The current study is an attempt to compare the potential effects of acute exposure of two widely used insecticides, chlorpyrifos (CPF) and indoxacarb (IDC), on the histopathology of fish brain and its impact on locomotory behavior of a catfish, Heteropneustes fossilis, as a non-target species. In our study, fishes of lentic habitats (n = 12/group) were exposed to LC50 doses of CPF (1.92 mg/l) and IDC (0.075 mg/l) for 96 hours. During the experiment, locomotory activities of control and exposed fishes (n = 6/group) were recorded at a regular period by ANY-MAZE software (Stoelting Co., Chicago, IL). At the endpoint of 96 hours, fishes were sacrificed for the histopathological study of the telencephalon region of the brain. The CPF toxicity induced highly degenerative changes and vacuolization in the neuronal cells of dorsal pars medialis (dDm) of the telencephalon, and substantial disturbances in the swimming pattern of mobile and immobile episodes, rotational locomotory movements; whereas IDC induced mild pathological changes in the dDm of telencephalon of fish brain, and irregular locomotory behavior in H. fossilis when compared to the control group. Thus, the present study concludes that IDC was found to be less toxic than CPF. Hence, IDC could be an alternate choice of the CPF at equal concentrations.
Key words: Chlorpyrifos, Indoxacarb, Telencephalon, Locomotory/swimming behaviour, H. fossilis
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