Growth in the global development of cities, and increasing public interest in beekeeping, has led to rises in the numbers of urban apiaries. Towns and cities can provide an excellent diet for managed bees, with a diverse range of nectar and pollen available throughout a long flowering season and are often more ecologically diverse than the surrounding rural environments. Accessible urban honeybee hives are a valuable research resource to gain insights into the diet and ecology of wild pollinators in urban settings. We used DNA metabarcoding of the rbcL and ITS2 gene regions to characterise the pollen community in Apis mellifera honey, inferring the floral diet, from 14 hives across an urban gradient around Greater Manchester, UK. We found that the proportion of urban land around a hive is significantly associated with an increase in the diversity of plants foraged, and that invasive and non-native plants appear to play a critical role in the sustenance of urban bees, alongside native plant species. The proportion of improved grassland, typical of suburban lawns and livestock farms, is significantly associated with decreases in the diversity of plant pollen found in honey samples. These findings are relevant to urban landscape developers motivated to encourage biodiversity and bee persistence, in line with global bio-food security agendas.

Honey samples were sourced from 14 Apis mellifera hives; 12 from Greater Manchester, one from Cheshire and one from Lancashire. Honey samples were diluted in molecular grade water (4x 10g/25ml per sample) centrifuged at 15,000 x g for 30 minutes. DNA was then extracted from the pellet, the rbcL and ITS gene regions were amplified and PCR products sequenced on an Illumina HiSeq using a V2 flowcell. Sequencing data were analysed using the DADA2 functionality in the QIIME2 package and taxa assigned using previously published databases and the NBCI nucleotide database. Species and genus assignments were checked for plausibility in the UK using the Royal Horticultural Society Horticultural Database, the Biological Records Centre Atlas of the British and Irish Flora and the Plants for a Future database, as well as online searches of UK garden centres.

Data were processed and analysed using the R statistical platform (version 4.0.4). R scripts are included in the data files and software required is included in the scripts.