Abstract
Buckwheat (Fagopyrum esculentum) is an important source of nutrition for humans, providing essential nutrients such as protein, fiber, vitamins, and minerals. Its cultivation is highly attractive to flower-visiting insects, which find abundant nectar and a moderate amount of pollen grains. This study aimed to characterize the taxonomic diversity and composition of flower-visiting insect communities in buckwheat crops across two sites in Chitwan district, Nepal and to assess whether temperature and relative humidity influence community structure. We further quantified the contribution of insect pollination to buckwheat yield by comparing pollinator-excluded plots (net-covered) with open-pollinated plots. In addition, we estimated the economic value of insect-mediated pollination and the nutritional contribution of buckwheat production on a per capita basis. Data were analyzed using non-metric multidimensional scaling, permutational multivariate analysis of variance, similarity percentage analysis, and (generalized) linear mixed-effects models. We found significant differences in flower-visiting insect community composition between the two study sites, independent of temperature and relative humidity, with twelve taxa contributing most to this dissimilarity. Open-pollinated plots exhibited higher buckwheat yields than pollinator-excluded plots, highlighting the importance of insect visitation for crop production. Despite the presence of managed Apis species, we recorded frequent visitation by flies and solitary bees, indicating that these taxa are likely important contributors to buckwheat pollination at local scales. Similarly, insect-mediated pollination significantly increased buckwheat production, and its absence would result in substantial economic losses of USD 2.6 million and reduced nutritional contributions, highlighting the vulnerability of buckwheat-based food security for the Nepalese communities due to pollinator decline.