507th MONTHLY MEETING
November 15th, 2013
All monthly meetings are open to the public. If you are interested in insects, please join us!
Members may bring exhibits for show-and-tell. If you have photos, video, or other media to share, please email the society.
Title: The diet breadth of Connecticut forest caterpillars and the predators that eat them
Ants are important predators of caterpillars in forests worldwide. In tropical forests, caterpillars with highly specialized diets avoid ant predation through chemical deterrence. In this talk I will describe research from my lab that looks at the role of dietary specialization on ant predation of caterpillars in Connecticut forests. Like most temperate tree species, the young leaves of the tree species in our study largely lack toxins that might be sequestered by caterpillars. We used a field experiment to determine the magnitude of ant predation on 21 caterpillar species over two years. To see if anti-predator behaviors of caterpillars correlated with diet breadth or ant predation, we subjected experimental caterpillars to a simulated predation trial. Interestingly, we found that dietary specialist caterpillar species experienced increased ant predation relative to generalist species. The simulated predation trials showed that specialist caterpillar species tended to remain still when attacked, whereas many generalist caterpillar species responded with avoidance behavior, such as thrashing, locomotion, or dropping. These results suggest that in the absence of chemical deterrence, the host specificity of specialist herbivores might constrain their ability to gain enemy-free space from ants. Previous work in the system has shown that the same specialist caterpillars experience reduced bird predation relative to dietary generalist caterpillars. Therefore, we have found a defensive trade-off for caterpillar species in Connecticut forests: dietary specialists sacrifice protection from ant predators to gain protection from birds, whereas dietary generalists sacrifice protection from birds to gain protection from ants.
Michael S. Singer is an Associate Professor of Biology and Environmental Studies at Wesleyan University. His research focus is on the ecology and evolution of plant-insect-carnivore interactions, including dietary specialization and self-medication behavior in caterpillars. He also enjoys caterpillar natural history, entomology, and botany.
- Wesleyan University
- Shanklin building, Rm. 201 (map)
- Location TBD