Can agricultural fungicides be a source of stress for non-target soil organisms? An ecotoxicological study on Eisenia fetida (Savigny, 1826)

Plant protection products, highly used in agriculture, can represent a source of stress for non-target soil organism and have a negative effect on ecosystems’ health. In particular, information on toxicological effects of fungicides are very poor or absent, despite their widespread use. The aim of this study was to evaluate the potential toxic effects of 4 commercial fungicides (Prosaro®, Amistar®xtra, Mirador® and Icarus®) on the earthworm Eisenia fetida (Savigny, 1826). Laboratory experiments were conducted using the filter paper test (FPT): E. fetida was exposed to increasing concentration of Prosaro® or Amistar®xtra, being the highest dose of treatment the recommended one for the usage in wheat farming. Field investigations were conducted transplanting E. fetida in cages in the soil of wheat and durum wheat fields before and during treatment with different combinations of the 4 fungicides. E. fetida specimens from laboratory and field work were analysed to evaluate vitality, potential neurotoxic effects (inhibition of acetylcholinesterase activity (AChE)), phase II enzymatic defense (glutathione S-transferase (GST)), oxidative stress (lipid peroxidation (LPO) and catalase (CAT) activity), genotoxic effects (Comet assay) and effect on the immune system (lysozyme activity). Laboratory studies with Prosaro® and Amistar®xtra showed alterations in organism’s vitality which increased with increasing treatment doses. Significant alteration of phase II metabolising enzymes (GST induction) and significant DNA fragmentation (Comet assay) with respect to controls were detected at environmentally relevant doses of Prosaro®. A statistically significant induction of GST was found in earthworms transplanted in the fields treated with Amistar®xtra alone and Amistar®xtra + Prosaro®. This study represents a first step towards a better understanding of commercial fungicides toxicological potential to non-target organisms. Data obtained indicate that deeper investigations are needed which should include long term artificial soil tests (AST) and further field studies