9306981 Lindroth Increasing concentrations of atmospheric CO2 and attendant climate change are expected to have significant impacts on forest ecosystems. You understanding of how these changes will affect ecological interactions, especially those between trees and tree-feeding insects, is at best rudimentary. Elevated CO2 can markedly alter the foliar chemistry of deciduous trees, including reductions in nitrogen and increases in carbohydrates and carbon-based secondary metabolites. These changes alter the performance of leaf-feeding Lepidoptera. CO2 interacts with other environmental factories (nutrient availability, defoliation) and possibly with plant genotype affect leaf chemistry and insect performance. This research investigates the direct and interactive effects of elevated CO2, resource availability and plant genotype on tree-herbivore-parasitoid interacations. The experimental system includes quaking aspen, red oak and sugar maple (which exhibit a range of inherent growth rates and shade tolorances), two leaf-feeding insects (gypsy moth and forest tent caterpillar) and a gypsy moth larval parasitioid (Cotesia melanoscelus). Carbon-nutrient balance theory provides a framework for development of three major goal associate hypotheses. These goals are to determine effects of elevated CO2 and 1) drought stress, 2) light availability, and 3) aspen genotype on tree chemical composition, and consequences for performance of insect herbivores and the parasitoid C. melanoscelus. %%% Numerous researchers and research agencies have identified studies on interactions of plants and herbivores as pivotal in understanding the ecological consequences of global change. This research will help address that need. Special features of this research include an emphasis on interactive effects of CO2 and environmental system, and use of tree and insect species that are ecologically and economically important components of North American deciduous forests.
