Abstract Detail


Felton, Josh [1], Fogel, Nina [2], Buehrle, Emily [3], Clones, Jessica [3], Miller-Struttmann, Nicole [4].

The Role of Non-native Plants in Urban Bee Visitation Networks.

Insect pollinators across the world have been declining due to a lack of floral resources, nesting sites, climate change, and the loss of natural environments from anthropogenic habitat modification. For instance, in urban environments, the construction of impervious surfaces limits viable habitats for ground-nesting bees, which account for 3/4 of bees globally. Moreover, the introduction of non-native plant species and low flower density favor generalist pollinators in urban environments. Gardeners often rely on many non-native ornamental plant species to provide aesthetic floral value to the garden throughout the full season, rather than planting natives. The organization of species interactions in a community, known as network structure, is influenced by the diversity and identity of the species within it. Communities with more specialized foragers tend to be more modular and robust to perturbations. If non-native plant species favor generalist foragers, then we predict that the visitation networks will be less modular with more exotic plants. In this study, we test whether the network modularity of bee visitation networks in residential and community gardens differs with the proportion of native and non-native plant species. Specifically, we address the following two research questions: How does the network modularity of gardens compare with different proportions of native and non-native species? What role do non-native plants have on the type of bees hosted in the garden? Observations on which plants bees visited were collected by citizen scientists from the Shutterbee Citizen Science Program on their properties in St. Louis, MO during the summer and early fall of 2020. A subset (37.0%, n = 60) of Shutterbee participants survey bees in gardens that are enrolled in the Audubon Society of Saint Louis’ Bring Conservation Home Program, which provides individualized land management recommendations. Each garden is given a conservation certification level based on the percentage of native plants, diversity of canopy levels, and eradication of invasive species. Network indices were calculated for all plant-pollinator communities using the bipartite package in R statistical environment. We tested for the effects of urbanization and conservation status (our proxy for proportion of native vs. non-native plants in the community) on network modularity via regression analysis. We found that residential gardens that were enrolled in the BCH program had higher modularity than gardens not in the program. Conversely, there was no significant difference in modularity when looking at urbanization. The makeup of pollinators was very similar between the low and high conservation status gardens. However, modules with non-natives plants often hosted only larger-sized bees in the Apidae & Megachilidae families. Information based on our results on which native plants support the greatest amount of native bee species in St. Louis could be used to inform residents on conservation practices that support diverse plant-bee networks. Small-scale modification of individual residential gardens may supplement or be part of a larger-scale plan to improve pollinator habitat as more and more of the global population move into urban landscapes.

1 - Colorado College, Organismal Biology and Ecology, 14 East Cache la Poudre St., Colorado Springs, Colorado, 80903, USA
2 - Saint Louis University, Department of Biology, 3507 Laclede Ave, St. Louis, MO, 63103, USA
3 - Webster University , Biological Science Department, 470 East Lockwood Avenue, St. Louis, MO, 63119, USA
4 - Webster University, 470 Lockwood Ave., St. Louis, MO, 63119, United States

Citizen Science
Urban ecology
non-native species.

Presentation Type: Poster
Number: PEC028
Abstract ID:775
Candidate for Awards:None

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