CULTURAL PEST CONTROL METHODS
Cultural control may be important in many pest control strategies. The section on "Environmental Management" treats of this in some detail. For example, the effective environment of an organism has been characterized by Rabb et al (1976) as weather, food, habitat (shelter, nests) and other organisms. Environmental management for biological control is concerned with the functional environment, i.e., the physical and biotic elements that directly or indirectly impact survival, migration, reproduction, feeding and the behaviors associated with these life processes. Although pest populations can be controlled directly through cultural control methods that modify the habitat, the main thrust of this section is conservation (maintenance of natural enemy abundance and diversity) and enhancement (increased immigration, tenure time, longevity, fertility and efficiency) strategies that can be used to manipulate natural enemies in agroecosystems. Habitat management is directed at (1) enhancing habitat suitability for immigration and host finding, (2) providing alternative prey/hosts during times when pests are scarce, (3) providing supplementary food (food sprays, nectar and pollen for predators/parasitoids), (4) maintenance of non economic levels of the pest or alternative hosts over long periods to ensure continued survival of natural enemies and (5) providing refugia for mating or overwintering. Cropping Techniques that enhance parasitoids through these five processes have been reviewed by Powell (1986) and shown in table form by Altieri & Letourneau (1996).
Approaches to manipulating natural enemies include several levels, from agroecosystem processes to eco-physiological features of individual organisms. The number of elements that can be manipulated and their degree of flexibility depend on characteristics of the agroecosystem. The role, methods and future directions of environmental management as a preventative control strategy are detailed after Vandermeer & Andow (1986) in the following sections.
A notable case is the successful cultural control of houseflies that breed in decaying melons in the American Southwest (Legner & Olton 1975, Olton & Legner 1973). The simple procedure of breaking-open culled melons at harvest accelerated decay of the breeding source and greatly reduced fly breeding. Another example is the elimination of breeding sites for the Australian bush fly, Musca sorbens, in the Marshall Islands by reducing the number of unleashed dogs on the islands as well as the deployment of an effective adult fly baiting procedure (Legner et al 1974. )