engleski

Measuring the ecotoxicological effects of neonicotinoids onto non-target organisms

Pesticides have brought remarkable benefits to mankind by increasing food production. At the same time, continuous use of pesticides has been reported to cause severe environmental problems. This research is focused on imidacloprid (IMI) which acts as an agonist of the insect acetylcholine receptor. Although IMI is an insecticide, there is evidence that it may be harmful to algae and invertebrates. A preliminary testing of IMI stability and metabolite production was performed by LC/MS. Consequently, we have explored the baseline toxicity of IMI (pure compound), Confidor® 200SL (commercial formulation) and 6-chloronicotinic acid (IMI-metabolite) on freshwater algae Scenedesmus subspicatus. The effect of these compounds was also explored on biochemical responses of non-target species like Gammarus fossarum. The algal cultures were exposed to different doses of tested compounds and a 96-h growth inhibition test was conducted. The algal cultures were more sensitive to the commercial formulation and IMI-metabolite. Furthermore, we tested the effects on individual animal performances and biochemical biomarkers. Our data demonstrated an overall low toxicity of IMI and its metabolite, with no significant changes in the mortality rate. The commercial formulation Confidor® demonstrated an increase in mortality at higher concentrations. Both IMI and Confidor® showed an increased number of inactive animals with only respiration movements left, while IMI-metabolite induced overall animal hyperactivity. Low concentrations of IMI (0.4 μM) resulted in increased lipid peroxidation (LP) levels. Higher concentration of Confidor® (2μM) induced a significant increase of GST activity and LP, while only moderate change in catalase (CAT). Interestingly, the metabolite did not affect LP, while altered significantly only the antioxidant system (GST and CAT). These preliminary approaches are based on the use of biochemical biomarkers to monitor pesticide contamination. Nevertheless, individual performances alterations can point to possible pollution problems and potential ecological consequences.

Gammarus; algae; imidacloprid; antioxidant enzymes; lipid peroxidation

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