Meeting Abstract
Amphibians are exquisitely sensitive to environmental conditions and have experienced widespread and rapid declines in recent decades due to global change. Amphibians in altered habitats may be subject to multiple anthropogenic stressors that have dramatic implications for population maintenance. Aquatic contaminants are ubiquitous and likely present a long-term challenge to amphibian health. Previous studies have documented altered stress hormone (corticosterone) levels in amphibians caused by contaminant exposure in both laboratory and field settings. In addition to primary effects on metabolism, altered corticosterone regulation may in turn influence diverse processes such as development, immunity, reproduction, and behavior. Here, we investigate the effects of the most important insect-killing systemic pesticide class, the neonicotinoids, on amphibian corticosterone regulation and associated physiology. Imidacloprid is the most commonly used neonicotinoid pesticide and has been found to contaminate aquatic environments yet little information is available on its effects in exposed aquatic animals. This study assessed the effects of imidacloprid exposure in the African clawed frog (Xenopus laevis) as a model for wild populations. Adult male (X. laevis) were exposed to environmentally relevant concentrations of imidacloprid by immersion for 48 days. Plasma corticosterone, metabolic, and immune endpoints were examined from samples collected under baseline and handling-stressed conditions. This study provides insight into the effects of a highly used, yet not extensively studied, aquatic contaminant on amphibian physiology.
