How urbanization affects crop pollination has scarcely been studied, especially in the tropics. Here, we focus on the richness and abundance of wild bees and their pollination services to 30 small-scale fields of Lablab purpureus, a globally wide-spread grain legume, in the Indian megacity Bangalore. Farms were selected along a gradient of urbanization, measured as percentage of impervious surface (grey area) at the landscape scale, ranging from 0% to 30%. We found that the abundance of lablab-visiting wild bees increased with increasing grey proportion on the landscape scale and that, in particular, ground-nesting and large-bodied bees benefitted, as well as Xylocopa bees. The higher availability of forage and open soils in low-density urban areas appeared to enhance bee populations in Bangalore. When pollinating insects were experimentally excluded, lablab plants produced 36% less and 31% lighter fruits. Yet, we did not detect any changes of pollination outcomes along the urbanization gradient, as lablab seem to receive stable pollination services. Finally, we found that the local bee richness was negatively affected by the number of on-field pesticide applications, resulting in 35% fewer species after 3 application rounds. In summary, we conclude that low density urbanization can be beneficial for wild bees in lablab farms, but intensive pesticide use could counteract this positive effect. Large and ground-nesting farmland bees benefited most from urbanization, but more studies on different crops in tropical cities are urgently needed.

城市化如何影响作物授粉的研究很少，尤其是在热带地区。在这里，我们专注于野生蜜蜂的丰富性和丰富度，以及它们对印度大城市班加罗尔的30 个小规模Lablab purpureus（一种全球广泛分布的谷物豆科植物）的授粉服务。农场是沿着城市化梯度选择的，以景观尺度的不透水表面（灰色区域）的百分比来衡量，范围从 0% 到 30%。我们发现，在景观尺度上，随着灰色比例的增加，参观实验室的野生蜜蜂的数量增加，特别是地面筑巢和大型蜜蜂以及Xylocopa受益蜜蜂。低密度城市地区的草料和开放土壤的可用性更高，似乎增加了班加罗尔的蜜蜂数量。当授粉昆虫被实验排除时，实验室植物产生的果实减少了 36% 和 31% 较轻的果实。然而，我们没有发现沿城市化梯度的授粉结果有任何变化，因为 lablab 似乎获得了稳定的授粉服务。最后，我们发现当地蜜蜂的丰富度受到现场农药施用次数的负面影响，导致 3 轮施用后物种减少 35%。总之，我们得出结论，低密度城市化可能有利于实验室农场的野蜂，但密集使用杀虫剂可能会抵消这种积极影响。大型和地面筑巢的农田蜜蜂从城市化中受益最多，