70 4. Discussion 七i aldiapause 4-1.Ecological significance of ini This s七udy has demonstra 七ed七ha 七 M. hime a nd C.bonneti are annual species and M. japonica a plurennial species. One 七i aldiapause way 七o assess 七heecological significance of ini is a comparison of life cycles be 七w een annua 工 andplurennial species. M. japonica wi七h ini七ialdiapause in addi七ion 七0 final diapause ex 七e nds i七s dis七ribu 七i on 七o a higher la 七i tude and al七itudethan M. hime and C . bonneti wi 七h ou七 ini 七i al diapause. This fac七 maysugges 七 七h a 七 七h eoccurrence of ini 七i al diapause at an early emb 工y onic s七age is rela 七ed 七o 七edw ith high la 七i 七u des and some specific fac七or(s) associa alti七udes. The ecological significance of ini七ialdiapause has been poin七edou 七 f or species with a mix 七u re of annual and biennial life cycles. Ando (1993a) showed 七ha 七 七h e pどopor 七i onof eggs en 七e ring ini 七i aldiapause was larger a七 higher la 七i 七u des in the Japanese G出 npsocleis species-complex. 工ngrisch (1986b) reported 七ha 七 七h e induc七ionof ini七ial diapause was associa七edwi七h paren 七a lsbor 七daycondi 七i ons in several species of European 七e七七 igoniids. S七ick insec七，Didymuria violescens has annual and/or biennial life cycles because of 七wo d iapause s七ages in 七heembryogenesis (Readshaw & Bedford， 1971)・ 工ncidenceof the firs七 diapausewas higher in 七he popula七ionfromhigher al 七i 七u dinal areas. These fac七smay 七 七h e occur 工e nceof ini 七i al diapause is 工elated七o sugges七 七 ha the la 七i 七u dinal climatic gradien 七， m os七 工 ikely 七he amoun 七 o f effective 七empera 七u res. 71 工n Hirosaki，M. hime begins to oviposit earlier and produces eggs mo 工e i ntensively in a shor 七e 工 七i methan T ! . japonica ( Fig. 7 )・ 工n M. hime，eggs laid in early Sep 七e mber onwards in 1995 and 七hose laid aftermid Augus七 in 1997 could no 七 r each 七he final diapause s七age (Fig. 11)・ Eggs befo 工e this s七age also can ove 工w in 七er. H owever， eggs deposi 七ed l a 七e in 七he season migh 七 h ardlyhave a chance of reproduc七ion， because 七heyhatch very la 七e i n 七he following year and 七hus have li七七le 七ime 七o reproduce af 七e radul 七 e mergence (Fig. 七ra 七edo viposi 七i onbyM. 12)・ Therefore， early and concen hime i s likely七o be highly adaptive. 1・ japonica，oviposition occurs in mid August or In 1 七e r. Because 七his species en 七e rs ini 七i al diapause a七 七he la early stage of embryogenesis，eggs deposited in late summer and autumn may be able 七o a七七 ain 七hediapause s 七a ge for overwl .n 七e ring. Fu工七hermo工e， those eggs 七ha 七 h ave overwin 七e redin ini 七i aldiapause s七ar 七 d eveloping in 七he spring， bu七 七hei工 developmen 七 i s in 七e rrup 七eda gain by 七he induc七ionof final diapause. Thus， 七 heirha 七c hingdoes no 七 occur a七 leas七 un 七i lthe second spring. 工n fact， mos七 eggs 七ed i n la 七e A ugus七 七 hroughmid Oc 七o ber in 1995 ha 七c hed deposi during a shor七 periodfrom la 七eλprilto e arly May in 1997 (Fig. 13). This fact indicates 七ha 七 七h e rela 七i vely large varia七ion in 七he 七imeof oviposition does no 七 a ffect 七he 七i mingof ha 七c hing in the second spring. According 七o my unpublished observa 七 エo ns，however，r n o s七 eggs ( 91.2も; n=68) survived a 7 r n o n t h exposure to 30C even when 七his chilling 七r ea 七m en 七 hadbeen applied 七o newly deposi 七ed e ggs ( 1-4 days 七e s 七hepossibili 七y 七ha 七 e ggs deposited old)・ This indica 72 la七e in 七he autumn can overwinter successfully even befo工e reaching 七he ini 七i aldiapause s七age. 