburg, Germany
[email protected]
The orchid genus Catasetum comprises about 170 perfume-producing species pollinated
exclusively by euglossine male bees. The floral scent bouquets vary considerably among species
and seem to play a pivotal role in pollinator shifts and speciation. Here, we used literature and
own data on the scent chemistry of 34 Catasetum species to test whether scent patterns predict
pollinating euglossine genera. The species emit in total 264 compounds, mainly monoterpenes (96
compounds), aromatics (68), and sesquiterpenes (25). The bouquet of a single species is normally
composed of a few dominant compounds (responding to ≥ 50% of the total scent discharge) and
several minor ones. Comparative and multivariate analyses of relative scent patterns showed that
the Catasetum species group according to pollinator genera, i.e. Eulaema, Euglossa or Eufriesea,
and that scent pattern differed significantly between groups. The perfume bouquet of species
pollinated by Eulaema and Euglossa showed a high dissimilarity (88%) and five compounds
responded for about 70% of this dissimilarity. (E)-carvone epoxide and benzyl acetate were
dominant compounds in the scent bouquet of species pollinated by Eulaema, while eucalyptol,
myrcene, and ipsdienol were dominant in the species pollinated by Euglossa. The median relative
amount of these five compounds differed significantly between species pollinated by Eulaema
and Euglossa. We avoided comparisons with the group of species pollinated by Eufriesea,
since this group was composed of only two species that did not show a clear scent pattern. We
conclude that the pattern of floral scents predict the genus of euglossine pollinator (i.e. Eulaema
and Euglossa), which suggests that the different bee genera have different olfactory preferences
for volatiles and that the plants adapt to the preferences of one of the bees. Our data also suggest
that plants pollinated by euglossines do not emit one specific type of scent but that different scent
patterns are subsumed under the euglossine bee-perfume orchid pollination syndrome.
Key words: Catasetum, euglossine bees, perfume-producing plants, pollination
132
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P36
SIP 15
POLLINATION
Thermogenesis and the chemical ecology of pollination
in endemic Australian Araceae
Miller RE 1, Farnier K 2, Barnes JC 3, Grant NM 3, Robinson SA 3, Steinbauer MJ 2
1 Department of Geography and Resource Management, University of Melbourne, Burnley
Campus, Richmond, Victoria 3121, Australia
2 Department of Zoology, La Trobe University, Melbourne, Victoria 3086, Australia
3 School of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
[email protected]
Thermogenesis is a trait usually associated with mammals and birds; however it also occurs
in some flowers. Thermogenesis in flowers is assumed to be of importance in the pollination
biology of these species, by enhancing scent volatilisation, and/or by the provision of a thermal
reward to insect pollinators. Heating may also be important for floral development. Despite the
ecological significance of thermogenesis in plant-pollinator interactions, little is known about
the prevalence of thermogenesis in the Australian flora. Further, the pollination and chemical
ecology of Australian Araceae – the family in which thermogenesis is most reported – is relatively
little documented.
We report findings on two endemic Australian arums, the rare Typhonium eliosurum, and
Alocasia brisbanensis. We characterised heat generation in different floral tissues, identified
insects visiting during male and female phases of flowering, and characterised floral volatiles
during different stages of anthesis. Alocasia brisbanensis showed negligible thermogenic
capacity, whereas tissues on the T. eliosurum spadix heat for several days. Heating in T. eliosurum
is associated with a strong unpleasant odour characterised by methylated decatrienes, p-cresol,
indole and skatole. These latter three compounds are typical constituents of dung-like aromas
in other Aroideae1, indole and skatole being strongly correlated with dung beetle pollination in
that subfamily2. By contrast, the sweet scent of A. brisbanensis inflorescences was dominated
by ionones and ionols. Insects most commonly associated with T. eliosurum were Diptera, in
particular of the family Sphaeroceridae, whereas two families of small beetles, Nitidulidae and
Staphylinidae dominated collections from A. brisbanensis. In the latter species, differences
in scent during anthesis were found, as were differences in the suite of insect visitors across
its geographic range. This initial work on two Australian endemics provides impetus for
future research into the pollination biology of native Australian Araceae, particularly those of
conservation concern.
1 Kite G et al. 1998. Inflorescence odours and pollinators of Arum and Amorphophallus (Araceae). In: Owens S,
Rudall P (Eds). Reproductive biology in systematics, conservation and economic botany. Pp. 295-315. Royal
Botanic Gardens, Kew.
2 Schiestl FP, Dötterl S 2012. The evolution of floral scent and olfactory preferences in pollinators: coevolution or
pre-existing bias? Evolution 66: 2042-2055.
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POLLINATION
SIP 15
Vulnerability of a fig – pollinator system to climate change
Sutton TL, DeGabriel JL, Riegler M, Cook JM
Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797,
Penrith NSW 2751, Australia
[email protected]
Figs (Ficus spp.) and their pollinating wasps (Agaonidae) share an obligate reproductive
mutualism. The mutualism is highly species-specific, and it was once thought that each of the
~750 Ficus species had its own unique pollinating wasp. Advances in molecular diagnostic
techniques have since uncovered several examples of multiple wasp species pollinating the same
fig species. The Port Jackson fig (Ficus rubiginosa) has a natural range of over 2000 km on the
east coast of Australia, from the tropics to the temperate zone, and is pollinated by wasps of the
Pleistodontes imperialis species complex. This comprises five species with partially overlapping
geographic ranges. Environmental niche modelling indicates that each species may be restricted
to a relatively narrow climate zone, and may be sensitive to shifts in temperature or humidity.
Pleistodontes imperialis sp. 1 has a distribution from near Brisbane in the subtropics, to
the much cooler southern range limit of its host plant in temperate southern New South Wales,
thus experiencing the coolest average conditions of the five P. imperialis species. As a result,
P. imperialis sp. 1 may be vulnerable to predicted increases in mean global surface temperatures,
increased aridity and frequency of extreme weather events. We collected P. imperialis sp. 1 popu­
la­tions from Sydney (Australia) and experimentally exposed them to a range of temperatures
from 25 to 40°C, coupled with high or low humidity (20 or 70% RH), and measured the mean
longevity of wasps under each treatment. We also incubated ripening figs at various temperatures
to test the effects on pollinator emergence. Spring and summer temperatures in Sydney often
exceed 35°C and the incidence of extreme climatic events is predicted to further increase with
climate change. For example, in January 2013 Sydney recorded its hottest ever day (46.5°C).
We found that the longevity and emergence rates of P. imperialis sp. 1 decrease greatly over a
temperature range of 25-40 °C, with sharp declines between 35°C and 40°C. Furthermore, we
found a smaller, but significant decrease in wasp longevity as humidity decreases at the lowermedium temperature treatments.
Our treatments represent realistic and imminent predicted changes in temperature patterns
and humidity that may have profound effects on the dynamics of the fig - pollinator mutualism
in southeastern Australia. Decreased longevity could mean that pollinators do not live long
enough to find a new host and complete their life cycle. Furthermore, sustained periods of high
temperature could kill pollinators before they exit the fig syconium. As a result, heat waves, such
as the one experienced in southeastern Australia in early 2014, could potentially cause short or
long term collapse of the local pollination system.
134
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P38
SIP 15
POLLINATION
Diversity and distribution of microbial communities
in floral nectar in two typical plants of the Sonoran Desert
von Arx M 1,2, Moore AF 2, Davidowitz G 2, Arnold AE 3
1 Institute of Systematic Botany, University of Zurich, Switzerland
2 Department of Entomology, University of Arizona, Tucson AZ, USA
3 School of Plant Sciences, University of Arizona, Tucson AZ, USA
[email protected]
There is increasing evidence that nectar-inhabiting microbes are important players in plantpollinator interactions. Describing the diversity and understanding the function of such “thirdparty” species is a major challenge to our understanding of plant-pollinator interactions. We
examined the frequency and abundance of bacteria and fungi in the floral nectar of hawkmothpollinated Datura wrightii (Solanaceae) and bat-pollinated Agave palmeri (Agavaceae) and
evaluated the effects of both time and flower visitation on microbial communities. Culturable
bacteria and fungi occurring in a total of 305 nectar samples were isolated and identified by
ribosomal gene sequencing. Our results show that microbes are common in Datura and Agave
nectar. We found a seasonality effect on the abundance of nectar microbes in D. wrightii, with
numbers of colony forming units peaking in the middle of the flowering season. We also found
higher numbers of microbes as the time available for visitation increased. Furthermore, for
the first time, we provide evidence for the presence of nectar microbes in floral nectar prior
to anthesis. Up to 60% of nectar samples collected from closed D. wrightii flowers contained
culturable microbes. Bacterial and fungal communities differed significantly between the two
plants even though sampling was conducted during the same season and in the same geographic
region. Our study confirms the ubiquity of nectar microbes in desert plants, suggests novel ways
of approaching the study of nectar microbe communities, and proposes exciting new perspectives
on the role of microbes in plant–pollinator relationships.
Keywords: bacteria, fungi, floral nectar; microbial communities, pollination.
P39
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135
Belowground Interactions
BELOWGROUND
INTERACTIONS
SIP 15
Australian grassland responses to root herbivory
and extreme rainfall
Barnett K, Johnson SN, Power S
The Hawkesbury Institute for the Environment, University of Western Sydney (UWS),
Richmond, NSW Australia
[email protected]
Climate models for the Australian continent predict more variable rainfall patterns in the future.
Plant community responses will depend on the sensitivity of component species to shifts in
rainfall patterns, and associated changes in competition; root herbivory has the potential to
exacerbate these effects. Soil surveys established the presence of herbivorous invertebrates in local
grasslands, the majority of which comprised of Soldier Fly (Diptera: Inopus sp.)(62%), weevil
(Coleoptera: Curculionidae)(7%), and scarab (Coleoptera: Scarabaeidae)(2%) individuals. In
order to investigate the effects of precipitation and root herbivory in grassland, we established a
large scale rainfall manipulation experiment at the University of Western Sydney’s Hawkesbury
Institute for the Environment. Irrigation regimes consist of ambient, drought (50% ambient), and
pulsed drought (longer time between heavy rainfall) amounts of water. In addition to changes in
rainfall, a root herbivory treatment (inoculation with Scarabaeidae larvae) was applied. Pulsed
drought plots currently see a significant decrease in root biomass and, given this is correlated to
herbivore performance, we anticipate a decline in root herbivore performance under this regime.
136
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P40
SIP 15
BELOWGROUND INTERACTIONS
Do genotypic and species level variation matter in abovebelowground interactions?
Bennett AE, Karley AJ
Ecological Sciences, James Hutton Institute, Errol Road, Invergowrie, Dundee DD2 5DA UK
[email protected]
The influence of belowground organisms on above-ground plant-insect interactions is a rapidly
developing field. The past decade has shown that belowground organisms such as mycorrhizal
fungi can influence the outcome of plant-insect interactions. Previous research has identified
differences in how functional groups of insects (phloem feeders versus chewers) respond to
plants associated with mycorrhizal fungi, however there is still a great deal of unexplained
variation in mycorrhizal fungal-plant-herbivore interactions.
Many of the currently published studies of above-belowground and mycorrhizal fungalplant-herbivore interactions tend to test only small numbers of plant species or genotypes. This
is despite our knowledge that plant genotype and species level variation strongly influence
mycorrhizal fungal-plant interactions and plant-insect interactions. Even more strikingly, these
studies have often used single genotypes of herbivore species to draw broad conclusions about
mycorrhizal fungal-plant-herbivore interactions.
Research in our group has focused on whether plant genotypic or species level variation
and insect genotypic variation alter the outcome of mycorrhizal fungal-plant-herbivore
interactions. We work in many systems, but lately we have found the interaction between
arbuscular mycorrhizal fungi, Solanum species such as potato, the potato aphid (Macrosiphum
euphorbiae), and endosymbionts of the potato aphid to provide significant insights into these
fundamental questions. In particular, we have found that plant genotypic and species level
variation can strongly influence herbivore growth and this can be modified by mycorrhizal fungi
and other soil organisms. In addition, genotypic variation within herbivores (and even genotypic
variation within endosymbionts of herbivores) can influence plant resource allocation and plant
associations with mycorrhizal fungi.
Thus we have accumulated significant evidence demonstrating the importance of genotype
and species level variation in above-belowground interactions.
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BELOWGROUND INTERACTIONS
SIP 15
Digesting the indigestible
Cambra I 1, Robert CAM 2, Gershenzon J 1, Erb M 2
1 Department of Biochemistry, Max Planck Institute for Chemical Ecology, Hans Knöll
Strasse 8, 07745 Jena, Germany
2 Institute of Plant Science, Section Biotic Interactions, University of Bern, Altenbergrain 21,
3013 Bern, Switzerland
[email protected]
Diabrotica virgifera (Coleoptera) is an important pest of cultivated maize causing up to one billion
dollar crop losses yearly in the USA. Yet, little is known about how this root herbivore copes with
plant defenses. Recent work demonstrated that D. virgifera can tolerate 1,4-benzoxazin-3-one
derivatives (BXDs), a group of secondary metabolites formerly considered a major defensive
barrier against herbivore insects. BXDs are stored as glycosides in cell vacuoles and converted
to reactive aglucones upon tissue disruption. Current knowledge suggests that BXD aglucones
inhibit the activity of digestive enzymes, specifically through an irreversible alkylation of
cysteine-proteases. Therefore, we investigated if BXD tolerance by D. virgifera larvae relies on
the production of resistant proteinases.
D. virgifera larvae were fed on BXD mutant maize seedlings whose BXD profile was
restored by indoline-2-one complementation. Using this setup, we were able to confirm that
D. virgifera is fully tolerant to BXDs. High throughput transcriptomic analysis revealed 1123
peptidases in D.virgifera midgut (348 cysteine-peptidases; 271 serine-peptidases; 287 asparticpeptidases and 217 metallo-peptidases). In accordance with our expectation, the main activity
detected in D. virgifera midgut came from cysteine-peptidases. Preliminary qPCR analyses
revealed that several peptidases were induced by BXDs, lending support to the hypothesis
that D. virgifera may avoid the negative effects of BXDs by peptidase overexpression. We are
currently aiming at using an RNAi approach to silence D. virgifera peptidases and investigating
their function in BXD tolerance in detail.
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P42
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BELOWGROUND INTERACTIONS
Measuring entomopathogenic nematode soil food webs
in Swiss wheat-maize agroecosystem for developing
root-herbivores sustainable biocontrol
Campos-Herrera R 1, Jaffuel G 1, Chiriboga X 1, Blanco-Pérez R 1, Fesselet M 2,
Půža V 3, Mascher F 2, Turlings TCJ 1
1 FARCE Laboratory, University of Neuchâtel, Emile-Argand 11, CH-2000 Neuchâtel,
Switzerland
2 Agroscope, Institut des Sciences en Production Végétale IPV, Route de Duillier 50, CP
1012, CH-1260 Nyon, Switzerland
3 Laboratory of Entomopathogenic Nematodes, Institute of Entomology, Biology Centre,
Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic
[email protected]
Wheat and maize are major crops in Switzerland. As part of a research consortium that explores
ways to improve soil health, we study how entomopathogenic nematodes (EPNs) can be better
exploited for the biological control of soil-dwelling insect pests. We employ a combination of
traditional measurements and new molecular methods to explore how belowground multitrophic
interactions (natural enemies, competitors, etc.) affect EPN activity and persistence under
different agro-ecological scenarios in two 30-year Swiss field trials. One experiment compared
tillage versus no-tillage and monoculture (wheat) versus crop rotation (maize), whereas the
second studied four levels of tillage in two soil types planted with wheat. Soil samples were
taken in April and in October 2013 (n = 88). EPN activity was assessed by the Galleria-bait
technique, detecting low mortalities in both sampling times (<5%), with no significant effect of
the treatments. Real time qPCR revealed that >95% of infected cadaver contained a mix of EPN
with the competing Acrobeloides-group and/or Oscheius sp. Less than 40% of the nematodes
that emerged from the original cadavers could succesfully establish in a culture, suggesting
that not all of the collected nematodes were entomopathogenic and competition occurs among
the nematode guilds. The available molecular probes identified and quantified 13 organisms
from the soil samples, comprising six nematophagous fungi (NF, Arthrobrotus dactyloides,
A. musiformis, A. oligospora, Hirsutella rhossiliensis, Paecilomyces lilacinus and Catenaria
sp.), the ectoparasitic bacterium Paenibacillus nematophilus, the free-living nematodes (FLN)
Acrobeloides-group and Oscheius sp, and four EPNs (Steinernema feltiae, S. carpocapsae,
Heterorhabditis bacteriophora and H. megidis). The development, optimization and evaluation
of nine additional EPN species with European distribution are ongoing (S. affine, S. intermedium,
S. bicornotum, S. weiseri, S. silvaticum-kraussei, S. poinari, S. glaseri, S. intermedium-group, and
H. zealandica). In general, only trace levels of EPN were detected in all soils. Heterorhabditis
spp. were the dominant EPN, with H. bacteriophora being significantly reduced by tillage
(P<0.001). Monoculture favored the competitors of EPN (P<0.01). The abundance of EPN,
NF and FLN was positively correlated (P<0.05). Since only low numbers of EPN are naturally
present in Swiss agricultural soils, an augmentation strategy may help to improve the control of
root pests of wheat and maize.
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BELOWGROUND INTERACTIONS
SIP 15
Testing the interactive effects of elevated temperature and CO2
on an above-/belowground herbivore system
Facey SL 1, Ellsworth DS 1, Staley JT 2, Wright DJ 3, Johnson SN 1
1 The Hawkesbury Institute for the Environment, University of Western Sydney (UWS),
Australia
2 The Centre for Ecology & Hydrology, Wallingford, UK
3 Imperial College London, UK
[email protected]
Little is known about how climate change will affect linkages between above- and belowground
systems, despite the recognised importance these interactions may have in shaping ecosystems.
This experiment determined the effects of increased temperature and atmospheric CO2 on the
development of Plutella xylostella caterpillars reared on mustard plants, with and without
belowground herbivores (scarab larvae). Plants were grown under elevated and ambient CO2
(640ppm/400ppm) and temperature (30°C/26°C) in a factorial design. Larval performance
(development times, pupal weights, total consumption), plant growth, photosynthetic rates and
above-/belowground biomass were quantified. Specific leaf weight, C, N and glucosinolate
content were also determined.
The CO2 and temperature treatments had no effect on total aboveground plant biomass.
Plants experiencing aboveground herbivory exhibited compensatory growth, growing 24%
bigger, on average, than those without herbivores. The ability of plants to respond in this way was
compromised, however, when belowground herbivores were also present. Caterpillar pupal mass
was higher under elevated CO2 compared to those reared under ambient CO2. Temperature had
a bigger impact than CO2, with caterpillars developing faster, but attaining a smaller mass at the
pupal stage under elevated temperatures. Belowground herbivores had no effect on aboveground
herbivore pupal mass. The results of this study suggest that P. xylostella larvae may develop
faster, but may become smaller at adulthood, indicated by the lower pupal mass, as the climate
warms. The implications these findings are ambiguous - on one hand shorter development times
could increase herbivory pressure as a result of more generations per year, but on the other hand
lower pupal mass could give rise to less fecund adults, resulting in smaller populations.
