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Individual Highlight

A suite of Introduced and Native Enemies Reduces Populations of the Emerald Ash Borer

Photo of An emerald ash borer larva feeding under the bark of an ash tree. Leah Bauer, USDA Forest ServiceAn emerald ash borer larva feeding under the bark of an ash tree. Leah Bauer, USDA Forest ServiceSnapshot : Originally from Asia, the emerald ash borer (EAB) is an invasive wood-boring beetle that attacks and kills ash trees in the United States. The long-term and sustainable management of this destructive pest involves the release of specialized insect natural enemies from Asia into our EAB-infested forests. At study sites in Michigan forests, Forest Service scientists and their research partners have found a suite of introduced and native natural enemies working in tandem to reduce populations of emerald ash borer.

Principal Investigators(s) :
Bauer, Leah 
Research Location : Study sites are located in Michigan
Research Station : Northern Research Station (NRS)
Year : 2014
Highlight ID : 631


In the United States, high densities of emerald ash borer (EAB) kill ash trees within five years, partly due to the lack of specialized insect natural enemies, or parasitoids, from its native range in Asia. Forest Service researchers collaborated with colleagues in the U.S. Department of Agriculture and university scientists since 2008 to study the impacts of introduced and native parasitoids on EAB populations and ash trees at forested study sites in Michigan. They are finding several introduced and native parasitoids that cause significant larval and egg mortality. To study interactions between parasitoids of EAB larvae, researchers caged different parasitoid species onto small and large infested ash trees. They found that Tetrastichus planipennisi, a relatively small parasitoid of EAB from China, was successful at killing EAB in young, thin-barked ash trees, whereas larger, native parasitoids in the genus Atanycolus were successful at killing EAB larvae in mature, thick-barked ash trees. These findings suggest that these parasitoids will coexist and work together to reduce the population densities of EAB larvae in our ash trees. Researchers continue to study the causes of changes in EAB population densities and the survival of regenerating ash trees at these Michigan study sites.

Forest Service Partners

External Partners

  • Michigan State Univ., E. Lansing, MI
  • USDA APHIS PPQ, Brighton, MI
  • USDA ARS, Newark, DE
  • Univ. of Mass., Amherst, MA

Program Areas