Influence of the temperature in the toxicity of herbicides 500SC® and Gamit® in tadpoles of Eupemphix nattereri (Leptodactylidae) and Rhinella schneideri (Bufonidae)

Abstract

Temperature increase and other environmental effects caused by global climate changes have documented extensive impacts on many species and ecosystems of the world. Changes in the abiotic factors can potentially alter the nature and distribution of many contaminants in the environment, and, therefore, the main challenge of ecotoxicologists is to predict the risks established by these interactions in biological level. Pesticides include the major group of toxic agents found in natural systems, and many of these compounds are derived from maintenance of sugarcane crop in Brazil. In the northwest of São Paulo - Brazil, many species of amphibians are distributed in areas of agriculture and their reproductive activities are restricted to the rainy season, which coincides with the period of greatest environmental contamination. Sulfentrazone and clomazone are herbicides widely used in sugarcane crop; however, they are considered potent environmental contaminants due to their chemical properties. Thus, the aim of this study is to evaluate the influence of temperature on the toxicity of herbicides Boral SC500C® and Gamit® in tadpoles of northwestern São Paulo Eupemphix nattereri and Rhinella schneideri. The tadpoles will be exposed to contaminants in concentrations of 0.01, 0.05 and 0.1 mg/L, under different temperature gradients (28ºC, 32ºC and 36ºC), during 3 and 8 days. We will analyze oxidative stress parameters by evaluating enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PDH) and lipid peroxidation. Enzymes activity of glutathione S-transferase (GST), acetylcholinesterase (AChE) and carboxylesterase (CBE) also will be evaluated and the rates of growth, development and malformations of the tadpoles will be recorded after exposure to different treatments. (AU)