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 primary prey, the western flower thrips, Frankliniella occidentalis (Pergande), 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 predator on the 3 plants affected the shape of the functional response of O. insidiosus to its prey. To assess the relationship between populations of O. insidiosus and its prey (thrips, aphids, leafhoppers, and whiteflies), bean, tomato, pepper, and corn plots were monitored at 2 field sites. At both sites, O. insidiosus density was significantly higher on bean and corn than on pepper (densities in tomato were intermediate). Although the phenology of the predator differed among crops, its population dynamics generally followed that of its prey. A direct (behavioral) density-dependent response was found to prey in pepper and tomato, whereas a delayed (reproductive) response was detected in bean and corn. Further, the ratio between the densities of O. insidiosus nymphs and adults (an indication of population growth) was higher in bean and corn than in tomato and pepper. The importance of plant characteristics to predator-prey interactions is discussed, and particular attention is given to the influence of the plant-feeding habits of O. insidiosus.