As humans continue to encroach on native bee habitats, the popularity of backyard beekeeping in addition to commercial honey production may exacerbate competition for resources already diminished by urbanization. Similar to the honey bees (Apis mellifera) that are used for these purposes, native bumble bees (Bombus spp.) are effective pollinators and social generalist bees. However, previous studies have shown that domesticated honey bees have the potential to compete with native bees for floral resources which could negatively impact native bee fitness. Humans raise and care for honey bees, and intervention of this kind may put honey bees at an advantage over native bees. This study aims to examine the relationship between honey bee abundance and bumble bee fitness using female intertegular distance as a proxy for fitness to determine if there is competition between honey bees and bumble bees. Bees were caught using pan traps and sweep nets from April to October of 2018 at six sites in Southeastern Massachusetts on an urban gradient. Bumble bees were separated by sex and their intertegular distances were measured using cellSens imaging software and a digital microscope camera.
Results/Conclusions
In the 2018 season, 156 bumble bees and 347 honey bees were collected for analysis. The intertegular distances of the bumble bees ranged from 2.83 mm to 6.10 mm. Pearson correlation analysis revealed a significant weak negative relationship (r = -0.49, p = 0.0066) between honey bee abundance and female bumble bee size. This suggests that there may be competition between bumble bees and honey bees that could negatively affect the fitness of bumble bees. Although additional data is needed to better understand this relationship, these findings are consistent with other similar studies and could indicate that there is a need to regulate the use of domesticated honey bees in order to promote a healthier native bee community.