Conservation in this discussion means modifying any environmental factors that are adverse to beneficials (DeBach, 1964) and adding requisites (McMurtry et al., 1995). This is a type of environmental insect control (Stern, 1981), a manipulation of the ecosystem to make it less favorable to the pest and more favorable to the natural enemies resulting in reduced pest levels (Mayse, 1983). Such approaches need to be considered in the context of the whole environment, the agroecosystem (target and adjoining crops) and surroundings, as these often have mutual connections. Many insects, whether classified as pests, beneficials, or indifferents, exhibit population drift (Stary, 1978; Bosch, 1987; Vorley and Wratten, 1987; van Emden, 1988). The boundary zone or ecotone where individual crops and noncrops overlap is frequently essential to the conservation and management of beneficials, both indigenous and introduced (DeBach, 1964; van Emden, 1965; Ridgway and Vinson, 1977; Stern, 1981; Powell, 1986; Gross, 1987; Martis, 1988; Altieri et al., 1993; Samways, 1993; Johnson and Wilson, 1995; McMurtry et al., 1995). Strict separation of ecosystems does not occur in nature.
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