add contact to address book
Associate Research Scientist
University of Michigan
Office Location(s): 3051A Nat. Sci.Lab: 3007, 3008, 3006 Nat Sci 734.764.7476
View Curriculum Vitae
Phenolic compounds (tannins and low-molecular weight phenolic acids) are chemical defenses that are widely produced by plants. They are found in especially high concentrations in tree leaves. By comparing insect species that differ in their abilities to tolerate these compounds, my lab has been building a better understanding of the key mechanisms that insects employ to tolerate high levels of these chemical defenses in their foods. A central hypothesis addressed by much of our work has been that phenolic compounds exert their effects on herbivores by producing detrimental oxidation products (semiquinone radicals and other reactive oxygen species). Therefore, we have focused in the past five years on improving methods for measuring many of these oxidation products, as well as on measuring a wide variety of antioxidant defenses in insects.
We are currently working on two major projects: (1) testing the roles of plant oxidative enzymes as defenses against caterpillars and (2) comparing the oxidative activities of tannins in herbivores. In collaboration with a plant geneticist (Peter Constabel), we are testing whether three putative defenses (polyphenol oxidase, peroxidase, and ascorbate oxidase) are effective defenses, as is widely believed. In collaboration with a phenolics chemist (Juha-Pekka Salminen), we are finding that different chemical classes of tannins have different abilities to act as "oxidative defenses" against herbivores such as caterpillars. These basic research projects have long-term importance for breeding and genetic engineering efforts to produce more resistant plants in agriculture and forestry.
Ecology and Evolutionary Biology
2019 Kraus Nat. Sci. Bldg.830 North University
Ann Arbor, MI