Time-dependent responses of the freshwater fish Australoheros facetus exposed to the neonicotinoid insecticide imidacloprid.

ITURBURU FERNANDO GASTÓN; GÖTTE JESSICA YAMILA; MENDIETA JULIETA; MENONE MIRTA LUJÁN; PANZERI ANA

Gainesville, Florida

Encuentro; 5th Young Environmental Scientists Meeting; 2016

Society of Environmental Toxicology and Chemistry

Neonicotinoids insecticides have been incorporated in agriculture increasingly in the last years. Nevertheless, some of these compounds have been banned temporarily in Europe because of its suspected toxicity to non- target insects. The objective of this work was to evaluate Imidacloprid (IMI) sublethal responses in the cichlid fish Australoheros facetus, testing antioxidant enzymatic responses and genotoxic effects. For this purpose, an acute time-response assay was carried out, exposing fish to 100 g/L IMI during 12, 24 and 48 h. Catalase (CAT), superoxide dismutase (SOD) and glutathione-S- transferases (GST) activities and H2O2 content were measured in liver, gills and brain, and micronuclei frequency (MN) was counted in red cells of blood. The biochemical biomarkers were determined by spectrophotometry. The MN was analyzed using an optical microscope.Catalase activity increased in liver and gills at 12 h, and returned at its basal activity levels at 24 and 48 h. This quick response was possibly due to detoxifycation of reactive oxygen species in gills, which are the first barrier for hydrophyllic compounds dissolved in water (like IMI). The activity of SOD increased at 24 h in brain, but at 48 h it decreased beyond the control baseline. This inhibition of SOD at 48 h was also observed in liver. GST resulted inhibited and the H2O2 content increased at 48 h only in brain. The MN frequency increased at 24 h. Previous work with this species have shown that brain can accumulate IMI from 24 to 48 h in brain. Therefore, the responses observed in the present assay indicate that it was a target organ in A. facetus. The significant increase of MN showed that IMI is genotoxic and the decrease of MN frequency at 48 h may be due the process of apoptosis in cells with DNA damage, but further studies are needed to test this hypothesis.All these responses observed were detected at the relatively high concentration of 100 g/L IMI, but still environmentally relevant taking into account the levels reported in the international literature.