140
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P44
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BELOWGROUND INTERACTIONS
The natural occurrence of entomopathogenic nematodes in
Swiss agricultural soils is not affected by management practices
Jaffuel G 1, Blanco-Perez R 1, Chiriboga X 1, Mäder P 2, Turlings TJC 1,
Campos-Herrera R 1
1 FARCE Laboratory, University of Neuchâtel, Emile-Argand 11, CH-2000 Neuchâtel,
Switzerland
2 Forschungsinstitut für biologischen Landbau (FiBL), Research Institute of Organic
Agriculture, Ackerstrasse 113, Postfach 219, CH-5070 Frick, Switzerland
[email protected]
Besides nutrients and water, microorganisms can significantly determine the quality of agricultural
soils. In the context of a research consortium that studies beneficial microorganisms and their
use in agriculture, we investigated factors that determine the efficacy of entomopathogenic
nematodes (EPN) as biocontrol organisms against soil dwelling insects in maize and wheat. In
April and October 2013, we sampled all 96 plots of the DOK experiment, a long-term Swiss
field trial on agricultural cropping systems. The complete randomized block design of this trial
allowed us to investigate how the presence and abundance of EPN populations are affected by
crop type (wheat, maize and grass, n = 32) and management systems (conventional with manure,
organic and biodynamic, each performed at two fertilizer levels, as well as a conventional system
without manure and a unfertilized control, n = 12). We used larvae of the wax moth Galleria
mellonella as baits to assess EPN abundance and then used qPCR analyses of soil samples to
quantify the presences of 13 species of EPN, as well as associated free living nematodes, six
nematophagous fungi and one ectoparasitic bacteria, Paenibacillus nematophilus. We recovered
five species of EPN (Steinernema feltiae, S. carpocapsae, S. affine, Heterorhabditis bacteriophora
and H. megidis), one group of free-living nematodes (FLN, Acrobeloides-group), and four
nematophagous fungi (Arthrobrotus oligospora, Paecilomyces lilacinus, Hirsutella rhossiliensis
and Catenaria sp.). Soil management systems had no impact on the presence of these organisms
(P > 0.05). However, crop type significantly shaped the abundance (P = 0.007) and activity (P
= 0.01) of nematodes (EPN + FLN), which were found to be more abundant and active in wheat
plots (P = 0.01). The total numbers of EPN in the soil samples were very low, implying that their
natural presence is not sufficient to have a suppressive effect on soil pest and an augmentative
approach is highly recommended. We will further assess different soil properties such as clay
content and soil microbial biomass to obtain a more comprehensive understanding of the factors
that determine the dynamics of these soil organisms in Swiss soils.
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BELOWGROUND INTERACTIONS
SIP 15
Breeding for resistance to root flies (Delia radicum) in cabbage,
Brassica oleracea – resistance screens among wild Brassica
species
Wang S 1, Steenhuis-Broers G 2, Voorrips RRE 2, Bonnema GAB 2, van Dam NM 3,
Bas N 4, Vosman B 2, van Loon JJA 1
1 Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands
2 Wageningen UR Plant Breeding, The Netherlands
3 Ecogenomics Group, Radboud University Nijmegen, Nijmegen, The Netherlands
4 Centre for Genetic Resources (CGN), Wageningen, The Netherlands
[email protected]
Cabbage root flies constitute the most damaging biotic factor in cabbage vegetable production in
Western Europe and North America. Root fly larvae (maggots) damage the root system of cabbage
plants early in the season which may result in plant mortality or serious growth retardation. The
threat to cabbage crops posed by root flies has recently become acute due to the legislative ban
by the European Union of the major chemical insecticide to control cabbage root flies. The
presence of antibiosis type of resistance against the larvae was evaluated in wild Brassica species
using greenhouse and field assays. In 2012, 95 accessions belonging to 18 Brassica-species have
been screened in a no-choice field test. Fifteen accessions were selected as putatively resistant,
which were then tested against root fly under greenhouse conditions in spring 2013. Three
accessions that showed a low average number of eclosed flies and a low average individual fly
dry weight are considered as highly resistant. We further evaluated the most resistant accessions
using two different root fly populations. Individual plants that showed strong resistance have
been crossed with susceptible plants in order to generate a mapping population. We next aim to
perform detailed analyses of larval behaviour, development and survival on the most promising
accessions. Preliminary tests of larval feeding preference suggested that freshly hatched larvae
are able to make choices between resistant and susceptible plants as food sources.
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Plant
Domestication and&Application
PLANT
DOMESTICATION
APPLICATION
Bean domestication and intraspecific competition interact
to influence performance in a bruchid beetle
Cuny MAC, Shlichta JG, Benrey B
University of Neuchâtel, 11 rue Emile-Argand, 2000 Neuchâtel
[email protected]
Crop domestication has selected for larger seeds in cultivated plants compared to their wild
relatives. This does not only result in a larger amount of resource for humans but also for the
insects that use these seeds.
Bruchid beetles that attack wild and cultivated seeds, often lay several eggs on a single
seed. Thus, variability in seed size as a result of domestication can have important implications
for their survival. We examined the effects of the interaction between seed size, as a result
of domestication, and intraspecific competition on several fitness components of Zabrotes
subfasciatus.
In the laboratory female beetles were exposed to wild and cultivated seeds of Phaseolus
lunatus (lima bean). We recorded the number of eggs laid on each seed, the number of adults that
emerged from the seeds, their sex and weight.
Overall, bruchid survival was negatively correlated with seed size on both cultivated and
wild seeds. In addition, a negative correlation was found between the initial number of eggs laid
by female bruchids and the weight of females that emerged from smaller, wild seeds. Although
this relationship was significant only at high egg densities.
Our results indicate that by selecting for larger seeds, domestication of Phaseolus lunatus
has reduced the intensity of intraspecific larval competition of Zabrotes subfasciatus. These
findings add to our understanding on the increased vulnerability of grain crops to insect pests.
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PLANT DOMESTICATION & APPLICATION
SIP 15
Aphid resistance in Solanum stoloniferum,
a wild species of potato
Drizou F 1,2, Partridge SJ 1,2, Smart LE 1, Martin J 1, Bass C 1, Ray R 2, Bruce TJA 1
1 Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
2 The University of Nottingham, Nottingham, Nottinghamshire, NG7 2RD, UK
[email protected]
[email protected]
Crop losses due to herbivorous insects are a major problem in agriculture and as a result increased
crop resistance has a pivotal role in preventing yield decline and improving global food security1.
Potato plants are an important food source globally. Cultivated potato, Solanum tuberosum, is
vulnerable to attack by aphids and the diseases they transmit. The aphid Myzus persicae has
evolved resistance to most insecticides and control options for growers are further limited by
EU restrictions on pesticide use. Therefore, we are exploring sources of host plant resistance in
a wild potato species with the ultimate aim of introgressing the resistance into cultivated potato.
In this study we aim to understand the interaction between M. persicae aphid and the cultivated
potato (Solanum tuberosum) and the wild potato (Solanum stoloniferum). We are examining the
preference of adult aphids to volatiles collected from the wild and the cultivated potatoes in fourarm olfactometer as well as the performance and fecundity of aphids feeding on these species.
Solanum stoloniferum has been reported as having some resistance to aphids2 and it
is possible to cross this species with S. tuberosum. We obtained 10 different lines from the
Wageningen genebank, grew them in the glasshouse at Rothamsted and tested them for aphid
resistance. Two lines were identified which had particularly high resistance to M. persicae: nymph
production over 24h was severely reduced when compared with S. tuberosum and there was zero
survival of nymphs after a 7 day period. Surprisingly, when we collected volatiles from one of the
resistant S. stoloniferum lines, they were found to be attractive in an olfactometer bioassay even
though it is a poor quality host. Samples of aphid RNA were collected and analysed by QPCR
to look at the expression of candidate genes by QPCR involved in detoxification of xenobiotic
compounds3. A cross of S. stoloniferum x S. tuberosum was made to investigate inheritance of
the resistance trait. The M. persicae potato interaction will be an increasingly important model
system for the study of insect-plant interactions because genomic resources now exist for both
the aphid and the potato.
1 Bruce TJA 2010. Tackling the threat to food security caused by crop pests in the new millennium. Food Security
2: 133-141.
2 Alvarez AE, Tjallingii WF, Garzo E, Vleeshouwers V, Dicke M, Vosman B 2006. Location of resistance factors
in the leaves of potato and wild tuber-bearing Solanum species to the aphid Myzus persicae. Entomologia
Experimentalis et Applicata 121: 145–157.
3 Bass C, Zimmer CT, Riveron JM, Wilding CS, Wondji CS, Kaussmann M, Field LM, Williamson MS, Nauen R
2013. Gene amplification and microsatellite polymorphism underlie a recent insect host shift. Proceedings of the
National Academy of Sciences doi: 10.1073/pnas.1314122110
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PLANT DOMESTICATION & APPLICATION
Effects of methyl jasmonate treatment of conifer seedlings
on pine weevil feeding
Fedderwitz F, Nordlander G, Ninkovic V, Björklund N
Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, SE-750 07
Uppsala, Sweden
[email protected]
Methyl jasmonate (MeJA) is a plant hormone and elicitor of plant defences. It can potentially
be used as a protection of conifer seedlings against attacks of the pine weevil (Hylobius abietis
(L.)). The pine weevil has an important economic impact on European forestry by its feeding on
the bark of several conifer species that may cause seedling mortality of up to 90 % during the
first three years after plantation.
We applied MeJA exogenously on Scots pine (Pinus sylvestris L.) seedlings to study the
effects on feeding behaviour in detail. Two laboratory experiments with treated and control
seedlings were conducted: One experiment with a large sample size (96 plants) and periodic
recording (3 measurements per 24 hours), and another experiment with a smaller sample size (20
plants) and continues video recording. Thus we were able to study different aspects of the feeding
behaviour. The seedlings were exposed to single pine weevils for five or four days, respectively.
Preliminary analyses show that MeJA decreases the debarked area at the end of the
experiment. This is due to a delay in the initiation of feeding on MeJA induced seedlings. Once
feeding began, the total area of feeding scars increased similarly in both treatment and control
group. Girdling occurred in both treatments at the same overall damage level (total bark removed
by pine weevil). The number of meals and their duration as well as feeding rate were similar with
both treatments.
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PLANT DOMESTICATION & APPLICATION
SIP 15
Non-specialized insect pests benefit from maize domestication
Gaillard M, Turlings T
FARCE laboratory, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel,
Switzerland
[email protected]
It has been largely reported that domestication of crop plants has weakened their defenses against
pathogens and insect herbivores. Maize (Zea mays mays), domesticated from teosinte (Zea mays
parviglumis) about 9000 years ago, appears not to have escaped this rule. It is more susceptible
to infestation and field damage than its wild ancestor. This observation strongly suggests that
defense levels are lower in maize than in teosinte, and it can be expected that insects will perform
better when feeding on maize than on teosinte. We assessed this for three guilds of maize-feeding
pests: leaf- chewing Spodoptera spp. (Lepidoptera: Noctuidae), root-feeding Diabrotica spp.
(Coleoptera: Chrysomelidae) and two species of leaf-piercing leafhoppers, Dalbulus maidis and
Zyginidia scutellaris (Hemiptera: Cicadellidae). They were fed on different lines of cultivated
maize or wild teosinte and their growth was recorded. Generally, insects performed better on
maize than on teosinte. This pattern was considerably stronger for generalist herbivores that are
supposedly less adapted to this plant’s defenses than maize specialists. The weakened defenses
in maize may partly explain the success and economical impact of various pests on this crop
worldwide. Identification of the compounds responsible for the superior resistance in teosinte
may help to improve maize resistance.
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PLANT DOMESTICATION & APPLICATION
Effect of mango breeding on laticiferous duct density and sap
content/pressure and its consequences on infestation by two
polyphagous fruit flies (Diptera: Tephritidae)
Adaime R 1, Birke A 2, Guillén L 2, Ortega F 2, Velázquez O 2, Angeles G 2, Aluja M 2
1 Embrapa Amapá, Rodovia Juscelino Kubitschek, km 5, N. 2600, 68903-419 Macapá,
Amapá, Brasil
2 Instituto de Ecología, A.C. Apartado Postal 63, 91000 Xalapa, Veracruz, México
[email protected]
An alternative of plant defense against the attack by herbivorous insects via the ingestion of
secondary metabolites is the toxic effect on eggs and newly emerged larvae of sap emanating
from laticiferous ducts/canals embedded in the fruit epicarp and endocarp or the sheer physical
pressure exerted by the sap when these canals are ruptured during oviposition by females.
We tested the hypothesis that density of laticiferous ducts (i.e. area occupied by ducts)
in the exocarp of ripening fruit of various mango cultivars would be correlated to successful
defense against Anastrepha obliqua and A. ludens, two polyphagous fruit flies attacking mangos
in Latin America. Experimenting with two mango cultivars known to be resistant to fruit fly attack
(Ataulfo and Tommy Atkins) and two known to be highly susceptible (Manila and Criollo), we
were able to demonstrate that resistance was at least partly explained by the density of laticiferous
canals in the epicarp and endocarp of fruit and also the volume of sap flowing from these canals
when the epicarp and endocarp was punctured by the aculeus of females piercing through it
during oviposition.
We discuss our findings with respect to their potential application in mango breeding
programs aimed at increasing resistance to the attack by herbivorous insects using fruit for larval
development.
Adaime R, Birke A, Guillén L, Ortega F, Velázquez O, Angeles G, Aluja M 2014. Effect of laticiferous duct density
and sap flowing from these ducts on infestation and development of immature stages of Anastrepha obliqua
(Macquart) and Anastrepha ludens (Loew) in four mango cultivars exhibiting various degrees of resistance to the
herbivores. Journal of Economic Entomology (submitted)
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PLANT DOMESTICATION & APPLICATION
SIP 15
Floral resources provided by Tagetes erecta as a strategy
for enhancing natural enemy activity in organic lettuce
Paiva IG 1, Zaché B 2, Silveira LCP 2
1 Programa de Pós-Graduação em Entomologia, Universidade Federal de Lavras, Campus
Universitário, Caixa Postal 3037, CEP37200-000, Lavras, MG, Brazil
2 Departamento de Entomologia, Universidade Federal de Lavras, Campus Universitário,
Caixa Postal 3037, CEP37200-000, Lavras, MG, Brazil
[email protected]
Predators and parasitoids can regulate pest populations in agroecosystems. In order to enhance
this ecosystem service, plant diversification can be an important tool. Therefore, information
on how different plant species affect the diversity and efficiency of entomophagous insects can
lead to the implementation of more sustainable crop production methods. Non-crop plants in the
agroecosystem can provide nutritional resources such as polen and nectar or provide alternative
hosts or prey, thus increasing the number and activity of carnivorous insects. A promising plant
species for enhancement of entomophagous insect activity in horticultural cropping systems in
Brazil is Tagetes erecta (Asteraceae). We conducted an experiment in an organic lettuce crop
with the aim of evaluating how flowering T. erecta affects activity of insect predators, parasitoids
and herbivores. The lettuce crop was divided into two plots: one had a single strip of flowering
T. erecta in the middle of the plot while the other plot was a lettuce monoculture. We measured
species richness, diversity and abundance in the lettuce monoculture and at six distances from
the T. erecta strip in the intercropped lettuce. The intercropped plot had greater abundance than
the lettuce monoculture (1.56 compared to 0.93 individuals/sample). Species richness was also
higher in the intercrop (125 species) compared to the monoculture (96 species) and Shannon
diversity was also slighty in the intercrop (H´=1.77) than the monoculture (H´=1.67). The number
of entomophagous insects per plant increased six-fold in the intercropped lettuce compared to the
lettuce monoculture, and there was a significant effect of distance to the T. erecta strip. Samples
taken up to 5.1 m from the T. erecta strip had significantly more predators and parasitoids than
samples further away. Therefore T. erecta has the potential to be used in conservation biological
control for enhancement of natural enemy activity. The mechanisms behind the increase in
numbers of natural enemies should be researched in order to better understand the use of this
plant as an intercrop in horticultural systems.
Financial support: Fapemig, CAPES, CNPq
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PLANT DOMESTICATION & APPLICATION
The use of resistant pear accessions as inter-stock in order to
reduce susceptibility to pear psylla Cacopsylla bidens (Šulc)
in commercial pear trees
Shaltiel-Harpaz L 1, Soroker V 2, Gershman Y 3, Mwafac I 2, Kedoshim H 1,
Hativ C 2, Bar Yaakov I 2, Rchemani D 4, Holand D 2
1 Migal Galilee Research Institute, P.O. Box 831, Kiryat Shmona 11016, Israel
2 Department of Entomology, Agricultural Research Organization, The Volcani Unit of
Deciduous Fruit Tree Sciences, Newe Ya’ar Research Center, Agricultural Research
Organization, P.O.B. 1021, Ramat Yishay 30095 Israel Center P.O.B. 6, Bet Dagan 50250,
Israel
3 University of Haifa in Oranim, Kiryat Tivon, 36006. Israel
4 Tel Hai College, Upper Galilee 12210 Israel
[email protected]
1. BACKGROUND: The pear psylla, Cacopsylla bidens (Šulc), is one of the most damaging
pests of commercial pear orchards in Israel. Psylla control is a major obstacle to efficient
integrated pest management, making research on cultivars with natural resistance to pear
psylla an attractive option. Recently, we have identified two pear accessions (Py.760-261
and Py.701-202) from the local Newe Ya’ar fruit tree live collection as having apparent
resistance to pear psylla. We have: 1. evaluate and characterized the resistance of the two pear
accessions to the pear psylla relative to the commercial cultivar Spadona Estiva; 2. Tested if
these accessions, when used as inter-stock, can provide the scion with reduced susceptibility
to pear psylla.
2. RESULTS: Our results indicate that the selection Py.760-261 is 10 times more resistant
than Spadona while Py.701-202 is 5 times more resistant. The resistance is manifested as
reduced survival of the nymphs while no effect was detected on oviposition. The resistance is
transferred from the inter-stock to the susceptible Spadona scion resulting Spadona 5 time less
susceptible to Psylla then when grafted on P. betulifolia as a rootstock. First year results also
indicate that the effect of both accessions inter-stocks is positively correlated to the inter-stock
length and to the presence of branches and/or leaves on the inter-stock.
3.CONCLUSIONS: The resistance mechanism in both accessions appears to be antibiosis
toward nymph and the resistance is transferred from resistance inter-stock to susceptible
scion. We are currently testing the secondary metabolites involved in the resistance and the
possible use of these resistant accessions as rootstock or as a source of resistant genes in
breeding programs as well studying the resistance mechanism.
Key words: Pear psylla, Resistant accessions, Antibiosis, Grafting
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PLANT DOMESTICATION & APPLICATION
SIP 15
Neonicotinoid insecticides alter induced defenses and
increase susceptibility to spider mites in crop plants
Szczepaniec A 1, Wulff J 2, Eubanks M 2
1 South Dakota State University, Plant Science Department, Brookings, South Dakota, USA
2 Texas A&M University, Department of Entomology, College Station, TX, USA
[email protected]
Chemical suppression of arthropod herbivores is the most common approach to plant protection.
Insecticides, however, can cause unintended, adverse consequences for non-target organisms.
Previous studies focused on the effects of pesticides on target and non-target pests, predatory
arthropods, and concomitant ecological disruptions. Little research, however, has focused on the
direct effects of insecticides on plants. Here we demonstrate that applications of neonicotinoid
insecticides, one of the most important insecticide classes worldwide, suppress expression of
important plant defense genes, alter levels of phytohormones involved in plant defense, and
decrease plant resistance to unsusceptible herbivores, spider mites Tetranychus urticae (Acari:
Tetranychidae). Using cotton (Gossypium hirsutum) and corn (Zea mays), we show that
transcription of phenylalanine amonia lyase, coenzyme A ligase, trypsin protease inhibitor and
chitinase are suppressed and concentrations of the phytohormone OPDA and salicylic acid
were altered by neonicotinoid insecticides. Consequently, the population growth of spider mites
increased from 30% to over 100% on neonicotinoid-treated plants in the greenhouse and by nearly
200% in the field experiment. Our findings are important because applications of neonicotinoid
insecticides have been associated with outbreaks of spider mites in several unrelated plant
species. More importantly, this is the first study to document insecticide-mediated disruption of
plant defenses and link it to increased population growth of a non-target herbivore. This study
adds to growing evidence that bioactive agrochemicals can have unanticipated ecological effects
and suggests that the direct effects of insecticides on plant defenses should be considered when
the ecological costs of insecticides are evaluated.
