Dealing with relatives and concrete: how to make the city a refuge for wild bees?

Wild bees are declining at alarming rates in rural environments, but cities have the potential to provide habitat for a surprisingly high diversity of these pollinators (Sirohi et al., 2025). At the same time, urban beekeeping is gaining ground as an increasingly popular hobby, spiking up honey bee numbers in cities worldwide (Lanner et al., 2025). Can these bees live together with their unmanaged relatives in an ever changing urban landscape? And how can this landscape function as a refuge for wild bee communities?

Urban filtering

Wild bees consist of around 20.000 species worldwide of which most are solitary and often live in mutualistic relationships with specific species of plants. Although we often think of the honey bee (Apis mellifera) as the primary driver of pollination, wild bees have been proven to be more effective pollinators, depending per plant species (Isaacs et al., 2017). This makes them invaluable for pollination in natural and urban areas. Although both diversity and population sizes have been declining due to land use change, habitat degradation, and pesticide use, cities can provide suitable habitats to a wide variety of wild bee species. As complex landscapes with a variety of both natural and built-up structures, cities provide many potential niches that can be colonized. According to a study by Banaszak-Cibicka et al. (2011), this can be seen as a filter, only allowing bees with specific ecological traits to colonize certain habitats. Parks or gardens with high densities of early-blooming trees and shrubs for instance would be much less suitable for species that emerge later in the summer.

According to a recent study by Sirohi et al. (2025), primarily eusocial and solitary bees use available resources within their limited flight range. Therefore, local habitat quality was found to be very important for there types of wild bee communities. More flowering plant species give a wider variety of floral diet options for numerous wild bee species while at the same time lowering competition between them. In contrast, areas with shade seemed to negatively affect bee diversity and abundance because they need sunny areas to maintain body temperatures while foraging. Habitat size had no effect on bee communities, likely due to the fact that these larger landscapes experienced more shade from trees and/or disturbances like mowing lawns. Based on these results, Sirohi et al. (2025) concluded that small patches of green space with adequate floral resources provide just as important habitats for wild bee species as relatively larger habitats in the city. For species with a limited flight range, smaller patches of high quality habitat can be used as stepping stones to move around the city in a wider extent.

Rise of the honey bee

With our help, the honey bee (Apis mellifera) has increasingly found its way into the city. They are super-generalists and highly mobile, visiting a large variety of plant species across the whole blooming season (Lanner et al. 2025). In contrast to many wild bee species, honey bees are highly eusocial, even communicating beneficial foraging resources to their peers to collect pollen and nectar with high efficiency throughout the city. With the advances of beekeeping care, honey bees are less exposed to natural pressures like periods of drought or excessive rain, ensuring greater survival. Along with the rise of urban beekeeping as a hobby, honey bee numbers have risen substantially in cities all around the world (Lanner et al. 2025). Often seen as an environmentally friendly, high densities of the honey bee might have the potential to threaten urban wild bee populations.

Higher honey bee densities in city areas with limited flower supply could lead to food shortages and consequent increased foraging competition between different pollinators. According to a recent case study by Lanner et al. (2025), a significant spatial overlap was found between high honey bee densities and hotspots of wild bee density in the city of Vienna. In many of these places there was high trait similarity between the wild bee species and the honey bee, indicating higher risk of foraging competition which could affect urban wild bee populations negatively.  The exact consequences and extent of competitive pressure however, will vary per city as it is dependent on the ecological traits of the species involved together with the availability of sufficient bee-suitable habitats. However, consequences could be dire, as MacInnis et al. (2023) found that a recent increase in honey bee numbers in the city of Montréal had resulted in a significant decrease in wild bee species richness.

How to move forward?

To ensure the city can offer a place of refuge to otherwise dwindling wild bee populations, a high diversity and abundance of floral plant life should be promoted throughout the city. These planted flowers positively affect wild bee diversity and could alleviate the risk of foraging competition with honey bees in the city (Lanner et al. 2025; MacInnis et al., 2023). Due to limited flight ranges, local small patches of diverse high quality habitat provide the key to bee-friendly and inclusive cities (Sirohi et al. 2025). Apart from the municipality, local residents could help substantially with making the city more bee-friendly and -inclusive by planting local flowering plant species in their urban gardens, around trees in the street, along roadsides or even on green roofs or balconies to avoid shade (Sirohi et al., 2025). Also, the monitoring of relative honey bee densities, their effects on local wild bee communities, and the implementation of consequent urban beekeeping regulations should become the standard for urban areas (Lanner et al. 2025). All of these measures could make urban areas truly bee-friendly, aiding in the conservation of many species deemed important for food security (Lanner et al., 2025; Sirohi et al. 2025)

References

Banaszak-Cibicka, W., & Żmihorski, M. (2012). Wild bees along an urban gradient: winners and losers. Journal of Insect Conservation, 16, 331-343.

Isaacs, R., Williams, N., Ellis, J., Pitts-Singer, T. L., Bommarco, R., & Vaughan, M. (2017). Integrated crop pollination: combining strategies to ensure stable and sustainable yields of pollination-dependent crops. Basic and Applied Ecology, 22, 44-60.

Lanner, J., Unglaub, P., Rohrbach, C., Pachinger, B., Roberts, S., & Kratschmer, S. (2025). How many bees fit in the city? A spatial ecological case study to conserve urban wild bees. Urban Ecosystems, 28(2), 21.

MacInnis, G., Normandin, E., & Ziter, C. D. (2023). Decline in wild bee species richness associated with honey bee (Apis mellifera L.) abundance in an urban ecosystem. PeerJ, 11, e14699.

Sirohi, M. H., Jackson, J., & Ollerton, J. (2025). Influence of urban land cover and habitat quality on wild bees. Urban Ecosystems, 28(2), 78.