Host Instar Preference of Peleteria robusta (Wiedman) (Diptera: Tachinidae) and Development in Relation to Temperature

Transcrição

1 July - September BIOLOGICAL CONTROL Host Instr Preference of Peleteri robust (Wiedmn) (Dipter: Tchinide) nd Development in Reltion to Temperture LUÍS A. FOERSTER AND AUGUSTA K. DOETZER Depto. Zoologi, Universidde Federl do Prná, C. postl , , Curitib, PR e-mil: foerster@bio.ufpr.br Preferênci Pelo Ínstr do Hospedeiro de Peleteri robust (Wiedmn) (Dipter: Tchinide) e Desenvolvimento em Relção à Tempertur RESUMO - O efeito de qutro temperturs no desenvolvimento do endoprsitóide lrvl Peleteri robust (Wiedmn), e preferênci do prsitóide por diferentes ínstres de seu hospedeiro, lgrt do trigo Mythmin (Pseudleti) sequx Frnclemont form vlidos. Fêmes de P. robust depositrm mis de um ovo sobre o corpo d lgrt hospedeir, porém pens um lrv conseguiu completr o seu desenvolvimento e empupr dentro do corpo d lgrt. O prsitóide completou o seu desenvolvimento pens em lgrts de qurto sexto instr de M. sequx, com preferênci pelo qurto e quinto ínstres. Lgrts de primeiro o terceiro ínstr exposts fêmes de P. robust não produzirm prsitóides. O prsitóide completou seu desenvolvimento té o estágio dulto em tods s temperturs e o período de incubção foi inferior 24h ns qutro temperturs vlids. A porcentgem de dultos de P. robust emergidos foi significtivmente mior 20ºC (56,2%) e 25ºC (70,0%) em comprção 15ºC (29,2%) e 30ºC (9,5%). O tempo de desenvolvimento desde oviposição té emergênci dos dultos vriou de 23,8 dis 30ºC té 90,3 dis 15ºC. As constntes térmics clculds pr os estágios de ovo+lrv, pup e pr o período entre oviposição e emergênci dos dultos form de 266,9; 235,5 e 457,5 grus-di, prtir de temperturs bse de 6,7ºC, 9,7ºC e 9,3ºC, respectivmente. A 20ºC e 25ºC, o tempo de desenvolvimento foi significtivmente menor pr os mchos em relção às fêmes. Juntmente com outros prsitóides já descritos, P. robust é mis um componente de um complexo de espécies que, em conjunto, cusm um impcto significtivo n redução de populções d lgrt do trigo. PALAVRAS-CHAVE: Insect, prsitóide, controle biológico, Mythmin sequx, exigênci térmic. ABSTRACT - The effect of four tempertures on the development of the lrvl endoprsitoid Peleteri robust (Wiedmn) s well s its preference for different instrs of the host, the rmyworm Mythmin (Pseudleti) sequx Frnclemont were evluted. Femles of P. robust lid more thn one egg outside the cuticle of the cterpillrs, however only one prsitoid developed nd pupted within the host. Femles of P. robust successfully prsitized the fourth- to sixth-instrs of M. sequx, with preference for the fourth nd fifth instrs of the host. No prsitoids emerged from cterpillrs exposed to P. robust femles between the first nd third instrs. The development of P. robust to the dult stge ws completed in the rnge between 15ºC nd 30ºC, nd the incubtion period lsted less thn 24h in ll tempertures evluted. Successful prsitism, s indicted by percentge of dult emergence, ws significntly higher t 20ºC (56.2%) nd 25ºC (70.0%), s compred to 15ºC (29.5%) or 30ºC (9.5%). Developmentl time from oviposition to dult emergence rnged from 23.8 dys t 30ºC to 90.3 dys t 15ºC. At 20ºC nd 25ºC, developmentl time ws significntly shorter for mles s compred to femles. The therml constnt for the egg + lrvl stges ws degree-dys (DD) bove lower threshold of 6.7ºC; the pupl stge required DD bove 9.7ºC; nd the development from oviposition to dult emergence ws completed in DD bove lower limit of 9.3ºC. Together with other prsitoids lredy described, P. robust is nother member of complex of species tht my hve considerble importnce in the nturl control of the whet rmyworm. KEY WORDS: Insect, prsitoid, biologicl control, Mythmin sequx, therml requirement.

