pj()(eecllllq, o! tile 7/11 lutei uat uiu«! WU/I',lIlq COli tel I'mI' 01/ Stcu ed-prohu ! PIO/ec/IOII - Voluille

Development and reproduction of Callosobruchus chinensis(Coleoptera: Bruchidae) on four legume plant seeds

Yongxue Deng, Longvhu LI and Zhimo Zhao'

Ab,/i'Uc/

Effects of commercially grown legume plant seeds on thedevelopment, sun ivorslup , and reproduction of the Chmesecowpea weevil, Cal/u'obllu:lw., clunetiu-: were studied inthe laboratory The percentage of Immature stages thatsurvived on mungbean , Plta-eotus ailleu." adzki bean, Pa uqulini«, soybean. GII/Cille mcn , and broad bean, VI(/aioba at 30 ± 1°C were lJI .i, 87 3, 63 5. and ,,(6 OSb,respecuvely Developmental time from egg to adult rangedhom 22 Id on mungbean to 37 "(d on soybean The averagenumber of eggs laid pel female were S..( I. 72 I, ..(..(3,18 3 on the above respective hosts and temale adults livedon an average at 7 8. 7 5, 5 6, and 6 2d on these samehost seeds The mtnnsic rate of natural mcrease ( I ) forCal/u;,oln 11(/111" chineu-i-. on mungbean was the highest1,1' vaned from 0 07663 on mungbean to 0 0.3,,(,,(28on broad

bean Based on life-table analvses ot Chmese cowpea weevilpopulations, we conclude that mungbean was the mostsuitable host for C (hlilei/I-I;, and broad bean the leastsuitable

Introduction

The brucllld Cal/o;,ohillclllll> clllllell'lI> (L ) IS a senouspest of stored legume seeds (Southgate, 1978) Eggs arelaid on the seeds surface m storage or pods m the held andlan-ae develop wlthm seeds causmg weight loss, decreasedgell1unatlOn potential and reductIOn m commerCIal yalue(Caswell, IlJ81) Beetle populatIOns bUild lapldly m stOlageand damage m telms of holed seeds can mClease to 9lJc,uaftel 6 months (Seck et al , IlJlJI) The seeds may bealmost completely hollowed out by feedmg actmtles of thelan-ae, and chalactenstlC emelgence hole are eVident atterthe adult leave the seeds 01l10,ohlllch II" ISone of the mostWidespread speCIes of genus Cal/ol->ohl Uc!IIIi> (Southgate,IlJ7S, Howe et al. 19M)!\1ungbean, Plw,eoilli> 111111'11.,. adzkl bean, P

al/qlllcllll->. soybean, GII/ellle 1/1a I , and broad bean. VICW

IIJepmtment of PIRnt Pl<l(eC(H,n, '-;,uthwe,t '\gncultuml UnlveNtv.

Ch()ngqmg 400716 ChmR

ioba are cultivated m southwest Chma mostly for the edibleseeds, wlnch serve as an Important source of protem m thehuman diet Damage to legume seeds m storage by theCal/o;,oblllc!W," clunensu. constitutes a major constramton toad availability The biology of CaI/OI->Oblllc!lIti>(/11111'1/',/;' has been studied by several researchers m Chma(Huan Jianguo , 1980, Zhang Shoudong , 1986) However,the essential information on the population dynamics ofCol/owbl Uc!III;" dynamics m Southwest Chma IS lackmgThe development of a sound pest management program mustbe based on a thorough understanding of the biology andecology of the pest This article repoi ts the effects of hostson the development. reproduction, and population dynamicsof C{ll/osobmc!lIli> (/11111'11;'1,'

Material and Methods

Chmese cowpea weevil source and Host The weevil adultswere collected hom seeds of P allgul((/ /.;, m Berber,Chongqmg P R China The ensuing stock colony wasmaintamed m mung beans wluch was stenlized With C060 - yray m glass Jar m the laboratory (32l, and 75'7c r h )After"'" 10 generations. the adult beetle trom the stockcolony was used for the tests All the tests were conductedm the Petn dishes (12 cm diameters)The adult weevtls tram the stock colony were collected

and moculated on Mungbean, Plwseolll,., all 1'1'11;' , adzklbean, P allgulwl;" soybean, GII/ellle /)IU.!, and broadbean. V/.CIU {ubu seeds to oVlposlte at 30°C Three Petndishes were prepared for total 150 beans m WlllCheach beanswas only kept 1 egg on seed surface at each host seed Afteradult emelged, the longeVity and fertility were measured

Results

Development and SurVivorship of Inmmtures Developmentaltune for the Immature stages on the four host plants ISplesented m Table 1 There wele slgmflcant differences mlength at tune from egg to adult emergence among thepopulatIOns on different host seeds IndlVlduals fed on adzktbean seeds developed slgmflcantly faster than those on anyother host seeds dunng the Immature stages In contrast.the mdlvlduals fed on soybean seeds had a slgmhcantl longertime ( = 36 8 days) from the eggs to adult emergence than

