Impacto de inseticidas sobre o comportamento de colêmbolos folsomia candida (collembola)

Abstract

The active ingredients (a.i.) selected have systemic action to combat insect pests in agricultural crops, and their mode of action is on the central nervous system of the organisms. Despite the increased use of selected molecules, the effect of these treatments has on non-target organisms living in the soil is unknow. This study aimed to evaluate the influence of the insecticides imidacloprid (IMI), clothianidin (CLO) and fipronil (FIP), used in seed treatment, on the behavior of Folsomia candida springtails in two types of Brazilian soil: Oxisol and Entisol. Thus, avoidance tests were carried out in the laboratory and based on guidelines of ISO 17512-2:2011, under controlled temperature and light conditions. The IMI was tested in both soils and the concentrations used were 1, 2, 4, 8 and 16 mg of a.i. per kg of dry soil (mg kg-1 ). To CLO, the concentrations was 0.04, 0.06, 0.09, 0.135 and 0.2 mg kg-1 for Oxisol, and 0.017, 0.026, 0.04, 0.06 and 0.09 mg kg-1 for Entisol. And to FIP, the concentrations of 1, 2, 4, 8 and 16 mg kg-1 and 2, 4, 8, 16 and 32 mg kg-1 were used, in Entisol and Oxisol, respectively. The tests were carried out in 5 repetitions per treatment, including a double control with soil without contaminants. Avoidance percentages were calculated for each treatment, and the Fisher's exact test was used to detect whether there was a significant avoid response at any concentration tested. The results found indicate that the i.a IMI, CLO and FIP, in their commercial formulations, caused a preferential effect on springtails in Oxisol and Entisol. In clayey textured soil, IMI and FIP caused significant avoid at the lowest concentrations tested, while only the highest concentration of CLO was avoided. Furthermore, at the highest concentrations of IMI and FIP, preference for contaminated soil was verified. In sandy soil, no significant avoidance was observed at any concentrations of the three molecules tested. However, in this type of soil, for most of the concentrations tested, a greater number of individuals was found in the contaminated soil, indicating a possible paralysis of individuals due to the mode of action of the insecticides being neurotoxic. Therefore, it was evident that the properties of the soil can affect the behavior of springtails, when exposed to contaminated soil with insecticides used in seed treatment. It can be concluded that the properties of the soil can influence the availability of pesticides in the soil, which can affect the behavior of springtails in the presence of insecticides.