工f 七his is true， ini七ialdiapausewould no 七 b ea prerequisi 七e f or overw l .n 七e ring. On 七he 0七her hand， some of 七heeggs deposi七edearly in 七he s eason fail七o main 七a in initial diapause un 七i lwin七er comes. As a result， 七heydevelop beyond 七his s七ageand ove工win 七er ( Table 4 )・ Suchindividua1s ha 七cha f七erthe firs七 win 七erwi 七h ou 七 e n 七e ringfina1 diapause. However， their 七c hingwas apparen 七l ydelayed compared 七0 ha 七h osewhich have 七e reda七 七 he final diapause 5七age (Fig・ 1 4)・ A delay overwin 七5 i n a delay in adul七 emergence， and in hatching 七ime resul increases 七he riskof failureto reproduce. Thus，it seems 七o b e impor 七a ntfor eggs of M. japonica 七o pass the firs七 win 七e ど i n initial diapause so 七ha 七 七h eycan postpone their ha 七c hing by ente工ingfinal diapause un七il 七he second spring. 工n cold r egions， ha 七c hing ear1y in 七he season would bemos七 impor七an 七 七o a 七七 a in sexual ma 七u rl . 七y e arly enough， and 七his appears 七o be made possible by passing the 1as七 win七erin final diapause occurring when embryogenesis has been a1mos七 comple 七ed. T herefo 工e，i ni 七i al diapause may have a dual role: 七i melyha 七c hingafter 七he firs 七 w inter， and i七 prevents un ensures 七he successful induction of final diapause. varia 七i onin body size rela 七ed 七o t he geographic gradien 七 o f heat uni七 is known in several species of cricke 七S (Masaki，1996)and seems to be wェ despreadamong 0七her insec七s. Body size of M. japonica is sma11er a七 higher al 七i 七u des (Tab1e 2 )・ Th工s reduced body sizemay be a resul 七 of adap 七a 七i onto highlands where 七hegrowing season is shor 七. 73 A prolonged ini 七i aldiapause occurs in some eggs of M. japonica (Table 6 )，as inmany 0七her 七ettigoniidspecies ( 工 ngrisch，1986c;Har 七l ey，1990)・ prolongeddiapause occurs in many 七axonomic groups and in differen七 environmen 七a l 七 o f several 七heore 七i cal condi七ions and has been 七he subjec works (Takahashi， 1977;walker， 1986; Seger & Brockmann， 1987). Takahashi ( 1977) 七heore 七i cally showed 七ha 七 u nder uns七able environmen 七a lcondi七ions individuals 七ha 七 c arryover 七0 七h e nex 七 season， evenwhen 七heirnumber is no 七 l arge， have 七i on s七abili七y. Like the a considerable effec七 on 七hepopula seed bank in deser 七 a nnualplan 七s ( Cohen，1966)，prolonged diapause appears to be a be 七hedging 七ac七ic against unpredictable catas七工ophes. 工n grisch (1986c) showed 七ha 七 fecundi 七y i s not reduced by 七heprolonged ini七ialdiapause in Decticus verrucivorus. Moreover， he revealed 七ha七， in 七i aldiapause eggs of Eupholidoptera smyrnensis，since 七he ini 七e mpera 七u redependence of oxygen consump 七i onis low， 七heeggs 七U工e s (Ingrisch， need very li七七 leenergy even a七 high 七empera 1987). Physiological cos七s of prolonged diapause are probably low in plurennial species of ka 七ydidb ecause i七 occurs in a very early embryonic stage. 七i aldiapause in ka 七y dids The presence of prolonged ini has been explained in rela 七i on 七0 七h eir unique abio七ic 1986c) and Ha 工七 l ey (1990)mentioned 七hat fac七ors. 