TOXICIDADE DE INSETICIDA À BASE DE IMIDACLOPRIDO EM ABELHAS NATIVAS E PLANÁRIAS DE ÁGUA DOCE

Abstract

The increase in population requires consequently an increase in agricultural production on a global scale. So, the increase in agricultural yield is also associated with the intensive and periodic use of agrochemicals. There are neonicotinoid insecticides (NNIs), a class with higher expressiveness in terms of its use worldwide, among the widely used agrochemicals for controlling pests. Imidacloprid (IMI) is a first-generation insecticide highlighted among NNIs used in a wide range of crops, although it is restricted or prohibited in many countries. Studies are increasingly needed to report safe concentrations of different compounds on terrestrial and aquatic organisms due to the potential adverse effects of IMI on non-target organisms. In this context, this study aims to evaluate the toxicity of an IMI-based insecticide on terrestrial non-target organisms (Tetragonisca weyrauchi, Tetragonisca fiebrigi, Tetragonisca angustula, and Tetragona clavipes) through ecotoxicological tests of Acute Topical Effect (ATE), Acute Residual Effect (ARE), as well as acute and chronic tests for the aquatic organism Girardia tigrina. Nominal concentration data showed that the four species of bees, T. weyrauchi, T. fiebrigi, T. angustula, and T. clavipes, exhibited different sensitivity levels when exposed to low IMI concentrations with greater sensitivity to the residual effect. Similarly, G. tigrina mortality was not found at environmentally relevant IMI concentrations. However, the insecticide significantly affected the flatworm locomotion, regeneration, and fertility. Considering the results, the data reported in this study allow for inference about lethal concentrations (in 48 h, Tetragonisca genus and in 24 h, T. clavipes and G. tigrine 9 species) that affect 10% and 50% of the test organisms (ATE: 39.96 and 610 µg a.i./L, ARE: 4.09 µg and 59.96 µg a.i./L for T. weyrauchi; ATE: 22.20 and 518.09 µg a.i./L, ARE: 3.35 and 98.85 µg a.i./L for T. fiebrigi; ATE: 8.97 and 85.84 µg a.i../L, ARE: 16.05 and 50.30 µg a.i./L for T. angustula; ATE: 1.58 and 45.20 µg a.i./L, ARE: 0.18 and 15.26 µg a.i./L for T. clavipes; 69,0806 and 113,855 mg a.i./L for G. tigrina), in addition to the NOEC (No Observed Effect Concentration - 100 µg a.i./L), and LOEC (Lower Observed Effect Concentration - 200 µg i.a./L) defined for tests with G. tigrina, which will be applied on ecotoxicology to determine safe and unsafe concentrations of IMI on non-targets. It is also expected to propose the use of T. weyrauchi, T. fiebrigi, T. angustula, T. clavipes, and G. tigrina as good bioindicators of IMI contamination, adding information that contribute to ecotoxicology and environmental protection agencies.