Managed honey bee (Apis mellifera L.) colonies have expanded globally, while wild bee populations continue to decline, raising concerns about interspecific food competition. We systematically reviewed 83 field studies evaluating food competition between A. mellifera and wild bees in both native (n = 30) and introduced (n = 53) regions. Of these, 78 studies assessed at least one of six predefined competition criteria, while five studies addressed none of the criteria but were still classified as competition studies in previous reviews. Most studies (82.1%) relied on indirect indicators of competition, whereas 17.9% employed direct fitness measures such as survival, fertility, or population. Floral resource overlap was consistently detected in 100% of studies assessing it (n = 75). In contrast, direct fitness outcomes were examined in only 4.8-12.0% of studies (n = 83), and negative impacts were reported in 12.5-30.0% of those cases (n = 4-10). Survival related outcomes differed between native and introduced regions, though sample sizes were small (n = 1-3). Statistical analyses showed that studies assessing foraging-related parameters were statistically independent of studies detecting fitness impacts (p < 0.001). Studies covering multiple competition parameters tended to yield more definitive conclusions, although the direction of effects varied and did not consistently indicate stronger negative impacts. Overall, while floral overlap is widespread, direct negative effects on wild bee fitness are less common and context-dependent. We recommend that future research prioritise standardised, direct fitness measures and that beekeeping practices should be adapted to local ecological conditions to reduce potential risks to wild bee populations.
Gratzer, K., Becker, D., & Brodschneider, R. (2026). Systematic review finds resource overlap but few direct effects of honey bees on wild bees. Journal of Apicultural Research, 1–13.
https://www.tandfonline.com/doi/full/10.1080/00218839.2026.2662040