工ngrisch ( developing emb工yos of 七ene ncoun 七er s 七工 o ngdesicca 七i onand 七h a 七 local summer fires some 七i mes sweep over an area killing all above ground s七ages. Ando (1993a) sugges七ed 七he 七y 七ha 七 d elayed adu工七 emergence in unusually cool possibili years decreases the chance of reproduc七ion 七o Gampsocleis 74 species-complex. Therefore，prolonged diapause could be a bet-hedging 5七ra七egyagains七 unpredic七ableadversity caused by climatic condi 七i ons in ka 七y dids. The presen 七 どe sul 七s suggest 七ha 七 ， b esides ai工 七emperature， fac 七o rs such as sunshine hours and snowcover period may grea七lyaffec七 七he 七i 七u des. life cycle of M. japonica a七 high al M. j aponicarequires a high 七empera 七u re for nymphal 七 a nd egg produc七ion (Fig. 10， Table 3 ) . developmen 工七 is well known 七ha 七 ， i n the sunlight， 七 he in 七e rnalbody tempera 七u reof grasshoppers is higher 七han 七he air surrounding it as a resul七 of basking (Uvarov， 1966， 1977; Begon， 1983)・ M. japonica frequen七lybasks i七self in 七he sun and 七hebasking behavior is more common in highlands 七han in lowlands (unpublished observa 七i on)・ Perhaps， 七he blackish body color is also effec 七i vein absorb工ngradian 七 h ea七. Resul 七5 o f field observa 七i ons sugges七 七 ha 七 y early fluc 七ua 七i ons of wea 七h erconditions tend 七o affec 七 七h e life 七i onsmore severely 七han 七ha 七 o f cycle of 七he alpine popula the lowland ones (Fig. 8 ) . For ex 剖n ple， 七 he cool summer was probably 七hemain facto 工 七h a 七 c auseddelayed adul七 emergence of M. japonica a七 七 he high alti七udes in 1993. Moreover， shor七 sunshine hours also seem七o have contribu七edto 七he failure of 七his species 七o comple七e nymphal developmen 七 a nd egg produc七iona七 analpine bog in Yamaga 七a P ref. in 1995. Thus， 七 he risk of extinction or a sharp reduc七ion in 七i on size would be higher in popula 七i ons a七 highe 工 popula alti 七u des. This leads to 七hepredic七ion 七ha 七 七h e incidence of prolonged diapause is highe 工 i npopula 七i ons a七 higher al七i七udes. This predic七ionmay be suppor 七edby 七h e resul 七S 75 of chil1ing experimen 七 七 ha 七 i nitia1diapause persisted longer in eggs derived from a higher a1 七i 七u de (Fig. 20，Tab1e 6 )・ Thus，ini 七i a1diapause in M . japonicamay be an impor七an七 1ifecyc1e 七rai 七 i nhabi 七a 七s w here 七hegrowing season is shor 七 a ndunpredic 七a b1e. 4-2.Mechanisms of ini 七i a1 diapause Factors 工egu1a 七i ng 七hedu工a七ionof ini 七i a1diapause are ano 七h e 工 i n七eres七ingprob1em. The mechanism of pro1onged diapause has been poor1y unders七ood， 七 houghmany examp1es of pro1onged diapause have been repor 七ed ( Danks，1987)・ 工n mos 七 species，many individua1s emerge after one year and fewe 工 individua1s remain in diapause for 七woor 七hreeyears. However，in some species，a sma1l frac七ionof individua1s remains in diapause much 10nger (Barnes，1952;Powel1，1989)・ Thus， 七he pa 七七 e rnof emergence fromdiapause is no 七 a 1ways a s七eadydec1ine over successive years. pro1onged diapause seems 七o be cont 工o lledmain1y by gene七l.C componen 七s， a nd part1y by responses to environmen 七a 1 cues. Hed1in e七 al . (1982) confirmed 七hatthe incidence of pro1onged diapause in 七h e cone mo 七h B arbara colfaxiana was grea 七era 七 七e mperatures in the 1abo工atory. 七ha 七 10wer Usha 七i nskaya (1972) 工epor 七ed prolongeddiapause of Leptinotarsa decemlineataoccurred only in bee七les in 1igh 七 s andy soi1s， but no 七 i nheavy， mois七， clay soils. 工ngrisch (1986c) showed 七hatdrough 七 cou1d serve as a token s七imulus for七he 七ermina 七i onof pro1onged ini七ia1dエapause in Tettigonia caudata. The means by which 七he difference 制 nong individua1s are p工ogr 百 四n edhave no 七 b eene1ucida 七e d. 