Diet of adult ladybird beetle host modifies the postdiapause development of the parasitoid Dinocampus coccinellae (Hymenoptera: Braconidae)

Our study showed that under natural conditions the rate and speed of postdiapause emergence by overwintering larvae of the endoparasitic wasp, Dinocampus coccinellae (Schrank) is enhanced when its ladybird beetle host Coleomegilla maculata (DeGeer) receives a nutritious (proteinaceous) diet during late winter and early spring. Living aphid prey provided during April and May yielded the fastest rates of D. coccinellae postdiapause development, followed by an artificial protein/carbohydrate diet and flowering (pollen-producing) heads of dandelion. D. coccinellae development was slowest when hosts received only sugar water or water alone. These results indicate that there is an interaction during late dormancy between host diet and subsequent parasitoid performance. From these studies we conclude that the initiation of feeding by C. maculata hosts, whether on prey or nutritious plant-based substances, during early spring may play an important role in the timing and success of postdiapause larval development and emergence by the parasitoid D. coccinellae. This interaction appears to be an adaptive feature that synchronizes the completion of the parasitoid's postdiapause development with the feeding and occurrence of potential ladybird beetle (C. maculata) hosts in spring. Thus, we conclude that at this point in their life cycles, the developmental success of both the host and the parasitoid are interdependent. It appears that the presence and utilization of aphid prey and/or a rich pollen source early in the spring season could have both positive and negative effects on the local population of ladybird beetle hosts.