Research Highlights

Summary

Mortality of eastern hemlock in the southern Appalachian Mountains is rapid and likely outpaces the ability of introduced predator beetles to establish, increase in number, and control adelgid populations. In a recent study in northern Georgia, Forest Service scientists and their university partners examined the potential for combining chemical insecticide treatments and predator releases (biological control) in the same stands. Hemlock trees treated with a low rate of imidacloprid insecticide had better crown health and eventually supported as many or more adelgid prey and beetle predators (Laricobius nigrinus) than untreated trees. Using cages to exclude predators from selected branches, the researchers also showed that predators significantly reduced adelgid populations during the winter and early spring. Results suggest the potential to expand an integrated approach to hemlock woolly adelgid management and help slow the pace of hemlock decline.

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