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P54
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PlantVOLATILES
Volatiles
PLANT
Terpene composition of leaves, stem and headspace
in the Australian tea tree
Bustos-Segura C, Külheim C, Foley W
Evolution, Ecology and Genetics, Research School of Biology, The Australian National
University, ACT 0200, Australia
[email protected]
Foliar terpene content in plants from the family Myrtaceae has been widely studied in the
Eucalyptus and Melaleuca genera. The high concentration of a variety of terpenes can have
effects on plant physiology and ecological interactions with natural enemies and mutualisms.
However, ecological interactions might be mediated in parts of the plant other than leaves, and
analyses of the terpene distribution in the whole plant can give us more information about the
production and transport of these compounds. Therefore, we studied the terpene composition in
stems, leaves and the plant’s headspace in three chemotypes of Melaleuca alternifolia in order to
obtain a better picture of the distribution of terpenes in the plant. The plants included in the study
presented foliar chemical profiles dominated by either terpinen-4-ol, terpinolene, or cineole.
We found consistent similarities in the chemical profile between leaves and stems of the
same plant and chemotype. However, the headspace profile differs from the leaf profile depending
on the chemotype provenance. Plants with a high concentration of cineole and terpinolene in
leaves and stems showed the higher abundance of those compounds in the headspace, although
their abundances were lower in the headspace than in the leaves. In contrast plants with high
abundance of terpinen-4-ol in leaves and stem, showed a headspace profile with high p-cymene
and g-terpinene, and low terpinen-4-ol. It is possible that these differences are produced by the
hydrophobic properties of the different molecules. These patterns could have implications for the
olfactory responses of herbivores and their natural enemies.
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PLANT VOLATILES
SIP 15
The diffusion of the herbivore-induced root signal
(E)-β-caryophyllene depends on soil texture and humidity
Chiriboga X, Campos-Herrera R, Jaffuel G, Roeder G, Turlings T
Fundamental and Applied Research in Chemical Ecology Laboratory, Institute of Biology,
Faculty of Sciences, University of Neuchâtel, Rue Emile Argand 11, CH-2000 Neuchâtel
[email protected]
Maize roots respond to feeding by larvae of Diabrotica virgifera virgifera by releasing
(E)‑β‑caryophyllene. This insect-induced root volatile attracts entomopathogenic nematodes
(EPN) and thereby helps to protect the plant against the root herbivore damage. Previous studies
have shown that diffusion of (E)-β-caryophyllene occurs through the gaseous rather than the
aqueous phase in sand, although a minimal amount of water was required to prevent vertical
evaporation, or to provide a water film that prevents direct adsorption to sand particles. To
fully understand the signaling function and efficiency of root-produced (E)-β-caryophyllene
as a belowground signal it is important to know how it diffuses through real soils and how
soil texture affects its diffusion. Our hypothesis is that clay and silt content of soils limits
diffusion. We tested this by applying synthetic (E)-β-caryophyllene to pure sand and various
soil texture types: i) CA (sand/silt/clay %, 32:17:51), ii) CL (44:30:26) and iii) CS (55:26:19).
Soils were collected at an experimental field site of Agroscope Changins-Wädenswil (Nyon,
Switzerland). Two concentrations of (E)‑β-caryophyllene were injected in a tray with one of the
four substrates: low (2.21 ul (E)‑β‑caryophyllene / 50 ml pentane) and high concentration (221 ul
(E)-β-caryophyllene / 50 ml pentane), at different levels of soil humidity levels (5%, 10% and
20% water). To measure diffusion, a Solid Phase Micro Extraction (SPME) fiber was inserted in
the soil at 5 or 10 cm from the injection point. An automated system removed the fiber every half
hour in order to insert it in a gas chromatogram coupled to a mass spectrometer. This allowed us
to quantify the adsorbed (E)-β-caryophyllene and follow diffusion over time.
At a low dose, (E)-β-caryophyllene diffused readily in sand, but in the soils it was not
detected at the measuring points. At the higher dose, (E)-β-caryophyllene was quickly detected
in sand and weak diffusion was found for the soils at 10 cm distance of the source. At 5 cm
of the source, in sand, (E)-β-caryophyllene was detected in considerable amounts within half
an hour after injection, whereas in soils CL, CA and CS we found a much slower, increasing
gradient of detection. Moreover, we observed that when we increased soil humidity (20% water),
diffusion of (E)-β-caryophyllene in soil improved. Soils with 5% water had very poor diffusion
of (E)‑β‑caryophyllene. Our results show that in real soils migration of (E)-β-caryophyllene
depends on moisture and soil texture. Unlike what was previously found for sand, diffusion
was better at higher water content, probably because the water film prevents interaction of
(E)‑β-caryophyllene with soil particles. This knowledge may help in our efforts to establish new
rational methods for the control of important soil dwelling pests.
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PLANT VOLATILES
Exotic herbivores modify the protective perfume
of Brassica rapa plants
Danner H 1, Desurmont G 2, Cristescu SM 3, Turlings T 2, van Dam NM 1
1 Department of Ecogenomics, Institute for Water and Wetland Research (IWWR), Radboud
University Nijmegen, 6525 AJ Nijmegen, The Netherlands
2 Institute of Biology, Université de Neuchâtel, Emile-Argand 11, CH-2000 Neuchâtel
3 Life Science Trace Gas Facility, Institute of Molecules and Materials, Radboud University
Nijmegen, 6525 AJ Nijmegen
[email protected]
Plants in their natural environment are continuously challenged by feeding of multiple herbivore
species, either consecutively or simultaneously. With global warming insects are expanding their
ranges northwards. As a consequence, plants are attacked by insect herbivores which they have
never encountered before. Furthermore, these new attackers might interfere with the volatilebased signaling between plants, herbivores and the enemies of the herbivores if plant volatile
emissions are altered with the presence of exotic herbivores.
Our study investigated the consequences of exotic herbivore attack on plant volatile
emissions (VOCs) of Brassica rapa plants. We investigated the plant’s response towards eight
different herbivore species either feeding alone or together with the native herbivore Pieris
brassicae.
We found several VOCs to be either up or down regulated depending on the herbivore
species feeding on the plants. For example, (E,E)-α-farnesene was emitted in much higher
quantities when the native species Mamestra brassicae was feeding on the plant. Also when
the native specialist P. brassicae and the exotic generalist Spodoptera littoralis were feeding
simultaneously farnesene emission was increased, but not when either species was feeding alone.
In all other treatments the emission of this sesquiterpenoid was not strongly affected. The green
leaf volatiles hexyl-acetate and 2-ethyl-hexanol both were emitted in higher quantities when the
native herbivore M. brassicae was feeding on the plants whereas 3-hexene-1-ol was induced
much stronger after herbivory by the exotic species M. configurata.
From these results we hypothesize that exotic herbivores have a strong impact on the
indirect defense of Brassica plants and possibly disrupt the tritrophic interactions between plants,
their native herbivores and enemies of the herbivores. An untargeted approach with the full set of
eight species will now help to identify qualitative and quantitative changes in VOC profiles that
are related to native or exotic herbivores.
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PLANT VOLATILES
SIP 15
What is the role of monoterpenes
in white spruce - spruce budworm interactions?
Despland E 1, Bourdier T 1, Ennis D 1, Torreblanca M 1, Bauce E 2
1 Biology Department, Concordia University
2 Département des sciences du bois et de la forêt, Université Laval
[email protected]
Monoterpenes, the quintessential conifer odour, are traditionally considered defensive compounds,
but their effects on lepidopteran folivores can occur at several different levels and seem
paradoxical. We attempt to disentangle the role of host monoterpenes in the interaction between
an important North American conifer defoliator, the eastern spruce budworm (Choristoneura
fumiferana) and one of its main host plants, white spruce (Picea glauca).
Monoterpenes are synthesized within the needle mesophyll and they are both volatile and
lipid soluble; hence, they are emitted by the stomata into the tree’s headspace and are present in
the foliar epicuticular waxes. We use laboratory bioassays to show that monoterpenes presented
within host-tree waxes diffuse into the airspace and attract female moths, but that they do not
appear to be detected on contact at the moment of oviposition. These compounds also stimulate
feeding by larvae, despite possible deleterious post-ingestive effects on larval development.
Chemical analysis of mature-tree foliage revealed a mix of 13 different monoterpenes.
Over the course of the first growing season studied, total monoterpene concentration inside the
needles increased, but the concentration in the epicuticular wax decreased. In the second year
of monitoring, both wax and foliar monoterpenes remained low throughout the season. Both
monoterpene profile and total concentration varied between trees, but were not correlated with
levels of defoliation observed in the field. However, correlations with oviposition rates suggested
that several monoterpenes (α-pinene, limonene & bornyl acetate) promote oviposition, while
others are deterrent (camphene & myrcene).
Monoterpenes thus appear to act as host recognition cues for budworm moths in search
of an oviposition site, as well as for feeding larvae. The field study confirms their role in host
plant choice, but paradoxically does not support a significant role for monoterpenes in natural
resistance to defoliation.
154
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PLANT VOLATILES
Does egg deposition alter the volatile emission
of Nicotiana attenuata in response to herbivore feeding?
Drok SJ, Steppuhn A
Freie Universität Berlin, Dahlem Centre of Plant sciences (DCPS) & Collaborative Research
Centre 973, Molecular Ecology Group, Haderslebener Str. 9, 12163 Berlin, Germany
[email protected]
Plants respond to feeding damage by herbivores with various direct and indirect plant defences.
Also eggs of herbivorous insect itself may elicit defensive plant responses, for example the
production of volatiles that attract egg parasitoids. Here we investigate, whether plants use egg
deposition as a stimulus to prepare their indirect defence responses to up-coming herbivory, as
egg deposition by a herbivorous insect often precedes feeding damage by the hatching larvae.
In greenhouse experiments, we examined the effects of egg deposition by Manduca sexta
on volatile emissions of Nicotiana attenuata in response to subsequent herbivory by its larvae in
a full-factorial design. Volatiles were collected one to four days after egg deposition and at the
first two days after herbivory of the hatching larvae. While we found no effects of egg deposition
on the volatile emission of N. attenuata, the feeding-induced volatile blend was altered in plants
that previously experienced egg deposition. The attractiveness of these volatile blends to Cotesia
congregata, a parasitoid of M. sexta, was tested in a Y-tube and 4-field olfactometers. Females
of C. congregata were attracted to the herbivore induced plant volatiles (HIPV) of N. attenuata
in both assays, but whereas they preferred HIPV blends of egg-primed over non-primed plants
in a Y-tube assay, they did not differentiate between egg-laden and egg-free plans in 4-field
olfactometer assays. Field experiments would be a powerful tool to gain more insight in the
ecological consequences of egg-primed HIPVs for indirect defence of N. attenuata.
P59
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155
PLANT VOLATILES
SIP 15
Volatile emission in black poplar (Populus nigra)
after pathogen and herbivore attack
Eberl F, Hammerbacher A, Gershenzon J, Unsicker SB
Department of Biochemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll Strasse 8,
D-07745 Jena, Germany
[email protected]
Under natural conditions, plants simultaneously face a multitude of antagonists such as herbi­
vorous insects and fungal or bacterial pathogens. However, most studies addressing defence
responses in plants under laboratory conditions focus on one attacker species only. Furthermore,
such studies usually investigate annual herbs. In order to study the responses of woody plants to
more than one enemy, the volatile emission of black poplar (Populus nigra) trees was analysed
upon single and combined infestation by the biotrophic leaf rust pathogen Melampsora laricipopulina and caterpillars of the generalist-feeding gypsy moth (Lymantria dispar). Caterpillar
feeding significantly induced the emission of all major volatile groups independently from fungus
infection. However, pathogen infestation reduced the overall amount of emitted volatiles in
black poplar and this trend was especially pronounced in herbivore-treated trees. Moreover, the
composition of the odour blend was changed when the plants were infected with M. larici-populina.
Since herbivore-induced plant volatiles were shown to mediate direct and indirect defence
against herbivores, these changes in emission might have consequences for biotic interactions in
the ecosystem. Whether, for instance, the modified composition of odour in pathogen-infected
trees impairs the attraction of parasitoids should be studied in future experiments. Generally, a
better understanding of the response to and the consequences of multiple stresses in poplar could
improve pest management and breeding of more resistant hybrids for silviculture.
156
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P60
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PLANT VOLATILES
An Assessment of Juvenile Hormone Mimicking Activity of Plant
Volatiles on Red Cotton Bug, Dysdercus koenigii
Gupta KK, Kayesth S
Deshbandhu College, University of Delhi, Kalkaji, New Delhi 110019, India
[email protected]
Juvenile hormone mimicking activity of hexane extract of Catharanthus roseus, Ocimum sanctum
and Lantana camara was evaluated by assessing growth, development and reproduction of
Dysdercus koenigii. The insects were exposed to of plant volatiles extracted in hexane. 1.0 ml of
hexane extract of concentrations 10%, 5%, 2.5% 1.25%, 0.625%, 0.3125% was used to make a
thin film in sterilized glass jars of capacity 500 ml. Ten newly emerged fifth instar nymphs or adult
bugs were placed in the jars for 24 hr for exposure to the plant volatiles. Impact of leaf extract
was recorded on survival and longevity, growth and development and reproductive bioactivities
of Dysdercus. The results indicated that treated insects had short life span than untreated insects.
The plant volatiles did not reduce the survival of the treated insects significantly. On the other
hand the hexane extract of the plants impaired the development of fifth instar nymphs. The
treated nymphs moulted into supranumery instars, adultoids or the adults with wing deformities.
These results were homologous to JH analogues of insects. The effects of hexane extracts were
dose related. The supranumery insects retained the nymphal characters except increased body
size and wing pads. Adultoids exhibited courtship and mounting attempts but were not able
to mate. The adults with wing deformities also had altered courtship behavior. Consequently,
percent successful mating was decreased significantly in the crosses between wings deformed
adults and normal adults. Treated females exhibited altered oviposition behaviour and decreased
fecundity. The eggs laid by the treated females failed to hatch. Catharanthus, Ocimum and
Lantana appeared to have potential molecules which possessed insect juvenile hormone like
activity. Potential application of these plant extracts in IPM was discussed.
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157
PLANT VOLATILES
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The production of volatile aldoximes and nitriles:
putative key players in the direct and indirect defense of poplar
Irmisch S, McCormick AC, Guenther J, Schmidt A, Gershenzon J, Unsicker SB,
Köllner TG
Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745 Jena, Germany
[email protected]
After herbivore infestation, poplar emits a very complex volatile blend which is thought to
play a role in direct as well as indirect defense. The volatile blend is dominated by terpenes,
but also contains alcohols and nitrogen-containing volatiles such as aldoximes. Previously we
characterized two cytochrome P450 enzymes of the CYP79D family responsible for volatile
aldoxime formation in Populus trichocarpa. While aliphatic aldoximes attracted herbivore
enemies and therefore may function in indirect defense, a putative function in direct defense
could be shown for phenylacetaldoxime.
Poplar also emits other nitrogen-containing volatiles whose formation and function we
have now begun to investigate. We first noted that poplar lines engineered to have reduced
expression of CYP79D genes not only produced less aldoximes, but also showed a reduced
emission of 2- and 3-methylbutyronitrile, benzyl cyanide and 2-phenylethanol. Thus, aldoximes
apart from being directly emitted seem to be precursors for other volatiles released by poplar
upon herbivore feeding. These results were confirmed through the transient expression of
CYP79D genes in Nicotiana benthamiana. In addition, a feeding experiment using deuteriumlabeled phenylacetaldoxime proved that this compound was further converted to benzyl cyanide,
2-phenylnitroethane and 2-phenylethanol in poplar leaves. Nitriles are known to occur in plant
metabolism as intermediates in the biosynthesis of other defense compounds, cyanogenic
glycosides and camalexin, and are formed through the action of P450 enzymes of the CYP71
family. We identified three highly similar CYP71 genes which were shown to be upregulated in
poplar upon herbivory. The genes were heterologously expressed in Escherichia coli and the
recombinant enzymes were tested in vitro with different aldoxime substrates. All 3 proteins were
active and converted 2-methylbutyraldoxime, 3-methylbutyraldoxime and phenylacetaldoxime
into the corresponding nitriles.
We also studied the effect of aldoxime derived nitriles on the behavior of Lymantria dispar
larvae, a generalist herbivore on poplar, in a four-arm olfactometer. Using natural occurring
concentrations, all of the tested nitriles had a strong repellent effect on L. dispar caterpillars
indicating the involvement of these compounds in the direct defense of poplar.
158
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PLANT VOLATILES
Boll weevil uses homoterpenes to identify cotton phenological
stages
Magalhães DM 1,2, Borges M 1, Laumann RA 1, Barasa SS 3, Birkett MA 3,
Blassioli-Moraes MC 1
1 Embrapa Genetic Resources and Biotechnology, Brasília, Brazil
2 Zoology Department, Biological Sciences Institute, University of Brasília, Brasília, Brazil
3 Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden,
UK
[email protected]
The boll weevil, Anthonomus grandis, is the main pest on cotton crops in the Neotropical region,
destroying cotton squares and bolls. Due to its high reproductive rate and endophytic behavior
at the immature stage, infestation levels increase very fast. Furthermore, boll weevils are able to
withstand fallow periods between crops, feeding on pollen of alternative plants, which can lead to
high potential outbreaks in the next cotton season. In Brazil, farmers have adopted heavy spraying
of insecticides to control this pest. Its aggregation pheromone can be used for monitoring the
population, but when cotton plants reach the reproductive stage, adult boll weevils are not caught
anymore in the pheromone traps and go straight to the plants. A previous study showed that boll
weevils prefer the volatiles emitted by cotton at the reproductive stage over vegetative plants1.
The aim of this work was to evaluate if the boll weevil might identify cotton phenological stages
based on their volatile profile.
Volatiles from the vegetative and reproductive stage of cotton Delta Opal were isolated
by air entrainment and identified by coupled GC-MS. The production of homoterpenes (E)-4,8dimethylnona-1,3,7-triene (DMNT) and (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT)
was higher at the vegetative compared to the reproductive stage, suggesting that the weevils could
use them to differentiate between host plant phenological stages. Y-Tube bioassays were carried
out using male and female boll weevils. When comparing the volatiles from reproductive stage
cotton plants to other cotton plants also at the reproductive stage + a mixture of synthetic DMNT
and TMTT at the same concentration released by a plant in the vegetative stage (mimicking a
plant in the vegetative stage) both sexes preferred the volatiles from the plants in the reproductive
stage (males χ2=3.81, p=0.04; females χ2=3.81, p=0.04). Weevils showed no preference when
given a choice between plants at the vegetative stage and a mimicking plant (males χ2=0.32,
p=0.57; females χ2=0.08, p=0.77). These results suggest that DMNT and TMTT might be used
by boll weevils to detect cotton phenological stages. Electrophysiological assays are being
conducted to confirm the antennal responses to these compounds.
