Biological control of crop pests

The initial enthusiasm with which the first modern insecticides, the chlorinated hydrocarbons, were greeted in the late 1940s and early 1950s has long since begun to wane. This is, in part, the result of the development of resistance by so many pests to many of the pesticides, and also because of the growing awareness of the dangers involved in a gradual poisoning of the whole environment. One result is that many governments have now introduced legislation designed to curb indiscriminate use of the more toxic and persistent insecticides (mostly chlorinated hydrocarbons) and indeed to prohibit the use of the most dangerous pesticides. Another result of this awareness is the acknowledgement of the desirability of trying to control pests by use of cultural or biological means. The single most promising aspect of cultural control is the development and use of resistant varieties of crops. In some texts this is regarded as a biological method of control, but this view is not generally held, since whilst it involves the reactions of living organisms, it is normally regarded as a distinct branch of agricultural science.

In this chapter biological control (BC) is viewed in the strict sense as the control (lowering) of pest populations by predators, parasites and disease-causing pathogens.