PARENT SESSION
Oral Session #77: Aquatic Ecology: Food webs, invertebrates. Presiding: R.A. Washington-Allen.
Friday, August 10, 2001. 8:00 AM to 12:00 PM. Hall of Ideas H.
Impact of predator cues and resource level on the survivorship, development, and behavior of midges.
MARTINEZ, LAURA1, DEBANO, SANDRA1, WOOSTER, DAVID2, 1 2
ABSTRACT- Predators have important impacts on prey through means other than consumption by affecting life history and behavioral traits. The magnitude of these effects should be influenced by factors such as prey condition, sex, and the length of exposure to predators. To examine these effects, we raised midges from first instar to adults with and without fish cues at three food levels. We found food level and the presence of fish cues affected both developmental rate and survivorship. Midges developing with fish cues or at higher food levels took less time to develop through larval instars. However, midges raised with fish cues or at low food levels were less likely to survive to fourth instar and later stages. To examine the effect of length of exposure to predators on behavior, third instar midges were used in a microhabitat choice experiment. Each microhabitat setup was assigned to a fish cue or non-fish cue treatment. Within each setup, midges were allowed to choose between a sheltered microhabitat with no food and an open microhabitat with food. In microhabitat setups without fish cues, midges raised with fish cues were more likely to select and build tubes in risky microhabitats with food. In addition, females were also more likely to engage in risk taking behavior than males. These results suggest that non-consumptive predator effects are mediated by factors both internal and external to the prey.
KEY WORDS: non-consumptive predator effects, midges, development, survivorship