Abordagem toxicológica de pesticidas : alterações comportamentais em peixe-zebra (Danio rerio)

Abstract

A large-scale food production necessitates the use of various chemicals to protect crops against potential losses from pests. The development of pest resistance to these chemicals, as well as improvements in their effectiveness on target species, lead to the continuous emergence of mixtures with different active principles in the market. However, elucidating the action of these chemicals on non-target species is essential. In this context, the aim of this study was to assess the influence of a commercial Bordeaux mixture (BM), consisting of commercial products containing copper, sulfur, and calcium, and a commercial insecticide (IM), containing cypermethrin and chlorpyrifos, used in viticulture and livestock farming on the behavior of zebrafish (Danio rerio). As these are commercial formulations, tests were conducted to determine the LC50 of the products. Based on these tests, exposure concentrations for behavioral assays were defined as 0.52 mg/L for BM and 0.00325 μL/L for IM. Fish were exposed to BM and IM for 48 hours, and the evaluated behaviors included locomotor parameters of speed and distance covered through an open-field test, where behaviors were observed at 1 h, 24 h, and 48 h of exposure. Social parameters of group preference, aggression, and interaction were also assessed during the 48-hour exposure period. Exposure to BM led to a decrease in distance and speed covered by the fish from 24 hours of exposure onwards. At 24 hours, the exposed group covered a distance of 23.9 ± 16.3 m at a speed of 46.6 ± 32 mm/s, while the control group covered 81.4 ± 8.6 m at a speed of 165.8 ± 17.5 mm/s. At 48 hours, the BM-exposed group covered 17.1 ± 14 m at an average speed of 36.9 ± 30.2 mm/s, whereas the control group covered a distance of 67 ± 8.6 m at a speed of 141 ± 18 mm/s. Few interactions were observed among fish exposed to BM, with an average of 6.5 ± 6.9 interactions compared to 144.8 ± 14.3 interactions in the Control group over a 5- minute period. In aggression tests, both IM and BM-exposed fish exhibited aversive behavior towards the mirror and more freezing events. These results demonstrate that the tested pesticides compromise exploratory, defensive, hierarchical, and sociable behaviors in fish, representing alterations in vital behaviors in non-target species. Therefore, it is necessary to conduct chemical characterization of these mixtures to understand their composition and the possible presence of toxic substances. Additionally, environmental assessments regarding the quantity of these chemicals in water bodies are crucial to evaluate potential risks to aquatic biota. [resumo fornecido pelo autor]