Department of Entomology, Texas A & M University, College Station, TX 77843-2475, USA.
J Insect Sci. 2011;11:3. doi: 10.1673/031.011.0103.
Koinobiont wasps start their lives as hemolymph feeders inside the host body, but before they egress from the host many become tissue predators. One species, the endoparasitoid Toxoneuron nigriceps Viereck (Hymenoptera: Braconidae), exhibits the unusual behavior of egressing before initiating tissue predation. After egression from the host, it reinserts its head into the host body to begin tissue feeding. These third instar T. nigriceps larvae show a significant increase in body size and mass after post-egression feeding. Through this project the importance of post-egression feeding in the development of T. nigriceps in its host the tobacco budworm, Heliothis virescens Fabricius (Lepidoptera: Noctuidae), has been evaluated. The study was conducted by preventing the egressed third instar T. nigriceps larvae from feeding on host tissue and observing whether they could undergo further development. Though some of the larvae that were prevented from post-egression feeding did undergo cocoon formation, pupation, and adult emergence they were inferior in terms of size, body mass, and survival to those that developed from larvae allowed to feeding after egression. Hence, it is concluded that post-egression host tissue feeding is essential for the normal development of T. nigriceps, as the prevention of feeding resulted in significantly lighter and smaller larvae, cocoons, and adults as well as deformed adults and reduced adult survival. Post-egression feeding as a host regulatory strategy is discussed.
拟寄生物蜂类在进入宿主身体内部之前，以血液为食，然而在它们离开宿主之前，许多会成为组织捕食者。有一种名为 Toxoneuron nigriceps Viereck（膜翅目：Braconidae）的内寄生蜂，表现出一种不同寻常的行为，即在开始组织取食之前离开宿主。从宿主中逸出后，它会将头部重新插入宿主身体，开始组织取食。这些第三龄 T. nigriceps 幼虫在进行逸出后取食后，其体型和体重显著增加。通过这个项目，评估了 T. nigriceps 在其宿主烟草夜蛾（烟草夜蛾）中的逸出后取食对其发育的重要性。这项研究是通过防止逸出的第三龄 T. nigriceps 幼虫取食宿主组织来进行的，并观察它们是否能够进一步发育。尽管一些被阻止逸出后取食的幼虫确实进行了化蛹和成虫羽化，但与那些允许逸出后取食的幼虫相比，它们在体型、体重和存活率方面都较差。因此，结论是，逸出后宿主组织取食对于 T. nigriceps 的正常发育是必不可少的，因为取食的预防导致幼虫、蛹和成虫明显更轻、更小，成虫畸形且成虫存活率降低。讨论了逸出后取食作为一种宿主调节策略。