1 Magalhães DM et al., 2012. Semiochemicals from herbivory induced cotton plants enhance the foraging behaviour
of the cotton boll weevil, Anthonomus grandis. Journal of Chemical Ecology 38: 1528-1538.
P63
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PLANT VOLATILES
SIP 15
Foraging behavior of three parasitoid species during dual
herbivore attack to plants; does herbivore density matter?
Ponzio C 1, Cascone P 2, Cusumano A 3, Weldegergis BT 1, Fatouros NE 1,
Guerrieri E 2, Dicke M 1, Gols R 1
1 Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands
2 CNR- Instituto per la Protezione delle Piante, Portici, Italy
3 Dipartimento di Scienze Agrarie e Forestali, Università delgi Studi di Palermo, Italy
[email protected]
Parasitoid wasps rely on herbivore-induced plant volatiles to locate their herbivorous hosts.
However, in nature, these parasitoids must deal with variation in the volatile cues that can originate,
for instance, from differences within and between plant species. Attack by multiple herbivores
adds another layer of complexity, as the presence of other herbivores on a host-infested plant
may differentially affect the foraging behavior of the parasitoids via modifications in the emitted
volatile blend. The focal interest of this study was to investigate, in a natural study system, the
effect of aphid density on the ability of different parasitoid wasp species to successfully locate
their hosts under different dual attack scenarios. Black mustard (Brassica nigra) plants were
infested with eggs or caterpillars of the Large Cabbage White butterfly (Pieris brassicae), alone
or in combination with Brevicoryne brassicae aphids. Using laboratory bioassays we compared
the effects of three aphid densities, during single and dual attack, on the host finding behavior
of three different parasitoid species that either parasitize the eggs (Trichogramma brassicae),
caterpillars (Cotesia glomerata) or aphids (Diaeretiella rapae). The composition of the induced
plant volatile blends was also analyzed, to discover if changes in the blend characteristics could
be corroborated with the observed wasp behavior.
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PLANT VOLATILES
Potential use of Tulbaghia leaf extracts in integrated control of
wheat aphids
Prinsloo GJ 1, Radebe PA 1, Richter JM 2
1 ARC-Small Grain Institute, Private Bag X29, Bethlehem 9700, South Africa
2 Department of Agriculture and Rural Development, Private Bag X0, Glen, 9360, South Africa
[email protected]
Tulbaghia violacea, an indigenous plant to Southern Africa, is traditionally used as a cure to
many human diseases. All plant parts have a typical garlic odor when damaged, which is caused
by two different sulphur compounds not present in common garlic. The compound alliin, causing
the characteristic odor in common garlic, is absent from T. violacea1. Common garlic is known
to have repellent and insecticidal properties against mosquito and stored grain pests2, but nothing
is known about the potential response of aphids and their parasitoids to these compounds. The
objective of this study was to determine the response of four wheat aphid species and two
parasitoids, Aphelinus hordei and Diaeretiella rapae, to volatiles from T. violacea leaf extracts
for possible use in an integrated pest management programme.
Two types of extracts namely an aqueous and light mineral oil extract was prepared
from leaves of T. violacea. The response of the aphid alates/parasitoids was tested in a four-arm
olfactometer using the computer program OLFA (Exeter software) to monitor the number of
entries made into the arm and the time spent in each arm. Aphids and parasitoids were reared in
a greenhouse at a mean temperature of 20°C under natural light conditions.
The wheat aphids Diuraphis noxia and Sitobion avenae were repelled by volatiles from
aqueous and mineral oil leaf extracts. The aphid Rhopalosiphum padi was attracted and slightly
attracted by aqueous and mineral oil extracts, respectively, while Metopolophium dirhodum was
attracted by both types. The parasitoids A. hordei and D. rapae were attracted to volatiles from
both extract types. These results suggest that it may be possible to repel certain aphids and to
attract natural enemies. The response of these insects was also tested to plants treated with these
extracts and these results will be discussed together with the possible impact such plant extracts
may induce under field conditions.
1 Van Wyk BE, Van Outshoorn B, Gericke N 2000. Medicinal Plants of South Africa. Briza Publications
2 Huang Y, Chen S-X, Ho S-H 2000. Bioactivities of Methyl Allyl Disulfide and Diallyl Trisulfide from essential oils
of garlic on two species of stored-product pests, Sitophilus zeamais (Coleoptera: Curculionidae) and Tribolium
castaneum (Coleoptera: Tenebrionidae). Journal of Economic Entomology 93: 537-543.
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PLANT VOLATILES
SIP 15
Molecular and metabolic bases of volatile isoprenoid-induced
resistance to abiotic stresses (MOMEVIP): challenging
Arabidopsis wild type and MVA pathway mutant plants
with climate scenarios
Senning M 1, Schnitzler J-P 2, Gruissem W 1
1 Department of Biology, Universitaetstrasse 2, ETH Zurich, CH-8092 Zurich, Switzerland
2 Helmholtz Zentrum München, Institute of Biochemical Plant Pathology, Research Unit,
Environmental Simulation, Ingolstaedter Landstr. 1, D-85764 Neuherberg, Germany
[email protected]
So far it is known, that plant volatile isoprenoids (VIPs) increase plants tolerance to abiotic stress.
For example, the photosynthetic apparatus in plants fumigated with isoprene or monoterpenes was
better protected against heat stress. However, the molecular mechanisms behind the protection
against abiotic stress remain so far unclear.
Based on the results of pilot experiments, three Arabidopsis MVA-pathway mutants (aact1,
hmgr1, hmgr2) were selected, that had been tested for their tolerance to abiotic stress as heat,
osmotic and drought stress. As the mevalonate (MVA) pathway is of central importance for the
plant fitness, alterations will validate the role of VIPs for pleiotropic effects caused by an altered
MVA activity. Plants were grown in phytotrons under four different climate scenarios (S1-4) in
an additive design starting with control condition (S1) followed by temperature elevation in S2,
altered temperature plus elevated CO2 levels in S3 and finally in S4, where plants additionally
experienced drought stress followed by re-watering.
How the selected genotypes responded to the selected climate change scenarios S2-4 and
control condition (S1) was characterized using non-invasive (e.g. electron transfer rate, infrared
technology) as well as invasive methods (RNASeq). Samples for transcriptomics analysis were
collected just before as well as ten and twelve days after the onset of the respective simulated
climate change scenario (i.e. reduced water content, increased temperature and elevated CO2levels).
Interestingly in wild type plants, when comparing the most severe scenario S4 with
control condition (S1), only two MVA pathway genes, AACT1 and HMGR1, were significantly
up-regulated at the end of day and at the end of night. Eight key regulators of the circadian
clock were strongly up-regulated at the end of night. Obviously the circadian clock was strongly
influenced by the combination of elevated temperature, increased CO2-levels and a limitation in
water supply. Under triple stress a scarecrow-like transcription factor but also brassinosteroid-6oxidase 2 were higher expressed in the hmgr1 mutant than in WT.
The data generated from this experiment will be used for modeling approaches to reveal
critical nodes between isoprenoid biosynthesis and abiotic stress response networks. In future the
knowledge gained from this experiment using Arabidopsis as a model plant could prove useful to
develop new biotechnological approaches to improve the ability of e.g. crop plants to cope with
future climate change.
162
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PLANT VOLATILES
Volatile emission in poplar: temporal dynamics and the role of
minor compounds in attracting herbivore enemies
Clavijo McCormick A, Boeckler GA, Irmisch S, Gershenzon J, Koellner TG,
Unsicker SB
Max Planck Institute for Chemical Ecology, Department of Biochemistry, Hans-Knöll-Straße 8,
07745 Jena, Germany
[email protected]
The role of herbivore-induced plant volatile as signals mediating indirect plant defense is wellknown. Studies in short-lived herbaceous plant species showed that biotic and abiotic factors,
such as herbivory and photoperiod, can strongly affect plant volatile emission. However, in
long-lived woody perennials there is only little knowledge on the temporal dynamics of volatile
emission and the underlying causes. The dynamic emission of specific volatiles may render some
compounds more suitable than others as signalling molecules in indirect tree defense.
The aim of our study was to elucidate the combined effects of herbivory and photoperiod
on volatile emission dynamics in the tree species Populus nigra (black poplar) and to determine
the compounds mediating the attraction of the gypsy moth (Lymantria dispar) parasitoids.
The emission dynamics of major volatile groups such as monoterpenoids, sesquiterpenoids,
green leaf volatiles, aromatics and nitrogenous compounds in response to photoperiod and
herbivore feeding differed strikingly. Some minor compounds such as nitrogenous aldoximes
were emitted immediately or shortly after herbivore attack, and ceased quickly after herbivore
removal, irrespective of photoperiod. These nitrogenous volatiles were also attractive for
parasitoids under laboratory and field conditions and their emission was strongly correlated to
actual herbivore damage.
Our results suggest that in the midst of herbivore-induced black poplar volatiles, there
is only a very small group of compounds such as nitrogen containing aldoximes that could be
reliable cues for natural enemies, informing about herbivore presence, and density.
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PLANT VOLATILES
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Exogenous application of methyl jasmonate changes
concentration and composition of individual pyrrolizidine
alkaloids in Jacobaea plants
Wei X 1, Vrieling K 1, Mulder PPJ 2, Klinkhamer PGL 1
1 Plant Ecology & Phytochemistry, Institute of Biology, Leiden University, Sylviusweg 72,
P.O. Box 9505, 2300 RA, Leiden, The Netherlands
2 RIKILT-Wageningen UR, Wageningen University and Research Center, P.O. Box 230,
6700 AE, Wageningen, The Netherlands
[email protected]
Defense systems against herbivores are induced through the ocatadecanoid pathway in many
plants. This pathway can be induced by treating plants with jasmonate. Pyrrolizidine alkaloids
(PAs) are typical secondary metabolites in Jacobaea plants. Many studies showed that PAs
play a role in resistance against herbivores. However, all these studies did not show if PAs are
inducible by herbivore attack. It was found that PA composition was changed in cell culture
after applying MeJA (Schulte, unpublished). To test how PAs varied in the intact plant, we
designed an experiment by adding different concentrations (0, 0.05, 0.1, 0.5, 1, 5 µg/µl) of
MeJA into medium of Jacobaea vulgaris and Jacobaea aquatica tissue culture plants. After two
weeks, all the plants were harvested and PA content was measured by LC-MS/MS. The results
showed that the total PA concentration was not changed upon applying MeJA. However, the PA
composition was significantly changed. With an increasing concentration of MeJA, there is a
shift of senecionine-like PAs to erucifoline-like PAs. In conclusion, exogenous addition of MeJA
can elicit PA synthesis and change individual PA concentrations and composition. Senecioninelike PAs can convert into erucifoline-like PAs. Changed PA composition can have influences on
herbivores like Mamestra brassicae.
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PLANT VOLATILES
Insect behaviour toward plants under biotic and abiotic stresses
Weldegergis BT, Zhu F, Poelman EH, Dicke M
Laboratory of Entomology, Wageningen University, P. O. Box 8031, 6700 EH Wageningen, The
Netherlands
[email protected]
The impact of abiotic stresses on multitrophic interactions can be positive, negative or neutral
depending on the mechanisms by which they interact or/and their order of arrival on the plant
host. Yet, there are very few scientific studies addressing interactions of insects with plants
in response to abiotic stresses. In order to be better prepared for the future in fortifying food
security, understanding the reaction of plants and insects to abiotic stress is crucial. In the current
study, in order to investigate the effect of drought on multitrophic interactions we used Brassica
oleracea (Brussels sprout) plants, the generalist herbivore Mamestra brassicae, and its parasitoid
Microplitis mediator. We tested: (1) performance of M. brassicae caterpillars, (2) oviposition
preferences of M. brassicae moths and (3) behavioral response of the parasitoid M. mediator as
a reaction to drought. In the interest of linking the observed insects’ behaviour, plant metabolites
including volatiles from the headspace and phytohormones from the plant tissues were studied.
Drought has changed the profile of plant-released volatile organic compounds (VOCs), and
especially when combined with herbivory an increase in the emission of nitriles and green
leaf volatiles (GLVs) was observed. Similarly, a plant hormone – salicylic acid was higher in
concentration in drought-stressed plants regardless of the presence or absence of herbivory.
On the contrary, in the presence of drought, the level of jasmonic acid was reduced compared
to only herbivore-infested plants. Moths preferred to lay their eggs on drought stressed plants
over controls, but their offspring had similar performance on both plant treatments. Behavior of
M. mediator parasitoids was not affected by volatile emission in response to drought stress. The
current work reveals that drought stress can change the outcome of interactions between moths
and plants in making choices for their offspring.
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Metabolomics&and
Molecular Mechanisms
METABOLOMICS
MOLECULAR
MECHANISMS
SIP 15
Protein post-translational modification in response
to caterpillar herbivory
Paudel JR 1, Lan Z 1, Bonneil É 2, Bede JC 1
1 Department of Plant Science, McGill University, Ste-Anne-de-Bellevue, Qc, Canada,
H9X 3V9
2 Institute for Research in Immunology and Cancer, Université de Montréal, Montréal,
Quebec, Canada, H3C 3J7
[email protected]
Plant responses to caterpillar herbivory occur rapidly, within minutes of the attack. Therefore,
protein post-translational modifications (PTMs) must be involved in the signaling cascade leading
to plant defence responses. As caterpillar labial saliva has been proposed to contain effectors
that affect the plant’s defence response1, we cauterized the spinneret of a subset of caterpillars
thereby preventing labial salivary secretion to allow the identification of caterpillar labial salivaspecific differences. Previously, we identified a caterpillar salivary-specific phosphorylation of a
lipoxygenase (LOX2) involved in the biosynthesis of the octadecanoid hormone, jasmonic acid2.
In this study, we focused on changes to the Arabidopsis thaliana (L.) Heynh. nuclear proteome
in response to herbivory by caterpillars of the beet armyworm, Spodoptera exigua Hübner. We
identified caterpillar herbivory- or caterpillar labial saliva-specific PTMs of four nuclear proteins.
For two transcription factors identified, expression of downstream target genes mirrored these
post-translational changes. On going studies are continuing to validate the relationship between
these modifications and the regulation of downstream plant defense pathways.
1 Tian, D, Peiffer M, Shoemaker E, Tooker J, Haubruge E, Francis F, Luthe DS, Felton GW 2012. Salivary glucose
oxidase from caterpillars mediates the induction of rapid and delayed-induced defenses in the tomato plant.
PLoS ONE 7: e36168.
2 Thivierge K, Prado A, Driscoll BT, Bonneil, E, Thibault P, Bede, JC 2010. Caterpillar- and salivary-specific
modification of plant proteins. Journal of Proteome Research. 9: 5887-5895.
166
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METABOLOMICS & MOLECULAR MECHANISMS
The consequences of natural variation in Bittersweet’s defences
to mollusc herbivores
Calf OW 1, Huber H 1, Peters JL 1, Steppuhn A 2, van Dam NM 1,3
1 Molecular Interaction Ecology, Radboud University Nijmegen, Heyendaalseweg 135,
6525 AJ Nijmegen, The Netherlands
2 Molecular Ecology, Freie Universität Berlin, Haderslebener Str. 9, 12163 Berlin, Germany
3 Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research (iDiv),
Deutscher Platz 5e, 04103 Leipzig, Germany
[email protected]
Plants have evolved diverse mechanisms of constitutive and inducible defences to herbivores.
A common motivation to study these defences is the quest for natural plant traits that might
increase the performance of our crops and cultivars. While the great majority of these studies
focuses on pest insects, gastropods, a voracious class of herbivores, are generally overlooked.
This may very well be caused by the fact that most gastropods are cryptic feeders that are mostly
active at night. However, this does not make them less relevant to the evolution of plant defence
strategies. In my PhD project, which has started in January 2014, I explore the natural variation
in feeding resistance to the grey field slug (GFS; Deroceras reticulatum) among accessions
of bittersweet nightshade (Solanum dulcamara) originating from different populations in the
Netherlands. I aim to analyse morphological, physiological, metabolomic and molecular plant
traits that are specifically associated with GFS feeding resistance and in addition I will examine the
consequences of these traits for insect performance and that of the natural herbivore community.
We hypothesize that: a) there is significant variation in constitutive resistance to GFS
feeding among accessions of S. dulcamara. These differences in resistance correlate with plant
resistance traits such as protease inhibitors (PIs), polyphenol oxidases (PPOs), alkaloids, trichome
density, leaf toughness and specific leaf area; b) GFS feeding induces a different combination
of signalling pathways in S. dulcamara than feeding by aphids (Myzus persicae), caterpillars
(Spodoptera exigua) or beetles (Leptinotarsa decemlineata), which is evident in the induced
gene transcription profile; c) GFS feeding triggers induced responses that affect plant resistance
to subsequent gastropod and insect herbivores; d) Early-season GFS feeding significantly affects
the composition of the natural herbivore community colonizing S. dulcamara and the amount of
damage that plants will suffer in the following season.
Our first results show that there is significant variation in the constitutive expression of
defence enzymes PIs and PPOs and that these enzymes, as well as the signalling hormones
salicylic acid (SA) and abscisic acid (ABA) are significantly induced upon GFS feeding.
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METABOLOMICS & MOLECULAR MECHANISMS
SIP 15
Direct defence responses in Solanum dulcamara
after insect egg deposition
Geuss D, Steppuhn A
Freie Universität Berlin, Dahlem Centre of Plant Sciences & Collaborative Research Centre
973, Berlin, Germany
[email protected]
[email protected]
Plants defend themselves against herbivores with a range of direct and indirect traits, many of
which are inducible by herbivore feeding. Because many herbivorous insects oviposit on their
host plant, recognition of egg deposition can enable the plant to respond to upcoming attack in
an early stage before larvae start feeding. We investigate whether Solanum dulcamara responds
to oviposition by herbivores with defence responses that affect the eggs and hatching larvae.
We found that S. dulcamara exhibits visible tissue modifications at the oviposition sites of the
generalist herbivore Spodoptera exigua and the specialist herbivore Acrolepia autumnitella. We
examined whether these modifications are associated with an oxidative burst and transcriptional
regulation of genes involved in a hypersensitive response that many plants deploy after pathogen
attack. To determine whether the plants response to oviposition may function as a direct defence
against the eggs, hatching rates of clutches with and without contact to the plant were examined.
Additionally we compared larval performance on egg-free and previously egg-laden pants and
measured chemical and molecular defence parameters of egg-laden and egg-free plants. Our
results indicate that S. dulcamara recognises egg deposition of S. exigua and responds with
direct defence responses that target both, the eggs and the hatching larvae.
168
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METABOLOMICS & MOLECULAR MECHANISMS
Oviposition by Pieris brassicae induces SAR
in Arabidopsis thaliana
Hilfiker O, Reymond P
Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland
[email protected]
In Arabidopsis thaliana oviposition by Pieris brassicae induces the expression of defense
genes associated with plant responses against pathogens. Cell death occurs underneath the eggs
and, consistently, salicylic acid (SA) was shown to accumulate in local and systemic leaves1, 2.
We performed bioassays to assess the growth of different strains of Pseudomonas syringae in
oviposited Arabidopsis plants and discovered that it was significantly reduced in both oviposited
and systemic leaves. We further characterized this response as a systemic acquired resistance
(SAR) and provide genetic evidence that egg-induced SAR involves the systemic signal pipecolic
acid and depends on ALD1 and FMO13. We also showed that insect eggs prime the plant against
future bacterial infections. This unique phenomenon might illustrate a strategy by eggs to prevent
the detrimental effect of bacterial pathogens on feeding larvae.
