Pest Control L7 English in Natural Science 自然科学の英語 2006 自然科学の英語-ENS-L7 Definitions • Pest: animal species that interferes with human activities • Weed: a plant ‘pest’ • Pest control: reduction of pest/weed populations to not damaging levels 1. Damage is measured in economic terms § Eradication (pest extinction) is practically impossible 2006 自然科学の英語-ENS-L7 Control of pest/weeds light more crop yield Disease Weeds Crop Insects losses Storage Total water crop pests weeds crop diseases * Rice 16.2% (Crammer, 1967) harvest yield Market yield storage pests nutrients 2006 12% 13 13* 20 48% 自然科学の英語-ENS-L7 Integrated Pest Management (IPM) • Use all methods of control in a scientific manner to reduce crop damage due to pests, weeds and diseases • Strategies – Natural control: natural enemies – Biological control: introduced predators, parasites or diseases; reproductive control – Agronomic control: crop rotation, strip cropping, burning, mulching, – Pesticides: treatment with chemical poisons 2006 自然科学の英語-ENS-L7 Agronomic control • Crop rotation – Change conditions for pest development – Based on life cycles • Strip cropping – Protect and foster natural enemies – Lower pest densities • Burning of crop residues – Destroy pest larvae – Re-start from scratch secondary succession • Mulching – Avoid weeds • Light competition • Chemical allelopathy Sustainable solutions (1-3 years) Require continuous use Alone or combined 2006 自然科学の英語-ENS-L7 Biological control Long-term solutions Sustainable Increase of predatory populations (After Van der Bosch et al. 1982) • Scientific basis – Each pest has natural predators, parasites and competitors – Bring equilibrium predator-prey below the economic threshold of pest 2006 自然科学の英語-ENS-L7 Efficacy of biological control Cottony-cushion scale (Icerya purchasi, Hemiptera) • Native country: Australia • Pest problem in California – Discovered 1872 – Pest in Citrus orchards (1887) • Control: – Cyanide pesticide: failure – parasite (Cryptochaetum iceryae, Diptera) – vedalia (Rodolia cardinalis, Coleoptera) • Achieved in 1 year • Total cost: $1,500 2006 Prickly pear (Opuntia stricta) • Native countries: Mexico, South America • Weed problem in Australia – Ornamental (1839) – Weed invasion: 1880-1925 243,000 km2 prickly thickets • Control: moth Cactoblastis cactorum from Argentina – Achieved in 10 years (1940) 自然科学の英語-ENS-L7 Parasites and diseases • Rabbits (Oryctolagus cuniculus) introduced in Australia (1859) – 20 years later became a serious pest: ate pasture desertification • Control: mixoma virus (Leporipoxvirus) from S America (1950) • Problems: – escape in Europe (non-target area) – resistance by natural selection (1965) BUT populations reduced < threshold 2006 Mixomatosis (Myers et al. 1954) 自然科学の英語-ENS-L7 Mixomatosis (Fenner and Myers 1978) Problems of biological control • Success rate 16% (Hall et al., 1980) • Reasons: – One species controls better than several • Competition loss of efficacy – Introduced species may prey on non-target species • Reduce efficacy • Side-effects on ecosystems To be effective • Only if economic injury exists • Specialist predators/parasites – Generalist snail (Euglandina rosea) eliminated 60% of native snails in Hawaii – Indian mongoose (Herpestes auropunctatus) in Hawaii, Okinawa and Pacific Islands • After research on ecological effects: demography 2006 自然科学の英語-ENS-L7 Sterilization • Irradiation of male insects (USDA, 1950s) • Background – X-rays caused sterility in male insects (1916) – Dr Edward Knipling (1954) in screw-worm fly (Cochliomyia hominivorax) - subtropical America • livestock in Florida • Forest insects in Canada • Melon fly (Bactrocera cucurbitae) in Okinawa (1972-1993) Koyama et al. 2004 • Tse-tse fly in Rhodesia 2006 自然科学の英語-ENS-L7 