Variations in natural-enemy foraging behaviour: essential element of a sound biological control theory.

Abstract

AbstractIntraspecific intrinsic variation in foraging behaviour is a common but often overlooked feature of natural enemies. 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 behaviour 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 behaviour through learning, which suits them for different host-habitat situations. A third factor in determining variation in foraging behaviour is the natural enemy'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 behaviour. We also discuss proposed avenues for managing these variations in applied biological control programmes.