1 Bruessow F, Gouhier-Darimont C, Buchala A, Metraux J-P, Reymond P 2010. Insect eggs suppress plant defence
against chewing herbivores. Plant Journal 62: 876-885.
2 Little D, Gouhier-Darimont C, Bruessow F, Reymond P 2007. Oviposition by pierid butterflies triggers defense
responses in Arabidopsis. Plant Physiology 143: 784-800.
3 Navarova H, Bernsdorff F, Doring AC, Zeier, J 2012. Pipecolic acid, an endogenous mediator of defense
amplification and priming, is a critical regulator of inducible plant immunity. Plant Cell 24: 5123-5141.
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Jasmonate signaling is involved in shoot growth reduction and
induced defense during phosphate starvation in Arabidopsis
Khan GA 1, Montpetit J 1, Vogiatzaki E 1, Glauser G 2, Poirier Y 1
1 Department of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland
2 Chemical Analytical Service of the Swiss Plant Science Web, University of Neuchâtel,
Neuchâtel, Switzerland
[email protected]
Phosphorus, mainly taken up by plants as inorganic phosphate (Pi), is one of the macronutrients
essential for plant growth. Phosphate deficiency triggers extensive changes in gene expression
as well as at the biochemical and developmental levels, leading to reduced shoot growth and
improved acquisition of the nutrient. The Arabidopsis thaliana PHO1 gene encodes a phosphate
exporter involved in loading phosphate into the xylem. The pho1 null mutant is deficient in shoot
phosphate and shows all the typical symptoms associated with phosphate deficiency, including
strongly reduced shoot growth. Yet, a reduced expression of PHO1 in roots triggered by gene
silencing leads to plants with reduced shoot Pi contents but WT like growth, suggesting that
shoot-Pi independent mechanisms are involved in reducing shoot growth under Pi deficiency.
Here we report that jasmonic acid is an important component in the plant’s responses to phosphate
deficiency. Marker genes associated with jasmonic acid synthesis and signal transduction
pathways are induced during phosphate deficiency. Furthermore, the pho1 mutant shows
an overall induction of defense pathway marker genes, accumulates more jasmonic acid and
salicylic acid in shoots, and shows an increased herbivory resistance. Double mutants between
pho1 and jasmonic acid synthesis (aos) or perception (coi1) mutants show suppression of the
growth reduction associated with Pi deficiency. Overall, these results highlight an important role
of the jasmonic acid pathway in mediating several of the key responses of plants to phosphate
deficiency.
170
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METABOLOMICS & MOLECULAR MECHANISMS
Plant defense in response to multiple insect attack
Kroes A, van Loon JJA, Dicke M
Laboratory of Entomology, Plant Sciences Group, Wageningen University, The Netherlands
[email protected]
In nature, plants are exposed to attacks by multiple herbivore species at the same time. To
cope with these attacks plants have evolved complex defense mechanisms. Not only do these
mechanisms negatively affect herbivores, they also indirectly affect the performance of natural
enemies that feed on these herbivores. Signal transduction pathways involved in plant defenses
are regulated by two key plant defense hormones: salicylic acid (SA) and jasmonic acid (JA).
Production of these hormones depends on the type of attacking insect. For example, defense
against aphids is mainly regulated by SA, whereas JA-mediated defenses are more effective
against caterpillars. It is known that SA and JA signaling pathways interact through crosstalk.
Crosstalk could affect the timing and intensity of plant defense which may result in either
facilitation or suppression of herbivore performance or indirect defense. This study investigates
the underlying mechanisms that regulate plant defenses to multiple attackers. We analysed
how different Brevicoryne brassicae aphid densities interfere with induced (indirect) defenses
against Plutella xylostella caterpillars in Arabidopsis plants. At a low aphid density, growth rate
of P. xylostella was increased, whereas caterpillars feeding on plants colonised by aphids at a
high density have a reduced growth rate. We hypothesise that aphids interfere with the SA signaltransduction pathway since caterpillars feeding on the sid2 mutant, which fails to accumulate SA,
were not affected by the presence of aphids. To establish the effect of aphid density on the induced
indirect defense against caterpillars, the choice of Diadegma semiclausum parasitoid wasps for
odours emitted by Arabidopsis plants infested with different aphid densities or only caterpillars
was analysed. Plants infested with aphids at a low density and P. xylostella caterpillars were
more attractive to parasitoids than plants infested with aphids at a high density and caterpillars.
This suggest that the presence of aphids at different densities interferes with caterpillar-induced
parasitoid attraction. Transcriptional analysis revealed that simultaneous feeding by caterpillars
and aphids at a low density induced the expression of SA transcription factor WRKY70 whereas
expression of WRKY70 was lower in plants induced with both caterpillars and a high aphid
density.
This study demonstrates that multiple insect attack affected plant defenses in a densitydependent manner. Moreover, our data show that the SA signal-transduction pathway is required
for aphid interference with induced defenses against caterpillars.
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OsHI-MAPK1 is a key factor regulating rice induced defense
and senescence
Li J, Liu X, Wang Q, Huangfu J, Lou Y
National Key Laboratory of Rice Biology, Institute of Insect Science, Zhejiang University,
Hangzhou, China
[email protected]
Rice (Oryza sativa), one of the most important food crops in world, suffers serious damage
from rice brown planthopper (BPH) Nilaparvata lugens (Stål) in Asia. Controling this pest with
environmentally-friendly management has become the most severe challenge to agricultural
scientists. OsHI-MAPK1 is a mitogen-activated protein kinase (MAPK) gene whose expression
levels were up-regulated following BPH infestation. To explore its function in herbivore-induced
defense response in rice, we obtained two transgenic lines (ir-mapk) with knock-down of OsHIMAPK1. Chemical analysis revealed that after BPH infestation, ir-mapk lines accumulated more
ethylene and nitric oxide, two small molecules involved in plant senescence, than WT plants
did, which subsequently resulted in poor tolerance of ir-mapk lines to infestation by female BPH
adults. Bioassay found that BPH preferred to feed and oviposit on WT plants over ir-mapk lines.
Moreover, the hatching rate of BPH eggs laid on ir-mapk lines was only half of that on WT plants.
This suggests that OsHI-MAPK1 negatively regulates antibiosis and antixenosis but positively
mediates tolerance in rice to BPH. In line with these findings, 225 differently-expressed genes
were observed between ir-mapk lines and WT plants when they were infested by female BPH
adults, and the up-regulated genes in ir-mapk lines enriched in chitinases, antioxidant activity
and defense responses. In summary, our results indicated that OsHI-MAPK1, via modulating at
least two phytohormones ethylene and nitric oxide, play a pivotal role in maintaining a trade-off
between defense and tolerance in plants to herbivores.
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Feeding by Whiteflies Induce the Production of Glucosinolates
Li J 1, Qian H 2, Wang Q 2,3, Liu S 1
1 Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect
Sciences, Zhejiang University, Hangzhou 310058, China
2 Department of Horticulture, Zhejiang University, Hangzhou 310058, China
3 Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement,
Ministry of Agriculture, Hangzhou 310058, China
[email protected]
The whitefly Bemisia tabaci is a species complex which poses as a disastrous threat to crop
production worldwide. The mostly sessile nymphal stage of whitefly can induce salicylic
acid (SA) defenses while suppress the effectual jasmonic acid (JA) defenses of its host plant.
However, our knowledge of the metabolic outcome of this interaction is pretty limited. Here,
we used two species of whiteflies to investigate it’s role in the production of glucosinolates in
Arabidopsis thaliana. Our results showed that whitefly feeding significantly increased the levels
of both aliphatic and indolic glucosinolates. At 21 day post the initiation of infestation, the levels
of aliphatic glucosinolates increased more than five-fold while the amount of total glucosinolates
doubled that of control non-infested plants. As far as we know, this is the first report on the
induction of defensive compounds by whitefly infestation. And it could be of great ecological
importance in the context of multiple infestations in the field.
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3-β-D-glucopyranosyl-6-methoxy-2-benzoxazolinone A novel detoxification product of maize benzoxazinoid
derivatives in Spodoptera spp.
Maag D 1,4, Köhler A 1, Dalvit C 2, Wouters FC 3, Vassão DG 3, Gershenzon J 3,
Wolfender J-L 4, Turlings TCJ 1, Erb M 3, Glauser G 2
1 Laboratory of Fundamental and Applied Research in Chemical Ecology, University of
Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
2 Chemical Analytical Service of the Swiss Plant Science Web, University of Neuchâtel,
2000 Neuchâtel, Switzerland
3 Max Planck Institute for Chemical Ecology, 07745 Jena, Germany
4 Laboratory of Phytochemistry and Bioactive Natural Products, University of Geneva,
University of Lausanne, 1211 Geneva, Switzerland
[email protected]
In order to defend themselves against arthropod herbivores, maize plants produce 1,4-benzoxazin3-ones (BXs), which are stored as weakly active glucosides in the vacuole. Upon tissue disruption,
BXs come into contact with β-glucosidases, resulting in the release of active aglycones and their
breakdown products. While some aglycones can be reglucosylated by specialist herbivores, little
is known about how they detoxify BX breakdown products. Here we report on the structure
of an N-glucoside, 3-β-D-glucopyranosyl-6-methoxy-2-benzoxazolinone (MBOA-N-Glc),
purified from Spodoptera frugiperda feces. In vitro assays showed that MBOA-N-Glc is formed
enzymatically in the insect gut using the BX breakdown product 6-methoxy-2-benzoxazolinone
(MBOA) as precursor. While Spodoptera littoralis and S. frugiperda caterpillars readily
glucosylated MBOA, larvae of the European corn borer Ostrinia nubilalis were hardly able to
process the molecule. Accordingly, Spodoptera caterpillar growth was unaffected by the presence
of MBOA, while O. nubilalis growth was reduced. We conclude that glucosylation of MBOA is
an important detoxification mechanism that helps insects tolerate maize BXs.
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METABOLOMICS & MOLECULAR MECHANISMS
Admixture in invasive plants:
the effects on chemistry and herbivory
Shi J 1, Gebauer S 1, Stahl M 2,Verhoeven KJF 3, Macel M 1
1 Plant Ecology, University of Tübingen, Auf der Morgenstelle 3, 72076 Tübingen, Germany
2 Zentrum für Molekularbiologie der Pflanzen (ZMBP), University of Tübingen, Auf der
Morgenstelle 32, 72076 Tübingen, Germany
3 Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB,
Wageningen, The Netherlands
[email protected]
Admixture, hybridisation between previously isolated genotypes/populations, can play an
important role in biological invasions. The admixed populations can have higher genetic
variation, novel genotypes and hybrid vigour. Here we investigated if admixture affects herbivore
resistance and plant chemistry in native and invasive population of the invasive plants Lythrum
salicaria. We made crosses within and between populations. We expected the effects of our
artificial admixture to be greater in the native populations because the invasive populations
from the introduced range are already admixed. Chemical diversity and herbivore resistance is
thought to increase in the admixed offspring. We measured plant performance and resistance to
specialist and generalist herbivores in the different crosses. Generalist herbivore performance was
decreasing on the between-population crosses but only in the native populations. To investigate
differences in chemical profiles and chemical diversity of the native and invasive populations
and different cross types we used an untargeted metabolomics approach. Furthermore, phenolic
composition of the plants was also analysed. The results will be discussed in light of plant species
invasiveness and herbivore resistance.
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Auxin as an herbivory-induced signal in Nicotiana attenuata
Machado RAR 1,2, Robert CAM 1,3, Arce CCM 4, Ferrieri AP 1,2, Xu S 2, Baldwin IT 2,
Erb M 1,3
1 Root-Herbivore Interactions Group; 2 Department of Molecular Ecology, Max Planck
Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745 Jena, Germany
3 Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland
4 Departamento de Entomologia, Universidade Federal de Viçosa, Viçosa, Brazil
[email protected]
The role of many phytohormones in plant-insect interactions has been widely studied. However,
little is known about the role of the auxin indole-3-acetic acid (IAA) in this context, despite its
involvement in plant development and stress responses. It was proposed that IAA is suppressed
after herbivore attack in tobacco1, but actual IAA levels have rarely been determined. We found
that IAA levels increase 4-fold in Nicotiana attenuata leaves following Manduca sexta attack2.
To investigate the induction in more detail, we measured IAA levels in different organs of plants
that were wounded and elicited with M. sexta oral secretions (W+OS) at different time points.
We found that IAA levels increased locally within minutes. A slight increase was observed in the
stems and systemic leaves. IAA levels remained elevated over 3 hours following elicitation. To
test whether the increase in IAA is plant or insect-derived, we measured IAA in oral secretions
and in plants following elicitation with fatty acid conjugates. Additionally, we quantified the
expression of known homologues of IAA biosynthesis genes followed by simulated herbivory.
The results show that N. attenuata plants rapidly increase the transcription of IAA biosynthesis
genes following elicitation, and that the increase in IAA pools is plant-derived. To investigate
potential consequences of IAA accumulation in herbivore attacked plants, we complemented
wounded leaves with JA and/or IAA. We observed that the simultaneous application of IAA and
JA triggered the accumulation of red pigments at the stem base, a phenotype that is also observed
in M. sexta infested and W+OS induced plants. This suggests that IAA can increase the production
of stem pigments and possibly other secondary metabolites. We currently work on identifying
the red pigments as well as the other IAA-inducible metabolites that accumulate in the stems and
leaves of wounded plants. To understand the role of auxin signaling in modulating responses to
insect attack in more detail, we are attempting to transiently silence auxin perception by using
the dexamethasone DEX-inducible gene silencing system3. Taken together, these experiments
will help to decipher the elusive role of IAA in plant-herbivore interactions.
1 Onkokesung N, Gális I, Von Dahl C, Matsuoka K, Saluz H, Baldwin IT 2010. Jasmonic acid and ethylene
modulate local responses to wounding and simulated herbivory in Nicotiana attenuata leaves. Plant Physiology
153(2): 785-798.
2 Machado RAR, Ferrieri PA, Robert CAM, Glauser G, Kallenbach M, Baldwin IT, Erb M 2013. Leaf-herbivore
attack reduces carbon reserves and regrowth from the roots via jasmonate and auxin signaling. New Phytologist
200: 1234-1246.
3 Schäfer M, Brütting C, Gase K, Reichelt M, Baldwin IT, Meldau S 2013. “Real time” genetic manipulation: a
new tool for ecological field studies. The Plant Journal 76: 506-518.
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METABOLOMICS & MOLECULAR MECHANISMS
Transcriptome analysis of Physalis philadelphica (husk tomato)
response to herbivory
Medina-Jiménez K 1, Dorantes-Acosta A 1, Caballero-Pérez J 2,
Martínez-de-la-Vega O 3, Sánchez-Hernández C 4, Arteaga-Vázquez MA 1
1 Laboratorio de Epigenética y Biología del Desarrollo, Instituto de Biotecnología y
Ecología Aplicada (INBIOTECA), Universidad Veracruzana, Avenida de las Culturas
Veracruzanas 101, Colonia Emiliano Zapata, ZIP 91500, Xalapa, Veracruz, México
2 Facultad de Ingeniería, Universidad Autónoma de Querétaro, Querétaro, México
3 Laboratorio Nacional de Genómica para la Biodiversidad (LANGEBIO), Irapuato, México
4 Centro Universitario de Ciencias Biológicas y Agropecuarias (CUCBA), Universidad de
Guadalajara, Guadalajara, Jalisco, México
[email protected]
Physalis philadelphica (commonly known as husk tomato), is native to central Mexico and has
an ancient tradition of dietary and medicinal usage. Husk tomato is grown mainly on irrigated
land and it is one of the major horticulture crops grown in Mexico1. Production of husk tomato
is affected by the presence of pests that chew on the foliage (Heliothis spp. Lyriomiza trifolii
and Trichobaris championi) or suck the plant sap (whiteflies, Bemisia tabaci). In order to
understand the molecular and genetic responses of P. philadelphia to herbivory, we employed
Next Generation Sequencing (RNA-seq) to characterize the transcriptome of plants exposed to
either Manduca sexta, Trialeurodes vaporariorum or exogenous application of jasmonic acid
(JA) treatments. We categorized differentially expressed genes (DEG) for each treatment and
interestingly, we observed reduced levels of genes involved in photosynthetic activity when
plants are attacked by both type of insects. Similar to that observed in Arabidopsis, we found
that JA elicits a dramatic increase of genes involved in the JA pathway including homologous of
PLA1, LOX2 and AOS2. In addition to the primary metabolic reconfiguration observed in plants
exposed to herbivory attack, we also identified DEG unique for each condition.
1 De Sahagún, B 1956. Historia general de las cosas de la Nueva España. Porrúa. México City Tomo 3: 367.
2 Wasternack C, Hause B 2013. Jasmonates: biosynthesis, perception, signal transduction and action in plant stress
response, growth and development. An update to the 2007 review in Annals of Botany 11:1021-1058.
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Plant metal hyperaccumulation acts as efficient defence
against specialist and generalist herbivores
Kazemi-Dinan A 1, Thomaschky S 1, Stein RJ 2, Krämer U 2, Müller C 1
1 Chemical Ecology, Bielefeld University, Universitätsstr. 25, D-33615 Bielefeld, Germany
2 Plant Physiology, Ruhr University Bochum, Universitätsstr. 150, D-44801 Bochum, Germany
[email protected]
Several metal-tolerant plants are able to accumulate extraordinarily high levels of metals in
their aboveground tissue. Such elevated metal concentrations may protect the plant against
antagonists. We tested the effects of cadmium (Cd) and zinc (Zn) hyperaccumulation in the
Brassicaceae Arabidopsis halleri on the preference behaviour of various specialist species,
including a potentially adapted field-population, as well as on the performance of a generalist1.
Feeding preferences were tested in paired-choice assays using (1) cabbage leaves to which metal
solutions were applied in different concentrations, (2) A. halleri leaves of plants grown either
on metal-amended or unamended soil, and (3) leaves of a transgenic AhHMA4 RNAi line which
accumulated far lower leaf metal concentrations compared to the wildtype of A. halleri. Feeding
by all specialists was significantly reduced by higher leaf metal concentrations in all set-ups.
The performance of the generalist was tested using artificial diet amended with either Cd and /
or Zn in different concentrations. Its survival was significantly decreased with increasing metal
concentrations, whereby the combination of both metals had an additive effect. In summary,
deterrent and toxic effects of metals play a key role in defence against herbivores with joined
metals enhancing the elemental defence. Thus, metal hyperaccumulation is ecologically beneficial
for plants.
1 Kazemi-Dinan A, Thomaschky S, Stein RJ, Krämer U, Müller C 2014. Zinc and cadmium hyperaccumulation
act as deterrents towards specialist herbivores and impede the performance of a generalist herbivore. New
Phytologist doi: 10.1111/nph.12663
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Plant defense under multiple stress conditions:
linking metabolomics and volatiles (META-VOC)
Papazian S 1, Khaling E 2, Albrectsen B 1,3, Blande J 2
1 Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, SE
2 University of Eastern Finland, Department of Environmental Science, Kuopio, FIN
3 University of Copenhagen, Dept. of Plant and Environmental Sciences, Copenhagen, DK
[email protected]
As part of the European collaboration A-BIO-VOC/ EUROVOL, our research focus on plant
defense and response to various biotic and abiotic stresses, with particular emphasis on the
role of volatile organic compounds (VOCs). Balancing between growth and defense, plants
continuously experience metabolic constraints. The main question we address is hence: how do
plants prioritize the allocation of cell-bound compounds and emission of VOCs under multiple
stress conditions? In the challenge of understanding plant strategies and interaction with their
environment, our approach can be defined as that of ecological metabolomics1.
