Complex urban environments provide Apis mellifera with a richer plant forage than suburban and more rural landscapes

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.全球城市开发进程的持续推进，加之公众对养蜂兴趣的日益高涨，推动了城市养蜂场（apiary）数量的增长。城镇可为人工管理的蜜蜂提供优质的食物来源：漫长的花期内可获取多样的花蜜与花粉，且城市生态系统的多样性往往高于周边乡村环境。便于开展研究的城市蜜蜂蜂箱，是探究城市环境中野生传粉昆虫食性与生态特征的宝贵研究资源。本研究针对英国大曼彻斯特都会区周边沿城市梯度分布的14个蜂箱，通过对rbcL与ITS2基因区域开展DNA元条形码测序（DNA metabarcoding），对西方蜜蜂（Apis mellifera）蜂蜜中的花粉群落进行表征，进而推断其采食的植物食性。研究发现，蜂箱周边城区用地占比与蜜蜂采食植物的多样性提升呈显著正相关；除本土植物外，入侵植物与非本土植物似乎对城市蜜蜂的生存繁衍起到了关键支撑作用。典型见于郊区草坪与畜牧场的改良草地占比，与蜂蜜样本中检测到的植物花粉多样性下降呈显著负相关。本研究结果可为致力于提升生物多样性、维持蜜蜂种群存续的城市景观规划开发者提供参考，契合全球生物粮食安全相关议程的发展方向。