Evaluating the neurobehavioral toxicity of the neonicotinoid pesticide, thiamethoxam, in two fish species
Abstract
Thiamethoxam (TM) is a commonly used neonicotinoid pesticide that acts as a nicotinic
acetylcholine receptor (nAChR) agonist. TM has been detected in surface waters at levels
above aquatic life benchmarks and has raised concerns about its potential toxicity to fish.
To address these concerns, the effects of chronic exposure to environmentally relevant
concentrations of TM were determined in two fish species. Acute and chronic exposures
to 0.02-163 μg TM/L were conducted in embryonic- and larval-stage fathead minnows
and in embryonic-stage zebrafish. Endpoints to assess health and neurotoxicity were
monitored throughout the duration of the exposure, including survival, hatching, foraging
efficiency, embryonic motor activity, and predator escape behavior. TM-exposed fathead
minnows experienced reductions in survival, changes to embryonic motor activity, and
altered predator escape behavior while TM-exposed zebrafish embryos experienced
reduced hatching rates and changes to the predator escape behavior. Lastly, molecular
modeling was used to gain preliminary insight on the interactions of TM with the nAChR
between organisms. While TM does not target fish, they still experience effects as a result
of TM exposure. Taken together, this research indicates that further investigation of the
effects of TM on fish is necessary to determine the impacts of this prevalent pesticide on
the health of aquatic ecosystems.
Subject
Pesticides
Biology
Toxicity