Entomopathogenic nematodes and parasitoid larvae of some wasps play important roles in the natural control of the pest insects. However, it has not been excluded that competition between nematodes and wasps may in some cases reduce their efficacy in the pest control. Using caterpillars of Spodoptera littoralis, we examined interactions between the nematode Steinernema carpocapsae and the venom of the parasitoid Habrobracon hebetor. The survival of S. littoralis caterpillars was reduced in a dose‐dependent manner when 5 to 500 nematodes or 0.005–0.1 venom units were applied to single caterpillars. High doses of either nematodes or the venom caused death within 1–3 days in all treated hosts. The low doses of nematodes killed caterpillars within a week, in some cases when they attempted to pupate. Caterpillars receiving low venom doses were characterized by extended survival time terminated with death due to starvation. Combined treatment of nematodes and the venom were mutually synergistic and elicited severe lethal effects. The nematodes were fully resistant to the venom and can feed and grow on the symbiotic bacteria in vitro. The venom impairs food processing and causes death of caterpillars due to starvation. Disruption of the hormonal regulation of metamorphosis by ecdysteroids and juvenile hormone could be responsible for defective moults block at different stages of the moulting process, regionally restricted moulting, moults to “intermediates” combining regions of newly secreted larval and pupal cuticles.

中文翻译：

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昆虫病原线虫与寄生蜂毒之间的竞争性相互作用

一些黄蜂的昆虫病原线虫和寄生幼虫在害虫的自然防治中起着重要作用。然而，并不排除线虫和黄蜂之间的竞争在某些情况下会降低它们在害虫防治中的功效。我们使用 Spodoptera littoralis 的毛虫，研究了线虫 Steinernema carpocapsae 和寄生蜂 Habrobracon hebetor 毒液之间的相互作用。当 5 至 500 条线虫或 0.005 至 0.1 毒液单位应用于单个毛虫时，S. littoralis 毛虫的存活率以剂量依赖性方式降低。高剂量的线虫或毒液导致所有接受治疗的宿主在 1-3 天内死亡。低剂量的线虫在一周内杀死了毛虫，在某些情况下，当它们试图化蛹时。接受低毒液剂量的毛毛虫的特征是存活时间延长，最终因饥饿而死亡。线虫和毒液的联合治疗是相互协同的，并引起了严重的致死作用。线虫对毒液具有完全抵抗力，可以在体外以共生细菌为食并生长。毒液会损害食品加工并导致毛虫因饥饿而死亡。蜕皮激素和保幼激素对变态的激素调节的破坏可能是导致蜕皮过程中不同阶段的有缺陷的蜕皮阻滞、区域性限制的蜕皮、蜕皮到结合新分泌的幼虫和蛹角质层区域的“中间体”的原因。 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 线虫和毒液的联合治疗是相互协同的，并引起了严重的致死作用。线虫对毒液具有完全抵抗力，可以在体外以共生细菌为食并生长。毒液会损害食品加工并导致毛虫因饥饿而死亡。蜕皮激素和保幼激素对变态的激素调节的破坏可能是导致蜕皮过程中不同阶段的有缺陷的蜕皮阻滞、区域性限制的蜕皮、蜕皮到结合新分泌的幼虫和蛹角质层区域的“中间体”的原因。 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 线虫和毒液的联合治疗是相互协同的，并引起了严重的致死作用。线虫对毒液具有完全抵抗力，可以在体外以共生细菌为食并生长。毒液会损害食品加工并导致毛虫因饥饿而死亡。蜕皮激素和保幼激素对变态的激素调节的破坏可能是导致蜕皮过程中不同阶段的有缺陷的蜕皮阻滞、区域性限制的蜕皮、蜕皮到结合新分泌的幼虫和蛹角质层区域的“中间体”的原因。 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .