This project focuses on the development of a technique to rear Toxoneuron nigriceps (Hymenoptera: Braconidae) in vitro from second larval instar to adult. Previously, T. nigriceps larvae were reared from second instar to third instar on artificial media, but died before pupating. T. nigriceps is a solitary endoparasitoid of the tobacco budworm, Heliothis virescens (Lepidoptera: Noctuidae). T. nigriceps spends the majority of its development feeding non-destructively by absorbing host hemolymph. However, after reaching its third, and final, larval instar, T. nigriceps egresses from the host and becomes a tissue predator, inserting its head back into the host’s body cavity to consume all remaining tissues but the head capsule and cuticle. The parasitoid will then spin a cocoon inside the pupation chamber formed by the host larva.

In order to develop a suitable artificial rearing technique for T. nigriceps, we are conducting a study to examine the importance of destructive host feeding, as well as a study on suitable artificial pupation chambers for pre-pupae. Preliminary data on host feeding indicates that although parasitoid larvae that are not allowed to host feed are smaller in size and mass than those allowed to feed normally, they are able to form cocoons and develop into normal adults. Observations on parasitoid cocooning suggest that commercially available gel capsules are suitable as artificial pupation chambers.