Imidacloprid induced behavioural, thyroid functions and hepatic changes in exposed African catfish

Abstract

Imidacloprid, a systemic neonicotinoid insecticide widely used across the world, has been discovered in numerous freshwater bodies. There are vast information available on the effects of imidacloprid on freshwater fish. This study further assessed the effects of acute
doses (0, 10, 30, 50 and 70 mg/L) of imidacloprid on behaviour, swimming, hepatic and thyroid parameters of African catfish (Clarias gariepinus) after 96 hours exposure. Imidacloprid caused significant behavioural alterations (gulping, abnormal surface distribution, under-reactivity, hypoactivity, reduced opercula activity and loss of buoyancy) in the fish. Reduction in swimming speed and distance travelled was observed in fish exposed to imidacloprid. The levels of amylase significantly increased, while alterations were also recorded in the levels of hepatic (ALT, AST, total and conjugate bilirubin and lipase) and thyroid (T3, T4 and TSH) biomarkers. The findings showed that imidacloprid has the potential to harm aquatic species, justifying restrictions on the use of imidacloprid-based pesticides especially near aquatic habitats.