Biocontrol of Pests 

DEVELOPMENT AND REPRODUCTION OF SEMICLAUSUM (: ) ON , PLUTELLA XYLOSTELLA (LEPIDOTERA: PLUTELLIDAE)

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Institute of Natural Resources, Massey University, Private Bag 11222, Palmerston North, New Zealand Corresponding author: [email protected] ABSTRACT This study investigated the development, emergence and mating of Hellen, an important parasitoid of diamondback PRWKLQWKHODERUDWRU\DW“ƒ&DQG5+ZLWKDSKRWRSHULRG RIK OLJKWGDUN 7KHSDUDVLWRLGV·GHYHORSPHQWDOSHULRGZDV VLJQLÀFDQWO\VKRUWHUDQGSXSDOZHLJKWVLJQLÀFDQWO\KLJKHULIWKHLUPRWKHUV SDUDVLWLVHGWKHIRXUWKLQVWDUODUYDHRI'%0 3  7KHRIIVSULQJVH[ UDWLRZDVVWURQJO\PDOHELDVHG  EXWQRVLJQLÀFDQWGLIIHUHQFH ZDVGHWHFWHGEHWZHHQKRVWLQVWDUV0RVWDGXOWVHPHUJHGGXULQJWKHÀUVW few hours of the photophase and none emerged during the scotophase. Mating had no effect on the longevity of both sexes, but small females OLYHGVLJQLÀFDQWO\ORQJHUWKDQWKHODUJHURQHV 3  0DOHDJHDQG size had no effect on mating success, whereas small females achieved KLJKHUPDWLQJVXFFHVVWKDQODUJHRQHV 3  7KHLPSOLFDWLRQRI this study in mass-rearing in the laboratory is discussed. Keywords: Diadegma semicalusum, Plutella xylostella, emergence, body size, mating.

INTRODUCTION 7KHGLDPRQGEDFNPRWK '%0 Plutella xylostella (L.), is the most destructive pest of FUXFLIHURXVFURSVZRUOGZLGHLQFOXGLQJ1HZ=HDODQG 7DOHNDU 6KHOWRQ&DPHURQ HWDO Diadegma semiclausum Hellen is one of the most important, solitary larval HQGRSDUDVLWRLGVRI'%0 7DOHNDU 6KHOWRQ DQGZDVLQWURGXFHGLQWR1HZ =HDODQGIURP(QJODQGLQWRPDQDJHWKH'%0SUREOHPV %HFN &DPHURQ 7DOHNDU 6KHOWRQ Diadegma semiclausum has great prospects for the biological FRQWURORI'%0EHFDXVHRILWVKLJKVSHFLÀFLW\DQGVHDUFKLQJDELOLW\ 6KLHWDO  7KHSDUDVLWLVPUDWHRI'%0E\D. semiclausumFDQEHDVKLJKDV ,JD :DONHUHWDO&KHQHWDO.ZRQHWDO EXWWKHUDWHLVRQO\LQ FRPPHUFLDOFURSVLQVSULQJ &DPHURQHWDO 7KHKLJKUHVLVWDQFHRI'%0WRWKH PDMRUFODVVHVRILQVHFWLFLGHV &DPHURQHWDO DQGELRSHVWLFLGHV 6KHOWRQHWDO  KDVOHGWRLQFUHDVLQJLQWHUHVWLQWKHUROHRISDUDVLWRLGVLQWKHELRORJLFDOO\EDVHG LQWHJUDWHGPDQDJHPHQWRI'%0DLPLQJWRUHGXFHUHOLDQFHRQLQVHFWLFLGHV 7DOHNDU  6KHOWRQ/LX 6XQ  The biology and ecology of D. semiclausum have been studied to some extent (Abbas 

