The increase in pesticide consumption has concerned regulatory agencies due to reported serious environmental impacts and public health problems. In Brazil, the insecticide fipronil and the herbicide 2,4-D have been applied intensively and simultaneously to agricultural crops. Until now, no information is available on the toxic effects of the mixture of these contaminants on non-target organisms that are indigenous to the Neotropical region. This project therefore aims to evaluate the toxic effects of fipronil and 2,4-D, separately and in mixture, on native species representatives of different trophic levels. To this end, toxicity tests will be conducted with the green algae Raphidocelis subcapitata, the cladoceran Macrothrix flabelligera and the fish Hyphessobrycon eques. The toxicity of water samples from mesocosms contaminated by multiple applications simulating actual field application practices (simulating spray drift) of the pesticides to the selected test organisms will also be evaluated. Besides lethal effects, behavioural responses such as avoidance after the fish and the cladoceran are exposed to the single pesticides and their mixtures, will also be assessed. Enzymatic responses to the pesticide treatments will also be evaluated by analysing enzyme biomarkers in the native fish H. eques. This will also be done for the exotic fish Danio rerio in order to enable comparing the sensitivity of these species based on the enzyme parameters. Besides this experimental work, this project also aims at conducting a bibliographical revision on the use of native species in the risk assessment of pesticides in the tropics and ultimately, conducting a preliminary risk assessment of these pesticides to tropical aquatic biota. The results of this research will provide a better understanding of the toxicity and potential risks of these pesticides (alone and in combination) to aquatic ecosystems and may substantiate regulatory actions by assisting the implementation of more restrictive measures for use of these pesticides.
News published in Agência FAPESP Newsletter about the scholarship: