ABSTRACT
This chapter examines some of what is known about foraging behavior within one group on natural enemies from a multitrophic perspective. It highlights interactions between the first trophic level (plants) and the third trophic level (parasitoids) because plants provide the context for other interactions. The chapter attempts to identify sources of variability in parasitoid responses to plants and to show how understanding of this variation might be used in improving biological control. It focuses on two model systems that have been the focus of research in our laboratories: Microplitis croceipes and Cotesia marginiventris. Cotesia marginiventris is a host generalist that attacks early instar noctuid larvae in at least a dozen genera. Three sources of intrinsic variation in responsiveness of parasitoids to various foraging cues have been identified: genotypic variation, phenotypic plasticity, and physiological state. The plant component of a parasitoids environment can be the source of several kinds of variation, each potentially affecting parasitoid foraging.