New Zealand Plant Protection 61: 322-327 (2008) www.nzpps.org

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Biocontrol of Insect Pests 

MATERIALS AND METHODS Breeding colony 7KHEUHHGLQJFRORQLHVRI'%0 and D. semiclausumVWDUWHGIURP'%0ODUYDH FROOHFWHGIURPDFRPPHUFLDOIDUPLQ3DOPHUVWRQ1RUWKLQ-DQXDU\DQGUHDUHGDW WKH(QWRPRORJ\DQG,30/DERUDWRU\0DVVH\8QLYHUVLW\DW“ƒ&DQG5+ ZLWKDSKRWRSHULRGRIK OLJKWGDUN 7HQ'%0ODUYDHZHUHWUDQVIHUUHGWRHDFK SRWWHGFDEEDJHVHHGOLQJ OHDYHV DQGWKHSODQWVZHUHLQGLYLGXDOO\PDLQWDLQHGLQ WUDQVSDUHQWSODVWLFMDUV FPLQKHLJKWðFPLQGLDPHWHU ZLWKWZRKROHV FPLQ GLDPHWHU FRYHUHGZLWKPHWDOPHVK DSHUWXUHVL]HRIWKHPHVK PP RQRSSRVLWH walls for ventilation. The parasitoid colony was maintained in a similar way where DPDWHGSDUDVLWRLGIHPDOHZDVUHOHDVHGLQWRDMDUZLWK'%0ODUYDHHDFKGD\'%0 DQGSDUDVLWRLGDGXOWVZHUHSURYLGHGZLWKKRQH\VROXWLRQVRDNHGLQFRWWRQEDOOV FPLQGLDPHWHU DVIRRG Development and emergence To determine whether hosts of different instar stages affected the development and body weight of D. semiclausumDPDWHGSDUDVLWRLGIHPDOHZDVUHOHDVHGLQWRWKHMDUZKHUH VHFRQGWKLUGRUIRXUWKLQVWDUODUYDHRI'%0ZHUHIHHGLQJRQDFDEEDJHVHHGOLQJ7KH parasitoid was allowed to stay for 24 h for oviposition and then removed. There were 6, DQGPDWHGIHPDOHSDUDVLWRLGVXVHGWRSDUDVLWLVHWKHVHFRQGWKLUGDQGIRXUWKLQVWDU ODUYDHRI'%0UHVSHFWLYHO\3DUDVLWLVHG'%0ODUYDHZHUHDOORZHGWRIHHGRQFDEEDJH seedlings until pupation. Once the parasitoids pupated, they were removed from the VLONHQZHEDQGZHLJKHGXVLQJDQHOHFWULFEDODQFH 0HWWOHU7ROHGR$*6ZLW]HUODQG  ZLWKDUHDGDELOLW\RIPJ3DUDVLWRLGSXSDHZHUHLQGLYLGXDOO\PDLQWDLQHGLQJODVV vials (4 cm in height × 2 cm in diameter) for emergence. Emergence was recorded hourly during the photophase, and the sexes of adults and the developmental period of parasitoids from eggs to emergence were also calculated. Emergence observation was also performed immediately after light-on to determine whether parasitoids emerged during the scotophase. Longevity To investigate whether mating and body size had any effect on the longevity of both sexes, mated and virgin adults were individually maintained in transparent plastic FRQWDLQHUV FPLQKHLJKWðFPLQGLDPHWHU ZLWKWZRFPPHVKFRYHUHGYHQWLODWLRQ holes. The parasitoids were fed with honey solution as above. Longevity of adults was UHFRUGHG7KHSDUDVLWRLGVXVHGZHUHWKRVHWKDWHPHUJHGIURP'%0SXSDHSDUDVLWLVHG at fourth instar larvae. Mating behaviour To investigate the effect of age and body size on mating success of both sexes, one male and one female D. semiclausum were paired in eight treatment combinations Q QXPEHURIUHSOLFDWHV   KROGVPDOOIHPDOHGD\ROGVPDOOPDOHQ   KROGODUJHIHPDOHGD\ROGODUJHPDOHQ   KROGVPDOOIHPDOHGD\ROGVPDOOPDOHQ   KROGODUJHIHPDOHGD\ROGODUJHPDOHQ   KROGVPDOOPDOHGD\ROGVPDOOIHPDOHQ   KROGODUJHPDOHGD\ROGODUJHIHPDOHQ   KROGVPDOOPDOHGD\ROGVPDOOIHPDOHQ   KROGODUJHPDOHGD\ROGODUJHIHPDOHQ  7KHERG\VL]HRISDUDVLWRLGVZDVGHÀQHGDVVPDOOZKHQSXSDOZHLJKWZDVOHVVWKDQ PJDQGODUJHZKHQSXSDOZHLJKWZDVJUHDWHUWKDQPJ7KHPDWLQJEHKDYLRXU RIHDFKSDLUZDVREVHUYHGLQDJODVVYLDO FPLQKHLJKWðFPLQGLDPHWHU IRU hour during the photophase. The number of mating successes, premating and mating periods were recorded. Data analysis $JRRGQHVVRIÀWWHVWZDVXVHGWRWHVWWKHGLVWULEXWLRQRIGDWDEHIRUHDQDO\VLV Developmental period data were not normally distributed even after transformation and

