Avaliação da toxicidade da associação dos herbicidas imazetapir e metsulfurom metílico, no modelo Eisenia fetida

Abstract

By the increasing demand for food, the traditional model of agriculture has been replaced by planting with applications of chemical fertilizers and agrochemicals in monoculture systems in order to increase their productivity. The exacerbated use, besides contaminating the various compartments of the environment, contributes directly to the destructuring of biodiversity. The E. fetida species adopted for this study is recommended and accepted in international protocols for toxicity testing. The objective of this study was to evaluate the effect of the commercial herbicides Vezir and Ally and their association on the survival, behavior and reproduction of the E. fetida test organism. The method consisted of the exposure of E. fetida individuals to various concentrations of the herbicides Vezir, Ally and their association. The guidelines established for the acute toxicity, reproduction and leakage tests were performed in accordance with ISO 11268-1 (ISO, 2012), ISO 11268-2 (ISO, 2012), ISO 17512-1 (2007) and ABNT NBR 15537 (2014). The individuals were divided into eight groups: Control, two LC50s individually (1000 mg Ally / kg and 2388.89 mg Vezir / kg, three groups exposed with LC50 association (25, 50 and 100%) of the two herbicides, two groups with the concentrations recommended for application to the rice culture and the association with this concentration. The animals were exposed for a period of 40 days. , The results suggest that the addition of these substances may lead to egg reduction, hatching, and appearance of new individuals, even at recommended doses, which did not present significant decrease in the short term, but in the long term may result in significant population losses; And mainly in high doses, which presented more immediately its negative effects on reproduction. The organisms exposed to Ally + Vezir LC50 and LC50 concentrations, respectively, 250 + 597.22 (25%), 500 + 1194,445 (50%) and 1000 + 2388.89 (100%) had a significant mortality rate and loss of biomass when compared to control. The associated doses of both the LC50 and the recommended exceeded the individual dosages negatively, with respect to biomass gain, and reproduction. No leakage behavior was observed at the recommended doses, however they presented: Slowness, rigidity, and insensitivity to mechanical stimuli. Lastly this study provides an important contribution to the knowledge of the toxicity of the herbicides Ally and Vezir, since these products are often applied together. It should also be noted that in the application of these herbicides caution should be exercised, since in practice there is no guarantee that the recommended dosage is in fact applied by farmers and that the irresponsible use of the herbicide may harm the local ecosystem.