Variations in parasitoid foraging behavior: Essential element of a sound biological control theory

Intraspecific intrinsic variation in foraging behavior is a common but often overlooked feature of parasitoids. These variations result from adaptations to the variety of foraging circumstances encountered by individuals of the species. We discuss the importance of understanding the mechanisms governing these intrinsic variations and the development of technologies to manage them. Three major sources of variation in foraging behavior are identified. One source for variation is genotypically fixed differences among individuals that are adapted for different foraging environments. Another source of foraging variation is the phenotypic plasticity that allows individuals to make ongoing modifications of behavior through learning, which suits them for different host-habitat situations. A third factor in determining variation in foraging behavior is the parasitoid's physiological state relative to other needs, such as food and mating. A conceptual model is presented for comprehensively examining the respective roles of these variables and their interactive net effect on foraging behavior. We also discuss proposed avenues for managing these variations in applied biological control programs.