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Biocontrol of Insect Pests 

WKXVDQDO\VHGXVLQJWKHQRQSDUDPHWULF.UXVNDO:DOOLVWHVW .:7 IROORZHGE\'XQQ·V procedure for multiple comparisons. Data on pupal weight, adult longevity, and premating and mating periods were normally distributed and thus analysed using ANOVA followed E\7XNH\·VVWXGHQWL]HGUDQJHWHVW%HFDXVHPDWLQJKDGQRHIIHFWRQDGXOWORQJHYLW\ longevity of mated and virgin individuals was pooled for analysis of the effect of body size on longevity. Parasitoid emergence data from second, third and fourth instar larvae were pooled and the emergence pattern during the photophase was analysed using non- linear regression. Chi-square tests were applied to analyse the mating success.

RESULTS Development and emergence 3DUDVLWRLGVGHYHORSHGVLJQLÀFDQWO\IDVWHU 3  DQGUHVXOWLQJSXSDHZHUH VLJQLÀFDQWO\KHDYLHU 3  ZKHQGHYHORSLQJRQ'%0IRXUWKLQVWDUODUYDH 7DEOH  1RVLJQLÀFDQWGLIIHUHQFHZDVIRXQGLQGHYHORSPHQWDOWLPHDQGSXSDOZHLJKWEHWZHHQ PDOHVDQGIHPDOHV 3!  7DEOH 7KHSURSRUWLRQRIIHPDOHSURJHQ\ DQG IRUVHFRQGWKLUGDQGIRXUWKLQVWDUUHVSHFWLYHO\ GLGQRWYDU\VLJQLÀFDQWO\EHWZHHQ WKHKRVWODUYDOVWDJHVDWSDUDVLWLVDWLRQ 3! 

TABLE 1: Developmental period from eggs to emergence (days) and pupal weight (mg) of D. semiclausum that parasitised DBM larvae of different instars. Means (±SE) followed by the same letters in columns are not VLJQLÀFDQWO\GLIIHUHQW 3!  '%0 Developmental period Pupal weight instar Male Female Mean Male Female Mean 2nd “ “ “E “ “ “E rd “ “ “E “ “ “E 4th “ “ “D “ “ “D

No individuals were observed to emerge during the scotophase. The emergence of SDUDVLWRLGVZDVFRQÀQHGWRWKHÀUVWKRXUVRISKRWRSKDVHDQGWKHQVLJQLÀFDQWO\GHFUHDVHG ZLWKWLPH 3 )LJ 

FIGURE 1: Emergence of D. semiclausum (number of adults/h) during the photophase.