Immunocontraception • Vaccine that reduces fertility – glycoproteins (ZPG) inhibit egg fertilization • Effective against wildlife populations – Deer in New York – Rabbits in Australia (invasive species) 2006 自然科学の英語-ENS-L7 Efficacy of immunocontraception • Sterilization produces fewer offspring • Surviving animals live longer - compensation – High level of sterility is required (>80% females) 2006 自然科学の英語-ENS-L7 Pheromone traps • Pheromones: chemical substances used by animals (mainly insects) to communicate – Moths and bark beetles • Kinds – aggregation – sexual - released by females to attract males • Advantages • Shortcomings – Species specific – Sex specific pheromones most effective (99%) – Tiny amounts used as baits – Work at long distance (30 kms) – No possible ‘resistance’ 2006 – Only adult insects – Not applicable to all insects pests – Seasonal efficacy (mating season) 自然科学の英語-ENS-L7 Chemical control: Pesticides • Pesticides are a short-term solution, the last tool to be used in IPM because: – Contaminate the environment (water, soil, air) and agricultural products (residues in vegetables, meat) – Non selective: affect also non-target species – Pest species eventually become resistant – In some cases have produced more pest problems • When can be used? – Whenever there is economic injury and other treatments are not effective 2006 自然科学の英語-ENS-L7 Kinds of pesticides Insecticides Insect pests Neurotoxic Herbicides Weeds Photosynthesis Organochlorines Triazines Organophosphates Phenylureas Carbamates Benzo-nitroamines Pyrethroids Neonicotinoids Natural compounds Germination Nitroanilines Chloroacetamides Growth regulators Growth inhibitors Stomach poisons Phenoxy-alkane Repellents 2006 Defoliants 自然科学の英語-ENS-L7 Fungicides Fungal diseases Inhibitors Respiration Phthalates Protein synthesis Other synthesis Triazoles Cell division Pesticides efficacy Economic benefit = crop value - cost of control • Pesticides less economic benefit • Control cost – Chemicals – Spraying equipment • tractor booms • airplane or helicopter – Personnel (applicators) • Despite increasing use after 30 years – More pests – More crop losses 2006 Crop losses in USA (Pimentel 1991, 1997) 自然科学の英語-ENS-L7 Insecticide problems for pest control • Kill natural enemies • Foster outbreaks of insects which become pests – California red scale (Aonidiella aurantii) on lemon trees after DDT – Cottony-cushion scale (Icerya purchasi) on Citrus after DDT – insects in rice crops (1965-1970) 2006 自然科学の英語-ENS-L7 (DeBach, 1974) Paddy fields in Japan Main pest species YEAR 1950 Pest type Technology Aims 2006 Leptocorisa chinensis Chilo supressalis Sogatella furcifera Nephotettix cincticeps Nilaparvata lugens Laodelphas striatellus Lissorhoptrus oryzophilus Lagynotomus elongatus Echinocnemus squameus Cnaphalocrocis medinalis Dicladispa armigera Nephotettix cincticeps Oulema oryzae Sogatella furcifera Scotinophara lurida Nilaparvata lugens Scirpophaga incertulas Lissorhoptrus oryzophilus Oxya spp 1960 1970 1980 Monophagous Univoltine 1990 2000 Polyphagous Multivoltine Polyphagous Multivoltine Virus vectors Green Revolution Fertilizers Irrigation Pesticides Mechanization Nursery-tray treatment Selective pesticides Increase yield Increase quality 自然科学の英語-ENS-L7 Low density Virus vectors IPM Education Organic Sustainability After Kiritanai (1992) Pesticide effects on ecosystems • Direct effects due to toxicity – Mortality: insecticides >fungicides>herbicides – Sublethal (non-target organisms) • Stress parasites and diseases • Reproduction: endocrine disruption (OC insecticides) • Abnormal growth (malformation) • Indirect effects - trophic web – Food depletion starvation • Herbicides: phytoplankton • Insecticides: zooplankton 2006 自然科学の英語-ENS-L7 