Seed predation increases with ground beetle diversity in a Wisconsin (USA) potato agroecosystem

Agri-environmental schemes (AES) are hypothesized to enhance biodiversity and ecosystem services in agroecosystems. We investigated how non-crop habitats in one AES influence seed-eating ground beetles (Coleoptera: Carabidae) and post-dispersal weed seed predation, an ecosystem service provided by these beetles. We found that the abundance of beetles was higher in the non-crop habitats than within the crop fields. Species diversity (measured by Simpson's D), however, was greater in crop fields than in non-crop habitats. In addition, beetle assemblages were distinct between the crop and non-crop habitats possibly due to differences in the frequency and intensity of disturbance between crop and non-crop habitats. Seed predation by small predators (mainly ground beetles) was greater in the non-crop habitat than within the potato field. Moreover, we found a positive association between seed predation and beetle diversity both within the crop and in the non-crop habitat which provides evidence of a relationship between biodiversity and ecosystem services. Yet, differences in species assemblages suggest that species identity also affects rates of seed predation.