Conference paper, poster, etc. #40898

Summary

Agriculture intensification and in particular pesticide use can affect soil fauna and its affiliated ecological functions (e.g. organic matter decomposition). Adapted from the ISO standard method for earthworm field studies (ISO 11268-3, 2014), we tested the effects of two fungicides, i.e., Cuprafor Micro® and Swing Gold® - used respectively in organic and conventional agriculture - on oligochaetes (Lumbricidae and Enchytraeidae) and the soil functioning (i.e., feeding activity and organic matter decomposition with the bait lamina and tea bag methods, respectively). The trial consisted on four replicates of six experimental treatments (control, Cuprafor Micro® and Swing Gold® at x 1 and x 10 the recommended dose, and a mixture of both pesticides at the recommended dose, 1,5 l.ha-1 of Swing Gold® and 4 kg.ha-1 of copper) in a meadow located near the Palace of Versailles (France). After 1, 6, 12, and 18 months of experiment (i.e., t1, t6, t12, and t18), we compared the species composition of annelids and functional endpoints between treated and non-treated plots. A lower Shannon diversity index was found for earthworms in the treatment with the mixture of both pesticides at t1 and t6. However, no effect on earthworm abundance was observed in the mixture treatment mainly explained by the compensation of earthworm species. We also found a lethal effect of Swing Gold® on anecic earthworms at t1, while an effect of copper on annelids at ten times the recommended dose (40 kg.ha-1 of copper) was observed only after 12 months. These results could be explained by the various pesticide mechanisms on life history traits (i.e., growth, reproduction). However, we showed no overall significant difference in total feeding activity, enchytraeid density and diversity between treatments with or without pesticide at t1, t6, t12 and t18. In the Swing Gold® treatment, earthworm community did not fully recovered 18 months after pesticide application. This study underlines the need to study pesticide effects on non-target organisms as well as functional endpoints for more than one year after pesticide application. Another sampling campaign will be performed in spring 2018.