[Pollinator] competition between urban honey bees and wild bees

[David Inouye]

Honey bees are native there, but can compete with other bees.

Renner, S. S., et al. (2021). "High honeybee abundances reduce wild bee 
abundances on flowers in the city of Munich." Oecologia 195(3): 825-831.
     The increase in managed honeybees (Apis mellifera) in many European 
cities has unknown effects on the densities of wild bees through 
competition. To investigate this, we monitored honeybees and 
non-honeybees from 01 April to 31 July 2019 and 2020 at 29 species of 
plants representing diverse taxonomic and floral-functional types in a 
large urban garden in the city of Munich in which the same plant species 
were cultivated in both years. No bee hives were present in the focal 
garden, and all bee hives in the adjacent area were closely monitored by 
interviewing the relevant bee keepers in both 2019 and 2020. Honeybee 
numbers were similar in April of both years, but increased from May to 
July 2020 compared to 2019. The higher densities correlated with a 
significant increase in shifts from wild bee to honeybee visits in 
May/June/July, while visitor spectra in April 2019 and 2020 remained the 
same. Most of the species that experienced a shift to honeybee visits in 
2020 were visited mostly or exclusively for their nectar. There were no 
shifts towards increased wild bee visits in any species. These results 
from a flower-rich garden have implications for the discussion of 
whether urban bee keeping might negatively impact wild bees. We found 
clear support that high honeybee densities result in exploitative 
competition at numerous types of flowers.


-- 
Dr. David W. Inouye
Professor Emeritus
Department of Biology
University of Maryland

Principal Investigator
Rocky Mountain Biological Laboratory