Acute Toxic Effects of Malathion on the 21^st Stage Larvae of the Marsh Frog


Abstract: Currently, amphibian decline is accepted as a global problem. One of the most important proposed causes for the decline is the use of agrochemicals, especially pesticides. Nevertheless, information about the impact of pesticides on amphibian populations remains scarce. The present study sought to identify the effects of malathion, an organophosphorus insecticide, on 21^{st} stage larvae of the marsh frog, Rana ridibunda, with an acute toxicity test using a static system. Each experimental group contained 10 healthy larvae and was exposed to different concentrations of technical and formulation grade malathion for 96 h. Concentrations of malathion that caused 50% mortality (LC_{50}) at 96 h were estimated using a probit analysis program. The results showed that formulation grade malathion (LC_{50} = 29 ppm) was more toxic than technical grade malathion (LC_{50} = 38 ppm). Malformations, certain signs of toxicity (hyperactive symptoms, loss of balance, motionlessness, and death), and growth retardation were observed in malathion-treated larvae.

Keywords: Acute toxicity test, malathion, organophosphorus insecticide, Amphibia, anuran larvae, marsh frog, Rana ridibunda

Full Text: PDF