Key Beneficials in Agroecosystems

Ideal integrated pest control should reflect ecological approaches that not only target the pest, but also account for the key natural enemies and associated interactions (LaSalle and Gauld, 1992; LaSalle, 1993). The success or lack of success of parasitic and predatory species is commonly linked to not only the target host, but other hosts, bioagents, habitats, and abiotic factors. Understanding the host range, host preferences, seasonal occurrence, interspecies competition and displacement, and habitat and food resource requirements of the beneficials is important to safeguarding them, increasing their numbers, and enhancing their performance. The diversity of beneficials in agroecosystems is often linked to natural or undisturbed environments. Where strong ties exist between biocontrol agents of agriculture and plant communities of natural diversity, it is important that these are identified and that the biodiversity linkages are preserved to undergird and support the existence of the beneficials year-round, and in some cases, for use in redistribution and introduction elsewhere. Some indigenous beneficials, though less important against present pests, may be key to preventing future introduced species from becoming problematic. Environmental diversity should be conserved regardless of what is known about the taxonomy or biology of the flora and fauna. BeneficiƔis or groups of beneficials that are active in individual cropping systems commonly move in and between crops and noncultivated ecosystems. Therefore, any search for beneficials for introduction purposes should include not only the agroecosystems of interest, but also the surrounding habitat (Waage, 1991).

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