Meeting Abstract
Amphibians inhabiting agricultural regions experience multiple stressors resulting from alterations to both the terrestrial and aquatic environment. Local influences on amphibian populations may vary widely, but contamination of surface waters is ubiquitous in intensively cultivated agricultural regions. Altered glucocorticoid (corticosterone) levels have been observed in amphibians exposed to contaminants in both laboratory and field experiments. In addition to primary effects on metabolism, altered corticosterone regulation may in turn influence diverse processes such as development, immunity, reproduction, and behavior. We investigated the effects of exposure to the neonicotinoid imidacloprid, a common active ingredient in systemic insecticides, on the amphibian stress response and associated physiology. Neonicotinoids are the most widely used class of systemic insecticides, have been detected in surface and ground waters, and have noted toxicity to invertebrates. However, relatively few studies have focused on the effects of neonicotinoid exposure to nontarget aquatic vertebrates. Adult male African clawed frogs (Xenopus laevis) were exposed to environmentally relevant concentrations of imidacloprid by immersion for 48 days. Plasma corticosterone and associated metabolic and immune parameters were examined from samples collected under baseline and handling-stressed conditions. This study provides insight into the effects of a common aquatic contaminant on amphibian physiology.
