Using pollen DNA metabarcoding to profile nectar sources of urban beekeeping in Kōtō-ku, Tokyo

OBJECTIVE: Apis mellifera is a species of honeybee that has been introduced around the world as an industrial beekeeping species. Recently, urban beekeeping has attracted attention as a means of ecosystem protection and urban greening. This study aimed to investigate nectar sources of urban beekeeping in Kōtō-ku, Tokyo using pollen DNA metabarcoding. RESULTS: We extracted DNA from pollen collected by the honeybees of a local urban beekeeping operation. DNA metabarcoding analysis was carried out by sequencing a part of the rbcL region of the chloroplast genome. A total of 31 samples collected between mid-March, 2018 and mid-October, 2018 yielded 54 operational taxonomic units (OTUs) comprising 14 families, 32 genera, and 8 species. Whereas 5 OTUs were profiled throughout all seasons, 38 OTUs were season-specific (spring, summer, or autumn). Therefore, we were able to infer seasonal nectar sources for the beekeeping operation at the family or genus level, as well as at the species level to a lesser extent. Our pollen-sampling strategy was effective for profiling season-specific nectar sources, with the exception of a few anomalies that can be accounted for by out-of-season flowering associated with artificial gardening and/or pollen accumulation over multiple seasons.