Tracing the movement of an invasive insect using stable isotopes

Research Issue

Polydrusus sericeus is a non-native weevil commonly found in the northern hardwood forests of Wisconsin and Michigan.  The immature weevil feeds primarily below ground on fine roots and the adult on leaf margins of hardwood tree species. To better understand the response of insect populations to increasing environmental pollution, we are using stable isotope analysis to trace the movement of this nonnative invasive insect in mixed tree communities grown under differing air quality conditions.

Our Research

The Polydrusus weevil was abundantly distributed at the Aspen FACE Experiment site,  Harshaw, WI in the mixed communities of trembling aspen (Populus tremuloides), paper birch (Betula papyrifera), and sugar maple (Acer saccharum) grown under elevated carbon dioxide and elevated ozone.  The weevil retains traceable elements in their bodies as they feed which can be analyzed. Stable isotopes of carbon and nitrogen can be used to determine the source populations of the weevil in the Aspen FACE Experiment, and to look for changes in the quality of their food sources.

Expected Outcomes

Our goal was to determine dispersal patterns for P. sericeus in the Aspen FACE Experiment where the insect populations and their food sources are exposed to elevated levels of carbon dioxide and background ozone concentrations that are similar to those found in large cities.  These results will help us better understand the temporal aspects of exposure, that is, if the insects are stressed by air pollution year after year, or if each year represents new populations and new exposures.

Research Results

Marquardt, Paula E.; Lund, Joanne N.; Mattson, William, J.  2011. You are what you eat: stable isotopes and plant-herbivore interactions under elevated carbon dioxide and ozone.  Annual meeting of the American Society of Plant Biologists, August 6-10, Minneapolis, MN.

Lund, Joanne N.; Marquardt, P.E. 2010. Analyzing the movement of an invasive weevil (Polydrusus sericeus) using stable isotopes.  Annual meeting of the Ecological Society of America, August 1-6, Pittsburgh, PA.

Research Participants

Principal Investigators

• Paula Marquardt, Research Plant Geneticist, U.S. Forest Service. Northern Research Station

Co-Investigators

• William Mattson, Jr., Supervisory Research Entomologist Emeritus, U.S. Forest Service. Northern Research Station
• JoAnne Lund, Biological Science Lab Technician, U.S. Forest Service. Northern Research Station