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Biocontrol of Insect Pests 

Longevity 0DWLQJGLGQRWVLJQLÀFDQWO\DIIHFWWKHORQJHYLW\RIHLWKHUVH[ 3  +RZHYHU WKHORQJHYLW\RIVPDOOIHPDOHV “GD\V ZDVVLJQLÀFDQWO\JUHDWHUWKDQWKDWRI ODUJHIHPDOHV “GD\V DQGVPDOOPDOHVKDGJUHDWHUORQJHYLW\WKDQODUJHPDOHV “DQG“GD\V  3   Mating behaviour When both sexes were released together, males always approached females with their wings vibrating. Upon female reception, they mated in tail to tail position. Mating VXFFHVVZDVVLJQLÀFDQWO\KLJKHULQVPDOOIHPDOHVWKDQLQODUJHURQHVZKHQWKH\SDLUHG ZLWKGD\ROGPDOHV 3   7DEOH +RZHYHUQRVLJQLÀFDQWGLIIHUHQFHVZHUH detected in mating success between ages or sizes of males when they were paired with GD\ROGIHPDOHV 3! DQGvice versa (Table 2). Parasitoid age and body size had no effect on the premating and mating periods (Table 2).

TABLE 2: Premating period (PMP, min), mating period (MP, min) and mating success (MS, %) of D. semiclausum at 12 or 24 h of age and with small or large body size. RUKROGIHPDOHVPDWHGZLWKGD\ROGPDOHV Female 6PDOOIHPDOHVPDOOPDOH /DUJHIHPDOHODUJHPDOH age PMP MP MS PMP MP MS 12 h “ “  “ “  24 h “ “  “ “  RUKROGPDOHVPDWHGZLWKGD\ROGIHPDOHV Male 6PDOOIHPDOHVPDOOPDOH /DUJHIHPDOHODUJHPDOH age PMP MP MS PMP MP MS 12 h “ “  “ “ 41.2 24 h “ “ 42.9 “ “ 

DISCUSSION +DUYH\ 6WUDQG  VXJJHVWHGWKDWSDUDVLWRLGVDWWDFNLQJIROLDUIHHGLQJKRVWVPD\ favour rapid development time over size while parasitoids that attack concealed hosts favour size over development time. In this study, when D. semiclausum attacked fourth LQVWDUODUYDHRI'%0LWGHYHORSHGIDVWHUDQGSURGXFHGODUJHUSURJHQ\LQGLFDWLQJWKDW D. semicalusum has the ability to adjust its development and growth rate according to host stage as reported in some other parasitoids, e.g. Aphidius ervi Haliday (Sequeira & Mackauer 1992). This may be because for the solitary parasitoids, large hosts contain PRUHUHVRXUFHVWKDQVPDOOKRVWV &KDUQRYHWDO 7KHVLPLODUGHYHORSPHQWDOSHULRG and body size for both male and female progeny from a given size of hosts suggests that sexes of D. semiclausum utilise similar amounts of host nutrients. Diadegma semiclausum is a haplodiploid where fertilised eggs develop to IHPDOHVDQGXQIHUWLOLVHGHJJVGHYHORSWRPDOHV&KDUQRYHWDO  VXJJHVWHGWKDW SDUDVLWRLGVFDQPDNHHIÀFLHQWXVHRIWKHVL]HYDULDWLRQLQWKHKRVWVE\GHSRVLWLQJIHUWLOLVHG eggs to large hosts to produce females and unfertilised eggs to small ones to produce PDOHV+RZHYHULQWKHSUHVHQWVWXG\QRVLJQLÀFDQWGLIIHUHQFHLQSURSRUWLRQRIIHPDOH progeny was found when D. semiclausum attacked hosts of different size, which does QRWVXSSRUWWKHSDUDVLWRLGVH[DOORFDWLRQVWUDWHJ\VXJJHVWHGE\&KDUQRYHWDO  7KH male-biased sex ratio of this species has been reported in both the laboratory (Yang et al.  DQGÀHOG .ZRQ HWDO 7KHIDFWWKDWIHUWLOLVHGHJJVRID. semiclausum may GHYHORSWRHLWKHUIHPDOHVRUPDOHV 1RGD PD\EHDWWULEXWHGWRWKHPDOHELDVHG VH[UDWLRLQWKHODERUDWRU\DQGÀHOGSRSXODWLRQV

