Effects of short-term managed honey bee deployment in a native ecosystem on wild bee foraging and plant-pollinator networks

Honey bees (Apis mellifera L.) are important agricultural pollinators, and there is increasing demand for forage habitat for managed colonies. However, there is also evidence that pasturing honey bee colonies within natural landscapes may negatively affect wild bees through resource competition. To assess resource competition between managed honey bees and wild bees, we conducted repeated, short-term deployments of honey bee colonies within Florida forests coinciding with seasonal wildflower bloom, and compared wild bee foraging with and without honey bee colonies present over multiple seasons. We recorded over 2000 bee visits including 196 pairwise bee-plant interactions. Deploying honey bee colonies was associated with a reduction in wild bee foraging rates, and honey bee and wild bee foraging rates were significantly, negatively correlated. Honey bees disproportionately visited resources with high floral density. Honey bee foraging preferences differed significantly from genera with small-bodied (Lasioglossum, Perdita, Augochlorella), and/or specialist species (Perdita, Andrena), as well as with Megachile, but overlapped with genera including larger-bodied (Bombus, Habropoda, Osmia, Xylocopa) and/or generalist species (Bombus, Xylocopa, Agapostemon). Deploying honey bee colonies did not significantly affect plant-pollinator network metrics. These results illustrate that short-term honey bee colony deployment can negatively affect wild bee foraging and that competition may be greater for certain genera, particularly larger-bodied bees or those with generalist diets though less for smaller-bodied and/or specialist bees. Our short-term, low-density deployment treatments may have precluded significant effects on network metrics and likely underestimate the effects of typical higher density and longer-term honey bee deployment.

Automated summary

Deploying honey bee colonies can have negative effects on wild bee foraging, with competition being greater for larger-bodied or generalist bees.