工n mos七 species， a 76 difference in 七he in 七e nsi七Y of diapause seems 七o be invo1ved. 工n 七emperater egions， 七he seasona1 七empera 七u recyc1es such as co1d-warm-co1d-warmusua11y seem七o be cues contro1ling pro1onged diapause. Theremigh 七 bea m echanismfor coun 七i ng win 七e rs， and 七he number of win 七e rs required 七o termina 七e prolonged diapause migh 七 be c onsiderably different 副 nong individuals. Whether such a mechanisrn rea11y exis 七 orn o 七 ， 七h e in 七e nsi 七Y o f pro1onged diapause s e e r n s 七o be gradua11y decreased wi七h increasing number of cold-warmcycles. 工n M. japonica，工epe 七i 七i onof co1d and warmtrea 七m ents was effec七ive to 七ermina 七e 七h epro1onged ini 七i al diapause. The three s七工 ains f r o r ndiffe工en 七 a ltitudinal a工eas showed simi1ar pa 七七e rns of response to high and low 七empera 七u re cycles: curnulative pe 工c en 七a ge 七errnination rapid1y increased af七er 七hefi 工S七 c hi11ingand thereaf七erslow1y bu 七 i ncreased 七 again af七e工 七 he second chilling (Fig. 20)・ This fac sugges七S 七ha 七 i n 七he fエe1d， 七he r e s u r n p 七i onof developrnen 七 synchronous1y occurs wi七hina shor 七 七i me af 七ero ve工wintering 七 c on 七i nuefur 七h erun七ilthe next year. The but does no percen 七a ge 七e工mina 七工 onw as significant1y differen 七 a mong 七he 七h ree s七rains， andmore eggs remained エn 1n1 七i a1diapause for a longer time in the popu1a 七i onf r o r n七he higher a1 七i 七u de. The fac七 七 ha 七 七h reecyc1es required 七o reactiva 七e a 1l ) eggs in Series A and two cyc1es 斗 n Series B (Tab1e 6 sugges七S 七ha 七 七e rmina 七i onof ini 七i aldiapause is affec 七edn o 七 only by 七henumber of chi1ling cyc1es， bu 七 a lsoby 七he 1eng 七h of chi11ing・ Deanand Har 七1 ey (1977) 工epor 七ed 七h e resul七s of chi1ling be七ween 1 and 180 days in Ehippigerida ephippiger (formerly Ephippiger cruciger) and conc1uded 七ha 七 77 prolonga 七i onof chil1ing for longer 七han 30 days did no 七 lncrease 七hepropor 七i onof eggs resuming developmen 七. On 七h e O七h erhand， in M. japonica，七heresul七s of chilling between 15 and 720 days showed七hatpercen 七a ge 七ermina 七i onof initial diapause was clearly increasedwi 七h p ro1onging chi11ing， 七h ough 七herewas no 七 significan 七 d ifference 出 nongchi11ing ranging from 15 七o 180 days (Fig. 21)・ However， 七he in 七e nsi七Y of initia1 diapause was ex 七工e me1yhigh and va 工i ab1e among individuals. Chi11ing for 680 days or 10nger seemed to cause many eggs 七o 10se 七heabi1i 七Y o f developmen 七. T he 10w percen 七a ge 七e rmina 七i onin 680-and 720 day-七工ea 七m ents migh七 be caused by 七ed七h e increase of such eggs. Many eggs which had 七ermina 七i al diapause af七erchilling for 520 days or shor 七e rcould ini hatch af七er 七he second chi1ling. Though percen 七a geteどmina 七i on 七ended七o be higher af 七er 10nger chil1ing， 七hemaximumva1ue of 七hepercen 七a ge af七e工 chilling for 15 七o 720 days was 89も in M. japonica(Ak965) in 1993 (Fig. 21)・ Onthe other hand， in 七he 七reatmen七swi七h co1d and warmcyc1es，percentage 七e r f f i l n a 七i on reached 100も af 七ert hree cycles in Series A and 七wocycles in Series B (Table 6 )・ In0七herwo工ds，all eggs 工esumeddeve10pmen 七 af七er chi11ing fo 工 a 七0 七a 1 of 270 or 360 days in 七hese 七r eatmen七s. Thus 七he ini 七i aldiapause in M. japonicawas 七e 工m ina 七edm ore smoo七h1yby 工epeti 七i onof cold and warm 七r ea 七m ents 七hanby a