PARENT SESSION
Oral Session #55: Predator - Prey Interactions.
Presiding: R. Dueser
Wednesday, August 7. 8:00 AM to 11:30 AM. Cochise Meeting Room, TCC.

Non-consumptive effects of predators on aphid population growth.

Nelson, Erik^*,1, Rosenheim, Jay¹, ¹ Univ. of California - Davis., Davis, CA

ABSTRACT- How do predators suppress prey population growth? We present evidence that predators suppress prey populations partly by inducing prey defensive behaviors, as well as by consuming prey individuals. Pea aphids respond to predators by interrupting their feeding and jumping off the plant (if they are quick enough!). Using field cages, we exposed small populations of pea aphids to three treatments: no predators; normal predators; and surgically disabled predators that foraged for aphids (disturbing them) but did not consume them. The experiments demonstrate that predators can reduce pea aphid population growth without consuming them. To explain the behavioral and physiological mechanisms of this effect, we also present results from field studies that describe the costs of pea aphid dropping behavior. When avoiding predators, pea aphids incur costs in terms of lost feeding time, and therefore lost reproductive opportunities. This work suggests that the behavioral effects of predators on prey individuals can translate into effects on prey populations.

KEY WORDS: non-consumptive effects, aphids, predation, behavior