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Hemlock Woolly Adelgid Predator Beetle Releases and Recovery Efforts in the North Georgia Mountains.

Photo of Predator beetles are used to control hemlock woolly adelgid, an insect pest shown here on an eastern hemlock twig. USDA Forest ServicePredator beetles are used to control hemlock woolly adelgid, an insect pest shown here on an eastern hemlock twig. USDA Forest ServiceSnapshot : Eastern hemlock are threatened by the invasive hemlock woolly adelgid. Three predators of this pest were released in North Georgia to combat this invasion. We found two are established and feeding on the adelgid.

Principal Investigators(s) :
Hanula, James L. 
Research Location : Chattahoochee National Forest
Research Station : Southern Research Station (SRS)
Year : 2015
Highlight ID : 936

Summary

Eastern hemlock are threatened by the invasive hemlock woolly adelgid (Adelges tsugae) that arrived in Georgia in 2003. In order to conserve some mature hemlocks in North Georgia, the Forest Service created over 100 Hemlock Conservation Areas throughout the Chattahoochee National Forest. Predatory beetles Sasajiscymnus tsugae, Laricobius nigrinus, and Scymnus sinunodulus were released in some of these areas. Following release, infested hemlock trees were sampled during spring 2010 to 2012 at some of these sites. Non-release sites 0.40 to 1.61 kilometers (.25 to .99 mile) from release areas were also sampled in 2012 to evaluate spread from release trees. Sasajiscymnus tsugae was found at three sites 3 years after release and at two other sites 2 years after release. Laricobius nigrinus was found at one site 3 years after release and at two sites 2 years after release. Scymnus sinunodulus was never recovered. The results demonstrate that S. tsugae and L. nigrinus, are established in North Georgia, however their population sizes, efficacy, and survival rates are still unknown. Sampling at non-release sites showed that the native L. rubidus is a common predator associated with A. tsugae populations, but its effect on them is also unknown.

Forest Service Partners

External Partners

  • Chattahoochee National Forest
  • University of North Georgia

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