Given the ample knowledge on the induction of direct and indirect defenses in brassicaceous
systems, the black mustard Brassica nigra has been chosen as a model organism for this project.
Here we investigate Brassica nigra defense against the specialist herbivore Pieris brassicae
(white-cabbage butterfly) under simultaneous high ozone (O3) conditions. O3 is a major air
pollutant, and due to anthropogenic activity its concentrations are constantly increasing. The
strong oxidant power of O3 can negatively affect plant growth and development, as well as
defense systems such JA/SA signaling2, glucosinolates3, and VOCs4.
In order to gain a more comprehensive view on the metabolic costs of plant growth and
defense under these concurrent stress conditions, we link the global metabolomic analysis of
leaf-bound metabolites (constitutive and induced, general and specialized compounds) to the
analysis of VOCs, an attempt we refer to as global METAbolome including Volatile Organic
Compounds, META-VOC.
1 Sardans J, Penuelas J, Rivas-Ubach A 2011. Ecological metabolomics: overview of current developments and
future challenges. Chemoecology 21:191–225.
2 Kangasjärvi J, Jaspers P, Kollist H 2005. Signalling and cell death in ozone-exposed plants. Plant, Cell and
Environment 28: 1021–1036.
3 Vandermeiren K, De Bock M, Horemans N, Guisez Y, Ceulemans R, De Temmerman L 2012. Ozone effects on
yield quality of spring oilseed rape and broccoli. Atmospheric Environment 47:76–83.
4 Pinto DM, Blande JD, Souza SR, Nerg AM, Holopainen JK 2010. Plant volatile organic compounds (VOCs) in
ozone (O3) polluted atmospheres: the ecological effects. Journal of Chemical Ecology 36: 22–34.
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Plant-mediated effects of several water stress intensities
on a leaf-chewer and a phloem feeder
Pineda A 1, Pangesti N 1, Soler R 2, Krosse S 4, van Dam N 3,4, van Loon JJA 1,
Dicke M 1
1 Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands
2 Terrestrial Ecology, NIOO, Wageningen, The Netherlands
3 Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research (iDiv),
Leipzig, Germany
4 Molecular Interaction Ecology, Radboud University Nijmegen, Nijmegen, The Netherlands
[email protected]
Plants in nature are exposed to multiple biotic and abiotic stress factors, such as drought and
herbivory. However, plant responses to these stresses have usually been studied in isolation.
In the last years several studies have addressed the effect of drought on herbivores, but with
different methodologies to induce water stress that have led to contrasting results. Here we
assess the effects of different intensities of water stress imposed to Arabidopsis thaliana, on the
preference and performance of the generalist herbivores Mamestra brassicae (leaf chewer) and
Myzus persicae (phloem feeder). To address a possible underlying mechanism, we analysed the
content of glucosinolates, the main defensive metabolites of this plant. After growing the plants
for four weeks, plants were stressed for one week or watered as normal. Three types of stress
were compared: no watering for 1 week and then re-water to field capacity (LD, as a mimic of
a low drought situation); no water for 1 week and then re-water to 60% of soil water content
(HD, as a mimic of a high drought situation); water every other day to 60% of soil water content
(CD, as a mimic of a continuous mild drought scenario). The results of this study show that
plant chemical defences to herbivory can change under a scenario of increased water stress, with
negative consequences for generalist herbivores. Further studies will evaluate whether this is the
case in a multitrophic situation.
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Induced plant defenses upon thrips infestation in Arabidopsis
Thoen MPM 1,2,3, Weldegergis BT 1 , Kloth KJ 1,2,3, Wiegers GL 1,3,
Bouwmeester HJ 2, Dicke M 1, Jongsma MA 3
1 Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH Wageningen,
The Netherlands
2 Laboratory of Plant Physiology, Wageningen University, P.O. Box 658, 6700 AR
Wageningen, The Netherlands
3 Plant Research International, Wageningen University and Research Center, P.O. Box 619,
6700 AP Wageningen, The Netherlands
[email protected]
Thrips are minute slender piercing-sucking insects represented by over 5000 species in the order
Thysanoptera. The western flower thrips, Frankliniella occidentalis, is a devastating pest insect
on numerous crop species worldwide. Exploring and understanding the molecular basis of plant
resistance mechanisms against thrips can greatly benefit the development of thrips-resistant
crops. We have studied naturally occurring variation in thrips resistance in the Arabidopsis
HapMap collection, a global collection consisting of 349 wild Arabidopsis thaliana accessions.
This led to the discovery of highly resistant accessions with hardly any feeding damage six days
post thrips infestation. In addition to these damage assays, we developed a novel phenotyping
platform that monitors the behaviour of insects in 60 parallel 2-choice leaf disc assays, using
automated video tracking. Applying this method with a highly resistant versus highly susceptible
accession revealed that thrips were spending more time on the leaf discs from the ‘resistant’
accessions in the initial two hours of screening. Then gradually the preferences shifted and after
five hours of screening, thrips start to spend more time on the susceptible accession. Volatiles
from the headspace of whole plants of these two accessions were analysed by GC/MS to identify
candidate compounds that could explain the initial thrips preference. Volatile profiles differed
significantly between the two accessions, and the difference was even more striking when plants
were infested with thrips for 24 hours. Additional 2-choice assays with thrips infested plant
material revealed that the resistant accessions became significantly more deterrent after thrips
infestation, whereas no difference in behaviour on clean versus thrips infested material was
observed in the susceptible line. Accordingly, thrips ‘resistance’ seems, at least in this case, to
be controlled by the plant’s ability to recognise the insect and respond with induced defences.
These induced plant defences are discussed in light of genome-wide association results from the
HapMap collection, to bring forward molecular candidates for thrips resistance in Arabidopsis.
P85
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181
METABOLOMICS & MOLECULAR MECHANISMS
SIP 15
OsHI-LRR2, a novel leucine-rich repeat receptor-like kinase,
plays important roles in herbivore-induced defense responses
in rice
Ye M, Hu L, Lou Y
Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, China
[email protected]
The leucine-rich repeat receptor-like kinases (LRR-RLKs), one of the largest superfamily of
receptor-like kinases (RLKs), have been proven to play specific roles in hormone responses,
developmental regulation, defense against pathogens and adaption to abiotic stresses. However,
their functions in plant defensive response against insects remain poorly understood.
Here we identified a rice LRR-RLK gene, OsHI-LRR2, whose transcripts were dramatically
enhanced in response to infestation by the rice striped stem borer (SSB) Chilo suppressalis
and the rice brown planthopper (BPH) Nilaparvata lugens, as well as mechanical wounding
and treatment with jasmonic acid (JA). On the contrary, the expression level of OsHI-LRR2
was strongly suppressed after salicylic acid (SA) treatment at 8 h. Silencing OsHI-LRR2 (ir-lrr)
revealed that OsHI-LRR2 was upstream of MAPK cascades, and positively regulated OsMPK3
and two WRKY transcription factors. Moreover, OsHI-LRR2 positively regulated SSB-induced
JA, ethylene levels and the activity of trypsin protease inhibitors (TrypPIs). The ir-lrr plants
were more severely damaged by SSB caterpillars than wild-type plants did. In contrast, silencing
OsHI-LRR2 enhanced the accumulation of BPH-induced SA and H2O2, which resulted in the
increased resistance to BPH compared with wild-type (WT) plants: BPH female adults preferred
to settle and oviposit on WT plants over ir-lrr plants; and the survival rates of BPH nymphs and
eggs as well as the fecundity of female BPH adults were lower on ir-lrr plants than on WT plants.
Our results suggest that OsHI-LRR2 functions as a vital component in defense responses in rice
against herbivores with different feeding habits by modulating specific signaling pathways.
182
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P86
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METABOLOMICS & MOLECULAR MECHANISMS
A novel EF-hand protein secreted from salivary glands
of the rice brown planthopper Nilaparvata lugens
functions as an effector for defense responses in rice
Yu H 1, Ye W 1, Ji R 1, Fu Q 2, Chen H 1, Lou Y 1
1 State Key Laboratory of Rice Biology, Institute of Insect Science, Zhejiang University,
Hangzhou 310058, China
2 Research and Development Center of Rice Production Technology, China National Rice
Research Institute, Hangzhou 310006, China
[email protected]
The brown planthopper (BPH), Nilaparvata lugens (Stål), a major rice pest in Asia, possesses
an extraordinary ability to overcome rice resistance by forming new virulent populations. Saliva
plays an important role in insect-plant interactions. However, little to nothing has been known
about the role of BPH saliva in BPH-rice interactions and virulence variation of BPH. Here we
cloned a gene Nl4777, which encodes a calcium-binding protein belonging to a secreted protein
of BPH salivary grands, and found its mRNA levels were significantly higher in BPH population
reared on rice variety Mudgo (containing a resistant gene BPH1) than in BPH population reared
on variety TN1 (susceptible variety). Knockdown of Nl4777 increased the mortality rate of BPH
nymphs and decreased the amount of honeydew secreted by female adults. Meanwhile, BPHs
with knockdown of Nl4777 had a higher mortality rate on Mudgo than on TN1, suggesting
Nl4777 plays an important role in manipulating BPH virulence. We also found that BPHs with
knockdown of Nl4777 elicited rice plants to produce higher levels of SA, H2O2, and volatiles, all
of which can enhance direct or indirect resistance of rice to BPH, demonstrating that Nl4777 acts
as an effector of defense responses in rice. These data indicate that Nl4777 plays an important
role in BPH virulence variation via functioning as an effector of rice defense responses.
P87
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183
Phylogenetics and
Co-Evolution
PHYLOGENETICS
& CO-EVOLUTION
SIP 15
The Aulacoscelidinae beetles and their Cycad hosts
Prado A 1, Windsor D 2, Bede JC 1
1 Department of Plant Science, McGill University, 21,111 Lakeshore Road, Ste.-Anne-deBellevue, Québec, Canada
2 Smithsonian Tropical Research Institute, Ancón, Panamá, Republic of Panama
[email protected]
The Phytophaga (>130,000 species), that include the Chrysomeloidea (leaf beetles), and the
Curculionoidea (weevils) contain close to 50% of phytophagous insect species and nearly 80%
of phytophagous beetle species1. Most Phytophaga are associated with angiosperms with the
exception of a few lineages within the Chrysomeloidea and Curculionoidea that are associated
with gymnosperms, particularly conifers (Order Coniferales) and cycads (Order Cycadales).
Information regarding these interactions between Phytophaga and gymnosperm hosts is
generally lacking. The research presented here focuses on the interactions between members of
the ‘pleiseomorphic’ chrysomelid subfamily Aulacoscelidinae and their host plant cycads. This
is speculated to be an ancient association; in fact, adult Aulacoscelidinae resemble Jurassic fossil
chrysomeloids in the extinct subfamily Protoscelidinae2,3. Adult Aulacoscelidinae beetles feed on
the new foliage and juices of New World cycads (Family Zamiaceae) from which they sequester
the plants toxic azoxyglycosides for their own defense4. Azoxyglycosides are part of the beetle’s
defensive secretions. Adult feeding is restricted to leaves between 10-100 days old. Despite
being cycad specialists, beetles avoid the most toxic young leaves and the completely toughened
mature leaves5. Their feeding pattern is highly synchronized with the annual leaf flush.
Aulacoscelidinae larvae feed on and develop within the megagametophyte of the cycad2
revealing a more intimate feeding relationship between Aulacoscelidinae and their New World
cycad host plants than was previously recognized. The molecular, morphological, ecological,
and fossil data reported herein broadly support an early association between Aulacoscelidinae
and their gymnosperm hosts.
1 McKenna DD, Farrell BD 2009. Beetles (Coleoptera). In: Hedges SB, Kumar S, eds. The timetree of life: Oxford
University Press, USA. p 278.
2 Prado A, McKenna DD, Windsor D 2012. Molecular evidence of cycad seed predation by immature Aula­
coscelidinae (Coleoptera: Orsodacnidae). Systematic Entomology 37: 747-757.
3 Zhang J-F 2005. The first find of chrysomelids (Insecta: Coleopetra: Chrysomeloidea) from Callovian-Oxfordian
Daohugou biota of China. Geobios 38: 865-871.
4 Prado A, Ledezma J, Cubilla-Rios L, Bede JC, Windsor D 2011. Two Genera of Aulacoscelinae Beetles
Reflexively Bleed Azoxyglycosides Found in Their Host Cycads. Journal of Chemical Ecology 37: 736-740.
5 Prado A, Sierra A, Windsor D, Bede JC 2014. Leaf traits and herbivory levels in a tropical gymnosperm, Zamia
stevensonii (Zamiaceae). American Journal of Botany 101: 437-447.
184
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P88
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PHYLOGENETICS & CO-EVOLUTION
Defensive toxins of neotropical Chrysomeline beetles better
reflect phylogenetic origin than host plant associations
Dury GJ 1,2, Windsor DM 2, Pasteels JM 3, Bede JC 1
1 Department of Plant Science, McGill University, 21,111 Lakeshore Road, Ste.-Anne-deBellevue, Québec, Canada
2 Smithsonian Tropical Research Institute, Ancón, Panamá, Republic of Panama
3 Unit of Ecology and Evolutionary Biology, Université Libre de Bruxelle, Brussels, Belgium
[email protected]
Leaf beetles use secrete chemicals for defence. These chemicals may be synthesized de novo or
sequestered from host plants and used directly or modified slightly. We investigated the possible
correlation between host plant and defensive toxins associated with Neotropical Chrosomeline
beetles. A molecular phylogeny was reconstructed to evaluate the relationships of 70 species of
Neotropical Chrysomelinae. We sequenced five gene segments: nuclear protein-coding CAD and
28S rDNA, mitochondrial 12S rDNA and protein-coding COI and COII. The phylogeny was
inferred using Bayesian and Maximum Likelihood (ML) methods and ancestral states of chemical
defence and host plants were reconstructed with ML and Maximum Parsimony methods. Natural
taxa distinguished by their chemical defence were supported by phylogenetic relationships. Host
plant switches suggest that, during leaf beetle evolution, some switches appear more likely than
others. Confirming previous studies, we find chemical defences are more conserved than hostplant associations.
P89
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185
PHYLOGENETICS & CO-EVOLUTION
SIP 15
Rapid evolution of Senecio pterophorus in response to climate
but not to herbivore release
Castells E 1, Colomer-Ventura F 2
1 Toxicology Unit, Departament de Farmacologia, Terapèutica i Toxicologia, Universitat
Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Catalonia, Spain
2 Center for Ecological Research and Forestry Applications (CREAF), 08193 Cerdanyola del
Vallès, Catalonia, Spain
[email protected]
Divergence in plant traits and trait plasticity after invasion has been proposed as an important
mechanism favouring invasion success. Current hypotheses predict a rapid evolution in response
to changes in the herbivore consumption pressure caused by a decrease in the enemies associated
at the area of origin (e.g. evolution of increased competitive ability –EICA– hypothesis), or in
the abiotic conditions after invasion.
Senecio pterophorus (Asteraceae) is a perennial shrub native from Eastern South Africa
and a recent invader in Western South Africa (~100 years ago), Australia (>70-100 years ago)
and Europe (>30 years ago). A biogeographic survey covering the entire distributional area of
S. pterophorus confirmed that plants from the introduced areas were subject to a lower herbivore
consumption compared with plants from the native area1, as expected by the enemy release
hypothesis. The four distributional regions also differed in their summer drought stress. Here
we have evaluated, simultaneously, the role of herbivore consumption and climate on the rapid
geographical divergence in plant traits and trait plasticity of the exotic plant S. pterophorus.
We performed a common garden experiment with plants sampled throughout the
entire known distributional area of S. pterophorus in the native and non-native ranges to test
geographical differences in individual-level traits, leaf-level traits and reproductive-level traits,
and their plastic response to water availability.
Native and non-native populations of S. pterophorus differed in plant traits, but not in
trait plasticity, in response to their local climatic conditions. Our results are contrary to the role
of herbivory as a selective factor after invasion and highlight the importance of climate driving
rapid evolution of exotic plants.
1 Castells E, Morante M, Blanco-Moreno JM, Sans FX, Vilatersana R, Blasco-Moreno A 2013. Reduced seed
predation after invasión supports enemy release in a broad biogeographical survey. Oecologia 173: 1397-1409.
186
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P90
SIP 15
PHYLOGENETICS & CO-EVOLUTION
Evolutionary aspects of cyanogenic glucoside biosynthesis
in butterflies and moths and their food plants
Castro ECP 1, Zagrobelny M 1, Bak S 1
Department of Plant and Environmental Sciences, University of Copenhagen,
Thorvaldsensvej 40, 1871 Copenhagen, Denmark
[email protected]
Larvae of butterflies that belong to the Heliconius genera (Papilionoidea) feed exclusively on
leaves of Passiflora plants (Passifloraceae) and both are cyanogenic. While some Heliconius
species obtain the cyanogenic glucosides linamarin and lotaustralin by sequestrations, others
are known to de novo biosynthesise the compounds from amino acids1. However, the molecular
basis for the synthesis is not known.
Linamarin and lotaustralin are also presents in Zygaena filipendulae (Zygaenoidea) moths
and its host plant Lotus corniculatus (Fabaceae). Two cytochromes P450 enzymes and a glucosyl
transferase (UGT) carry out the biosynthetic pathway of these aliphatic cyanogenic glucosides
in Z. filipendula larvae as well as in the L. corniculatus plants2. A phylogenetic analysis of
the underlying genes showed that though plants and Z. filipendulae synthesize cyanogenic
glucosides in essentially the same way using the same enzyme systems, the pathways have
evolved convergently in the two kingdoms and are thus not phylogenetically related2. We do not
know if de novo biosynthesis of cyanogenic glucosides evolved in an ancestor to butterflies and
moths or if the pathway has evolved recurrently in Lepidoptera.
The aim of this work is identify and characterize the enzymes involved in de novo
biosynthesis of linamarin and lotaustralin in Heliconius melpomene, as well as to unravel the
evolution of the cyanogenic glucoside pathway in Lepidoptera. Our preliminary studies of the
Heliconius genome indicated putative homologs to both of the Zygaena cytochromes P450 from
the cyanogenic glucoside pathway in the H. melpomene genome. RT-PCR analysis showed that
all these putative homologous genes are expressed in H. melpomene imagos. If the cyanogenic
glucoside pathway in butterflies and moths are homologous, the pathway could have evolved in
the common ancestor of Zygaenoidea and Papilionoidea, or even earlier, rendering this pathway
an ancient invention.
1 Nahrstedt A, Davis RH 1983. Occurrence, variation and biosynthesis of the cyanogenic glucosides linamarin and
lotaustralin in species of the Heliconiini (Insecta, Lepidoptera). Comp. Biochem. Physiol. Volume 75B: 65-73.
2 Jensen NB, Zagrobelny M, Hjernø K, Olsen CE, Houghton-Larsen J, Borch J, Møller BL, Bak S 2011. Convergent
evolution in biosynthesis of cyanogenic defence compounds in plants and insects. Nature Communication
Volume 2: 273-280.
P91
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187
PHYLOGENETICS & CO-EVOLUTION
SIP 15
Coevolution between bacterial endosymbionts and their psyllid
hosts of the Cardiaspina genus (Hemiptera: Psyllidae)
Hall A, Cook J, Johnson S, Riegler M
Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797,
Penrith NSW 2751, Australia
[email protected]
Psyllids, also known as jumping plant-lice, are tiny sap-feeding insects belonging to the
hemipteran suborder Sternorrhyncha. The critically endangered Cumberland Plain Woodland
(CPW) of Western Sydney, Australia has recently experienced massive infestations by a psyllid
belonging to the lace lerp genus of Cardiaspina (Hemiptera: Psyllidae). This psyllid outbreak
severely impacts ecosystem function and is raising grave community concerns, because
Eucalyptus moluccana (Grey Box), the only host plant of this psyllid, is the dominant tree species
in the region. Cardiaspina psyllids have not been reported previously from Grey Box, making
our study the first description of this host-herbivore relationship. The first aim of our study was
to determine the placement of this Cardiaspina sp. within the genus using mitochondrial and
nuclear DNA sequences.
