Agricultural Use of Insecticides Alters Homeostatic Behaviors and Cognitive Ability in <i>Lymnaea stagnalis</i>

Lymnaea stagnalis is an ecologically important, stress-sensitive, freshwater mollusk that is at risk for exposure to insecticides via agricultural practices. We provide insight into the impact insecticides have on L. stagnalis by comparing specific behaviors including feeding, locomotion, shell regeneration, and cognition between snails collected at two different sites: one contaminated by insecticides and one not. We hypothesized that each of the behaviors would be altered in the insecticide-exposed snails and that similar alterations would be induced when control snails were exposed to the contaminated environment. We found no significant differences in locomotion, feeding, and shell regeneration of insecticide-exposed L. stagnalis compared with nonexposed individuals. Significant changes in feeding and shell repair were observed in nonexposed snails inhabiting insecticide-contaminated pond water. Most importantly, snails maintained and trained in insecticide-contaminated pond water did not form configural learning, but this cognitive deficit was reversed when these snails were maintained in insecticide-free pond water. Our findings conclude that insecticides have a primarily negative impact on this higher form of cognition in L. stagnalis. Environ Toxicol Chem 2023;42:2466-2477. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.