Cypermethrin- and fipronil-based insecticides cause biochemical changes inPhysalaemus gracilistadpoles

Insecticides used for agricultural pest control, as cypermethrin-based insecticide (CBI) and fipronil-based insecticide (FBI), are constant threats to non-target aquatic organisms. This study aimed to investigate the effect of different concentrations of cypermethrin and fipronil on neurotoxicity and oxidative stress inPhysalaemus gracilis.Physalaemus gracilistadpoles were exposed to five insecticide concentrations and a control treatment, with six replicates. During the experimental period, the tadpole mortality rate was evaluated and after 168 h, the neurotoxic enzyme activity and metabolite quantification related to the antioxidant system were measured. Tadpoles reduced acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities when exposed to 20 mu g L-1CBI and at all FBI concentrations, respectively. Glutathione S-transferase (GST) and superoxide dismutase (SOD) activities showed an increase from concentrations of 6 mu g L(-1)and 20 mu g L(-1)of CBI, respectively. After exposure ofP. gracilistadpoles to FBI, inhibitions of AChE and BChE were observed at the highest concentrations evaluated (500 and 1500 mu g L-1). SOD activity decreased from 50 mu g L(-1)of FBI; however, catalase (CAT) and GST activities and carbonyl protein levels increased, regardless of the evaluated dose. We observed that both insecticides promoted oxidative stress and neurotoxic effects inP. gracilistadpoles. These results suggest that biochemical biomarkers can be used for monitoring toxicity insecticides for the purpose of preservation ofP. gracilis.

Automated summary

This study revealed that cypermethrin and fipronil had neurotoxic and oxidative stress effects on Physalaemus gracilis, including reduced enzyme activity and increased antioxidant enzyme activity. Biochemical biomarkers can be utilized for monitoring the toxicity of insecticides on P. gracilis for preservation purposes.