Assessing the impact of agricultural strategies on soil Artropods: a case study using environmental DNA

Elucidating how agricultural practices affect soil arthropod’s communities is of relevant for both scientific and economic interests. Thus, using DNA metabarcoding approach, Arthropods communities inhabiting soil of organic and conventional farms were characterized. Soil samples were collected from organic and conventional farms, covering the margin and three levels towards the center of a stable meadow and a barley field in both farms; each sample consisted of 10 homogenized cores of soil (~560 cm3), sampling was performed in spring, summer and autumn Soil texture, pH, N and C parameters were measured. DNA was extracted from three replicates of each soil sample. A fragment mitochondrial cox1 was amplified using three primer pairs and sequenced using Illumina Miseq. Raw sequences were processed and analyzed using Qiime to obtain Operational Taxonomic Units (OTUs) table. Approximately 75% of the obtained reads were identified as Animalia, and among these ~80% as Arthropods. α-diversity indices barley field in conventional farming were significantly lower (OTUs= 854, H'= 5.34±0.53, Pielou’s evenness= 0,77±0,06) comparing with the other samples (OTUs> 1100, H'> 6 and Pielou’s evenness> 0,8). Fitting the farming system, the field, position as factors in NMDS showed that Arthropods communities were not affected by the collecting season and the farming system (organic vs conventional), instead crop vs stable meadows and the position in the field (margin vs middle) have a strong effect. Soil properties affected the Arthropods communities, especially the pH on Chilopoda and Diplopoda and the C/N ratio on Arachnida and Insecta. Our results pointing out that the strategy of farm management does not affect the arthropod communities of the soil as much as the soil properties itself, while the position in the filed had a major effect, highlighting the importance of green corridors for maintaining the soil biodiversity and the agroecosystem functioning.