Effects of dimethoate on tree frog (Hyla arborea) larvae

Considering the global decline of amphibian populations, the present study aimed to investigate the sensitivity of tree frogs to a common pesticide, dimethoate. Our study reports the effects of dimethoate on 21st - and 25th-stage Hyla arborea larvae under standardized laboratory conditions in an acute toxicity test using the static system. Specimens used for testing were obtained from the eggs of mating pairs collected at a local natural pond. Each experimental group contained 10 healthy larvae exposed to 5 different concentrations of technical grade dimethoate for 96 h. For each concentration, including the controls. 3 replicates were used. The concentrations of dimethoate causing 50% mortality (LC50) after 96 h were estimated using a probit analysis program. Regarding the lethal concentrations, 21st-stage larvae were more sensitive (LC50 = 20.27 ppm) than the 25th-stage larvae (LC50 = 37.37 ppm). Malformations such as edema and tail deformaities were observed in 21st- and 25th-stage larvae, respectively. Retardation of growth was also observed in dimethoate-exposed 21st-stage larvae. Certain signs of toxicity. such as initial hyperactivity symptoms, followed by loss of balance, motionlessness, and finally death, were observed. © TÜBİTAK