颈双缘姬蜂毒液对寄主小菜蛾的免疫抑制作用

Immunosuppression effects of venom of pupal endoparasitoid wasp, Diadromus collaris (Gravenhorst) on its host, Plutella xylostella pupae

对颈双缘姬蜂Diadromus collaris（Gravenhorst）及其毒液引起寄主小菜蛾Plutella xylostella的一些生理效应进行了研究。结果表明，颈双缘姬蜂寄生寄主后可引起寄主小菜蛾蛹总血细胞及浆血细胞和颗粒血细胞数量的上升。寄生后1天观察，血细胞延展行为受到影响，表现在颗粒血细胞放射状丝的产生及浆血细胞伪足的形成受到抑制。通过毒液对寄主离体幼虫血细胞延展行为、形态及活性影响的研究，发现毒液抑制了寄主离体浆血细胞的延展，但对颗粒血细胞的影响不明显；毒液引起寄主浆血细胞和颗粒血细胞的破裂和死亡，毒液对寄主幼虫血淋巴酚氧化酶活性有一定的抑制作用，当反应至40、60及80min时，毒液处理和未经毒液处理的寄主血淋巴在490nm处的吸光值差异比较明显。对毒液蛋白成分的聚丙烯酰胺凝胶电泳分析发现，毒液中有9种多肽，分子量介于9．50．2kD，其中50．2、30．5、28．2、25．1和12．6kD的多肽含量较高，与其他蜂毒液的一些作用已知的蛋白条带相似，因而推测它们同样具有免疫及发育抑制作用。结果证明颈双缘姬蜂毒液能破坏寄主细胞及体液因子调节的免疫反应。

The venom of pupal endoparasitoid wasp, Diadromus collaris （Hymenoptera ： Ichneumonidae） and its immunosuppression effects on the pupae of host Plutella xylostella （Lepidoptera： Plutellidae ） were preliminarily studied. The total number of hemocytes and the numbers of two types of hemocytes （plasmatocytes and granular cells） increased in the hemolymph of parasitized host pupae as compared with those in non- parasitized hosts. The morphology and behavior of plasmatocytes and granular cells in the hemolymph of parasitized host pupae were also changed. The adhesion and spreading behavior were inhibited in plasmatocytes and granular cells in one day after oviposition. The spreading behavior in plasmatocytes from the host larvae was also suppressed whereas that of granular cells was not significantly affected in the in vitro culture experiments. Isolated crude venom also caused the death and break of plasmatocytes and granular cells. The in vitro culture experiments also indicated that the venom of this pupal endoparasitoid inhibited the phenoloxidase activity of hemolymph of host larvae in a certain extent, especially when the reaction time is up to g0, 60 and 80 minutes. The venom SDS-PAGE showed that nine protein bands were present, ranging from 9 to 50.2 kD, including 50.2, 30.5, 28.2, 25.1 and 12.6 kD, which were similar to proteins acted as the inhibitors for host development and immunity in other parasitoid-host systems. The results above demonstrated that venom of D. collaris could impair cell and humor-mediated immune responses of the host.