Wednesday, December 13, 2006

The exotic banded elm bark beetle and the smaller European elm bark beetle: Abundance and host attraction

Jana C. Lee, jctlee@ucdavis.edu1, Shakeeb Hamud, shamud@fs.fed.us2, Jose Negron, jnegron@fs.fed.us2, Jeff Witcosky, jwitcosky@fs.fed.us2, Steve Munson, smunson@fs.fed.us2, and Steven J. Seybold, sseybold@fs.fed.us2. (1) University of California, Entomology, 720 Olive Drive, Suite D, Davis, CA, (2) USDA Forest Service, 720 Olive Drive, Suite D, Davis, CA

In April 2003, the banded elm bark beetle (BEBB), Scolytus schevyrewi Semenov, an invasive from Asia, was first detected in North America in Colorado and Utah. To date, BEBB has been detected in 21 states. BEBB attacks elm trees (Ulmus spp.) and may potentially vector the fungal pathogen causing Dutch elm disease. BEBB shares a similar biology and appearance to an established invasive, the European elm bark beetle (EEBB), Scolytus multistriatus (Marsham). However, BEBB seems to attack standing trees more aggressively and appears now more abundant than EEBB in the Rocky Mountain regions, suggesting that it may have displaced EEBB and/or is better able to colonize regions beyond EEBB’s range. Our objectives were to determine the relative abundance of BEBB and EEBB in California, Nevada, Utah, Colorado and Utah. A trap Siberian elm log, baited funnel trap, and passive plexiglass Schmidt trap were set up at four sites of each state and monitored from May to September. Initial samples suggest that BEBB is far less common than EEBB in California, and BEBB increases in abundance from Nevada, Utah, Colorado and Wyoming. The attraction of BEBB and EEBB to hosts American elm, U. americana, and Siberian elm, U. pumila, and the same hosts infested with conspecifics are being tested with flight traps baited with bolts and infested bolts. BEBB is more attracted to Siberian than American elm, and appears to respond similarly to hosts recently infested with conspecifics as to uninfested hosts.

Species 1: Coleoptera Curculionidae Scolytus schevyrewi (banded elm bark beetle)
Species 2: Coleoptera Curculionidae Scolytus multistriatus (smaller European elm bark beetle)