Mendez-Rivera_2022_Aquat.Toxicol_250_106231

Conventional agriculture uses pesticides intensively. Once pesticides are released into the environment, they can be toxic to non-target organisms. Exposure of amphibians to pesticides can be lethal and affect their growth, development and behavior. beta-endosulfan is a persistent organochlorine that has been detected in environmental samples within protected sites in Costa Rica, far from agricultural areas. The aim of this study was to evaluate the lethal and sublethal effects, as well as changes in three biomarkers (Cholinesterase activity [ChE], glutathione S-transferase activity [GST] and lipid peroxidation [LPO]) in tadpoles of Isthmohyla pseudopuma exposed to beta-endosulfan. A 96-h acute test (20, 40, 60, 80, 100 and 200 microg/L) was performed in order to calculate the median lethal concentration (LC(50)), while effects on growth and development were assessed during a 4-weeks chronic test (10, 20, 30 and 50 microg/L). In addition, we measured the aforementioned biomarkers in tadpoles exposed to concentrations below the LC(50). The 96-h LC(50) for this species was 123.6 microg/L. We found no evidence of beta-endosulfan influencing any of the three biomarkers evaluated. At 50 microg/L, both length and total weight of tadpoles decreased with respect to the control. Also, at 30 and 50 microg/L we observed that individuals showed a slower development. Therefore, we demonstrated that at sublethal concentrations, beta-endosulfan negatively affects I. pseudopuma at early stages causing tadpoles to develop slower and smaller than normal.