Diversity of co-flowering plants at field margins potentially sustains an abundance of insects visiting buckwheat, Fagopyrum esculentum, in an agricultural landscape

Pollinators have been declining in recent years due to changes in land use, and the negative impacts on food production are concern. Wildflowers play an important role in maintaining pollinators and pollination services in agricultural landscapes, but little is known about the effects of wildflowers at field margins on crop pollinators. We aimed to clarify the relationship between crop pollination and the species richness of wildflowers at field margins through sharing of flower visitors. We focused on insects that visit the flowers of buckwheat, Fagopyrum esculentum, in fields in Japan. Field surveys were conducted to investigate flower-visiting insect communities in both the pre-blooming and blooming periods of buckwheat in summer and autumn. The community structure of flower-visiting insects differed between buckwheat and wildflowers in both seasons, but buckwheat shared beetles with co-flowering plants in autumn. The abundance of insects visiting buckwheat increased with species richness of co-flowering plants in autumn but was not related to wildflowers in summer. The morphological similarity of floral traits would not be important for these positive effects of wildflowers. Thus, co-flowering plants have positive or neutral effects on the insects visiting buckwheat, which may contribute to the enhancement of buckwheat yields.