Biological control: challenges and opportunities

Abstract Biological control, the use of living organisms as pest control agents, has enjoyed varying popularity over the past century, but today is well established as an important component of integrated pest management. We examine some current challenges to the use of biological control and particularly to classical biological control, the introduction of exotic natural enemies. These include conflicts of interest (1) with the conservation of native species and (2) between agricultural lobbies. On a scientific level, we examine two debates over the ecological and genetic basis of successful control. The challenge of Murdoch et al. (Am. Nat. 125, 344-366 (1985)) to the notion of stability in pest populations under biological control, reveals that the stabilizing mechanisms may differ between pest taxa with different patterns of spatial dynamics. With respect to the hypothesis of Hokkanen & Pimentel (Can. Ent. 116, 1109 (1984)) on the better chances of ‘new associations’ in biological control, we present an analysis that reaches different conclusions. Finally, we discuss future prospects for the different approaches to biological control, and suggest that longterm control methods, such as introduction and inoculation, will be used increasingly in the future.