sing1e 10ng co1d七rea 七m en七. The resu1七s of cons七an 七 七e mpera 七u re 七reatmen 七s s howed 七h a七 chil1ing is no 七 a 1ways necessary 七0 七erminate 七he 七i al diapause (Fig. 17，Tab1e 5)・ 工n general，diapause ini 78 deve10pmen 七 i nwin 七erd iapause is very slow a七 high 七e mpera 七u reswhereas low tempera 七u res allowrapid diapause deve10pmen 七 ( Danks，1987)・ However，the initial diapause in M. japonica was gradua 工1 y 七ermina 七eda 七 c onstan 七 七e mperatures be 七ween 1 5 and 250C above 七hedevelopmental zero and was 七e rminatedmore effec七ivelyby 15 and 20oC. On the 0七he 工 hand， Har 七l ey and Dean (1974) repor 七ed 七ha 七 i neggs of Ehippigerida ephippiger 七he highest propor 七i onof initia1 developmen 七 c an be induced by star 七l.ng 工n cuba 七i onat 30oC. 工七 is not ce工七 ainwhether 七he七empe工a 七u reduring induction or af七er induction affec七s initial diapause in 七e nsi 七y . For 七 Teleogryllus emma w hich has an annual ex出 nple，in 七he c工icke 工y onic diapause， 七empera 七u reduring life cycle wi七h an emb inducing diapause influences the fu 七ure i ntensi 七Y o f diapause (Masaki，1962). The fac七 七 ha 七 c hi11ingis not necessary 七0 七ermina七e ini 七i a1 diapause in all eggs sugges七S 七ha 七 i ni七ialdiapause is simi1ar 七o shor 七 d iapause in many species 七ha 七 i s 七eda 七 ac ons七an 七 h igh 七empera 七u re sporadically 七ermina (Danks， 1987)， bu 七 i ts in 七e nsi 七y i s much higher and variable. Rapid diapause七ermina 七i onat 200C sugges七5 possibili 七y 七h a 七 eggs laid early in 七he season un 七i mely develop beyond 七h e initial diapause s七age. Outdoor expe工iments showed 七ha 七 al 七h ough M. japonica usually begins 七o deposi七 eggs inAugus七 or la 七er ( Fig. 7 )， 七here is a possibil エ七y 七ha 七 e ggs unusually deposi七ed in July ha 七c haf七er 七he firs七 win 七er ( Tab1e 4， Fig. 七i aldiapause in this ka 七y didseems 七o 14)・ However， 七he ini 七e. be obliga Differen 七 七e mperature 七rea 七m ents revealed 七he similar 79 and dissimilar charac 七e ris七ics of ini七ialdiapause compared 七0 七hec o m r n o n shor 七 win 七erd iapause in other insec七s . 工n i 七i al diapause was 七ermina 七eda 七 cons七an 七 七e mpe 工a 七u res above 七hedevelopmen 七a l zero and many individuals were eac七iva 七edb y long chilling， bu 七 i ts in 七e nsitywas very high ど 七i aldiapause eggs with higher in 七e nsi 七Y and variable. Ini 七e rprolonged diapause. Cold and seem 七o bemore likely 七o en warm cycles 七erminatedinitial diapause r n o工e effec七ively七han a single long chilling. Two successive exposures 七o cold and warm tempera 七u resr n a y be impor 七a n 七 c ues for 七ermina 七i onof 七h is diapause. 4-3.S u m r n e r and final diapauses According 七0 七h epresen 七 S七udya nd my unpublished 七i on，s u m r n e r and final diapauses occur in 七he all observa three species 5七udied，while ini七ialdiapause only in M. japonica. These 七hree 七ypesof diapause showed differen七 ermal response七o cope wi七h differen 七 七h adap 七a 七i onal problems. Developrnental arres 七 1 n 七he egg 5七age a七 high 七e r n p e r a 七u re have been known inmany species of ka 七y dids (Har七工 ey， 1990) and at leas七 one species of cricke 七 ( Tanaka， 1986). 工 七 generally occurs a七 an intermedia 七e 5七a ge of embryonic developmen 七 b efore subs七an 七i alwater absorp 七i on. 工n 七h is 七hesis， 1 convenien 七l yuse " s u m r n e r diapause" for the 七a l arres 七. H owever， Har 七l ey (1990) refers such developrnen 工e s七 七0 ar 七h e high 七e r n p e r a 七u reinhibi 七i onperhaps causedby lowering of developrnental 七e r n p e r a 七urer ange wi七h age. 