Biological control of pests has been conducted for decades in entomology, plant pathology, and weed science. Despite the common goal, research has been conducted relatively independently in these fields. Has this independence impeded or facilitated the development of biological control? The practice of biological control has been largely an empirical process of finding the appropriate agent to control the identified target pest. Because the biology of arthropods, pathogens, and weeds is quite divergent, independence may have facilitated practical implementation of biological control. Yet the elucidation of underlying principles of biological control that span the fields may help guide future efforts, and efforts to integrate biological controls with current production practices may require interdependent development of multiple agents and targets. The contributions to this book address this theme by focusing on the practical problems of selecting, developing, implementing, and evaluating biological control agents.
This book deviates significantly from previous efforts by restricting the geographic scope of inquiry to work in cool temperate regions, with particular emphasis on the north temperate Nearctic region (Chapter 1). Biological control has been commonly observed to vary with weather, cropping system, and variation in population biology of the target pests. By emphasizing cool temperate regions, all contributors share experience with similar climates, similar cropping systems, and, in some cases, similar pest complexes. Ecological theoreticians may find the theoretical discussion foreign, but these common bases have facilitated our efforts to identify themes that interweave the disciplines and have grounded discussion in practical reality. This reality is concerned more with the problems of management and evaluation. Consequently, the ecology of management, the methodologies of evaluation, and the structure of feedback between evaluation and management inform our treatment of the theoretical basis of biological control.
We review parts of the history of biological control in cool temperate regions in Chapter 1. No compelling evidence indicates that classical biological control is less successful in temperate regions than in other biogeographic regions of the world, and even if such evidence existed, it would only imply that we would have to try harder for successes. The potential for biological control in cool temperate regions seems vast, but to facilitate our ability to learn from our efforts, we need to implement operational standards for the evaluation of success.
The next four chapters provide perspectives on the selection of potential biological control agents for further development. It is frequently suggested that natural