DOI
https://doi.org/10.25772/YJVT-AS45
Defense Date
2015
Document Type
Thesis
Degree Name
Master of Science
Department
Biology
First Advisor
Dr. Karen M. Kester
Abstract
The catalpa sphinx, Ceratomia catalpae, is a specialist on Catalpa trees, which produce iridoid glycosides (IGs). Whereas some trees are defoliated every year, others escape herbivory. Caterpillar populations are either heavily parasitized by the braconid wasp, Cotesia congregata, or remain unparasitized. We hypothesized that these patterns could be explained by variable IG concentrations among trees and insect responses to these chemicals. IG concentrations varied among trees. Percent defoliation was positively related to IG concentration. In comparisons of insect responses to relatively high or low IG concentrations, moths preferred to oviposit on trees with high IG concentrations. Caterpillars did not display a feeding preference nor did wasps differ in searching responses to leaf discs with high or low IG concentrations. Results indicate that observed patterns of herbivory can be explained by moth oviposition preferences for trees with high IG concentrations.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
5-8-2015