Ruth Henderson
Major Professor: Dr. Bradleigh Vinson
Ph.D. Candidate
"The importance of Destructive Feeding in the development of the Endoparasitoid, Toxoneuron nigriceps (Hymenoptera:Braconidae)."
Toxoneuron nigriceps (Hymenoptera: Braconidae) 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 tissue 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 the elements needed 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 rates, will be compared between parasitoids subjected to several postegression 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 and adult mass than both the non-feeding and the scraped tissue feeding treatments. There is no significant difference in cocoon formation among treatments; however, adult emergence is significantly reduced in the non-feeding treatment.