IMPACT OF GENERALIST PREDATORS ON A BIOLOGICAL CONTROL AGENT,CHRYSOPERLA CARNEA: DIRECT OBSERVATIONS

Abstract

Generalist predators in terrestrial arthropod communities have traditionally been viewed as predators whose dynamics are less tightly coupled to any particular prey species, but whose ecological roles are in other respects analogous to those of specialist predators. Biological-control theory for predator–prey interactions has been based upon a model of communities composed of three discrete trophic levels—plants, herbivores, and predators—in which biological control agents are top consumers and in which different species of predators interact only through competition for shared prey. Experiments employing single-plant field enclosures have suggested, however, that some generalist predators in the cotton agroecosystem function as higher-order predators, releasing populations of an herbivore, the cotton aphid Aphis gossypii, from control by another predator, the lacewing Chrysoperla carnea. Here we demonstrate through focal observations of neonate C. carnea foraging freely in the field that the high levels ...