A DNA metabarcoding approach to characterize soil arthropod communities

Belowground arthropod communities are diverse and our ability to characterize them remains logistically difficult and time consuming. Molecular metabarcoding techniques are routinely used to assess the diversity of both microbial and some 'macrobial' taxa across a range of environments, but the use of such techniques for characterizing soil arthropod diversity remains limited. Here we used three approaches to profile soil arthropod communities at the family level of resolution across 10 distinct sites via morphological identification, metabarcoding of DNA from the extracted arthropods, and metabarcoding directly from bulk soils. Although the three methods differed to some degree in their ability to detect some individual taxa, we found that all three methods yielded well-correlated site-level estimates of diversity (Spearman's ρ ≥ 0.63 with P < 0.05 for all correlations) and overall arthropod community composition (Mantel ρ ≥ 0.45 with P < 0.05). Of particular note is that DNA extracted directly from bulk soil yielded results comparable to analyses of DNA from extracted arthropods. Thus, DNA metabarcoding of bulk soil will likely be a useful tool for those researchers looking to incorporate multi-domain comparisons or for studies that require rapid assessments of arthropod diversity across a large number of soil samples.