PS 56-125 - Does habitat diversity drive predation? Effects of forest diversity on artificial caterpillar predation

Thursday, August 10, 2017
Exhibit Hall, Oregon Convention Center
Anna E. Nordseth, Biology, James Madison University, Harrisonburg, VA

The alteration of trophic interactions due to climate change willbe one of the most influential factors in determining future ecosystem health. Climate change is expected to allow insects to expand outside their historic ranges and milder winters will allow pests to proliferate which may reshape the relationship between plants, insect herbivores, and their predators. Without sufficient controls on populations, insect pest outbreaks can cause widespread damage and mortality in forested ecosystems.Theenemies hypothesis proposes that more diverse plant communities may be naturally protected against excessherbivore pest damagedue to top-down controls by predatorssuch as arthropods, birds, and mammals.In this study, we examined the effects of tree species diversityonpredationrates ofinsect herbivoresusing artificial caterpillars in an existingforest diversity experiment in Edgewater, Maryland.Artificialcaterpillars were installedon selected trees within plots containing one, four, and twelve treespeciesand checked regularly for signs of predator damage.


Plot-leveltreediversity did not have an effect oncaterpillarpredation rates.Instead, species-specific impacts were seen ascaterpillars on sycamores(Platanusoccidentalis)were attacked morefrequently. Additionally,caterpillars on tallertreeshad a higher attack rate, likely because greater canopy coverprovidedbetter foraging habitat for predators.Our findings suggest that, after three years of restoration, forest diversity is not the most important driver of predation on insect herbivores. Rather,faster growing trees that more quickly establishcanopy cover, attract more predators and should therefore be utilized in forest restoration.