The importance of destructive host feeding in the development of the endoparasitoid Toxoneuron nigriceps (Hymenoptera: Braconidae)

This study focuses on the importance of destructive host feeding in the development of the koinobiont endoparasitoid, Toxoneuron nigriceps (Hymenoptera: Braconidae). T. nigriceps is a solitary parasitoid of Heliothis virescens (Lepidoptera: Noctuidae) larvae. As they develop within the host, T. nigriceps larvae feed by absorbing nutrients from the host hemolymph. When they emerge from the host as third instar larvae, the parasitoids then chew a hole in the host cuticle and begin destructive feeding, leaving only the cuticle, trachea and head capsule. By examining how post-egression feeding influences the development of T. nigriceps, we may be able to gain a better understanding of what it will take to create an effective artificial rearing system for this koinobiont.

In this study larval mass, cocoon mass and adult mass, as well as the cocoon formation and survival rate, will be compared between parasitoids subjected to several post-egression feeding treatments. The treatments include larvae allowed to host feed normally (control), larvae not allowed to host feed, larvae fed tissue that has been scraped out of the host remains, and larvae fed a non-insect derived food, such as processed meat. Preliminary data show that parasitoids from the control treatments have greater larval mass, cocoon mass, adult mass, percent cocoon formation, and percent adult emergence than both the non-feeding and the scraped tissue feeding treatments.