Among the search for new types of pesticides, the fungicide azoxystrobin (AZX) was the first patent of the strobilurin compounds, entering in the market in 1996. Its use worldwide is growing, mainly linked to soybean production, although its effects in non-target organisms are almost unknown. The goal of the present work was to evaluate effects of short-term AZX exposure to the aquatic macrophyte Myriophyllum quitense, focusing on oxidative stress parameters and DNA fragmentation. Significant inhibition of the antioxidant enzyme systems were observed at 50 μg/L AZX for catalase and peroxidase (p < 0.05). Lipid and DNA damage were significant at 50 and 100 μg/L AZX. These biomarkers were sensitive to AZX and can be used in a battery to evaluate the occurrence of AZX in freshwater ecosystems.

Azoxystrobin is a strobilurin of growing concern in aquatic environments because it is the most sold fungicide worldwide, however, the information available about its effect on aquatic non-target organisms is scarce. The objective of the present study was to evaluate potential physiological, biochemical, and genetic effects at environmentally relevant (1-10 lg/L) and elevated (100-500 lg/L) concentrations in the aquatic macrophyte Myriophyllum quitense exposed to the commercial formulation AMISTAR Ò . Following an acute 24-h exposure, there were no effects of AMISTAR Ò on photosynthetic pigments at any of the concentrations evaluated. Glutathione-S-transferase activity was significantly elevated at 1 and 10 lg/L AZX. Significant decrease of catalase and guaiacol peroxidase activities in plants exposed to 500 lg/ L, and to 100 and 500 lg/L, respectively, and an increase in glycolate oxidase activity at 500 lg/L was observed. DNA damage at 100 and 500 lg/L was observed. These data indicate that although environmentally relevant levels of AMISTAR Ò did not result cytotoxic, this fungicide was genotoxic, affecting the physiological process of photorespiration and caused oxidative damage at high concentrations. In this sense, it is necessary to explore sublethal responses in non-target organisms because some effects could promote further potential long-term biological consequences in a context of repeated pulses of exposure.

Imidacloprid (IMI) is a neonicotinoid insecticide widely used in agricultural activities all around the world. This compound is transported from croplands to surrounding freshwater ecosystems, producing adverse effects on nontarget organisms. Because of the relevance of aquatic macrophytes in the above-mentioned environments and the lack of studies of potential effects of IMI on them, this work aimed to assess the mitotic process and potential genotoxicity in the aquatic macrophyte Bidens laevis L. Although the analysis of the Mitotic Index (MI) showed that IMI was not cytotoxic, the Cell Proliferation Kinetics (CPK) frequencies evidenced modifications in the kinetics of the mitotic process. Indeed, the anaphases ratio decreased at 10 and 100 μg/L IMI, while at 1000 μg/L an increase of prophases ratio and a decrease of metaphases ratio were observed. Regarding genotoxicity, IMI produced an increase of the abnormal metaphases frequency from 10 μg/L to 1000 μg/L as well as an increase in clastogenic anaphases-telophases frequency at 100 and 1000 μg/L. In addition, aneugenic anaphases-telophases and C-mitosis frequencies also increased at 1000 μg/L, confirming the effects on the mitotic spindle. Considering the genotoxic effects on B. laevis through two different mechanisms (aneugenic and clastogenic) and the wide spread use of IMI in agriculture, these mechanisms of toxicity on macrophytes should be considered among other recognized effects of this insecticide on aquatic biota.