Influência da temperatura atmosférica e da redução da umidade do solo sobre o potencial tóxico de clotianidina para colêmbolos folsomia candida, em neossolo

Abstract

The effects of increasing atmospheric temperature and the reduction of soil moisture on the toxicity of a commercial formulation for seed treatment based on clothianidin were assessed through chronic toxicity tests with collembolans Folsomia candida in a natural tropical soil (Entisol). The risk of clothianidin for collembolans was also evaluated using the ToxicityExposure Ratio (TER) approach. To carry out the tests, the organisms were exposed to increasing concentrations of clothianidin at temperatures of 20, 25 and 27 ºC in combination with two soil moisture conditions: 30 and 60% of the water holding capacity (WHC). The effect of temperature and soil moisture on collembolans reproduction was verified through the number of F. candida juveniles generated after 28 days of exposure to the insecticide in the soil. It was observed that the increase in atmospheric temperature increased the toxicity of clothianidin based on the EC50 values (concentration that reduces collembolans reproduction by 50%, compared to the control). The influence of soil moisture on the toxicity of the molecule was not clear (based on EC50 values), however, there was a reduction in collembolans reproduction in all treatments with lower soil moisture (including the control). In general, when estimating the environmental risk of clothianidin for F. candida in Entisol, the TER values also showed increased risk with increasing temperature, indicating that climate change scenarios should be considered in pesticide environmental risk assessments. and that the findings of this study are somewhat worrying, as they may represent a change in soil balance.