Behavioral Responses of Unio tumidus Freshwater Mussels to Neonicotinoid Pesticide Contamination

This investigation examined the behavioral responses of freshwater mussels to neonicotinoid pesticide exposure, a widely implemented agricultural crop protection agent. The study systematically evaluated the behavioral modifications of U. tumidus under controlled laboratory conditions, with particular emphasis on shell dynamics and activity patterns during both acute (2.5 h) and prolonged (20 h) exposure to imidacloprid at 50 µg/L concentration. The experimental findings revealed consistent and statistically significant behavioral alterations. Upon initial pesticide exposure, specimens exhibited an immediate reduction in shell aperture, followed by a sustained period of enhanced opening amplitude. Activity metrics demonstrated acute elevation immediately post-exposure, indicative of stress-induced responses, subsequently achieving homeostatic equilibrium before declining in later temporal phases. These behavioral modifications demonstrated statistical significance across all four experimental iterations, indicating a robust and reproducible stress response pattern. This study demonstrated that exposure to high concentrations of the neonicotinoid pesticide imidacloprid significantly affects the freshwater mussel causing significant, repeatable changes in mussel behavior: initial shell closure followed by prolonged opening and increased activity, indicating stress and subsequent toxic effects.