Effects of the insecticide β-endosulfan on tadpoles of Isthmohyla pseudopuma (Anura: Hylidae)

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 mu g/L) was performed in order to calculate the median lethal concentration (LC50), while effects on growth and development were assessed during a 4-weeks chronic test (10, 20, 30 and 50 mu g/L). In addition, we measured the aforementioned biomarkers in tadpoles exposed to concentrations below the LC50. The 96-h LC50 for this species was 123.6 mu g/L. We found no evidence of beta-endosulfan influencing any of the three biomarkers evaluated. At 50 mu g/L, both length and total weight of tadpoles decreased with respect to the control. Also, at 30 and 50 mu g/L we observed that individuals showed a slower development. Therefore, we demonstrated that at sublethal concentrations, beta-endosulfan negatively af-fects I. pseudopuma at early stages causing tadpoles to develop slower and smaller than normal.

Automated summary

Conventional agriculture using pesticides has toxic effects on non-target organisms. This study evaluated the lethal and sublethal effects of beta-endosulfan on I. pseudopuma tadpoles, as well as changes in three biomarkers. Results showed that at sublethal concentrations, beta-endosulfan negatively affected tadpole development.