Rutkoski_2020_Chemosphere_250_126162

Organophosphate insecticides such as chlorpyrifos are commonly detected in surface waters around the world, where they are highly toxic to many organisms. The frog Physalaemus gracilis uses water sources located in open fields as reproductive sites, where it is exposed to insecticides. The study aimed to evaluate the lethal and sublethal effect of a commercial chlorpyrifos formulation on P. gracilis tadpoles (Anura: Leptodactylidae). In acute toxicity tests, five chlorpyrifos concentrations between 750 and 2,000 mug L(-1) were tested. Chronic toxicity, swimming activity, morphological and enzymatic changes, as well as levels of non-protein thiols (NPSH), carbonyl proteins and lipid peroxidation were evaluated at five insecticide concentrations between 11 and 500 mug L(-1). The highest mortality rate of P. gracilis tadpoles occurred at 24 and 48 h, with an LC50 of 893.59 mug L(-1). At all chlorpyrifos concentrations, tadpoles displayed reduced mobility and spasms. Morphological anomalies were observed in the mouth and intestine, especially at the highest concentrations used. Acetylcholinesterase activity decreased at 250 and 500 mug L(-1), catalase activity increased at all concentrations, and superoxide dismutase and glutathione S-transferase increased from 90 mug L(-1) to 30 mug L(-1), respectively. We also observed increases in NPSH levels at chlorpyrifos concentration starting at 30 mug L(-1) and increases in carbonyl proteins from 90 mug L(-1) of pesticide. Taken together, these data suggest that the insecticide chlorpyrifos presents acute and chronic risks for P. gracilis, causing neurotoxic effects and oxidative damage, culminating in high risk for this species.