Showing papers by "Riccardo Bommarco published in 2000"

Landscape Management and Resident Generalist Predators in Annual Crop Systems

Abstract: Pest suppression using biological control instead of chemicals, is an important step towards sustainable food production. A long term objective for efficient biocontrol is to enhance abundance or persistence of resident natural enemy populations (Altieri, 1987). It is widely accepted that the large homogenous habitat represented by modem agricultural crop fields, coupled with the use of pesticides, is detrimental to natural enemies of insect pests in particular and biodiversity in general. Several empirical studies have demonstrated that a simplification of the agricultural landscape leads to a decrease in natural enemy activity, reproductive success and abundance (Flaherty, 1969; Dempster & Coaker, 1974; Landis & Haas, 1992; Corbett & Rosenheim, 1996; Bommarco, 1998a), but in general we know little about the processes creating these patterns. Interactions between insect pests, their host plants and natural enemies have most often been studied within crop fields. However, agroecosystems are much more than simply the fields of our studied crops. Adjacent crops and non-crop elements can have a substantial impact on insect communities in an agricultural setting. We can, to a certain extent, manipulate the agricultural landscape. It is possible to change the proportion of different habitats (the composition) and their arrangement (the configuration) in an agroecosystem. But at present we need more knowledge about the consequences of such changes on the population dynamics of predators and other resident species. Important questions for the future are whether it is feasible to change cultivation practices such that natural enemy efficacy is increased, and how large these alterations need to be in order to generate tangible results.