Classical Biological Control of Environmental Pests

Exotic species commonly invade areas of conservation concern. Such species may threaten native species or ecosystems, either attacking individual species, or changing ecosystem characteristics in ways that make them less suitable for the continued existence of one or more native species. Among the potential effects of exotic species are crowding, changes in water table levels, fire frequency or intensity, altered soil fertility or chemistry, and altered levels of predation or disease. Chemical, mechanical and biological methods each may be used to control exotic species in some cases. Chemical and mechanical methods are difficult to apply to large areas and must be repeated periodically to prevent pest resurgence. Classical biological control often has high initial costs but is permanent in nature and self propagating, such that large areas can be treated economically. Risks of biological control are minimal if agents are appropriately screened to determine host range prior to introduction and if introductions are conducted using appropriate quarantine procedures. Biological control is a useful approach for control of a variety of kinds of environmental pests that threaten the conservation of native species and ecosystems, including exotic plants, herbivorous and predacious arthropods, other invertebrates, and in some instance vertebrates.