工n grisch (1987) sugges 七S 七ha 七 ， i n Eupholidoptera smyrnensis， 80 i七 is energetically profi 七a ble 七0 七h e embryo to spend 七he hot season in penultirna 七e d iapause ( a七 S七a ge 20). Though developmental delay and summer diapause was observed under high 七empera 七u recondi 七i ons in 七he 七hreespecies used for the presen 七 S七u dy， i七 mus七 no 七 o ccurinM. japonica and nor 七h ern popula 七i ons of M. hime and C.bonneti in 七heiroriginal habi 七a 七sw here summer is ra 七h ercool. On 七he 0七herhand，七 he eggs of sou 七h ernpopulations of 七he la 七 七e r 七wo species mus七 encoun 七er h igh tempera 七u res. 工n M. hime，b ecause Os s七rain begins 七o oviposit in la 七e J une，七 heeggs of itmus七 spend 七h e ho 七七e st season (Fig.30)・ 工n o utdoor experimen 七 ， the embryonic developmen 七 o f Os delayedmore conspicuously in 七he 七ede arlie 工 ， w hile the eggs of Ao developed eggs deposi wi七hou 七 a nydelay irrespec 七i veof 七he oviposi 七i on 七ime (Fig. 31)・ 工 七 seems 七ha 七 七h edevelopmen七a1 de1ay and summer diapause allow七heeggs 七o survive the ho 七 七e s七 season and 七o reach 七he final diapause s七agemore synchronously in au七umn than expec 七edf rom七he long egg-laying pe 工i od. Final diapause occurring in 七hema 七u re embryo is never 七e rmina 七eda nd 七heeggs gradually shrink and even 七u allydie 七 a 七 2 50C or higher. if 七heyare kep 工 七 can be characterized by 七he requiremen 七 f or a low 七emperature for 七erminationas 七e l arval diapause (Hodson and Weinmann，1945; in 0七herphara Masaki，1956; Readshawand Bedford，1971)・ 工n七工 a- and in 七e rspecific varia 七i onof final-diapause in七ensitywas found in 七hepresen 七 S七u dy ( Fig. 1 5， Fig.27)・ Diapause in 七e nsity is higheど inplurennial species ( M. japonica) 七han in annual species (M. hime)，and a1so in 七he population from七he sou 七h ernregion. These resul 七s m ay be explained as fol1ows. 81 工n 七hep 1urennia1 (and biennia1) species main1y inhabi 七i ng coo1 regions，the eggs which termina 七edi ni 七i a1diapause in 七err esume deve10pmen 七 s oonaf七er 七he soi1 七empera 七u re wln 工i ses above 七he10wer七hresho1dand reach 七he fina1 diapause S七a gewi七hou七 de1ay. Therefore， 七 heyhave 七o spend under mi1d七empera七urecondi 七i ons as 15-20oC for a 10ng 七ime. 工n annua1 species， 七he eggs of sou 七h ernpopu1ation mus七 spend 七u mnaf七er 七erminationof summer diapause. 10ng au 工ngrisch ( 1985) sugges七s another ro1e of fina1 diapause in 1ife cyc1e regu1a 七i on. He shows 七ha 七 七h ereare 七wo pa 七七 e rns of ha 七c hing 工n 七e七七 igoniidspecies. 工n 1a 七e ha 七c hing species (e. g・Conocephalus，Phaneroptera)，七he 七e i s no 七 a ffectedby 七he1eng 七h o f coo1ing hatching da 七 i near1y ha 七c hing species (e. g・/>1etrioptera， period，bu Tettigonia)， ex 七e nsionof 七hecoo1ing period advances 七he ha 七c hing da 七e . He considered 七his response 七o be an adap 七a tion 七o ha 七c hing as ear1y as 1a 七e s pring. 工n M. hime(A0140)， 七hemean ha 七c hing 七imewas decreased by 七 f urther pro1onga七ionof chi11ing 七o 100 days， bu pro1onga 七i ondid not affec七 七he ha 七c hing 七ime (Fig. 16)・ In M. japonica ( A0220)， on 七he0七her hand， 七hemean ha 七c hing 七i mewas shor 七e nedby pro1onga 七i onof chi11ing七o 180 days. Fina1 diapause may be more impor 七a n 七 a s regu1a 七or f or 七ing favorab1e 七imingof hatch in M. japonica main1y inhabi snowy areas where 七he growing season is short. 