Superparasitism as an Adaptive Strategy for Insect Parasitoids

of limited size, and so confine their offspring to a fixed amount of food. In contrast a predator's offspring can always hope to find more prey items when the present meal is insufficient to complete development. Therefore, the foraging behavior of parasitoids is under even stronger natural selection than that of predators. Parasitoid search­ ing and selection behavior is thus an ideal subject to test theories based on natural selection. In this paper we review theory and empirical evidence concerning an important aspect of selection: parasitoid behavior in relation to parasitized hosts. Most parasitoids are able to recognize hosts parasitized by conspecifics or by themselves (an ability referred to as host discrimination) and to reject such hosts, but they often lay a second clutch of eggs in or on them (an act called ). Long considered the result of mistakes made by imperfect animals, superparasitism is now recog­ nized as adaptive in a number of situations. Theory predicts when parasitoids should avoid superparasitism and when not. In this paper we review the evidence that both superparasitism and its avoidance can be adaptive. We briefly discuss interspecific superparasitism (often called multiparasitism ) and the importance of superparasitism for population stability.