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Title: 10 Risk to Ash from Emerald Ash Borer: Can Biological Control Prevent the Loss of Ash Stands

item Duan, Jian
item DRIESCHE, ROY VAN - University Of Massachusetts
item BAUER, LEAH - Us Forest Service (FS)
item KASHIAN, DANIEL - Wayne State University
item HERMAS, DANIEL - The Ohio State University

Submitted to: Biology and Control of Emerald Ash Borer
Publication Type: Book / Chapter
Publication Acceptance Date: 5/1/2015
Publication Date: 6/30/2015
Citation: Duan, J.J., Driesche, R., Bauer, L., Kashian, D.M., Hermas, D.A. 2015. 10 Risk to Ash from Emerald Ash Borer: Can Biological Control Prevent the Loss of Ash Stands. Biology and Control of Emerald Ash Borer. (2015): p. 151-163.

Interpretive Summary:

Technical Abstract: Ash trees were once relatively free of serious, major diseases and insect pests in North America until the arrival of EAB, which was first detected in North America in Michigan in 2002. As of February 2014, EAB had been detected in 22 U.S. states and two Canadian provinces, killing millions of ash trees. The ecological and economic value of ash justify appropriate measures to manage this invasive pest, and the current EAB biological control program was initiated shortly after its detection in the United States due to the failure of eradication efforts. The premise underlying the classical EAB biological control program is that EAB outbreaks are rare in China and other parts of its native range, in part because effective natural enemies prevent or quickly suppress EAB outbreaks. The EAB biological control program has resulted in the introduction and successful establishment in North America of three exotic parasitoids (two larval parasitoids T. planipennisi and S. agrili and one egg parasitoid O. agrili) sourced from the native range of EAB in northeastern China. An additional species of EAB parasitoid, S. galinae, is also currently under review for potential releases against EAB in the northeast U.S. The key question is whether these introduced parasitoids, once established, can effectively regulate the EAB population at sufficiently low densities such that an equilibrium can be maintained between EAB and its natural enemies that permits survival and regeneration of ash in North American forests. To answer this question, we examined various factors that may potentially affect the risk to ash from EAB invasion, including population dynamics of EAB in both the newly invaded region and its native range (Northeast Asia), and dominant biotic factors that regulate EAB populations in its native range. We suggest that ash tree resistance and natural enemies (parasitoids) are the two dominant biotic factors that have the potential to regulate EAB population dynamics. A population dynamics model parameterized with egg and larval parasitism rates (~ 60%) observed in EAB’s native range found that natural enemies coupled with moderate to high levels of host plant resistance has the potential to reduce the growth rate of EAB populations below compensatory levels, and thus maintain EAB populations at low-density, equilibrium levels, which may be critical to permit survival and regeneration of ash in the aftermath of EAB invasion in North America forests.