Metabarcoding of honey to assess differences in plantpollinator interactions between urban and non-urban sites

Ever-faster rates of urbanization have led to the substantial loss of agricultural land and natural areas. Furthermore, vegetated land is often fragmented and dominated by nonnative plant species within urban areas, which is likely to impact plant-pollinator interactions. However, the study of plant-pollinator interactions is labor intensive and remains challenging. Here, we compared plant species visited by honeybees in urban versus non-urban sites, using metabarcoding to identify pollen in honey samples. We identified a total of 262 plant genera, 15 of which were represented predominantly. Samples varied greatly in terms of plant composition, the number of nonnative genera and the number of crop plant genera. Even though land cover differed between urban and non-urban sites, plant diversity in the honey did not. We discuss our results in the light of challenges associated with the spatial scale of bee activity, preference behavior in flower visitation, and statistical power.