2 406 Foerster & Doetzer The rmyworm Mythmin (Pseudleti) sequx Frnclemont is the most importnt chewing species on winter cerels in Southern Brzil. The cterpillrs re prsitized by more thn ten species of Hymenopter nd Dipter, which ltogether hve n importnt role in the nturl control of the rmyworm (Gssen 1986). Despite the diversity of nturl enemies, chemicl control remins s the dominnt method for controlling rmyworm, lrgely due to the lck of knowledge bout the impct of prsitism on the biology of the host. Ymmoto et l. (1998) nd Doetzer & Foerster (1998) evluted the effect of hymenopterous prsitoids on food consumption of the lrvl stge of M. sequx nd therml requirements for the development of the eulophid Euplectrus ronni (Brèthes) nd the brconid Glyptpnteles muesebecki (Blnchrd) developing on lrve of M. sequx were estblished by Ymmoto et l. (1998) nd Foerster et l. (1999). The Tchinide Peleteri robust (Wiedmn) is one of four species of Peleteri cited by Guimrães (1962) s occurring in Brzil. There re no references bout the biology of P. robust, lthough dt re vilble for other tchinids prsitizing lepidopterous lrve (Gross & Rogers 1995, Reitz 1996, Rodriguez-del-Bosque & Smith, 1996, Crdoz et l. 1997). In this pper, results on the effect of different tempertures on the development of P. robust, s well s on the prsitoid preference for the host instr re reported. Mteril nd Methods The experiments were conducted in the Lbortório de Controle Integrdo de Insetos do Deprtmento de Zoologi, Universidde Federl do Prná, Brzil. Adults of P. robust were obtined from lbortory rered prsitized M. sequx cterpillrs tht hd been collected from whet in Lp County, Southern Prná Stte, Brzil. Adults were fed with 50% honey/wter solution nd kept in climtic chmbers t 20ºC temperture, 70 ± 10% reltive humidity nd 12h photophse. To determine the hosts instr rnge of P. robust, 15-dy-old mted femles were exposed for 24h to first through sixth instrs M. sequx in free choice tests. The pre-oviposition period of P. robust lsted c. 15 dys, s previously recorded for L. jlisco on E. loftini (Dyr) (Rodriguez-del-Bosque & Smith 1996). Three cterpillrs of ech instr were plced in 14 cm dimeter petri dish with femle of P. robust nd fed with kicuyo grss (Pennisetum clndestinum Hochts.). The tretment ws repeted eight times. At the end of the exposure time, the femles were discrded nd the number of prsitized cterpillrs for ech instr ws counted. The results were submitted to nlysis of vrince (ANOVA) nd the mens clssified by thetukey s test. After host instr preference determintion, the developmentl time of P. robust ws evluted t constnt tempertures of 15ºC, 20ºC, 25ºC nd 30ºC ± 1ºC, 70 ± 10% reltive humidity nd 12h photophse. Fifth instr hosts were exposed to P. robust femles for 24h nd then the cterpillrs were kept individully nd rered ccording to Foerster (1996). The number of prsitized cterpillrs nd successful dult emergence, s well s the developmentl time between oviposition nd puption nd from puption to dult emergence of P. robust ws recorded for ech temperture. The therml constnt (K) nd the lower threshold temperture ( ) were clculted by the liner eqution regression method for the egg + lrvl nd pupl stges, s well s for the entire developmentl period, from oviposition to dult emergence. The stndrd error for K nd ws clculted ccording to Cmpbell et l. (1974). Results for developmentl time in reltion to temperture were submitted to ANOVA nd the mens clssified by Tukey s test (P<0.05). Successful dult emergence mong the tempertures ws compred by the c 2 (Chi-squre)test (P<0.05). At 20ºC nd 25ºC, developmentl time ws evluted seprtely for mles nd femles nd the results were submitted to nlysis of vrince (ANOVA) nd the mens clssified by Tukey s test (P<0.05). Results nd Discussion No prsitism ws recorded on first to third instr hosts, wheres femles of P. robust successfully prsitized cterpillrs between the fourth nd sixth instr, s observed for other tchinids prsitizing lepidopterous lrve (Gross & Rogers 1995, Reitz 1996, Crdoz et l. 1997). The frequency of oviposition on the lst three instrs of M. sequx showed significnt preference for the fourth nd fifth instrs in comprison to the sixth instr of the host (Fig. 1). Although more cterpillrs were prsitized in the fifth thn in the fourth instr, the difference ws not sttisticlly significnt. Number of prsitized hosts th 5 th 6 th Host instr Figure 1. Men number (± S.E.) of M. sequx cterpillrs prsitized by P. robust in reltion to host instr in freechoice tests. (8 replictes of 3 cterpillrs of ech instr fter 24h with prsitoid femle) Ovipositions were mde on the cuticle of the cterpillrs, nd up to 28 eggs were recorded on single host. Within 24h fter eclosion, the lrve of P. robust penetrted the integument of the cterpillrs, however, only one prsitoid completed its development. A similr condition is described for the tchinid Lydell jlisco Woodley prsitizing cterpillrs of Eoreum loftini (Dyr) (Rodriguez-del- Bosque & Smith 1996). The pupl stge of P. robust ws b

