Monday, December 10, 2007 - 8:41 AM

Electrophysiological response of the dogwood borer, Synanthedon scitula (Lepidoptera: Sesiidae), to apple tissue volatiles

Daniel L. Frank,, Virginia Polytechnic Institute and State University, Entomology, Alson H. Smith Jr. Agricultural Research and Extension Center, 595 Laurel Grove Rd, Winchester, VA, Aijun Zhang, Aijun.Zhang@ARS.USDA.GOV, USDA-ARS, Plant Sciences Institute, Invasive Insect Biocontrol and Behavior Laboratory, Bldg. 007, Rm.312, BARC-West, 10300 Baltimore Ave, Beltsville, MD, Tracy C. Leskey,, USDA-ARS, Appalachian Fruit Research Station, 2217 Wiltshire Road, Kearneysville, WV, and Christopher Bergh,, Virginia Polytechnic Institute and State University, Alson H. Smith, Jr. Agricultural Research and Extension Center, 595 Laurel Grove rd, Winchester, VA.

The dogwood borer, Synanthedon scitula (Harris), has become an increasingly important pest in apple orchards throughout eastern North America. When planted on clonal, size-controlling rootstocks, many apple cultivars form adventitious root primordia, which are commonly called burr knots, below the graft union of trees. Burr knots appear to be a preferred resource for oviposition by female dogwood borer. Despite information on the relationship between burr knots and dogwood borer infestation, very little is known about the stimuli associated with host location and oviposition site selection by mated females. Coupled gas chromatography-electroantennogram detection (GC-EAD) analysis of volatiles collected from infested burr knot, uninfested burr knot, and no burr knot tissue demonstrated that 15 compounds produced repeatable antennal responses from females. There were no differences in the response of antennae from virgin and mated females, and the antennal response of females to host odors was stronger than that of males. Use of the solid-phase microextraction (SPME) technique revealed that a single volatile compound emanating from larval dogwood borer frass elicited a strong female antennal response. This compound was also present in volatiles collected from infested burr knot tissue, and was later identified by GC–mass spectrometry (MS) as bergamotene. Further GC-MS analysis revealed that no bergamotene was present in volatile collections from cut apple bark, dogwood borer larvae feeding on lepidopteran diet, and dogwood borer larvae alone.

Species 1: Lepidoptera Sesiidae Synanthedon scitula (dogwood borer)