Increasing the quantity of forb and grass cover can enhance bee and predatory ground beetle abundance

Background/Question/Methods:  Habitat restoration has been recommended to curb the decline of bee and increase the abundance of predatory ground beetles. Regarding this fact, it is still unknown that which component of the plant coverage has the most important role to maintain and increase bee and ground beetle abundance. To answer the question that whether native prairie or weed have the same importance for bee and predatory ground beetles and to test the hypothesis that the higher forb coverage can result in higher beneficial insects, we assessed native bee communities and predatory ground beetle assemblages in strips of various forb vegetation mixes and cropped areas. We planted prairie buffer strip in four sites around Iowa, varying the proportion of prairie forbs. These sites had different populations of natural weeds. We determined identity and percent cover of prairie and weed species in buffer strip during the growing season (May to August) of 2016. In addition, using a variety of common sampling methods we captured bees and ground beetles during the growing season in strips and cropped areas.

Results/Conclusions:  Higher forb coverage can both increase the bee and ground beetle population, however, the quality of forb (prairie/weed) coverage has a different effect on bees compared to ground beetles. The increase in prairie coverage would lead to a boost in number of bees whereas weeds do not. However, only the enhancement of weed (forb and grass) can ascend ground beetles abundance.