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Hemlock Woolly Adelgid Insecticide Treatment Assessment in Great Smoky Mountains National Park

Published by National Park Service | Department of the Interior | Metadata Last Checked: January 25, 2026 | Last Modified: 2016-10-11T00:00:00Z
The hemlock woolly adelgid was first documented in the Great Smoky Mountains National Park in 2002. Since then park personnel have embarked on multi-faceted management programs to reduce adelgid populations on hemlocks. To date, the factors responsible for effective treatment of hemlock woolly adelgid are not fully understood. The ultimate goal of this project is to determine the effectiveness of imidacloprid treatment regimes and possible non-target impacts to aquatic systems. The objectives of field sampling for this study are as follows: 1) to conduct a chemical analyses of imidacloprid and imidacloprid metabolites in hemlock trees from selected treatment areas; 2) to collect adelgid population data from hemlock trees from selected treatment areas; and 3) to assess the impact of imidacloprid on aquatic habitats in the park. The endpoint of this project will be to supply the park with a hemlock woolly adelgid management plan. Three field sites were selected for the hemlock foliage work: two in the park--Anthony Creek and Hesse Creek--and one near the park (Mountain Homes Incorporated). Concentrations of imidacloprid, olefin, and other metabolites were determined in foliage samples from the three sites. Both imidacloprid and olefin were present in the samples 4-7 years after initial application, with concentrations of imidacloprid below LD50 in most samples and olefin above LD50 for HWA in most samples. Ten streams adjacent to treatment sites have been sampled for aquatic work above and below the treatment site: Alum Creek, Camel Hump Creek, Cane Creek, Chasteen Creek, Dunn Creek, Indian Creek, Indian Camp Creek, Kingfisher Creek, Panther Creek, and Shop Creek. Ten streams that are not adjacent to treatment areas have also been sampled for comparisons: Big Branch, Cattail Branch, Coalen Ground Branch, Hammer Branch, Hesse Creek, Kephart Prong, Noisy Creek, Robinson Creek, Tabcat Creek, and Webb Creek. Water samples were also tested for imidacloprid and its metabolites.

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