Utilization of host-formed and artificial pupation chambers by the parasitoid Toxoneuron nigriceps (Hymenoptera: Braconidae)

Larvae of the parasitoid Toxoneuron nigriceps Vierek (Hymenoptera: Braconidae) usually spin cocoons and pupate within pupation chambers formed by their host, Heliothis virescens F. (Lepidoptera: Noctuidae). In the field these chambers are formed in the soil, while in the laboratory H. virescens larvae often form pupation chambers in the semisolid diet they are reared in or in the cotton balls used to plug the rearing vials. T. nigriceps will spin cocoons and pupate in both diet and cotton balls. If an in vitro rearing system is to be developed for T. nigriceps, it will need to include a pupation chamber. In this study, late 3rd instar parasitoid larvae will placed in various potential artificial pupation chambers, as well as host-formed chambers. Test chambers include cotton balls, test tubes, gel capsules and 35mm Petri dishes. Host-formed chambers in the H. virescens diet will be used for comparison. For each treatment, proportion of cocoons formed, mass of cocoons, and proportion of adult wasps emerged will be recorded and compared. Additionally, chambers formed in soil by both healthy and parasitized H. virescens larvae will be compared to see if parasitoid manipulation plays a part in pupation chamber formation.