I address the hypothesis that predators suppress prey populations partly by inducing prey defensive behaviors, as well as by consuming prey individuals. Pea aphids (if they are quick enough!) respond to predatory damselbugs by interrupting their feeding and jumping off the plant. I tested whether the behavioral effects of damselbugs limit pea aphid population growth by growing aphid populations in field cages, and exposing them to three treatments: no damselbugs; normal damselbugs; and surgically disabled damselbugs that could disturb aphids but not consume them. Results demonstrate that damselbugs can reduce pea aphid population growth by their presence alone, suggesting that the total effect of damselbugs on aphid populations may be partly mediated by behavioral effects. To explain the mechanism of this effect, I measured the strength of several potential costs of pea aphid dropping behavior, including heat stress, secondary predator exposure, and lost feeding time. This work suggests that behavioral effects of predators on prey individuals can have implications at the population level.
Species 1: Homoptera Aphidae Acyrthosiphon pisum (pea aphid)
Species 2: Hemiptera Nabidae Nabis americoferus (damsel bug)
Keywords: avoidance behavior, non-consumptive effects
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA