Host- and Food-Foraging of the Parasitoid Microplitis croceipes: Learning and Physiological State Effects

We conducted three laboratory experiments to determine the effects of learning and physiological state on the foraging behavior of Microplitis croceipes (Cresson). When given a choice between host- and food-associated odors in a wind tunnel, hungry females that had experienced these two odors showed a preference for the latter whereas the well-fed females preferred the former. Intermediately fed females with ovipositional experience preferred a host-associated odor, whereas females without such experience preferred a food-associated odor. In the wind tunnel, when host- and food-plants were present, hungry females foraged for foods more than for hosts whereas well-fed females foraged for hosts. Host-searching efficiency of females decreased as they became hungry in the wind tunnel containing host plants. We conclude that M. croceipes can learn host- and food-associated odors, and respond to these odors based on their physiological state, such as hunger and ovipositional experience. The present study suggests that hunger and the availability of food are important factors affecting foraging behavior by parasitoids in nature.