Avaliação dos efeitos do agrotóxico imidacloprido e microplástico polietileno sobre micro- artrópodes em diferentes tipos de solos

Abstract

Microplastics (MPs) and pesticides are frequently found together in agricultural soils. However, there is a significant research gap regarding the ecological impact of these pollutants, both in- dividually and in combination, on soil microarthropods. Soil organisms play a crucial role in ecological stability, promoting ecosystem resilience and facilitating vital processes such as di- sease control, soil structuring, and nutrient cycling. Therefore, this study aimed to investigate the effects of the insecticide imidacloprid and polyethylene MPs, both alone and combined, on two species of springtails (Folsomia candida and Sinella curviseta) and the predatory mite Hypoaspis aculeifer, across three distinct soil types. The results revealed differential sensitivi- ties among the species to the pollutants and significant interactions between these contaminants and the soil types. For the predatory mite H. aculeifer, low sensitivity to imidacloprid was ob- served at low concentrations, but significant adverse effects on reproduction were noted at higher concentrations, with EC50 values for reproduction of 1124 mg/kg, 84 mg/kg, and 350 mg/kg in Tropical Artificial Soil (SAT), clay soil, and sandy soil from Brazil, respectively. Sinella curviseta exhibited higher toxicity in natural soils, significantly affecting springtail re- production, with EC50 values of 0.58 mg/kg in sandy soil, 0.66 mg/kg in clay soil, and 2.89 mg/kg in artificial soil. This demonstrates the vulnerability of S. curviseta to relatively low concentrations of imidacloprid. Conversely, S. curviseta showed no negative impact on survival and reproduction when exposed to MPs in the tested soils. Meanwhile, F. candida was sensitive to both contaminants, with a significant reduction in reproduction when exposed solely to MPs, particularly in clay soil, with an EC50 of 2.4 mg/kg. When exposed simultaneously to both contaminants, F. candida exhibited significant reproductive responses, with EC20 of 0.029 mg/kg and EC50 of 0.151 mg/kg. These results indicate a considerable increase in the sensiti- vity of F. candida under dual stressor exposure. Therefore, the physicochemical properties of the soil play a crucial role in organism sensitivity to pollutants, highlighting the need for a comprehensive approach to adequately assess environmental impacts and guide sustainable soil management policies. These findings underscore the importance of considering not only diffe- rent species of terrestrial arthropods but also the contaminants and soil characteristics when evaluating environmental risks.