分别在小菜蛾体内的菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾2龄幼虫亚致死剂量(=LC10)的阿维菌素和氟虫睛,研究上述杀虫剂处理对寄主体内菜蛾绒茧蜂结茧率和羽化率的影响.结果表明:在菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾LC10剂量阿维菌素处理的菜叶后,菜蛾绒茧蜂的结茧率分别下降26.6%,22.8%和5.8%,饲喂小菜蛾LC10剂量氟虫睛处理的菜叶后,菜蛾绒茧蜂的结茧率分别下降76.9%,42.5%和18.5%.上述阿维菌素处理对菜蛾绒茧蜂成虫羽化率影响不显著,但上述氟虫睛处理可显著抑制菜蛾绒茧蜂成虫羽化率,在菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾LC10剂量氟虫睛处理的菜叶可导致菜蛾绒茧蜂成虫羽化率分别下降53.1%,36.1%和47.8%.结果显示,即便是对寄主小菜蛾幼虫很低的剂量(LC10剂量)也会显著危害小菜蛾幼虫体内的菜蛾绒茧蜂的生长发育.此外,饲喂小菜蛾幼虫亚致死剂量杀虫剂对菜蛾绒茧蜂生长发育的影响与杀虫剂种类及蛾绒茧蜂发育阶段有关.%Effects of insecticides on the cocoon formation and adult emergence in the field population of Cotesia plutellae were studied. Sublethal dosage of avermectin or fipronil was fed to the 2nd instar larvae of host Plutella xylostella (DBM), in which the parasitoid C. plutellae were at the egg, early and mid larval stages. When compared to the control, the cocoon formation of C. plutellae reduced by 26.6%, 22.8% and 5.8% if parasitized DBM larvae were fed on leaves treated with avermectin when the immature parasitoids were at the egg, early larval and mid larval stages, respectively, and by 76.9%, 42.5% and 18.5%, respectively if parasitized DBM larvae were fed on leaves treated with fipronil. No significant depression on the adult emergence of C. plutellae was found in avermectin treatment. However, the adult emergence of the parasitoid reduced by 53.1%, 36.1% and 47.8% at the egg, early and mid larval stages of the parasitoid in fipronil treatment. The results indicated that avermectin and fipronil, even at very low dosages (= LC10 to the host insects), might still cause serious damage to the parasitoid's eggs or larvae.The effects of the insecticides on cocoon formation and adult emergence of C. plutellae varied depending on different insecticides and different developmental stages of the endoparasitoid.
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