Onthophagus taurus Increases Soil Microbes Associated with Nutrient Cycling in California Pastureland Soils

When grazed intensively, grasslands can result in biodiversity loss and increased greenhouse gas emissions. However, when grasslands are maintained using agroecological practices, they can create diverse habitats and act as carbon sinks. Carbon sequestration in soil is mediated by the soil microbial community, which is largely affected by influxes of nutrients and the soil arthropod community. One such arthropod, the tunneling dung beetle Onthophagus taurus (Schreber 1759) incorporates animal dung into the soil, influencing both the soil microbial community and nutrient cycling. While dung beetles do affect the soil microbial community, there is a dearth of studies that examine the effect of tunneling dung beetles on soil microbial communities that may be associated with nutrient cycling. This study looks at the effect of the tunneling dung beetle O. taurus on the fungal, bacterial, and archaeal community of grassland soil in an in situ experiment in California's Central Coast region, using eDNA metabarcoding of the 16S locus for bacteria and archaea and the ITS1 locus for fungi. We find that O. taurus has a clear effect on the soil microbial community and its presence increases the abundance of soil microbes affiliated with degrading plant materials and carbohydrate metabolism.