Delimitation and management of emerald ash borer (Coleoptera: Buprestidae) at an outlier infestation in southwestern New York State, United States of America: case study

Authors: FIERKE, M. K. - State University Of New York- College Of Environmental Science And Forestry; FOELKER, C. - State University Of New York- College Of Environmental Science And Forestry; WHITMORE, M. - Cornell University; Vandenberg, John; CARLSON, J. - New York State Department Of Environmental Conservation

Submitted to: The Canadian Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/3/2013
Publication Date: 8/2/2013
Citation: Fierke, M., Foelker, C., Whitmore, M., Vandenberg, J.D., Carlson, J. 2013. Delimitation and management of emerald ash borer (Coleoptera: Buprestidae) at an outlier infestation in southwestern New York State, United States of America: case study. The Canadian Entomologist. doi: 10.4039/tce.2013.39.

Interpretive Summary: The emerald ash borer (EAB) is an invasive insect that has killed millions of ash trees and has spread to most northeastern states. We selected 91 ash trees for girdling to use as a survey tool for EAB presence. Sticky traps were also deployed in these trees for possible early detection of flying adults. We chose these trees up to 10 km of away from the center of an infestation in western NY. We also girdled up to 8 ash trees in each of 18 clusters near the presumed center of the infestation. These were meant to attract EAB from the surrounding area and concentrate the population for more carefully targeted management. Trees were felled and debarked, and larval galleries were counted. Based on survey trees, the extent of the infestation was estimated to be nearly 50 square km. Trees within clusters at the core of the infestation had highest numbers of larvae, averaging 9 per square meter of bark surface. Girdled trees in clusters near the core infestation had significantly higher numbers of larvae than ungirdled controls, indicating the efficacy of this treatment for attracting beetles. Subsequent tree destruction will help lower local EAB densities and aid in managing infestations of this pest.

Technical Abstract: Research objectives were to develop an adaptive delimitation technique and to implement and evaluate management of emerald ash borer (EAB) Agrilus planipennis in the first infestation discovered in New York State. Delimitation was accomplished using 91 girdled “sentinel” trap trees deployed up to 10 km away from the purported infestation center. Sentinel trees were cut and debarked; 12 were positive for EAB larvae and the spatial extent of the infestation was estimated at around 48 km squared. Management included girdling clusters of 3-8 trap trees as population “sinks” to attract EAB and concentrate larvae for targeted removal. Three trees were debarked from each of 18 sinks. Sinks nearest the infestation core had the highest numbers of larvae. Only one of eight sinks deployed in response to sentinels positive for an EAB on its PPT had larvae. Weekly monitoring of purple prism traps (PPTs) hung in sentinel trees facilitated early detection of adults at 12 sentinel trees and allowed a quick response (deployment of additional sentinels and sinks). Comparison of larval densities in girdled trap trees from nine positive sinks to proximate ungirdled control trees revealed significantly more larvae infesting sink trees (mean 9.4 plus or minus 2.1 (SE) larvae/m squared) than control trees (2.0 plus or minus 1.1). This indicates clusters of girdled trap trees destroyed prior to the following year’s emergence would lower local EAB densities. However, as sinks established near the edge of the known infestation were negative for larvae, sinks should be established near known population centers to be most effective as a management tool.