Genotoxic and oxidative damage in the freshwater teleost Prochilodus lineatus exposed to the insecticides lambda-cyhalothrin and imidacloprid alone and in combination

In agricultural areas insecticides mixtures are frequently used, such as the combination of the pyrethroid lambda-cyhalothrin (LC) together with the neonicotinoid imidacloprid (IMI). Because of their extensive use, these insecticides can be found in freshwater bodies producing effects on aquatic organisms. However, there is a lack of studies concerning the combined effects of LC and IMI and their possible interactions. The objective of this study was to evaluate genotoxic and oxidative effects of LC and IMI, isolated and in binary mixture, on the neotropical freshwater teleost curimba (Prochilodus lineatus). Juveniles of P. ltneatus were exposed to LC (0.15 mu g L-1), IMI (100 mu g L-1), LC + IMI or only to water (CTR) for 48, 96, 144 and 192 h. The occurrence of DNA damage (comet assay), was evaluated in erythrocytes, gills, liver and brain cells, the frequency of micronucleus (MN) and nuclear abnormalities (ENA) was measured in erythrocytes and protein carbonylation (PCC) and lipid peroxidation (LPO) were determined in gills, liver and brain. The results showed that LC and IMI, both alone and in combination, cause DNA damage in different tissues and ENA in the erythrocytes of P. lineatus. In addition, after shorter exposures a synergistic interaction between the insecticides was found in the blood and in the liver. LC showed to be the most toxic insecticide, even at much lower concentrations than IMI, causing DNA damage in all tissues analyzed, indicating that the effect of mixture is mainly due to the presence of the pyrethroid. The mixture LC + IMI also caused an increase in PCC and LPO in gills and liver after shorter exposures, indicating a probable synergistic interaction. The result of this interaction leads to an increased toxicity in shorter times, which can be harmful to fish in their natural environment.