3 July - September 2002 Neotropicl Entomology 31(3) 407 completed within the host body, during the pre-pupl stge of M. sequx, regrdless of the instr the cterpillrs hd been prsitized. This shows tht the prsitoid is ble to regulte host growth in order to synchronize its development to the stge of development of the host t the time of prsitism (Vinson & Iwntsch 1980). The highest percentge of dult emergence ws obtined t 25ºC (70.0%), followed by 20ºC (56.2%), without sttisticl difference between the two tretments. Survivl to the dult stge ws significntly reduced both t 15ºC nd 30ºC, with the lowest emergence rte recorded t 30ºC (Tble 1). In ll tempertures, except t 20ºC mortlity ws higher in the pupl stge in comprison to the egg + lrvl stges (Tble 1). Tble 1. Mortlity of P. robust during the immture stges nd percentge of individuls tht reched the dult stge t different tempertures. N Mortlity (%) Lrvl Pupl stge stge b c Temperture Developmentl time from oviposition to puption rnged from 12.6 to 38.6 dys t 30ºC nd 15ºC, respectively (Tble 2). The durtion of the pupl stge ws similr or longer thn the egg + lrvl stges, depending on the rering temperture. In the eulophid prsitoid E. ronni, the pupl stge ws lso longer thn the egg + lrvl stges (Ymmoto et l. 1998), while in the brconid G. muesebecki the egg + lrvl stges were twice s long s the pupl stge in the sme host (Foerster et l. 1999). Tble 2. Developmentl time (men ± S.E.) of the immture stges of P. robust on the fifth instr M. sequx t different tempertures. Temperture N Durtion (dys) Survivl to dult stge (%) Percentges followed by the sme letter do not differ by c 2 test (P<0.05). Egg+lrv Pup Totl ± ± ± ± 0.38b 20.3 ± 0.33b 38.9 ± 0.67b ± 0.28c 15.6 ± 0.27c 28.7 ± 0.45c ± 0.33c 12.0 ± 0.41d 23.8 ± 0.25d Mens followed by the sme letter in the columns do not differ by Tukey s test (P<0.05). The developmentl time ws seprtely evluted for mles nd femles t 20ºC nd 25ºC (Tble 3). For both tempertures mles developed significntly fster thn femles; probbly sexul mturtion in mles is slower thn in femles nd the fster rte of development observed in mles compenstes for their slower sexul mturtion in Tble 3. Developmentl time (men ± S.E.) of mles nd femles of Peleteri robust t two tempertures. Temperture Durtion (dys) Sex Egg+lrv Pup Totl 20 Mles 17.2 ± 0.44b 19.0 ± 0.44b 36.2 ± 0.80b Femles 19.4 ± ± ± Mles 12.4 ± 0.36d 14.8 ± 0.26d 27.2 ± 0.35d Femles 13.9 ± 0.43c 16.4 ± 0.34c 30.3 ± 0.49c Mens followed by the sme letter in the columns do not sttisticlly differ by Tukey s test (P<0.05). reltion to the femles. Reitz (1996) lso reported fster developmentl times for mles of the tchinid Euceltori bryni Sbrosky nd E. rubentis (Coquillett) prsitizing cterpillrs of Helicoverp ze (Boddie). The therml units required by P. robust to complete the egg + lrvl stges totled degree-dys (DD) bove lower threshold of 6.7ºC, while the pupl stge ws completed fter DD bove lower limit of 9.7ºC (Tble 4, Fig. 2). The development from oviposition to dult emergence required DD bove lower temperture of 9.3ºC. Compred to hymenopterous prsitoids of M. sequx, the developmentl rte of P. robust is slower thn tht of G. muesebecki (Foerster et l. 1999) nd E. ronni (Ymmoto et l. 1998). On the other hnd, the lower threshold temperture of the egg nd lrvl stges of P. robust (6.7ºC) is c. 2ºC less thn tht of G. muesebecki nd more thn 4ºC less thn the lower limit of E. ronni, indicting tht the egg nd lrvl stges of P. robust re more cold tolernt thn these stges of the two hymenopterous prsitoids. Tble 4. Regression eqution, regression coefficient (R 2 ), lower threshold ( ) nd therml constnt (K) of P. robust prsitizing lrve of M. sequx. Stge Regression eqution R 2 ±S.E. K ±S.E. (DD) Egg+lrv y= ± ± 13.6 Pup y= ± ± 9.2 Cycle y= ± ± 17.9 The results showed tht the effectiveness of P. robust s biocontrol gent is prtilly impired by the superprsitic behvior, which leds to the development nd survivl of single prsitoid. Other tchinids ly supernumerry eggs on their hosts, like Trichopod gicomellii Blnchrd nd T. pennipes (Fbr.) on the green stink bug Nezr viridul (L.) (Heteropter: Penttomide). However, unlike P. robust, which kills the host in the lrvl stge, prsitism by Trichopod species occurs during the dult stge, nd the hosts continue to mte nd oviposit fter prsitism (Hrris & Todd 1982, Coombs & Khn 1998). Together with other prsitoids lredy described ttcking M. sequx (Doetzer & Foerster 1998, Foerster et l. 1999, Ymmoto et l. 1998), P. robust is prt of complex of species, which cuse significnt impct on the rmyworm popultion.

