Biomarkers responses in the earthworm Eisenia fetida (Savigny, 1826) exposed to commercial fungicides: laboratory and field toxicity assessment

The use of pesticides in agriculture is a common practice to protect crops all over the world. However, pesticides potentially affect soil macro-and microorganism because only 0.1% of an applied pesticides reaches the target organism. Earthworm is a model organism in ecotoxicological research and it is a useful bioindicator of chemical toxicity in terrestrial ecosystem. The aim of this study was to evaluate the potential toxic effects of commercial fungicides (two foliar and two ear diseases with double and single active substance) on the earthworm Eisenia fetida (Savigny, 1826). E. fetida was exposed to sub lethal concentration of fungicides in laboratory and field condition and a set of biomarkers were investigated. In laboratory experiments, animals were exposed in a filter paper test to increasing concentration of the four fungicides. Field investigations were conducted transplanting E. fetida in cages in the soil of wheat and durum wheat fields during treatment with different combinations of the four fungicides. All the E. fetida were analysed to evaluate vitality, inhibition of acetylcholinesterase activity, glutathione S-transferase, lipid peroxidation, catalase activity, total glutathione, Comet assay and lysozyme activity. Laboratory studies with the fungicide with double active substances showed alterations in organism’s vitality which increased with increasing treatment doses. Significant alteration of GST enzymes with respect to controls were detected at environmentally relevant doses of ear deseases fungicide. The laboratory treatment with foliar fungicides caused an alteration of LPO which increased with increasing treatment doses, and an increase inhibition of lysozime activity. All the fungicides showed a total glutathione levels decrease probably due to a cellular degeneration caused by oxidative stress. The Comet assay showed the highest DNA fragmentation values in the experiment with fungicides with double active principle. In the field studies, the test proved that leaf fungicides have greater toxicity compared to those applied to the ears. Foliar fungicide with double active substances revealed to have the most toxic effects, inhibiting the lysozyme activity and determining high levels of GST and LPO. This study represents a first step towards a better understanding of commercial fungicides toxicological potential to non-target organisms and a wide set of biomarkers allowed to investigate the main toxicological effect on these organism