Honeybee dominance alters foraging of wild pollinators across Europe

Apis mellifera L. (the western honeybee) is one of the most common pollinator species worldwide. Its high abundance is often associated with the introduction of managed colonies, raising concerns about potential impacts on wild pollinators. Here, using a European plant-pollinator interaction dataset, we quantify resource overlap between honeybees and wild pollinators, and changes in diet specialisation along a gradient of honeybee dominance. Increasing dominance is associated with reduced resource overlap between honeybees and wild pollinators, indicating stronger niche partitioning, while wild pollinators simultaneously exhibit a more generalist pattern of floral resource use. Although high local floral diversity provides increasing foraging opportunities for wild pollinators, it does not mitigate these effects. Our results suggest that avoidance behaviours are likely the dominant mechanism underlying the observed patterns, although niche complementarity may also explain the patterns observed in some species. The importance of these potential shifts in resource use for wild pollinator population dynamics, changes in community diversity, and long-term ecosystem functioning remains an open question. Hence, it is vital to identify the minimum number of honeybee hives needed to balance pollination needs with the conservation of wild pollinators. High honeybee dominance is associated with reduced resource overlap between honeybees and wild pollinators and with increased diet breadth in wild pollinators. Greater floral diversity does not modify these patterns.