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Abstract
The systemic insecticide imidacloprid is commonly used to protect trees against attack by the
Adelges tsugae (Hemlock Woolly Adelgid [HWA]), an invasive pest that threatens
Tsuga canadensis (Eastern Hemlock) and
T. caroliniana (Carolina Hemlock) in eastern North America. Although there have been some studies documenting the short-term (1–3 years) impact of imidacloprid on non-target arthropods in hemlock systems, almost nothing is known about the impact over longer time scales. Here, using a set of trees which were experimentally treated 3 and 9 years prior to this study, we found that while the impact of imidacloprid on HWA may be approaching the limits of detection and efficacy on trees treated 9 years ago, there is still an intermittently detectable impact on HWA density. Similarly, 9 years after application there is a subtle but detectable increase in arthropod richness and a shift in canopy-arthropod community composition. Results from the 3-year treated trees were, however, ambiguous, but may be the result of detectable cross-contamination of insecticide among trees.
Citation
Kung, Wing Yi; Hoover, Kelli; Cowles, Richard; Trotter, R. Talbot, III. 2015. Long-Term Effects of Imidacloprid on Eastern Hemlock Canopy Arthropod Biodiversity in New England. Northeastern Naturalist. 22(1): NENHC-40-NENHC-55.
