Maintaining the diversity of wild bees is a priority for preserving ecosystem function and promoting stability and productivity of agroecosystems. However, wild bee communities face many threats and beekeeping could be one of them, because honey bees may have a strong potential to outcompete wild pollinators when placed at high densities. Yet, we still know little about how beekeeping intensity affects wild bee diversity and their pollinator interactions. Here, we explore how honey bee density relates to wild bee diversity and the structure of their pollination networks in 41 sites on 13 Cycladic Islands (Greece) with similar landscapes but differing in beekeeping intensity. Our large-scale study shows that increasing honey bee visitation rate had a negative effect on wild bee species richness and abundance, although the latter effect was relatively weak compared to the effect of other landscape variables. Competition for flowering resources (as indicated by a resource sharing index) increased with the abundance of honey bees, but the effect was more moderate for wild bees in family Apidae than for bees in other families, suggesting a stronger niche segregation in Apidae in response to honey bees. Honey bees also influenced the structure of wild bee pollination networks indirectly, through changes in wild bee richness. Low richness of wild bees in sites with high honey bee abundance resulted in wild bee networks with fewer links and lower linkage density. Our results warn against beekeeping intensification in these islands and similar hotspots of bee diversity, and shed light on how benefits to pollination services of introducing honey bees may be counterbalanced by detriments to wild bees and their ecosystem services.

中文翻译：

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养蜂业对爱琴海群岛野生蜜蜂多样性和授粉网络的影响

保持野生蜜蜂的多样性是保护生态系统功能和促进农业生态系统稳定性和生产力的优先事项。然而，野生蜜蜂社区面临着许多威胁，养蜂业可能是其中之一，因为蜜蜂在高密度放置时可能有很强的潜力击败野生传粉媒介。然而，我们仍然对养蜂强度如何影响野生蜜蜂的多样性及其传粉媒介的相互作用知之甚少。在这里，我们在 13 个基克拉迪群岛（希腊）的 41 个地点探索了蜜蜂密度与野生蜜蜂多样性及其授粉网络结构的关系，这些地点具有相似的景观，但养蜂强度不同。我们的大规模研究表明，增加蜜蜂访问率对野生蜜蜂物种的丰富度和丰度有负面影响，尽管与其他景观变量的影响相比，后者的影响相对较弱。对开花资源的竞争（如资源共享指数所示）随着蜜蜂数量的增加而增加，但对蜜蜂科野生蜜蜂的影响比其他科的蜜蜂更温和，表明蜜蜂科的生态位隔离更强，以应对蜜蜂。蜜蜂还通过野生蜜蜂丰富度的变化间接影响了野生蜜蜂授粉网络的结构。在蜜蜂丰度高的地点，野生蜜蜂的丰富度低，导致野生蜜蜂网络的链接较少，链接密度较低。我们的结果警告了这些岛屿和类似的蜜蜂多样性热点地区的养蜂集约化，