Biological Control of Insects

Abstract

Biological control of insects is a very broad subject and if in discussing it one were to tack on all of biological manipulations utilized or sug­ gest ed for insect control, treatment might well require several vol umes. Therefore, in view of available space and writer's experience, this paper will be concerned only with biological control of insects as effected by predators and parasitoids (natural enemies). Insect control by such factors as genet ically determined host resistance to pest insects, autosterilizatio n, and pheromonal manipulations of pest biology or behav ior, will not be dis­ cussed. Nor will paper touch upon microbial control of insects or biolog­ ical control of weeds by insects. These are highly complex subjects which deserve attention of appropriate specialists. In any event, biological con­ trol of insects as effected by predators and parasitoids is a sufficiently meaty subject to occupy allotted pages. The author belongs to that group which adheres to a broad concept of biological control of insects. This is concept of Stern et al (77 ) and DeBach (13), which defines biological control as the action of parasites, predators, and pathogens in main taining another organism's population den­ sity at a lower average than would occur in their absence. This describes a natural phenomenon-the regulation of a species' numbers by natural ene­ mies. There is no stipulation that biological control involve man's manipula­ tion of natural enemies, but on other hand definition accommodates this possibility. The current paper will treat two major aspects of biological control: classic and naturalistic. The paper will not meticulously examine all of recent literature. Instead, critical publications, both old and new, will be cited as they relate to matters bearing on present status of biological control of insects. Finally, discussion will concentrate on developments subsequent to 1960, which marks end of period treated by com­ prehensive volume Biological Control of Insect Pests and Weeds (12).