FUNCTIONAL AND NUMERICAL RESPONSES OF ORIUS-INSIDIOSUS (HETEROPTERA, ANTHOCORIDAE) TO ITS PREY IN DIFFERENT VEGETABLE CROPS

The functional response of Orius insidiosus (Say) to one of its primar y prey, the western flower thrips, Frankliniella occidentalis (Pergand e), was measured on bean, tomato, and pepper plants in the greenhouse. Fewer thrips were taken by the predator on tomato than on bean plants , and a lower attack coefficient was calculated on tomato than on bean and pepper plants. Differences in the searching behavior of the preda tor on the 3 plants affected the shape of the functional response of O . insidiosus to its prey. To assess the relationship between populatio ns of O. insidiosus and its prey (thrips, aphids, leafhoppers, and whi teflies), bean, tomato, pepper, and corn plots were monitored at 2 fie ld sites. At both sites, O. insidiosus density was significantly highe r on bean and corn than on pepper (densities in tomato were intermedia te). Although the phenology of the predator differed among crops, its population dynamics generally followed that of its prey. A direct (beh avioral) density-dependent response was found to prey in pepper and to mato, whereas a delayed (reproductive) response was detected in bean a nd corn. Further, the ratio between the densities of O. insidiosus nym phs and adults (an indication of population growth) was higher in bean and corn than in tomato and pepper. The importance of plant character istics to predator-prey interactions is discussed, and particular atte ntion is given to the influence of the plant-feeding habits of O. insi diosus.