Plant-derived environmental DNA reveals fine-scaled community differentiation in grassland arthropods

The loss of plant diversity in grasslands is implicated as one of the main causes of arthropod decline. The loss of a single plant species can have a cascading effect on specialized arthropod species. It is thus critical to expand our understanding of plant-arthropod interactions. Detecting plant-arthropod interactions, however, has been difficult, as it requires the observation of individual plant visits. A possible solution to this problem is offered by environmental DNA (eDNA) analysis. Here, we test the utility of eDNA to detect fine-scaled community differentiation in grassland arthropods in Germany. Based on eDNA from 13 plant species, we explore community differentiation between plant species, and between flower and green parts of individual plants. We show that eDNA successfully recovers extremely fine-scaled community differentiation. Plant species, as well as plant compartment, emerge as major drivers of arthropod community composition in grasslands, with the differentiation being particularly pronounced in herbivorous arthropods. Terrestrial eDNA on plants thus appears to be deposited in a very localized fashion, making this tool ideally suited to detect very fine-scaled community differentiation. Considering the high specificity we observe in our analysis, our results highlight the necessity of integrating vegetation surveys into future monitoring of arthropod communities.