PARENT SESSION
Oral Session #9: Trophic structure and community interactions. Presiding: B. Menge.
Monday, August 6, 2001. 8:00 AM to 11:45 AM. Hall of Ideas I.
Behavioral assessment of potential disruption of biological control by intraguild predation.
Chang, Gary1, 1
ABSTRACT- The net impact of predators on a prey population may be disrupted if the predators also consume each other (an interaction called intraguild predation, IGP). Theory predicts disruption if the predators consumed in IGP are superior exploiters or if predators attack each other in preference to other prey. In an open field setting, I compared the exploitative abilities and consumption preferences of four insects that attack pea aphids by following freely-foraging individuals for 15-minute observation periods or until the focal insect was lost. I recorded what the insects encountered and the outcomes of those encounters. Parasitoid wasps and syrphid fly larvae were victims of IGP, while lady beetles and lacewings were perpetrators of IGP. The pea aphid attack rates of parasitoids, syrphid larvae, lady beetles, and lacewings were 0.87, 0.70, 0.68, and 0.74 pea aphids per individual per hour, respectively. These four rates were not significantly different. The ratio of IGP events to other predation events was less than 1:9, and did not differ significantly from the ratio of potential IG prey individuals to other potential prey individuals. Thus, the behavioral-level data predict that IGP should not disrupt biological control of the pea aphid under the study conditions.
KEY WORDS: generalist predators, foraging behavior, biological control, insects