Effects of landscape metrics on Apis and non-Apis pollinators and seed set in common buckwheat

Crop pollination is an essential ecosystem service, which, when provided by wild pollinator species, can be negatively affected by human activities at a landscape scale. Various pollinator species can be affected by landscape factors and/or act at different spatial scales. We investigated whether different landscape factors at different spatial scales are correlated with pollinator abundances and pollination success. We examined common buckwheat, which is a self-incompatible crop species, pollinated by managed honeybees, native honeybees, and wild non-honeybee insects. To determine the effects of landscape factors at different spatial scales, we sampled flower-visiting insects and recorded seed sets. Results from the sampled flower visitors indicated that the abundances of managed honeybees, native honeybees, and wild non-honeybee insects were significantly related to the distance of managed hives, the area of forest cover within a 3-km radius, and the area of forest and grassland cover within a 100-m radius, respectively. Additionally, the latter two influential factors of the landscape, but not the distance of managed hives, showed significant positive correlations with the seed set. These results suggest that considering landscape factors at different spatial scales associated with the characteristics of managed and wild pollinators would help to ensure crop yields.