Abstract
Ascogaster reticulatus WATANABE (Braconidae) is an egg-larval parasitoid of certain tortricids, e.g., Adoxophyes sp. (Ad) and Adoxophyes orana fasciata WALSINGHAM (Ao). In this study, the host preference by A. reticulatus was tested among two habitual hosts, Ad and Ao, and three unusual host species, Pandemis heparana DENIS et SCHIFFERMULLER (Ph), Homonamagnanima DIAKONOFF (Hm), and Hoshinoa longicellana WALSINGHAM (Hl). The tow-choice tests showed that the order of oviposition preference among the five tortricids was Ad=Ao>Hm>Hl>Ph. Female parasitoids deposited eggs in all of the tortricid egg masses. Among parasitized egg masses of the unusual host species (Ph, Hm and Hl) artificially reared, parasitoid larvae egressed only from Ph larvae, made cocoons and then emerged. Parasitoid eggs hatched in Hm and Hl eggs and became 1st-instar larvae, then grew after the host eggs hatched. However, the parasitoid 1st-instar larvae were encapsulated by the hemocytes of these host larvae of later instars. The Hm egg mass coated with the Ad egg mass extract containing the kairomone increased oviposition time and percent parasitism by A. reticulatus. To the noctuid moth, Leucania separata (WALKER) (Ls), the parasitoid showed no response to the egg mass, but coating of the kairomone on the egg mass stimulated oviposition. The parasitoid eggs hatched in Ls eggs, but the 1st-instar larvae were soon encapsulated with melanin on their surface.
