Bee diversity across a range of socio-economic neighborhoods

Background/Question/Methods

While urbanization is on the rise across most US cities, the core of many of these same cities, including St. Louis, are shrinking. This shrinkage relates to issues of social inequality like food deserts. Community gardens have potential for addressing this issue and at the same time provide valuable resources to native bee pollinators. Unfortunately, little is known about the status of bee communities and the pollination services they provide within these inner city environments. In order to asses this we sampled twelve community gardens across a range of economic and ethnic neighborhoods located within St. Louis’ urban core. Neighborhoods varied from low to middle high socio-economic status and predominantly African-American to diverse to mostly caucasian communities. Plantings were almost exclusively vegetables (tomatoes, peppers, pumpkins), fruits (apples, peaches, and berries) and herbs (sage, basil, and various mints). Sampling was done in a systematic fashion and took place weekly from mid May to late September 2013, 2014 and 2015. We sampled at a rate of 0.25 person per hour hectare for all bee species using aerial nets. All collected individuals were mounted, labeled and identified to species.

Results/Conclusions

Over 80 bee species representing five families and thirty-one genera were collected. Early-­mid July to late August was the peak of abundance and diversity. Some notable species include Bombus pensylvanicus, which is uncommon and believed to be in decline in parts of its range, Bombus auricomus, which is uncommon as well as Bombus fraternus, which is uncommon, especially in urban settings. Megachile addenda and Megachile frugalis represent new records for St. Louis city. Bees included generalist and specialist foragers as well as kleptoparasitic, native and non-native species, some of which say a lot about the habitat quality. The total bee diversity observed in the garden (alpha diversity) represents over 80% of the total bee diversity for the area (gamma diversity). Our results have significance for managing ecosystem services across the urban environment of cities.