七e rerare known 七o be co1d Some species of egg-overwin hardy and ab1e 七o spendwin 七ers afe1y in 七he pre-diapause S七a ge (Tanaka， 1992;Ando， 1993b; 工shiguri， 1997)・ Especia11y，mos 七 i ndividua1soverwin 七era t pre diapause 田 82 S七a ges in 七he nor 七h ernpopu1a 七i ons of 七herice grasshopper， Oxya yezoensis ( Ando，1993b) and 七he ka 七y did，Conochephalus 工s higuri， 1997)・ 工shiguripointed ou 七 七ha 七 japonicus ( fur 七h er study is necessary 七o find 0七herexarnp1es of overWln七erlnga七 七he pre-diapause stage. Eggs of M. hime(A0140) before 七he fina1 diapause s 七a gea1so cou1d overwin 七e rand ha 七c hedaf 七er 七h e firs 七 w in七erwi 七h ou七 entering fina1 diapause (Fig. 12)・ However，because 七hose n u c h 1a 七e r in 七he season， overwin 七e ringbefore eggs ha七chedr fina1 diapause s e e r n s no 七 七o b e adaptive. 工n univo1 七i neegg-overwin 七e rers of some cricke七S (Masaki，1996) and a七 1eas七 onegrasshopper (Ando， 1993b)， pho七operiodhas been known 七o con 七工0 1the ra 七e o f 1arval developmen 七. S hor 七 p ho 七o periodacce1era 七e s， and 10ng pho 七o perioddece1era七es， larva1 developmen 七. M oreover， 1arva1 deve10pmen 七 七i me 七ends 七o be shor 七e r in nor七hern 七h ernpopula 七i on. As a resu1 七 ， b o七h populations 七han in sou 七h ern popula 七i ons of 七hose species emerge as northern and sou adul七s a七 a1most七he same 七ime in autumn and can 1ay eggs in appropria七e 七imebefore win七er (Masaki， 1963;λndo， 1998)・ Adjus七men 七 o f adu1 七 e mergence 七工meto au 七u mn is impo 工七 a n 七 f or 七h ese species 七o p工even 七 un 七i me1ydiapause七ermina 七i onbefore 七er， b ecause in 七e nsityof 七heiregg diapause is re1a 七i ve1y win 10w and can ha 七c hunderconstan 七 h igh 七e r n p e r a 七u 工e c onditions. 工n M. hime，on 七he0 七h erhand， adu1 七 e rnergence occurred abou七 onemon七h earlie工 in 七he sou 七h ernpopu1ation七hanin 七h e nor 七h ernpopu1a 七i onin 七heiror ェgina1habi七a七s and 工e gula 七i onr n e c h a n i s r nof nympha1 deve10prnen 七 is unknown. As a resu1t，in 七he southern popu1ation，eggs began 七o be 1aid 83 before mid summer. Their developmen 七 w as delayed and they entered summer diapause a七 S七a ges 18-19 in 七he ho 七七 e st season. Af 七e r summer， 七heysynchronously resurned developmen 七 and 工eacheda七 七hefinal diapause stage. The higher diapause l .n 七e ns1 . 七Y o f 七he sou 七h e工n eggs is useful 七o survive 七he long 七i ons. mild 七ernperaturecondi The role of egg s七age in life cycle regulation is very l . mpor 七a n 七 inthe biennial and plurennial species. However， 七h is s七age also plays an impor 七a nt role in annual species. 84 5 . 5山 mn ary The 1ife cyc1e and diapause charac七eris七icswere 七y didspecies 七o unders七and 七he compared 田 nong 七hree ka eco1ogica1 func七ionof 七he egg 5七agewi 七h 七wo o r 七hree diapause 5七ages. Metrioptera japonica inhabi 七i ngnor 七h e 工n 10w1ands and sou 七h erna1pine 工egions required two ormore years to comp1e 七e i ts 1ife cyc1e and showed 七wo 七ypes of embryonic diapause:one occurs jus七 af七erb1as七oderm 七i on (ini七ia1diapause) and 七heotheど shor七1ybefore forma hatching (fina1 diapause). Some eggs of this species remained in ini 七i a1 diapause for severa1 years. The incidence of pro1onged diapause was higher in eggs derived from highe工 a1 七i 七u des. Metrioptera himeand Chizuella bonneti are univo1tine and en七ereddiapause