death migration consumers starvation algal blooms Decline of birds of prey 1963 Ratcliffe: survey of Peregrine falcon in UK – 1/5 birds bred successfully 1964 Hickey et al.: surveys in US confirmed trend and raised alarm - raptors were disappearing due to continuous reproductive failures 2006 自然科学の英語-ENS-L7 1966 Ames: reproductive failure of birds of prey correlated to shell-thinning 1967 Ratcliffe: eggshell thinning in certain raptors since 1947 (Nature 215:208) 1968 Hickey & Anderson: eggshell thinning in predators / fishing-eating birds pesticides blamed DDT in agriculture (England) 2006 自然科学の英語-ENS-L7 1969 Laboratories confirmed the cause of eggshell thinning: organochlorines Until 1974: debate on how DDT and organochlorines affected eggshell thinning • • DDE caused shell thinning in birds of prey, but not in gallinaceous species (Cooke, 1975) PCBs did not cause eggshell thinning (Peakall, 1993) Cascade effect of DDT & cyclodienes Bioaccumulation Calcium metabolism Eggshell thinner Embryo mortality Decline reproductive rate 2006 自然科学の英語-ENS-L7 Local extinctions Partridge (Perdix perdix) in many countries • Causes of decline – – – – Nest loss (26%) chick mortality (29% 44%) hunting (7%) winter loss (38%) Lack of food Potts (1986) 2006 自然科学の英語-ENS-L7 Decline of birds due to pesticides – Herbicides eliminate weeds reduce insects and seeds – Food shortage (insects, seeds) increase chick mortality Species Tree sparrow Year decline started Farmland (%) Countrywide (%) 1978 -87 -76 1979 -85 -62 1978 -82 -78 Before 1969 -78 -78 1981 -75 -60 1975 -66 -52 1985 -46 -42 (Passer montanus) Turtle dove (Streptopelia turtur) Grey partridge (Perdix perdix) Spotted flycatcher (Muscicapa striata) Skylark (Alauda arvensis) Song thrush (Turdus philomelos) Lapwing (Vanellus vanellus) 2006 自然科学の英語-ENS-L7 Other ecosystems Waterways Crops Forests Urban Transport routes Air Long-range transport Volatilisation Drift Runoff Groundwater Rivers 2006 Leaching 自然科学の英語-ENS-L7 Drains Rivers, lakes Ocean Pesticide losses Transport route Category % applied rate Spray drift Aerial application Ground-rig Manual (backspray) 5 - 10 0.1 – 3 ? Volatilization Very volatile Less volatile 50 - 90 1 - 10 Leaching* Water soluble Moderately soluble 40 - 90 10 - 25 Runoff Water soluble Insoluble 3-6 1-2 *Difficult to estimate due to sorption and slow movement 99% Pesticide losses environmental contamination (Pimentel et al., 1992) 2006 自然科学の英語-ENS-L7 Dissipation of pesticides Half-life: the time required to reduce to half the amount of a substance Volatilisation Plants Photolysis Biodegradation Absorption UV Photolysis Water Soil Photolysis Hydrolysis Biodegradation Sedimentation Biodegradation Hydrolysis Leaching Residue 2006 自然科学の英語-ENS-L7 Residues in crop plants and products deposit diffusion sequestration metabolism translocation uptake 2006 自然科学の英語-ENS-L7 Ensuring food safety • Cost of the Green Revolution • Check residue levels in food – National produce (market) – Imports from other countries (31 Quarantine Stations Japan) • Analytical laboratories – Huge cost for governments • Reject food with residues >MRL (Maximum Residue Limit) Imported (2001) Tested Residues found Fresh vegetables 997,000 67,796 (6.8%) 729 (1.06%) Frozen vegetables 717,000 21,501 (3%) 93 (0.43%) 32.5 million 2.4 million (7.4%) Total food items 2006 自然科学の英語-ENS-L7 * Figures indicate tons References • Charles J. Krebs, 2001. Ecology 5th ed. / 応 用動物昆虫学 room B-226 • David Pimentel, 1991. Handbook of Pest Management in Agriculture. CRC Press, Florida, USA • F. Moriarty, 1983. Ecotoxicology. Academic Press / 応用動物昆虫学 room B-207 • Rachel Carson, 1962. Silent Spring. Houghton Mifflin / 応用動物昆虫学 room B207 2006 自然科学の英語-ENS-L7
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