Wednesday, December 13, 2006

Sex ratio of emerald ash borer (Agrilus planipennis) (Coleoptera: Buprestidae) adults captured on healthy and stressed ash trees from 2003 to 2006

Sarah M. Smith, smith462@msu.edu1, Deborah G. McCullough, mccullo6@msu.edu2, Therese M. Poland, tpoland@fs.fed.us3, and David Cappaert, cappaert@comcast.net1. (1) Michigan State University, Entomology, 243 Natural Science Bldg, East Lansing, MI, (2) Michigan State University, Entomology, Forestry, 243 Natural Science Building, East Lansing, MI, (3) USDA Forest Service, North Central Research Station, 1407 S. Harrison Rd, East Lansing, MI

Emerald Ash Borer (EAB), an invasive beetle native to Asia discovered in 2002 has killed an estimated 12 to 15 million ash trees (Fraxinus sp.) in southeast Michigan. Established populations have also been found in other areas of Michigan and in Ohio, Indiana, Illinois and Ontario. Adult beetles typically begin oviposition only after feeding on ash foliage for at least two weeks. Newly hatched larvae chew through the bark, then feed and develop in the phloem. Detection of low-density EAB populations are difficult because newly infested trees exhibit few, if any external symptoms. Understanding more about the behavior of adult beetles could improve EAB detection and survey methods. From 2003 to 2006, we conducted studies in several southeast Michigan sites to evaluate attraction of EAB to healthy ash trees, trees stressed by girdling, herbicide, wounding or methyl jasmonate, a stress eliciting compound. Number of beetles trapped on sticky bands on trap trees at each site was measured weekly during each field season. We subsequently examined all captured beetles under a stereomicroscope to determine gender. Male gender was verified by long, dense gold hairs on the prosternum, sternum and gula, and by relatively narrow abdominal sternites; females lack the hairs and have broad abdominal sternites. Male:female ratios were analyzed to assess whether male and female beetles respond differently to tree stress treatments, trap tree exposure or sticky band height.

Species 1: Coleoptera Buprestidae Agrilus planipennis (emerald ash borer)