Keywords: Rhinella arenarum, larval development, amphibians, tadpoles, cypermethrin, commercial formulation, agrochemicals, lethal effects, sublethal effects, morphological alterations, toxicity bioassays, insecticides, risk assessment, agroecosystems
Comparative toxicity of cypermethrin and a commercial formulation on Rhinella arenarum larval development (Anura: Bufonidae)
In this study we report the effects of cypermethrin (CY), a growing use insecticide, comparing the toxicity of the active ingredient (AI) and a commercial formulation (CF) on a non–target organism, Rhinella arenarum. The results showed a highly significant increase (p < 0.05) toxicity of both substances over time, obtaining a 96 h LC–50 of 28.07 mg CY/L and 11.20 mg CY/L, and a 336 h LC–50 of 0.0048 mg CY/L and 0.00065 mg CY/L, for AI and CF, respectively. Furthermore, the toxicity of CF was greater than AI at all exposure periods, reaching up to seven times. The larvae presented alterations in behaviour as hyperkinesia and spasmodic contractions up to total absence of movements. Considering these results and the risk assessment conducted, we conclude that CY represents a potential direct risk considering lethality, or indirect by sublethal effects for the survival of this amphibian in agroecosystems.