Document: JAS-3-56-26

Predation of European corn borer eggs by Coleomegilla maculata DeGeer in the presence of alternative foods.

HARMON, J.P.* and D.A.ANDOW

University of Minnesota, St. Paul, MN 55108, USA ¹

Abstract:
Generalist arthropod predators can have an enormous influence on the population dynamics of target prey, yet their interactions with alternative foods often make it difficult to predict the predator's response to different communities of target and alternative foods. To investigate the effects of alternative food on predation, we studied the polyphagous coccinellid, Coleomegilla maculata DeGeer and its most common prey in Minnesota maize: European corn borer eggs, corn leaf aphids, and corn pollen. We conducted a study with large field cages to determine how the presence of aphids and pollen influence the predation of high and low densities of European corn borer eggs by C. maculata. Our results indicate (1) Per capita predation on European corn borer eggs was density dependent in the absence of alternative foods; (2) Per capita predation on eggs was lower and inversely density dependent when corn pollen was available; and (3) Cages with large corn leaf aphid densities had small and inconsistent differences in egg predation from cages with low aphid densities, regardless of pollen availability. Laboratory studies help show how the foraging behavior of individual C. maculata can be influenced by the type and density of available foods. An understanding of how alternative prey influence predator foraging for target prey could be an important step in facilitating effective biological control by generalist arthropod predators.

Keywords: generalist predators, foraging behavior, alternative foods, functional response

This abstract is being presented at: 4:15 PM in session:
Oral Session #31: Agroecology.