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Biocontrol of Insect Pests 

The emergence pattern of parasitoids is usually linked to behavioural adaptations and UHSURGXFWLRQVWUDWHJ\VXFKDVIHHGLQJPDWLQJDQGRYLSRVLWLRQ +HHWDO 5HVXOWV IURPWKLVVWXG\DQGWKDWRI

ACKNOWLEDGEMENTS :HWKDQN6RODU3URGXFH)DUP3DOPHUVWRQ1RUWKIRUDOORZLQJXVWRFROOHFW'%0 DQGSDUDVLWRLGVIURPWKHLUYHJHWDEOHIDUPDQG'UV6=\GHQERVDQG6*ROGVRQIRUWKHLU FRQVWUXFWLYHFRPPHQWV7KLVVWXG\ZDVSDUWO\IXQGHGE\1HZ=HDODQG·V,QWHUQDWLRQDO Aid and Development Agency.

REFERENCES $EEDV067%LRORJLFDODQGHFRORJLFDOVWXGLHVRQDiadegma semiclausum Hellen (Hym., Ichneumonidae), a larval parasite of the diamond-back moth, Plutella xylostella (L.) (Lep., Plutellidae) in Egypt. Anzeiger fur Schadlingskunde, 3ÁDQ]HQVFKXW]8PZHOWVFKXW] %HFN1*&DPHURQ3-'HYHORSLQJDUHGXFHGVSUD\SURJUDPIRU%UDVVLFDVLQ1HZ =HDODQG,Q7DOHNDU16HG Diamondback moth and other crucifer pests. Proceedings RIWKHVHFRQGLQWHUQDWLRQDOZRUNVKRS7DLQDQ7DLZDQ3S &DPHURQ3-6KHOWRQ$0:DONHU*37DQJ-'&RPSDUDWLYHLQVHFWLFLGHUHVLVWDQFH RI1HZ=HDODQGDQG1RUWK$PHULFDQSRSXODWLRQVRIGLDPRQGEDFNPRWKPlutella xylostella /HSLGRSWHUD3OXWHOOLGDH 1HZ=HDODQG-RXUQDORI&URSDQG+RUWLFXOWXUDO 6FLHQFH &DPHURQ3-:DONHU3-.HOOHU0$&RPSDUDWLYHPHDVXUHVRIWKHKRVWVSHFLÀFLW\ of Cotesia rubecula and C. plutellae +\PHQRSWHUD%UDFRQLGDH 3URFHHGLQJVRIWKH 6L[WK$XVWUDODVLDQ$SSOLHG(QWRPRORJLFDO5HVHDUFK&RQIHUHQFH3S &KDUQRY(/+DUWRJK5//RVGHQ-RQHV:7YDQGHQ$VVHP-6H[UDWLRHYROXWLRQ LQDYDULDEOHHQYLURQPHQW1DWXUH &KHQ=0LDR6

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Biocontrol of Insect Pests 

,JD0(IIHFWRIUHOHDVHRIWKHLQWURGXFHGLFKQHXPRQLGSDUDVLWRLGDiadegma semiclausum (Hellen) on the diamondback moth, Plutella xylostella (L.) in an H[SHULPHQWDOFDEEDJHÀHOG-RXUQDORI$SSOLHG(QWRPRORJ\DQG=RRORJ\  .ZRQ03DUN..ZRQ+'HYHORSPHQWDOFKDUDFWHULVWLFVRI Diadegma semiclausum+HOOHQ +\PHQRSWHUD,FKQHXPRQLGDH DODUYDOSDUDVLWRLGRI Plutella xylostella/ /HSLGRSWHUD

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