Biodiversity or natural habitat resources are dwindling, in large measure because of urban and agricultural spread and commercial development (LaSalle and Gauld, 1992). Natural enemies that demonstrate an ability to become community members in an agroecosystem have, in general, a much better chance to survive compared with those associated only with natural ecosystems. Through adaptation, at least some beneficials have overcome or are overcoming the biodiversity crisis by moving into or between cultivated landscapes. Plant diversity in cultivated landscapes contributes to overall biodiversity, whereas monocultures, especially large-scale monocultures, usually result in fewer species. In all cases, the diversity of beneficials and their management in agroecosystems should be considered from a dual viewpoint, inclusive of both the agroecologist and nature conservationist (Samways, 1993).
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