Development of urban agglomerations and the intensification of agriculture profoundly affect bees’ food resources, hence ecosystem services such as pollination. A solitary bee, Osmia bicornis (syn. O. rufa), is an effective springtime pollinator of crops, decorative and wild plants. However, it is largely unknown if this species is conservative or plastic in pollen collection in different environments. New breedings of O. bicornis were established in localizations qualified as urban (90 % of built-up infrastructure), suburban (55–65 %), and rural (up to 20 %). From each nest randomly chosen samples of unused pollen provisions were collected and analysed. Moreover, literature databases of food composition of O. bicornis was compiled to show overall tendencies in the choice of plant type, habitat, as well as pollen coating and size. Our field study showed that in the less human-modified environment O. bicornis collected higher diversity of pollen types to build its provision, compared to more urban areas (Simpson diversity index was 3.7 in rural, 2.8 in suburban and 2.2 in urban sites). Literature review showed that bees repeatedly collected pollen from commonly available trees like oaks, maples, horse chestnut and elms. Field data also revealed that the use of tree pollen was especially common in urban sites while bees from suburban and rural sites included pollen of herbaceous plants and shrubs. Neither the shape nor the size of the pollen mattered to bee foraging choices. However, bees frequently used pollen dispersed by wind in urban sites. The main conclusion is that polylectic bees opportunistically collect pollen of plants present in the environment and number of plant taxa may be limiting factor for studied bees. The welfare of O. bicornis requires planting trees such as oaks, willows, maples, and representatives from Rosaceae family, and it is especially advisable in urban sites where herbaceous flowering plants are less common than in urban and suburban areas. Hence, keeping even singular trees may complement the bee food base in urbanized areas.

城市群的发展和农业的集约化深刻影响蜜蜂的食物资源，从而影响授粉等生态系统服务。Osmia bicornis (syn. O. rufa ) 是一种孤独的蜜蜂，是农作物、装饰性植物和野生植物的有效春季传粉者。然而，这个物种在不同环境中的花粉收集是保守的还是可塑的，在很大程度上是未知的。O. bicornis 的新育种建立在符合城市（已建成基础设施的 90%）、郊区（55-65%）和农村（高达 20%）的地方。从每个巢中随机选择未使用的花粉样品进行收集和分析。此外，O. bicornis食物成分的文献数据库编制以显示植物类型、栖息地以及花粉涂层和大小选择的总体趋势。我们的实地研究表明，在较少人为改造的环境中，O. bicornis与更多的城市地区相比（辛普森多样性指数在农村为 3.7，在郊区为 2.8，在城市地点为 2.2），收集更多的花粉类型以建立其供应。文献综述表明，蜜蜂反复从橡树、枫树、七叶树和榆树等常见树木上收集花粉。现场数据还显示，在城市地区使用树木花粉尤为普遍，而来自郊区和农村地区的蜜蜂则使用草本植物和灌木的花粉。花粉的形状和大小对蜜蜂的觅食选择都不重要。然而，蜜蜂经常在城市地区使用风吹散的花粉。主要结论是，聚合蜜蜂会随机收集环境中存在的植物的花粉，植物分类群的数量可能是研究蜜蜂的限制因素。的福利O. bicornis需要种植橡树、柳树、枫树和蔷薇科代表等树木，尤其建议在草本开花植物不如城市和郊区常见的城市地区。因此，即使是单一的树木也可以补充城市化地区的蜜蜂食物基地。