Psyllids are also known for their intimate interactions with bacterial endosymbionts.
Many bacterial taxa have evolved obligate endosymbiotic associations with animal hosts, often
characterised by vertical transmission of bacteria to host offspring. Candidatus Carsonella ruddii
is the primary obligate endosymbiont of psyllids, while Arsenophonus is a genus of bacteria
described in a range of arthropods and can be either vertically or horizontally transmitted. This
study aimed to test the phylogenetic congruence of both bacteria with the phylogeny of their
psyllid hosts, by using mitochondrial and nuclear host genes and at least two bacterial genes.
We found that the Grey Box psyllid is very closely related to Cardiaspina species that
feed on other eucalypt species in the Box group, supporting strong conservation of host plant
associations. In fact, very low levels of genetic differentiation suggest that they could all be one
species, and this finding creates the need for a more comprehensive phylogenetic analysis of the
Cardiaspina genus. Candidatus Carsonella ruddii has been found with 100% prevalence in all
species of the Cardiaspina genus tested and appears to have a phylogeny congruent to that of its
host supporting the idea of long-term cospeciation with the host. Unexpectedly, Arsenophonus
also has 100% prevalence in almost all Cardiaspina species screened. This makes the genus
Cardiaspina an ideal system in which to compare phylogenetic congruence with the insects
of a vertically transmitted primary symbiont and a secondary symbiont shown in other insect
groups to be transmitted both vertically and horizontally. For the first time, we have tested such
coevolutionary relationships at the lowest taxonomic level (between species) in the Psylloidea
superfamily.
188
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P92
SIP 15
PHYLOGENETICS & CO-EVOLUTION
Molecular evolution of flavin-dependent monooxygenases
adapted for the detoxification of plant pyrrolizidine alkaloids
in Lepidoptera
Heidemann F, Ober D
Botanisches Institut, Christian-Albrechts-Universität, Am Botanischen Garten 1-9, 24118 Kiel,
Germany
[email protected]
Pyrrolizidine alkaloids (PAs) are typical secondary metabolites produced by plants for chemical
defense. PAs occur in two convertible forms: as nonpolar tertiary alkaloid and as polar N-oxide.
In plants, PAs predominantly exist as nontoxic N-oxide. If incorporated in animals, the N-oxide
is reduced to its lipophilic form being toxic for unadapted species. There are several lepidopteran
species having the ability to ingest PAs from plants without getting harmed. To this effect, most
is known about the Arctiidae (tiger moths)1. Some arctiid species own adapted flavin-dependent
monooxygenases (FMOs) that are able to use the toxic form of PAs as substrate and to oxygenate
it back into the nontoxic N-oxide. Within arctiids, there is evidence that recruitment of FMOs
for detoxification evolved by gene duplication processes2. Besides arctiids, there are also some
nymphalids (brush-footed butterflies) known to feed on PA containing plants. They primarily use
PA-derivatives to build up pheromones. Our aim is to reveal the molecular evolution of PA-specific
FMOs within Lepidoptera (predominantly for Nymphalidae and Arctiidae). We try to discover
whether recruitment of FMOs for PA-detoxification happened several times during evolution of
Lepidoptera. Currently, we are about to identify the PA-specific FMO in Danaini (Nymphalids)
with the objective to clarify, if gene recruitment in nymphalids occurred independently of the
gene recruitment event in arctiids. And if so, did it similarly evolve from a gene duplication
process? The method we use is maximum-likelihood phylogeny based on encoded amino acid
sequences for PA-specific FMOs. Search for FMO sequences are conducted by cDNA screening
using degenerated primers and by Illumina sequencing. With the aid of heterologous expression
in E. coli, we also try to verify the specifity for PAs of the identified enzymes.
1 Langel D, Ober D 2011. Evolutionary recruitment of a flavin-dependent monooxygenase for stabilization of
sequestered pyrrolizidine alkaloids in arctiids. Phytochemistry 72: 1576–1584.
2 Sehlmeyer S, Wang L, Langel D, Heckel DG, Mohagheghi H, Petschenka G, Ober D 2010. Flavin-dependent
monooxygenases as a detoxification mechanism in insects: new insights from the arctiids (Lepidoptera).
PLoS ONE 5: e10435
P93
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189
PHYLOGENETICS & CO-EVOLUTION
SIP 15
Host plant-specific remodeling of midgut physiology in the
generalist insect herbivore Trichoplusia ni
Herde M 1, Howe G 2
1 Department of Plant Biochemistry, Dahlem Center of Plant Sciences, Freie Universität
Berlin, 14195 Berlin, Germany
2 4275 Molecular Plant Science, Michigan State University, East Lansing, Michigan, USA
[email protected]
Species diversity in terrestrial ecosystems is influenced by plant defense compounds that alter
the behavior, physiology, and host preference of insect herbivores. Although it is established
that insects evolved the ability to detoxify specific allelochemicals, the mechanisms by which
polyphagous insects cope with toxic compounds in diverse host plants are not well understood.
Here, we used defended and non-defended plant genotypes to study how variation in
chemical defense affects midgut responses of the lepidopteran herbivore Trichoplusia ni, which
is a pest of a wide variety of native and cultivated plants. The genome-wide midgut transcriptional
response of T. ni larvae to glucosinolatebased defenses in the crucifer Arabidopsis thaliana was
characterized by strong induction of genes encoding Phase I and II detoxification enzymes. In
contrast, the response of T. ni to proteinase inhibitors and other jasmonate-regulated defenses
in tomato (Solanum lycopersicum) was dominated by changes in the expression of digestive
enzymes and, strikingly, concomitant repression of transcripts encoding detoxification enzymes.
Unbiased proteomic analyses of T. ni feces demonstrated that tomato defenses remodel the
complement of T. ni digestive enzymes, which was associated with increased amounts of serine
proteases and decreased lipase protein abundance upon encountering tomato defense chemistry.
These collective results indicate that T. ni adjusts its gut physiology to the presence of host plantspecific chemical defenses, and further suggest that plants may exploit this digestive flexibility
as a defensive strategy to suppress the production of enzymes that detoxify allelochemicals.
190
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P94
SIP 15
PHYLOGENETICS & CO-EVOLUTION
The evolutionary relationship between constitutive and induced
detoxification resistance in generalist herbivores
Morin S, Halon E, Elbaz M
Department of Entomology, the Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100,
Israel
[email protected]
The ability to detoxify plant toxins is considered one of the major weapons insect have evolved
in their coevolutionary ‘arms race’ with plants. Generalist insect that feed on a wide range of
plant families, can utilize two different modes for regulating their detoxification genes: the
constitutive mode, in which the detoxification genes are expressed independent of encountering
a defended plant, and the induced mode, in which the detoxification genes are activated only
after contact with the plant toxic chemistry. The inducible mode is assumed to be advantageous
over the constitutive mode, largely because it is believed to confer an adaptive plasticity that
enables reducing the costs associated with maintenance of detoxification.
Here, we used two Bemisia tabaci sibling species [the Middle East - Asia Minor 1 (B)
and Mediterranean (Q)], as a model system for studying the evolution of constitutive and
induced detoxification resistance. Expression analyses of detoxification genes, belonging to
the cytochrome P450 monooxygenases, glutathione S-transferases, UDP-glycosyltransferases
and carboxylesterase families, indicated that about half of the genes analyzed were significantly
over-expressed in the Q species (relative to the B species) when feeding on sucrose diet, strongly
suggesting that the Q species have adapted the “always ready for a challenge” constitutive
detoxification resistance strategy for dealing with toxic plant chemistry.
As the Q species of B. tabaci can tolerate better than the B species highly defended
plants, we argue that the importance of constitutive detoxification resistance may have been
underestimated. It may actually be more advantageous for generalist herbivores, in various
ecological contexts, to move from one plant species to the other with their detoxification system
turned on at all times, as these species are likely not to have the ability, anyway, to respond to
specific compounds with the “right” optimal gene.
P95
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191
PHYLOGENETICS & CO-EVOLUTION
SIP 15
Plant-herbivore interactions in diploid and tetraploid cytotypes of
Centaurea phrygia
Skuhrovec J 1, Münzbergová Z 2,3
1 Dept. Plant Ecology and Weed Science, Crop Research Institute, Prague, Czech Republic
2 Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic
3 Institute of Botany, Academy of Sciences of the Czech Republic, Průhonice, Czech Republic
[email protected]
Herbivory is one of the key interactions affecting plant fitness. In spite of the large quantity
of data on the effects of herbivores on various plant groups, we still know very little on the
interaction of herbivores with individuals of different ploidy level. Changes in plant-herbivore
interactions as a consequence of polyploidization are, however, likely as polyploidization is
known to have many strong effects on plant life.
We studied plant-herbivore association in two cytotypes of Centaurea phrygia in natural
conditions as well as in two experimental gardens. We also explored the importance of herbivores
as selection agents affecting phenology of the species.
In our study, higher seed damage in tetraploids is combined with lower seed set in the
tetraploids leading to much lower overall seed production in tetraploids compared to diploids.
This corresponds to the wider range of habitats occupied by the diploids compared to the
tetraploids. The differences in seed damage between the cytotypes may be explained by different
herbivore communities associated with the different cytotypes. This result may be possibly
explained by high differences in the amount of seed damaged caused by single seed predators.
Specifically, each of observed pre-dispersal predator groups has different attack strategy and the
way of seed consumption. Due to this, the simple number of seed predators thus may not be in
fact informative. In the study, we found higher number of seed predators in diploids but higher
seed damage in the tetraploids. This fact can be explained by the fact that tetraploids host higher
densities of weevils and caterpillars causing higher seed damage. In contrast, diploids hosted
seed-predators causing lower seed damage such as tephritids and gall midges.
The study demonstrated that ploidy level plays a key role in plant-herbivore association
in the system. The general pattern was similar between field conditions and two experimental
gardens suggesting that the observed patterns are not due to the occurrence of the different
cytotypes in different habitats. The strong differences in herbivore community composition
and seed damage can be explained by flowering phenology, suggesting that the differences in
phenology may be the key factor explaining the observed pattern. However, other factors such as
differences in flower head size, morphology and content of nutrient and secondary metabolites
may also contribute to these differences. In addition, the herbivores represent an important
selection factor on flowering phenology in the system and the selection pressure is consistent
with the observed differences in flowering phenology between cytotypes. This possibly suggests
that the differences in flower head phenology between the cytotypes may not be the cause, but
a consequence of differential selection pressure by the herbivores. Separation the causes and
consequences is, however, not possible using the current dataset.
192
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P96
SIP 15
PHYLOGENETICS & CO-EVOLUTION
Molecular phylogeny for the Australian jumping plant lice and
lerp insects (Hemiptera: Psylloidea) reveals host specificity
Taylor GS 1, Fagan-Jeffries EP 1, Steinbauer MJ 2, Austin AD 1
1 Australian Centre of Evolutionary Biology & Biodiversity, School of Earth & Environmental
Sciences, University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
2 Department of Zoology, La Trobe University, Melbourne, Victoria 3086, Australia
[email protected]
Jumping plant-bugs or ‘psyllids’ (Hemiptera: Psylloidea) show a high level of host specificity,
where psyllid families are often associated with certain plant families, often with congruence
at the generic level, and many species are associated with single, or few closely related plant
species1, 2. Whether they have co-evolved with their hosts, or have undergone periodic host
switches and subsequent radiations on ‘novel’ hosts, or a combination of both, has been little
investigated3.
In this study, comprising the first comprehensive molecular research on the Australian
Psylloidea on a sclerophyllous flora characterised by its evolution in an aridifying environment4,
phylogenetic analysis of 140 isolates using combined COI (441 bp) and 18S (813 bp) sequences
data depicted a basal monophyletic clade for the Australian sponyliaspidine Aphalaridae, host
specific to the Myrtaceae. This clade comprised a weakly resolved backbone supporting each
of Cardiaspina+Blepharocosta, Glycaspis, Creiis+Lasiopsylla (all lerp-formers); Anoeconeossa
+Eucalyptolyma, Platyobria and Blastopsylla (all free-living on flush, meristematic foliage); and
Phellopsylla+Phyllolyma (stem and bark-inhabitants) +Ctenarytaina (free-living, flush foliage
feeders). A second major lineage contained a poorly resolved clade of Acizzia (Psyllidae) (multiple
hosts including Fabaceae, Loranthaceae, Sapindaceae) nested within a diverse assemblage
of the Triozidae. This latter family depicted a high degree of structure associated with their
host taxa, including Aacanthocnema on Allocasuarina and Casuarinicola on Casuarina (both
Casuarinaceae), Trioza on Eremophila and Myoporum (both Scrophulariaceae) and Schedotrioza
on Eucalyptus (Myrtaceae). Ongoing studies aim to further resolve the potential cophylogeny of
the Australian psyllid fauna and their hosts.
1 Taylor GS, Jennings JT, Purcell MF and Austin AD 2011. A new genus and ten new species of jumping plant-lice
(Hemiptera: Triozidae) from Allocasuarina (Casuarinaceae) in Australia. Zootaxa 3009: 1-45.
2 Taylor GS, Moir ML 2013. Further evidence of the co-extinction threat for jumping plant-lice: three new
Acizzia (Psyllidae) and Trioza (Triozidae) from Western Australia. Insect Systematics and Evolution. DOI:
10.1163/1876312X-00002107.
3 Percy DM, Page RDM, Cronk Q 2004. Plant-insect interactions: double-dating associated insect and plant
lineages reveals asynchronous radiations. Systematic Biology 53: 120-127.
4 Steane DA, Nicolle D, Sansaloni CP, Petroli CD, Carling J, Kilian F, Myburg AA, Grattapaglia D, Vaillancourt
RE 2011. Population genetic analysis and phylogeny reconstruction in Eucalyptus (Myrtaceae) using highthroughput, genome-wide genotyping. Molecular Phylogenetics & Evolution 59: 206-224.
P97
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PHYLOGENETICS & CO-EVOLUTION
SIP 15
Contrasting dispersal and inbreeding in a fig-pollinating wasp
and its parasitoid
Sutton TL, DeGabriel JL, Riegler M, Cook JM
Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797,
Penrith NSW 2751, Australia
[email protected]
Figs (Ficus spp.) and their pollinators (Hymenoptera: Agaonidae) are a classic example of
obligate symbiosis, having evolved completely interdependent life histories. Their symbiosis is
exploited by host-specific parasitoid wasps, which kill pollinator offspring and can thus reduce fig
pollen transfer. Interactions between the fig, pollinator and parasites play an important role in the
coevolution of this system. Pollinator dispersal mediates gene flow of the host fig, and therefore
has implications for the maintenance of fig species boundaries. Furthermore, attack by parasitoids
may actually help stabilise the mutualism by reducing seed predation by pollinator offspring.
Previous studies indicate that some fig-pollinating wasps are capable of long-distance dispersal,
but little is known about the dispersal and mating systems of their parasitoids. Differential
dispersal capacity between pollinator and parasitoid may affect fig – pollinator dynamics in the
short term, particularly in isolated fig populations, as well as long-term coevolution. Here, we
present the first comparative microsatellite analysis of a fig-pollinator and its parasitoid.
We collected Pleistodontes imperialis sp. 1, a pollinator of Port Jackson figs (Ficus rubi­
ginosa), and its parasitoid (Sycoscapter sp. A) at a series of sites located from about ten to
several hundred km apart in eastern Australia, and genotyped all wasps at six microsatellite loci.
Preliminary results indicate that genetic differentiation between sites is lower in P. imperialis
sp. 1 compared to Sycoscapter sp. A. This supports the idea that pollinators are capable of longdistance dispersal, while their parasitoids disperse more locally. Despite this, Bayesian clustering
analyses determined that each species forms a single genetic population over hundreds of
kilometres. Inbreeding measures were higher in the pollinator, consistent with our prediction
that fewer pollinator than parasitoid females contribute eggs to each fig, limiting the diversity of
potential mates in the next generation.
Pollinator wasp populations are large and geographically expansive. Fig and pollinator
gene flow thus occur over large distances and may prevent the evolution of local genetic
adaptation between sites with differing climates. Lower dispersal distances in parasitoids may
be more likely to allow local genetic adaptation, and also leave more isolated fig and pollinator
populations free from parasites.
194
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ADDENDUM
Addendum
PHYLOGENETICS &
CO-EVOLUTION
The sensory basis of host shifts in phytophagous insects
Roessingh P 1, Petr Nguyen P 2, Heiko Vogel H 3, Grosse-Wilde E 3, Menken S 1
1 IBED, University of Amsterdam, Netherlans
2 Biology Centre of the ASCR, Institute of Entomology, Czech Republic
3 Max Planck Institute for Chemical Ecology, Jena, Germany
[email protected]
Host shifts are common in the evolution of phytophagous insects. Shifting to a new host is only
possible after accepting a new host. Changes in chemoreception must therefore be a first step in
the evolution of new species. Yponomeuta species shifted from Celastraceae to Rosaceae. This
shift was probably aided by a phytochemical bridge formed by sugar alcohols common to the
two plant families. Small ermine moths of the genus Yponomeuta only feed on plants containing
particular sugar alcohols as phagostimulants. Caterpillars have a simple sensory system with
receptor proteins located in sensilla on the mouthparts that completely control larval host
acceptance behaviour. We aim to reconstruct the evolutionary changes in the sensory system of
specialised Yponomeuta moths related to the historical host shift from Celastraceae to Rosaceae
and back.
Larval transcriptomes of Y. evonymella (sensitive to sugar alcohols of both the ancestral
and derived host plants), Y. padella (only sensitive to sugar alcohols of derived rosaceous hosts)
and Y. cagnagella (renewed sensitivity to sugar alcohols of Celastraceae) were sequenced on the
Illumina platform and assembled de novo. We used blast searches with a reference set of 312
lepidopteran gustatory receptors and GO annotation to identify candidate sensory receptor genes.
Clear clusters of receptors were found, each containing representatives of most of the
species. Several candidate gustatory receptors were found, including one that might be a sugaralcohol receptor similar to BmorGr8, a confirmed inositol receptor. All but two lepidopteran Grs
are “candidates”: functional studies are urgently needed!
P99
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195
PLANT VOLATILES
ADDENDUM
SIP 15
Malicious signals – when plants should not eavesdrop
Blande JD, Li T.
Department of Environmental Science, University of Eastern Finland, Kuopio, 70211, Finland
[email protected]
The first evidence that plants can communicate with each other through the emission of volatile
chemicals was published approximately 30 years ago. Since then, a large body of work has
accumulated, both supporting and refining the idea. That plants can detect volatile cues and
respond by altering their defences, would now seem to be beyond question. However, the reason
for such interaction to evolve is more contentious. Why would a damaged plant provide a
helpful cue for competing neighbours? One of the more convincing explanations to date is that
plants – in ‘crying for help’ – provide cues that can be eavesdropped on by near neighbours. If
plants can detect and respond to volatile cues from neighbouring plants, it stands to reason that
they could also detect and respond to cues from other volatile-emitting community members.
