Toxicidade das misturas dos agrotóxicos sulfentrazona, fipronil e carbendazim em embriões e larvas de zebrafish (Danio rerio)

Abstract

Contamination of surface water by pesticides is commonly associated with a combination of substances rather than a single compound, as multiple active ingredients are commonly applied simultaneously to crops and/or a variety of crops utilize the same water sources. But the current evaluation of the effects of these pesticides is predominantly based on the isolated substances, so the ecological relevance may be underestimated. Therefore, this study aimed to investigate the effects of the combined use of three pesticides, sulfentrazone, fipronil and carbendazim. For this, we analyzed lethality, sublethality and epiboly in zebrafish embryos, and behavioral changes in zebrafish larvae, through tests of thigmotaxis, touch sensitivity, optomotor response, bouncing balls and exploratory activity. The three pesticides isolated caused toxic effects on the embryos. Sulfentrazone was the most lethal, showing a significant difference in the three concentrations used, with up to 50% of egg coagulation. As well as, in the epiboly test, the isolated pesticides carbendazim and sulfentrazone, reduced the percentage of epiboly more than their mixtures in relation to the control, reducing 30% and 25% respectively. However, in the behavioral tests there were significant changes in the larvae exposed to the isolated pesticides and also their mixtures. In the bouncing balls test, all exposed groups showed a significant difference in relation to the control, with carbendazim being the one that showed the greatest difference, more than 30% difference in the response to the stimulus and 40% in the grouping of the larvae. In the exploratory activity it was possible to observe the synergistic effect of the binary mixtures, significantly in carbendazim + fipronil, reducing up to 10 cm the distance travelled and 10 cm/s the average speed of the larvae in relation to the control. Through our results we observed that the toxicity of the mixtures differs depending on the analyzed endpoints. Therefore, studies that seek to understand the effects of pesticide mixtures are important, because they will help to understand the effects more realistically, since the additive effects of these mixtures are still poorly understood.