Plant-Insect Interactions
Ray Williams
Associate Professor
Assistant Chairperson
Ph.D., University of South Carolina
For more information, see My Webpage
My primary research interests surround the interactions between plants and herbivorous insects. I am particularly interested in the mechanisms driving feeding on plants by insects. These include nutritional requirements (and constraints) on insect consumption, growth, and fecundity, as well as the role of defensive allelochemicals. Over the past several years I have been investigating how global climate change scenarios of increasing atmospheric CO2 and temperature may alter important tree-insect interactions. Working in collaboration with scientists at Oak Ridge National Laboratory, The University of South Carolina, and Duke University, many of the effects CO2-enrichment has on tree feeding hymenopteran and lepidopteran caterpillars have been explored.My studies have demonstrated numerous responses of trees to increased atmospheric CO2,including reductions in leaf nitrogen and increases in leaf carbohydrates, carbohydrate:nitrogen ratio, and carbon-based phenolics. Responses of insects include increased consumption, selection of leaves based on age, and compensatory increases in the ability to utilize available nitrogen. In addition to leaf feeding insects, my collaborators and I are now looking at litter microarthropod responses to increasing CO2 concentration at large-scale CO2 enrichment sites. I am also involved in other areas of research outside global climate change. These include investigations into the composition of litter microarthropod communities on cliff faces. Attempts are being made to relate litter quality (carbon:nitrogen ratio, carbon-based phenolics, etc.) to the composition of the litter fauna in these unique and potentially threatened ecosystems. Future research directions include the genetic structure of threatened insect populations (especially Order Lepidoptera) and the role of plant and insect genetic variability in insect responses to plant resource availability.
Selected Publications
Williams, R.S., Lincoln, D.E., and Thomas, R.B. (1994) Loblolly pine grown under elevated CO2 affects early instar pine sawfly performance. Oecologia 98:64-71.
Williams, R.S., Lincoln, D.E., and Thomas, R.B. (1997) Effects of elevated CO2-grown loblolly pine needles on the growth, consumption, development, and pupal weight of red-headed pine sawfly larvae reared within open-topped chambers. Global Change Biology 3:501-511.
Williams, R.S., Thomas, R.B., Strain, B.R., and Lincoln, D.E. (1997) Effects of elevated CO2, soil nutrient levels, and foliage age on the performance of two generations of Neodiprion lecontei (Hymenoptera: Diprionidae) feeding on loblolly pine. Environmental Entomology 26:1312-1322.
Williams, R.S., Lincoln, D.E., and Norby, R.J. (1998) Leaf age effects of elevated CO2-grown white oak leaves on spring-feeding lepidopterans. Global Change Biology 4: 235-246.
Williams, R.S., Norby, R.J., and Lincoln, D.E. (2000) Effects of elevated CO2 and temperature-grown red and sugar maple on gypsy moth performance. Global Change Biology 6:685-696.
Williams, R.S., Lincoln, D.E., and Norby, R.J. (2003) Development of gypsy moth larvae feeding on red maple saplings at elevated CO2 and temperature. Oecologia, 137: 114-122
Hansen, R.A., Williams, R.S., and Lincoln, D.E. (2001) Non-litter effects of elevated CO2 on forest floor microarthropod abundances. Plant and Soil 236: 139-144.
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