Larvae of the specialist aspen-feeding herbivore Phyllodecta laticollis emit salicyl aldehyde as a
defence response. We hypothesised that in addition to acting as a component of the beetle larva’s
defence, it may also provide a cue that can be detected by plants. We previously found that
two induced defences of hybrid aspen, secretion of extra-floral nectar and emission of volatile
organic compounds, are modulated in response to volatile cues from neighbouring plants1. Here
we show that salicyl aldehyde also modulates the same traits. Interestingly, plants exposed to
salicyl aldehyde displayed reduced levels of extra-floral nectar secretion. We question whether
P. laticollis-emitted volatiles can reduce the defence responses of host and/or neighbouring plants
and examine the consequences of eavesdropping on malicious signals.
1 Li T, Holopainen JK, Kokko H, Tervahauta AI, Blande JD 2012. Herbivore-induced aspen volatiles temporally
regulate two different indirect defences in neighbouring plants. Functional Ecology 26: 1176-1185.
196
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ADDENDUM
PLANT VOLATILES
Plant volatile emission is affected by different virulent
AP phytoplasma strains
Rid M 1,2, Ayasse M 2, Gross J 1
1 Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Plant
Protection in Fruit Crops and Viticulture, Schwabenheimer Strasse 101, 69221 Dossenheim,
Germany; Tel. +49 (0) 6221 86 805 21
2 University of Ulm, Institute of Experimental Ecology, Albert-Einstein-Allee 11, 89069 Ulm,
Germany; Tel. +49 (0)731 50 22663
[email protected]
Apple proliferation (AP) is one of the most severe diseases in apple growing areas. Infected
apple trees show typical symptoms such as witches’ broom, tasteless and dwarf fruits. The
disease is caused by the cell-wall lacking bacterium Candidatus Phytoplasma mali (AP
phytoplasma). In former studies it was shown that AP infested apple trees emitted higher amounts
of the sesquiterpene β-caryophyllene, by which the vector insect Cacopsylla picta (Hemiptera:
Psyllidae) was attracted, and thus the dispersal of the AP phytoplasma may be facilitated1, 2.
In the presented study two Ca. P. mali strains causing different severity of symptoms in
apple plants were analyzed and compared. Headspace samples from healthy and infected model
plant tobacco (Nicotiana occidentalis) were investigated via thermodesorption and GC-MS
analysis. Amounts of ethyl benzoate and a not yet identified sesquiterpene differed between the
odour bouquets of healthy and by Ca. P. mali infected tobacco plants. Additionally, a significant
quantitative difference of this sesquiterpene was measured in the headspace of plants infected with
the two different strains. Furthermore, the vector insect C. picta was able to distinguish between
the two different strains based on their odour composition. Ongoing research aims to clarify the
link between the virulence of a phytoplasma strain and the emission of the sesquiterpene as well
as the role of volatile organic compounds for virulence and epidemiology of phytoplasmas.
1 Mayer CJ, Vilcinskas A, Gross J 2008. Phytopathogen lures its insect vector by altering host plant odor. Journal
of Chemical Ecology 34: 1045-1049.
2 Mayer CJ, Vilcinskas A, Gross J 2008. Pathogen-induced release of plant allomone manipulates vector insect
behavior. Journal of Chemical Ecology 34: 1518-1522.
P101
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197
ADDENDUM
198
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PARTICIPANT
LIST
Participant List
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Invited Speakers
Nadir Alvarez
[email protected]
University of Lausanne
CHE
76
Peter Anderson
[email protected]
Swedish University of Agricultural
Sciences Alnarp
SWE
62
Toby Bruce
[email protected]
Rothamsted Research
GBR
56 144
Yolanda Chen
[email protected]
University of Vermont
USA
53
Susanne Dobler
[email protected]
Hamburg University
DEU
81
Gaëtan Glauser
[email protected]
University of Neuchâtel
CHE
42 55 66 73 170
174
Martin Heil
[email protected]
CINVESTAV Irapuato
MEX
26 110
Martine Hossaert
[email protected]
CEFE, CNRS, University of
Montpellier
FRA
41
Erik Poelman
[email protected]
Wageningen University
NLD
60 87
Philippe Reymond
[email protected]
University of Lausanne
CHE
68 71 169
Christelle Robert
[email protected]
University of Bern
CHE
49 138 176
Florian Schiestl
[email protected]
University of Zurich
CHE
36 37 131
Eric Schmelz
[email protected]
University of California San Diego
USA
59
Roxina Soler
[email protected]
Netherlands Institute of Ecology
(NIOO-KNAW) Wageningen
NLD
46 180
Sharon Strauss
[email protected]
University of California Davis
USA
25
199
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PARTICIPANT LIST
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200
Hiroshi Abe
[email protected]
RIKEN BioResource Center
Tsukuba
JPN
Jeffrey Ahern
[email protected]
University of Turku
FIN
Benedicte Albrectsen
[email protected]
Umeå University
SWE
98 179
Jared Ali
[email protected]
Michigan State University
USA
80
Martin Aluja
[email protected]
Instituto de Ecología Xalapa
MEX
57 120 147
Daniel Anstett
[email protected]
University of Toronto
CAN
82 99
Agnès Ardanuy
[email protected]
Universitat de Lleida
ESP
100
Michèle Bandoly
[email protected]
Freie Universität Berlin
DEU
75
Kirk Barnett
[email protected]
University of Western Sydney
AUS
136
Imke Bartelsmeier
[email protected]
Wageningen University
NLD
Jacqueline Bede
[email protected]
McGill University
CAN
166 184 185
Alison Bennett
[email protected]
James Hutton Institute Dundee
GBR
137
Betty Benrey
[email protected]
University of Neuchâtel
CHE
53 55 110 143
Franziska Beran
[email protected]
Max Planck Institute for
Chemical Ecology Jena
DEU
83
Arjen Biere
[email protected]
Netherlands Institute of Ecology NLD
(NIOO-KNAW) Wageningen
35
Mascha Bischoff
[email protected]
Cornell University Ithaca
USA
39
Ruben Blanco Perez
[email protected]
University of Neuchâtel
CHE
141
97
82 99
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James Blande
[email protected]
University of Eastern Finland
Kuopio
FIN
Christiane Bobillier
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University of Neuchâtel
CHE
Christelle Bonnet
[email protected]
University of Lausanne
CHE
Zoe Bont
[email protected]
University of Bern
CHE
Jan Bruin
[email protected]
Entomologia Experimentalis et
Applicata
NLD
Carlos Bustos
[email protected]
Australian National University
Canberra
AUS
151
Onno Calf
[email protected]
Radboud University Nijmegen
NLD
28 167
Ines Cambra
[email protected]
Max Planck Institute for
Chemical Ecology Jena
DEU
138
Raquel Campos-Herrera
[email protected]
University of Neuchâtel
CHE
139 141 152
Pasquale Cascone
[email protected]
National Research Council
Portici
ITA
Eva Castells
[email protected]
Universitat Autònoma de
Barcelona
ESP
186
Érika Castro
[email protected]
University of Copenhagen
DNK
187
Xavier Chiriboga
[email protected]
University of Neuchâtel
CHE
139 141 152
Lucie Conchou
[email protected]
CEFE Montpellier
FRA
Louie Coscos
[email protected]
Cork
IRL
Simona Cristescu
[email protected]
Radboud University Nijmegen
NLD
153
Maximilien Cuny
[email protected]
University of Neuchâtel
CHE
55 143
Antonino Cusumano
[email protected]
University of Palermo
ITA
63 179 196
68
101 160
102 103 160
201
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Sandra da Silva
[email protected]
Universidade Federal de Lavras
BRA
104
Holger Danner
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Radboud University Nijmegen
NLD
153
Marjolein de Rijk
[email protected]
Wageningen University
NLD
105
Thomas Degen
[email protected]
University of Neuchâtel
CHE
128
Emma Despland
[email protected]
Concordia University Montreal
CAN
154
Gaylord Desurmont
[email protected]
University of Neuchâtel
CHE
128 130 153
Marcel Dicke
[email protected]
Wageningen University
NLD
Sylvia Drok
[email protected]
Freie Universität Berlin
DEU
27 58 60 64 89
101 102 105 112
113 114 160 165
171 180 181
Franziska Eberl
[email protected]
Max Planck Institute for
Chemical Ecology Jena
DEU
Swantje Enge
[email protected]
University of Copenhagen
DNK
Matthias Erb
[email protected]
University of Bern
CHE
David Ermacora
[email protected]
University of Neuchâtel
CHE
Micky Eubanks
[email protected]
Texas A&M University
USA
106 150
Sarah Facey
[email protected]
University of Western Sydney
AUS
140
Nina Fatouros
[email protected]
Wageningen University
NLD
64 84 102 160
Frauke Fedderwitz
[email protected]
Swedish University of
Agricultural Sciences Uppsala
SWE
145
Minghui Fei
[email protected]
Netherlands Institute of Ecology NLD
(NIOO-KNAW) Wageningen
107
Enric Frago
[email protected]
Wageningen University
NLD
155
156
50 73 138 174 176
27
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Julia Fricke
[email protected]
University of Bern
CHE
Mickael Gaillard
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University of Neuchâtel
CHE
146
Daniel Gervasi
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University of Zurich
CHE
37 131
Daniel Geuss
[email protected]
Freie Universität Berlin
DEU
168
Andrew Gherlenda
[email protected]
University of Western Sydney
AUS
29
Marian J. Giertych
[email protected]
University of Zielona Góra
POL
108
Rieta Gols
[email protected]
Wageningen University
NLD
53 64 93 101 102
107 113 160
Sandrine Gouinguené
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University of Neuchâtel
CHE
Juergen Gross
[email protected]
Julius Kühn-Institut
Dossenheim
DEU
Emilio Guerrieri
[email protected]
National Research Council
Portici
ITA
Larissa Guillén
[email protected]
Instituto de Ecología Xalapa
MEX
147
Rayko Halitschke
[email protected]
Cornell University Ithaca
USA
45
Aidan Hall
[email protected]
University of Western Sydney
AUS
109 188
Vinzenz Handrick
[email protected]
Max Planck Institute for
Chemical Ecology Jena
DEU
73
Jeffrey Harvey
[email protected]
Netherlands Institute of Ecology NLD
(NIOO-KNAW) Wageningen
60 93 107
Thure Pavlo Hauser
[email protected]
University of Copenhagen
DNK
86
Franziska Heidemann
[email protected]
University Kiel
DEU
189
Detlev Helmig
[email protected]
University of Colorado Boulder
USA
197
101 160
203
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204
Marco Herde
[email protected]
Freie Universität Berlin
DEU
190
Sara Hermann
[email protected]
Cornell University Ithaca
USA
65
Johnattan Hernandez-Cumplido University of Neuchâtel
[email protected]
CHE
110
Olivier Hilfiker
[email protected]
University of Lausanne
CHE
169
Ivan Hiltpold
[email protected]
University of Missouri
USA
48
Lingfei Hu
[email protected]
University of Bern
CHE
182
Wei Huang
[email protected]
University of Bern
CHE
Meret Huber
[email protected]
Max Planck Institute for
Chemical Ecology Jena
DEU
50
Alisa Huffaker
[email protected]
University of California
San Diego
USA
59
Sandra Irmisch
[email protected]
Max Planck Institute for
Chemical Ecology Jena
DEU
158 163
Geoffrey Jaffuel
[email protected]
University of Neuchâtel
CHE
139 141 152
Scott Johnson
[email protected]
University of Western Sydney
AUS
29 47 109 122 136
140 188
Aino Kalske
[email protected]
University of Turku
FIN
Kim Karlsson Moritz
[email protected]
Swedish University of
Agricultural Sciences Uppsala
SWE
Eliezer Khaling
[email protected]
University of Eastern Finland
Kuopio
FIN
179
Ghazanfar Abbas Khan
[email protected]
University of Lausanne
CHE
170
Peter Klinkhamer Leiden University
[email protected]
NLD
54 70 72 92 127
164
Karen Kloth
[email protected]
NLD
58 181
Wageningen University
88
32 116
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Angela Köhler
[email protected]
University of Neuchâtel
CHE
38 174
Suzanne Kos
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Leiden University
NLD
72
Tuuli-Marjaana Koski
[email protected]
University of Turku
FIN
63
Corinna Krempl
[email protected]
Max Planck Institute for
Chemical Ecology Jena
DEU
85
Anneke Kroes
[email protected]
Wageningen University
NLD
171
Grit Kunert
[email protected]
Max Planck Institute for
Chemical Ecology Jena
DEU
83 90 91
Diane Laplanche
[email protected]
University of Neuchâtel
CHE
128
Anne-Violette Lavoir
[email protected]
Université de Nice
Sophia Antipolis
FRA
111
Jenny Lazebnik
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Wageningen University
NLD
112
Kirsten Leiss
[email protected]
Leiden University
NLD
54 70 72
Jiancai Li
[email protected]
Zhejiang University Hangzhou
CHN
172
Jie Li
[email protected]
Zhejiang University Hangzhou
CHN
173
Tao Li
[email protected]
University of Eastern Finland
Kuopio
FIN
Yehua Li
[email protected]
Wageningen University
NLD
113
Tiantian Lin
[email protected]
Leiden University
NLD
92
Maria Litto
[email protected]
University of Naples Federico II
ITA
Yin-Quan Liu
[email protected]
Zhejiang University Hangzhou
CHN
Martina Lori
[email protected]
University of Bern
CHE
63 196
33
205
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206
Tobias Lortzing
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Freie Universität Berlin
DEU
28
Dani Lucas-Barbosa
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Wageningen University
NLD
44 114
Daniel Maag
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University of Neuchâtel
CHE
174
Mirka Macel
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University of Tübingen
DEU
175
Ricardo Machado
[email protected]
Max Planck Institute for
Chemical Ecology Jena
DEU
176
Diego Magalhães
[email protected]
Embrapa Brasília
BRA
159
Osnat Malka
[email protected]
The Hebrew University
of Jerusalem
ISR
74
Karina Medina
[email protected]
Universidad Veracruzana Xalapa MEX
177
Steph Menken
[email protected]
University of Amsterdam
NLD
195
Paulo Milet Pinheiro
[email protected]
University of Ulm
DEU
40 132
Xoaquín Moreira
[email protected]
University of Neuchâtel
CHE
115
Shai Morin
[email protected]
Hebrew University of Jerusalem
ISR
Karen Muller
[email protected]
CNRS Dijon
FRA
34
Caroline Müller
[email protected]
Bielefeld University
DEU
67 118 178
Duy Nguyen
[email protected]
Radboud University Nijmegen
NLD
69
Paul Ode
[email protected]
Colorado State University
USA
93
Colin Orians
[email protected]
Tufts University Medford
USA
117
Iris Paiva
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Universidade Federal de Lavras
BRA
148
52 74 191
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Helga Pankoke
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Bielefeld University
DEU
Galini Papadopoulou
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Wageningen University
NLD
Stefano Papazian
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Umeå Plant Science Centre
SWE
179
Martin Pareja
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Universidade Federal de Lavras
BRA
104 119
Carlos Pascacio-Villafán
[email protected]
Instituto de Ecología Xalapa
MEX
57 120
Foteini Paschalidou
[email protected]
Wageningen University
NLD
64
Victoria Pastor
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University of Neuchâtel
CHE
Andrea Pena
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University of Neuchâtel
CHE
Stefan Pentzold
[email protected]
University of Copenhagen
DNK
Ezio Peri
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University of Palermo
ITA
Georg Petschenka
[email protected]
Cornell University Ithaca
USA
79 81
Ana Pineda
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Wageningen University
NLD
84 180
Camille Ponzio
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Wageningen University
NLD
101 102 160
Mathilde Poyet
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UMR CNRS Villeurbanne
FRA
121
Christophe Praz
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University of Neuchâtel
CHE
42
Godfried Prinsloo
[email protected]
ARC-Small Grain Institute
ZAF
161
Teresa Quijano
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Wageningen University
NLD
Sergio Rasmann
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University of California Irvine
USA
118
94
103
61
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208
Lianqiong Ren
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University of Neuchâtel
CHE
Gregory Roeder
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University of Neuchâtel
CHE
Arthur Roemer
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Université de Nice Sophia
Antipolis
FRA
Peter Roessingh
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University of Amsterdam
NLD
John Romeo
[email protected]
University of South Florida
Tampa
USA
Michael Rostás
[email protected]
Lincoln University
NZL
Quint Rusman
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Wageningen University
NLD
James Ryalls
[email protected]
University of Western Sydney
AUS
Ilham Sbaiti
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University of Neuchâtel
CHE
195
51
122
Jörg-Peter Schnitzler
Helmholtz Zentrum München
[email protected]
DEU
162
Melanie Senning
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ETH Zurich
CHE
162
Liora Shaltiel Harpaz
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Migal Galilee Research Institute
ISR
149
Gwen Shlichta
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University of Neuchâtel
CHE
55 143
Diego Silva
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Universidade Federal de Lavras
NLD
123
Jiří Skuhrovec
[email protected]
Crop Research Institute Prague
CZE
124 192
Jeltje Stam
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Wageningen University
NLD
89 113
Michael Stastny
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University of Ottawa
CAN
125
Martin Steinbauer
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La Trobe University Melbourne
AUS
78 133 193
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Johan Stenberg
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Swedish University of
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SWE
32 116 126
Jörg Stephan
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Swedish University of
Agricultural Sciences Uppsala
SWE
126
Andrew Stephenson
[email protected]
Pennsylvania State University
USA
30
Anke Steppuhn
[email protected]
Freie Universität Berlin
DEU
28 75 155 167 168
Holly Summers
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University of Bern
CHE
43
Timothy Sutton
[email protected]
University of Western Sydney
AUS
134 194
Adrianna Szczepaniec
[email protected]
South Dakota State University
USA
150
Manus Thoen
[email protected]
Wageningen University
NLD
58 181
Vincent Trunz
[email protected]
University of Neuchâtel
CHE
42
Ted Turlings
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University of Neuchâtel
CHE
128 130 139 141
146 152 153 174
Sybille Unsicker
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Max Planck Institute for
Chemical Ecology Jena
DEU
156 158 163
Nicole van Dam
[email protected]
German Centre of Integrative
Biodiversity Research Leipzig
DEU
28 69 142 153 167
180
Joke Van Elven
[email protected]
Rijk Zwaan Breeding B.V.
NLD
Joop Van Loon
[email protected]
Wageningen University
NLD
Maryse Vanderplanck
[email protected]
University of Mons
BEL
Louise E.M. Vet
[email protected]
Netherlands Institute of Ecology NLD
(NIOO-KNAW) Wageningen
Fanny Vogelweith
[email protected]
INRA Villenave d'Ornon
FRA
31
Martin von Arx
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University of Zurich
CHE
135
64 112 114 123
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209
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210
Ilka Vosteen
[email protected]
Max Planck Institute for
Chemical Ecology Jena
DEU
91
Shuhang Wang
[email protected]
Wageningen University
NLD
142
Daniela Weber
[email protected]
University of Neuchâtel
CHE
Xianqin Wei
[email protected]
Leiden University
NLD
127
Berhane Weldegergis
[email protected]
Wageningen University
NLD
60 102 160 165
181
Hao Xu
[email protected]
University of Neuchâtel
CHE
128
Noureddine Yassaa
[email protected]
USTHB Algier
DZA
Meng Ye
[email protected]
Zhejiang University Hangzhou
CHN
182
Wenfeng Ye
[email protected]
Zhejiang University Hangzhou
CHN
183
Zhaonan Yu
[email protected]
Zhejiang University Hangzhou
CHN
129
Feng Zhu
[email protected]
Wageningen University
NLD
60 107 165
Tobias Züst
[email protected]
Cornell University Ithaca
USA
77
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