Integrating biological control and chemical suppression to save our ash resources

USDA Forest Service Forest Health Protection (Southern Region); University of Kentucky; Kentucky Division of Forestry

SUMMARY: The emerald ash borer (EAB) is an exotic tree-killing beetle first discovered in Michigan infesting urban ash trees in 2002. Infestations spread rapidly, and EAB is currently found in 20 states and two Canadian provinces. EAB will likely become pervasive throughout the southern region, as it’s already been discovered in five states in the South (Kentucky, Tennessee, Virginia, North Carolina, and Georgia). In states with long-established EAB infestations (>5 years), EAB eradication attempts have failed. Chemical protection works but is impractical on a broad scale and is not sustainable. Releases of biological control agents are ongoing, but ash mortality is occurring rapidly, making establishment of natural enemies problematic.

Kentucky’s position at the geographic forefront of the invaded range has provided a unique and exciting opportunity to evaluate sustainable management approaches and characterize the repercussions of the EAB invasion. Researchers are assessing the effects of natural enemy releases on EAB populations and on forest structure and composition. They are also evaluating the feasibility of a potentially sustainable ‘greener’ approach to EAB management, coupling biological control releases with application of reduced rates of insecticides.

EFETAC'S ROLE: This project is supported by Eastern Threat Center funding.

STATUS: Completed

PROGRESS: Baseline vegetation censusing is complete in 5 Kentucky counties at the geographic front of the EAB invasion. Site treatments, including chemical application (imidacloprid), biological control releases, and reduced rates of chemical applications coupled with biological control releases, have been implemented. Insect monitoring is ongoing. Vegetation assessments and site treatments were repeated in 2014.

Davidson, W., LK Rieske. Under revision. Establishment of classical biological control targeting emerald ash borer is facilitated by use of insecticides, with little effect on native arthropod communities. Biological Control.

Davidson, W, LK Rieske. 2015. Native parasitoid response to emerald ash borer (Coleoptera: Buprestidae) and ash decline in recently invaded forests of the central United States. Annals of the Entomological Society of America. DOI 10.1093/aesa/sav068.

Davidson, W, LK Rieske-Kinney. 2014. Emerald Ash Borer natural enemies are here – can they make a difference? Kentucky Woodlands Magazine, Vol. 9, Issue 2.


W Davidson, LK Rieske. Insecticides facilitate establishment and recruitment of natural enemies for sustainable emerald ash borer management. Poster presentation, USDA Interagency Research Forum on Invasive Species. 13-16 January, Annapolis, MD.

W Davidson (Presenter), LK Rieske. Can we save our ash? Developing a sustainable approach to EAB management. 2014 Emerald Ash Borer National Research and Technology Development Meeting. 15-16 Oct., Wooster, OH.

W Davidson, LK Rieske. Can local natural enemies help mitigate emerald ash borer damage and preserve our ash? Ohio Valley Entomological Association, Columbus, OH, 31 October 2014.

W. Davidson, LK Rieske. Saving our ash: A sustainable approach to emerald ash borer management. Meeting of the Southern Forest Insect Work Conference, Charleston, SC, 22-25 July 2014.


Emerald Ash Borer in Kentucky

Kentucky's Office of the State Entomologist

Lynne Rieske-Kinney, University of Kentucky Department of Entomology, or 859-257-1167

Updated May 2016

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