Success in classical biological control

Classical biological control in the past has been characterized by numerous unsuccessful attempts and by relatively few outstanding successes. An analysis of the recent developments in the theoretical and applied aspects of classical biological control reveals, however, that introducing parasites (predators, pathogens, herbivores) against pest organisms apparently has a considerable potential of solving or lessening many important pest problems of the world. In this review, classical biological control was found to be applicable everywhere in the world regardless of temperature or moisture conditions, and native pests were found to be as susceptible to biological control as introduced pests. Biocontrol success was found to be a function of several independent variables (e.g., characteristics of the pest and control organism and the target ecosystem) and many dependent variables (e.g., the methods of selecting, propagating, and introducing the control organism). Knowledge about the interactions between these factors and other, external factors, will help to find probable ways of improving the success rate in introducing natural enemies. This has already been demonstrated by the steady increase in the efficiency of biocontrol work in the last 30 to 40 years.