Host Specificity of Insect Parasitoids and Predators

BiO[OgiCa, control has beeil used more often against inseet pests than against any other graur of organisms. The most commonly used agents in these eHorts are ather inseets or related arthropods. These so-called beneficial speeies are classificd a5 eicher prcdators or parasiroids. Predators typically consumc several prey during their lives and can be predacious when immature, as adult:;, ur during both phases of thei! lives. ßy contrast, parasitoids live freely as adults but when immature feed in or on the body of an er her arthropod-the host-eventually killing ir. lnseet predators and parasitoids are referred to collectivelv as natural enemies. . Predators are distributed broadly across approximately 20 inseet orders (Ncw 1991). Parasitoids, by contrast, are more restricted taxonomically, occurring <:lImost cxelusively in the orders Hymenoptera (allts, bees, and wasps) and Diptera (flies; Clausen 1940). Nevertheless~ parasitoids are ineredibly abundant eomponents of aImost every ecosystem, both in terms of speeies and absolute nllmbers of individuals. Although estimates vary widely, rhe parasitie Hymenoptera may number