on1y a七 a 1a七e 七i nespecies hatched over a embryonic 5七age. These univo1 re1a 七i ve1y10ng period of 七imein spring but emerged as adu1 七5 b y summer，because 七heyoccur on1y at 10w1ands. The 七i me of adu1t emergence in M . japonica a七 high a1七i七udes varied grea七1y fromyear七o year，and adu1ts appeared 七i ve1y1a 七e i n 七he season. Because eggs of 七his species re1a survived a period of chi11ing even befoどe reaching the ini 七i a1diapause s七age，ini 七i a1 diapause is probab1y not a prerequisi 七e f or overwin 七e ring. Varia 七i on in the 七imeof 七i onor induc七ionof ini七ia1diapause did no 七 a ffect oviposi 七h e 七imingof ha 七c hing 七ha 七 occurred七woyears 1a 七er. 工七 appears 七ha七 in M.japonica in 工七 i a1diapause p1ays an impor 七a n 七 r o1e in the con 七工 0 1 of 七he 1ife cyc1e in habita七s where 七he growing season is shor 七 a nd unpredic七ab1e. 85 工n M. hime，七heembryo daveloped withou 七 d elaybefore reaching s七age 24 a七 20，22.5 and 250C. At 27.5 and 30oC，on the 0七herhand，marked delay was observed，al 七h ough 七he ini七ialdevelopmen 七 p 工o ceededguickly. This re 七a rda 七i on at high 七empera 七u reswas more s七riking in the sou 七h ern popula 七i on. Especially，a七 30oC，eggs s七oppeddevelopmen 七 a 七 stages 18-19 and were considered 七o en 七ers ummer diapause， during whichwa 七e rabsorp 七i onwas suppressed. A shif七 of 七e mperature from 300C 七o 20 and 250C termina 七eds ummer diapause and 七he eggs s七ar 七e d 七o develop and absorb wa 七er ど apidly，while 七he eggs remaining a七 300C s七ayeda七 S七a ges 1 8-19. Adult emergence occurred in earlymid June and began 七o l ay eggs before mid summer. 工n an outdoor experimen 七， embryonic developmen 七 d elayedmore conspicuously in 七he eggs deposi 七ede arlier in a sou七hernpopula 七i on. 七h e developmen 七a ldela y 工七 seems 七ha 七 and summer diapause allow七heeggs 七o 七e s 七 s easonand 七o reach the final diapause survive 七he hot s七agemore synchronously in au 七u mnthan expec七edfrom七he long egg-laying period. 七u reemb工yois never Final diapause occurring in 七hema termina 七eda nd the eggs gradually shrink and eventually die if 七heyare kep 七 a 七 h igh 七empera 七u res. A cold 七工 ea 七men 七 i s necessary 七0 七e rmina 七e f inal diapause. Diapause in 七e nsi七Y is higher in 七heplurennial species (M. japonica) 七han in 七he annual species (M. hime)，and also in 七hepopula 七i on from七he sou 七h ernregion. The high in 七e nsi 七y o f final diapause enables eggs 七o survive long period under mild七emperature condi 七i ons before win 七er. 86 6.Acknowled 伊n ents 工 amgra 七e ful 七o Prof. Y . Ando for givingr n e a chance 七O S七u dy katydid life cycles and reading a draf 七. 工 七h ankProf. Emer. S.Masaki for invaluable advice and reading the draft. 1 wish七0 七h ankalso Associa 七e P rof.Y. Shiro 七a f or con 七i nuous encouragemen 七. T he draf七 was read and improved by Prof. Y.Harada (Hi工osakiuniversi 七y )，prof.K. Suzuki ( 工wat e Universi七y)，Dr. M.Go 七o ( Y a r n a g a 七a u niversity) and Dr. K. Kurarnochi (Obihiro university of Agricul 七u reand Ve 七e rinary Medicine)・ Thanks are also due to S.Kawano for kind 七e chnical advice，T . Shimizu for useful sugges 七i on，K. Tani， T.Wa 七a nabe，工. Kasai，Y. Kudo，K. Yamamoto，Y . Ishiguri，O. Narita，K.Suzuki and K . 工wa七a for looking af 七ermy i nsec七S while 工 was away. 工n 七h e bog a七 anal 七i 七u deof 1400 m in M七. 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