Short-term effects of two fungicides on enchytraeid and earthworm communities under field conditions

Abstract

Because of the wide use of pesticides in agriculture, there is still a need of higher-tier field studies to assess ecotoxicological effects of commercial formulations on a wider variety of non-target soil organisms such as soil annelids. We here tested the effects of different concentrations of two fungicide formulations, i.e., Cuprafor Micro (composed of 500 g kg copper oxychloride) and Swing Gold (composed of 50 g l epoxiconazole and 133 g l dimoxystrobin) on two families of terrestrial oligochaetes (Lumbricidae and Enchytraeidae) after 1 month of exposure. We also assessed the feeding activity of soil organisms using the bait lamina method. Along with the feeding activity, the enchytraeid density, diversity and communities were not different in the control and the contaminated plots. By contrast, epigeic earthworms were absent and earthworm diversity and densities of anecic species decreased significantly in the plots contaminated at ten times the recommended dose of the Swing Gold formulation. The copper fungicide (at 0.75 and 7.5 kg Cu ha) and the treatment with the pesticide mixture (Cuprafor Micro at 0.75 kg Cu ha and Swing Gold at the recommended dose) did not affect Oligochaeta communities compared with the control, except the Shannon index for earthworms in the mixture of both fungicides. Responses of the two annelid families to the tested pesticides were different with higher effects observed on the diversity and the community structure of earthworms compared with enchytraeids. This study allowed detecting early changes on oligochaete populations after pesticide application.

A two years field experiment to assess the impact of two fungicides on earthworm communities and their recovery

“…Cuprafor Micro® made of copper oxychloride and used in organic farming; Swing® Gold made of dimoxystrobin (DMX) and epoxiconazole (EPX), and used in conventional farming) on earthworm communities under field conditions over two years. This study is the continuation of a previous study conducted by Amossé et al (2018). They showed that Swing® Gold at 10 × the recommended field rate (RR) drastically reduced anecic and epigeic earthworm diversity and abundances one month after application.…”

“…These significant effects found at short term (i.e. one month after application) in Amossé et al (2018) persisted for at least twelve months after the fungicide application.…”

“…The study site was a meadow located in Versailles, France (48°48'31''N, 2°05'26''E) that had not received pesticides for more than 20 years. Detailed information about the experimental site is described in Amossé et al (2018).…”

“…The experimental trial consisted of four replicates of six treatments randomly located (24 plots, see Amossé et al, 2018). In accordance with the guideline (ISO 11268-3, 2014), the area of each plot was 100 m² (10 m x 10 m), and the whole 100m² area was treated with fungicides.…”

“…Considering these results and the lack of knowledge regarding the pesticide effects over a long period in field trials, we assessed the effects of these fungicides on the different earthworm species present in this field and the recovery of the earthworm community. The experimental design presented by Amossé et al (2018) was thus followed with the investigation of the earthworm abundance, biomass, and diversity at 1, 6, 12, and 24 months after the first fungicide applications (MAFA). We tested the following hypotheses: 1) the two fungicides have different effects (amplitude and duration) on the different earthworm ecological groups and species, 2) the mixture of the two fungicides has stronger effects than those observed for each fungicide applied separately.…”