Potencial tóxico do fipronil para colêmbolos Folsomia candida em latossolo sob o cenário de mudanças climáticas

Abstract

Brazil is on the list of the largest consumers of pesticides in the world; in this scenario, climate change resulting from anthropogenic action can affect the yield of crops and lead to a decrease in agricultural production. To avoid this situation, farmers use pesticides to mitigate the effects of climate change and keep pests away from crops, one of them being the active ingredient (a.i.) fipronil, used in seed treatment and that has as its mode of action the blockade of the chloride channel, inhibiting the receptor of gamma-aminobutyric acid (GABA). Despite being beneficial from the point of view of crop protection, it has a toxic effect on non-target species, which can be amplified by the climate changes that have occurred on a global scale. Thus, we proposed to study the impact of fipronil on springtails of the species Folsomia candida in Brazilian Oxisol under standard conditions – 20 °C and 60% of the water holding capacity (WHC) - and under the condition of simulating climatic effects - temperature increase of 25 and 27 °C and decrease of moisture content to 45% WHC under increasing concentrations of fipronil. The parameters evaluated were: concentrations that reduce 10 and 50% of the juveniles generated (EC10, EC50), highest concentration with no observed effect (NOEC), lowest concentration with observed effect (LOEC), and toxicity exposure ratio (TER). Fipronil reduced the collembolans reproduction in all tested scenarios, being this effect even higher under the most extreme conditions, where only the drought condition, even in control, represented a stressful factor to the organisms. Thus, it obtained the lowest value of EC10 and EC50 in the condition of 27 °C and 45% WHC. The increase in the effects of the a.i. was also observed for the value of EC10, which, for 45% and 60% WHC at 27 °C compared to 20 °C was 7 and 1.2 times higher, respectively. Finally, the estimated toxicity exposure ratio for a soybean crop with seed treated at a concentration of 200 mL kg-1 seed indicated that there is significant risk (TER<5) for the ecosystem under all conditions proposed in the study.