In the midst of a “pollination crisis,” in which insect pollinator populations are experiencing significant declines, studies of native bee richness and abundance indicate diverse communities of wild bees persisting in cities around the world, such as Berlin, Germany; Birmingham, Northampton, and Swindon in the UK; Melbourne, Australia; Guanacaste, Costa Rica; Vancouver, Canada; Berkeley, Chicago, and New York City in the USA. Cities often contain greater bee species diversity than what would be expected from a more traditional viewpoint of urban areas. Yet, we don’t have a clear understanding of how socio-economic activities in the city contribute to the spatial and temporal partitioning of the bee community diversity.
We surveyed bee communities in 16 sites across St. Louis city, i.e., the urban core, in 2015, and 22 sites in 2016. Sites were classified according to location within the city (north, central, and south), the type of management (community garden, urban farm, prairie pocket, empty lot), and by neighborhood socio-economic status (poor, lower-medium, upper-medium). We conducted aerial netting sampling at each site every other week at a rate of one person-hour per 0.25 hectare. All bees were collected except bumblebee queens, which were photographed and then released.
Results/Conclusions
We identified a total of 111 species of bees from sampling locations within the city of St. Louis. The north side of the city, which correlates with the poorest area, has the greatest bee species richness with 72 species. This is followed by the central corridor with 57, and finally the south side, which correlates with the highest socio-economic status, with 39 species. In terms of management, urban farms had the greatest richness, 66, followed by community gardens, 53, and then prairie pockets, 28. The greatest species turnover occurred between the suburb of Ferguson and the south side of St. Louis.
In a parallel study, we have identified a total of 128 species of bees for the greater St. Louis metro area. Of those 128 species, 111 are those found in the urban core, and over 30% of the species are only found on the north side. We hypothesize that the north side’s disproportionate contribution to the overall diversity is aided by the abandoned and decaying infrastructure and empty plots, as well as the decreased human population density of the area.