107

Pl'Oeeedmgs of the 7th Internatwnal Wm'kmg Canfereuee on Stored-prodnet ProtectIOn - Volume 1

did msects fed on adzki bean ( = 21 9 days), mung bean ( =21 8 days), or broad bean ( = 25 0 days)There were significant difference in percentage of

survival from egg to adult stages on the different host seeds(p<O 0001, Table 2) Callosobruchu» chinensi« fed onmungbean had the highest percentage of survival from egg toadult (91 2%), whereas the populations fed on soybean andbroad bean seeds had significantly lower survivorship (63 3,and 46 1%, respectively)Adult Longevity and Reproductive Capacrty Adult females

lived significantly longer on mung bean or adzki bean (7 8and 7 5 days, respectively) than on soybean (5 6 days) orbroad bean (6 2 days) (Table 3) The female reared onmung bean and adzki bean laid """4 - 5 times more eggs(averages, 84 1 and 72 1 eggs per female, respectrvely )than those reared on broad bean seeds (18 3 eggs perfemale)Life-table statistics (rm and A) of the population on 4 host

seeds are summanzed m table 4 r m was calculated usingHowe (1953) equation 1m = log (NS )/( T + 1I2L)Callosobruchus reared on mung bean had a sigruficantlhigher mtnnsic rate of mcrease (1 m = 0 07663) and ahigher frrute rate of mcrease (A= 1 07964) than the femalereared on other host seeds

Table 1. Mean developmental periods (days) of Immaturestages of Callosobruch us chineneis on 4 hostseeds at 30'C

Host seeds egg Larva + pupa From egg to adult

Mung bean 3 7 18 2 21 9Adzkl bean 3 5 18 3 21 8Soybean 3 5 33 3 36 8Broad bean 3 8 21 2 25 0

Table 2, Survlvorshlp ofCallosobl'uch usat 30'C (%)

Immature stages ofehmenS1S on 4 host seeds

Host seeds egg Larva + pupa From egg to adult

93 3 97 7 91 288 0 99 2 87 382 7 76 8 63 354 7 84 2 46 1

Mung beanAdzkl beansoybeanBroad bean

Table 3. OvIpOSItion (eggs per female) and longeVIty offemale C ehznensls on 4 host seeds at 30'C

Host seedsMean longevIty offemale (day)

Mean number,eggs per female

Mung beanAdzkl beansoybean

Broad bean

7 87 55 66 2

84 172 144 318 3

Table 4. Companson of life table parameters of Cch mens/)) on 4 host seeds at 30'C

Host seedsthe mtnnsic rateof mcrease ( 1 .u )

the fmrte rateof increase (,,)

Mung beanAdzki beanSoybeanBroad bean

o 07663o 07226o 03645o 03428

1 079641 074931 037121 03487

Discussion

Although Calloeooruchus chmensis generally has a Wide rangeof host seeds, many researchers funk Callosobrw:hus chmensiscan not damage soybean seeds and the larvae can not survivewhen fed on soybean (Yaoqi Cheng, 1984, Jianguo Huan,1980) We chscovered Callosob1'1u:hns chmensis was the mostsenous insect of stored soybean III Xicang city, SichuanProvince, Our results also showed Callceooruchu» chmensisChongqmg stram can develop very well when we used soybeanas host seedsWe have demonstrated that host seeds had a significant

effect on the developmental time, survivorship, longevityand oviposition of Calloeooruchus citwens IS Theseresults are m general agreement with the observations forCallosobl'lu:hns spp by other authors (Dma , 1971, Epino,1982, Katryar , 1982) Van Lenteren and Nodus (199G)have stated that shorter development time and greater totalovrposition on a host reflect the suitability of the hostTherefore, because the Callosobrucluu: chmensispopulations that fed on mung bean and adzki bean showedhIgher mtrmslC rates of mcrease resultlllg from fasterdevelopment. hlgher surviVorshIp, and hlgher OVlposltionrates. these 2 speCles are presumably more sUltable hostseeds for thls Callosobrzu:hus chmensls In the future,efforts should be devoted to the physlology and blOchemlstryof crops to develop reSIstance to damage by Ca llosobruc1lUschmensls m Southwest Chma

References

Southgate, B J 1979 BlOlogy of Bruchldae Ann RevEntomol 24 449 - 473Glga, D P 1983 Comparative hfe hIstory studles of fourCallosobrztehus specles Wlth speclal reference to Crhodeslarus J Stored Prod Res 19(4) 189 - 198Epmo, P B 1982 MechallIsm of reSIstance m mungbeanto Callosobruchus ehmens18 Phlhppme EntomologIstVol 4 447 - 462SJunoda, K 1984 RelaltonsJup between adult feechng andenngratlOn from beans of azukJ. bean weeVIL, C cJunenslsApphed Entomol And Zool 19(2) 202 - 211Huan Jianguo 198G StudIes on blonomocs of C ehtneYlS18J of Zhengzhou Gram College No 4 22 - 28

108