Pesticides: effects of acute and chronic exposure of diflubenzuron and pyriproxyfen in zebrafish (Danio rerio)

Abstract

The production and release of pesticides in Brazil have significantly increased in recent years, resulting in the presence of many unknown chemicals in the environment. Diflubenzuron (DFB) and Pyriproxyfen (PPF) are two pesticides belonging to the class of insecticides widely used in agricultural crops and urban areas. This study aimed to evaluate the effects of acute and chronic exposure to diflubenzuron, pyriproxyfen, and their mixtures on the survival, ontogenetic development, and behavior of Zebrafish (Danio rerio). For these evaluations, Zebrafish embryos were exposed to different concentrations of both products (0.025, 0.125, 0.25, 1.25, 2.5, and 10 mg/L) in an acute exposure for 120 hours post-fertilization (hpf), as well as to their mixtures: 0.025 mg/L PPF + 10 mg/L DFB (Mix A), 0.125 mg/L PPF + 10 mg/L DFB (Mix B), and 0.25 mg/L PPF + 10 mg/L DFB (Mix C). Mortality, teratogenicity, and cardiotoxicity were observed in treated animals and their control groups (water and DMSO) throughout the exposure. For neurotoxicity assessment, optomotor response and avoidance tests were used. In the chronic exposure, embryos were exposed for 30 days, using concentrations of 0.025 and 0.125 mg/L (DFB) and 0.379 and 0.758 mg/L (PPF) obtained from the LC50 calculation. After chronic exposure, the animals were tested for new tank, aggression, and sociality tests. The results of the acute exposure demonstrated that survival and hatching were affected by the concentrations of PPF and DFB and by the pesticide mixtures at lower concentrations. Exposure to the mixtures caused more malformations than isolated exposure, suggesting a potentiating effect. After chronic exposure, the fish exposed to DFB showed greater reductions in locomotor patterns, while those exposed to PPF spent more time at the top of the water column. The findings indicate that DFB alters locomotor patterns, and PPF alters social and environmental perception patterns. Thus, it is important to reduce the use of these types of pesticides in both agricultural and urban environments to minimize effects on the health and well-being of animals and humans, as well as on the environment