Cold hardiness of emerald ash borer and its biological control agents
New invasive insects are detected regularly in North America. Often those insects have a history of causing severe damage to plants. A common question is, “Will these new insects eventually spread and become a problem in my state?” Because insects are cold-blooded, the temperature of the environment has a major impact on where they will do well or not so well. Winter temperatures may be especially important in preventing the establishment of new pests in parts of North America.
Emerald ash borer was first detected in 2002 and by 2009 had spread to Minneapolis and St. Paul, MN. Populations in this metropolitan area mark the northwest bounds of EAB’s distribution in North America. Minnesota has nearly one billion ash trees, more than any other state. Ash trees, particularly black ash (Fraxinus nigra), are abundant in the northern part of the state. Winter temperatures in this region are also substantially colder than anywhere else in North America where EAB has invaded. How might EAB respond to these temperatures if it is moved to northern Minnesota or other similarly cold climates in northern New York and New England? Will cold temperatures interfere with efforts to use biological control agents to control EAB in states like Minnesota?
My research supports efforts to predict and prevent invasive species from becoming widespread in North America. Specifically we are assessing the cold hardiness of emerald ash borer and its biological control agents, Spathius agrili, Tetrastichus planipennisi, and Oobius agrili. We are measuring the temperatures at which these insects freeze and die. We are also measuring how long these insects can survive at sub-zero temperatures. We then use this information to develop models to relate winter temperatures to expected levels of mortality.
The models that are generated from our research are used to produce maps to illustrate where insects are or are not likely to successfully overwinter. This information can be used by policymakers to support decisions to regulate the movement of goods that might move a pest such as emerald ash borer into new areas. This information can also be used to improve regional and state monitoring efforts, allowing regulatory officials to concentrate surveys in areas where emerald ash borer is likely to overwinter. Improved models of EAB winter mortality will allow us to refine regional estimates of the number of ash trees likely to be killed by emerald ash borer over time. Lastly, better information about the cold hardiness of emerald ash borer biological control agents will help us to recommend which species to release in different geographic areas.
Venette, R.C.; Abrahamson, M. 2010. Cold hardiness of emerald ash borer, Agrilus planipennis: a new perspective. In: Black ash symposium: proceedings of the meeting; May 25-27, 2010. Bemidji, MN. US Department of Agriculture, Forest Service, Chippewa National Forest.
- Robert C. Venette, USDA-Forest Service- NRS Research Biologist
- Mark Abrahamson, & Jon Osthus, Minnesota Department of Agriculture
- Lindsey Christianson & Anthony Hanson, University of Minnesota
- Jonathan Lelito & Juli Gould, USDA APHIS PPQ
Last Modified: 04/03/2015