Semester

Summer

Date of Graduation

2019

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Wildlife and Fisheries Resources

Committee Chair

Petra Wood

Committee Co-Chair

Donald Brown

Committee Member

Yong-Lak Park

Abstract

The insecticide imidacloprid is widely used to mitigate hemlock (Tsuga spp.) mortality resulting from the invasive hemlock woolly adelgid (HWA), but evidence suggests that

imidacloprid can have negative effects on adjacent stream systems. Imidacloprid exposure causes physiological changes, bioaccumulation, and reduced survival in anurans, and induces physiological impairment and reduced survival in benthic macroinvertebrates. In this thesis, we assessed whether HWA treatments using imidacloprid affect stream salamander abundances and benthic macroinvertebrate community composition. We also investigated whether imidacloprid or its metabolites bioaccumulate in benthic macroinvertebrates or salamanders and cause sublethal effects. We conducted this study in two National Park Service units of West Virginia and the Monongahela National Forest (MNF) and used standard sampling methods to survey stream salamanders and benthic macroinvertebrates. We also euthanized salamanders of the genus Desmognathus to assess imidacloprid and metabolite bioaccumulation and concentrations of the stress hormone, corticosterone. We provide strong evidence that salamanders and stream invertebrates bioaccumulate imidacloprid and that imidacloprid is associated with sublethal effects in salamanders, including reduced body condition and increased corticosterone levels. Additionally, we detected negative effects of imidacloprid treatments on Desmognathus spp. abundances and on benthic macroinvertebrate community composition within MNF. This study demonstrates unintended effects of imidacloprid treatment on adjacent stream organisms.

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