Unwelcome Pests Often Hitch a Ride

EFETAC and Canadian Researchers Investigate the Firewood Connection

Firewood showing emerald ash borer damage. Photo by Troy Kimoto, courtesy of Bugwood.org.

Firewood has ignited a national debate, especially in campgrounds, because it can carry unwanted forest insect pests across state borders and potentially even between the United States and Canada. Many of these nonnative pests are well-known—hemlock woolly adelgid, emerald ash borer, Asian longhorned beetle—for causing significant ecological and economic damage, including the deaths of millions of trees in the United States.

Eastern Forest Environmental Threat Assessment Center (EFETAC) research ecologist Frank Koch and Canadian Forest Service research scientist Denys Yemshanov are determined to tap into the mysteries surrounding alien forest pest invasions such as those facilitated by firewood transport and to help land managers prepare for and respond to the spread of these unwelcome guests.

The researchers’ joint interest in invasive pests dates back to 2008, when their early models simulated pest invasions from entry locations through time, incorporating critical data related to insects host, population growth, and movement. Now Koch and Yemshanov focus their collaborative work on assessing and mapping pest invasion risk, providing a suite of cutting-edge modeling tools and data products designed to help improve the understanding and forecasting of risks and impacts particular to known and emerging nonnative invasive species.

“Research to develop appropriate risk assessment, prevention, and mitigation strategies has become increasingly complex,” says Koch, who with Yemshanov examined data from more than 7.2 million reservations from 2,500 campgrounds across the country managed by federal agencies for the study on firewood transport risks they published  in the April issue of the Journal of Economic Entomology.

Adult emerald ash borer. Photo courtesy of Bugwood.org.

“Strategies must address multiple pests and incorporate environmental and economic factors over very large regions in North America as well as take into account  climate, land use and other human and non-human-related activities.” Koch notes that some national parks like the Shenandoah in Virginia have instituted an Outside Firewood Ban to slow the spread, in this case, of the emerald ash borer. The ban requires that visitors not bring any firewood into the park but gather or purchase wood onsite.

Unique to Koch and Yemshanovs risk assessments is the ability to incorporate uncertainty, factoring in critical information both known and believed to be known about the invading species. Beyond their recent focus on the firewood issue, they are also investigating human-assisted introductions and spread in general, highlighting how activities such as trade, economic development, transportation, and recreation play a role in invasive pests establishing and expanding their populations.


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