4 408 Foerster & Doetzer A) Egg+lrv = Developmentl time (dys) B) Pup =9.7 5 Developmentl rte (l/d) 90 C) Cycle = Temperture ( 0 C) Figure 2. Effect of temperture on developmentl time (dys) ( ) nd on developmentl rte (1/D) (+) of P. robust nd therml requirements of the immture stges of the prsitoid Acknowledgments The uthors re grteful to Dr. J.H. Guimrães of the University of São Pulo for the identifiction of P. robust. Finncil support ws provided by the Conselho Ncionl de Pesquis e Desenvolvimento (CNPq) nd the Fundção Arucári. Voucher specimens of P. robust re deposited in the reference collection of the Lbortório de Controle Integrdo de Insetos do Deprtmento de Zoologi, Universidde Federl do Prná. Literture Cited Crdoz, Y.J., N.D. Epsky & R.R. Heth Biology nd development of Lespesi letie (Dipter: Tchinide) in two lepidoptern species in the

5 July - September 2002 Neotropicl Entomology 31(3) 409 lbortory. Fl. Entomol. 80: Cmpbell, A., B.D. Frzer, N. Gilbert, A.P. Gutierrez & M. Mckuer Temperture requirements of some phids nd their prsites. J. Appl. Ecol. 11: Coombs, M. & S. Khn Fecundity nd longevity of green vegetble bug, Nezr viridul, following prsitism by Trichopod gicomellii. Biol. Control12: Doetzer, A.K. & L.A. Foerster Efeito do prsitismo por Glyptpnteles muesebecki (Blnchrd) no consumo e utilizção do limento por Pseudleti sequx Frnclemont. An. Entomol. Soc. Brsil 27: Foerster, L.A Efeito d tempertur no desenvolvimento ds fses imturs de Pseudleti sequx Frnclemont, 1951 (Lepidopter: Noctuide). An. Soc. Entomol. Brsil 25: Foerster, L.A., M.R.F. Avnci & A.K. Doetzer Effect of temperture on the development nd progeny production of Glyptpnteles muesebecki (Blnchrd) (Hymenopter: Brconide) prsitizing lrve of Pseudleti sequx Frnclemont (Lepidopter: Noctuide). An. Soc. Entomol. Brsil 28: Gssen, D.N Prsitos, ptógenos e preddores de insetos ssocidos à cultur do trigo. Psso Fundo, Embrp-CNPT. 86p. (Circulr Técnic, 1). Gross, H.R. & C.E. Rogers Reproductive biology of Euceltori rubentis (Dipter: Tchinide) rered on lrve of Helicoverp ze (Lepidopter: Noctuide). Biol. Contr. 5: Guimrães, J.H Espécies brsileirs do gênero Peleteri Desvoidy, 1830 (Dipter: Tchinide). An. Acd. Brs. Ciênc. 34: Hrris, V.E. & J.W. Todd Longevity nd reproduction of the southern green stink bug, Nezr viridul, s ffected by prsitiztion by Trichopod pennipes. Entomol. Exp. Appl. 31: Reitz, S.R Development of Euceltori bryni nd Euceltori rubentis (Dipter: Tchinide) in different instrs of Helicoverp ze (Lepidopter: Noctuide). Ann. Entomol. Soc. Am. 89: Rodriguez-del-Bosque, L.A. & J.W. Smith Jr Rering nd biology of Lydell jlisco (Dipter: Tchinide), prsite of Eoreum loftini (Lepidopter: Pyrlide) from Mexico. Ann. Entomol. Soc. Am. 89: Vinson, S.B. & G.F. Iwntsch Host regultion by insect prsitoids. Qurt. Rev. Biol. 55: Ymmoto, A.C., A.K. Doetzer & L.A. Foerster Efeito d tempertur no desenvolvimento de Euplectrus ronni (Brèthes) (Hymenopter, Eulophide) prsitndo lgrts de Pseudleti sequx Frnclemont (Lepidopter: Noctuide) e impcto do prsitismo no consumo limentr do hospedeiro. Act Biol. Pr. 27: Received 18/07/01. Accepted 12/08/02.