PS 48-251 - Bee diversity along a restored highway embankment corridor

Abstract: Most of the world’s food crops and wild flowering species depend on animals for pollination. Yet pollinators are declining due to habitat degradation and loss. One way to augment pollinator habitat, especially in cities in which land is at a premium, is to convert public areas covered in non-native lawn grasses into suitable habitat. An example of such areas are highway embankments and right-of-way easements. We investigated the bee diversity at a newly restored embankment on the south facing slope of I-44 in the city of St. Louis, MO. We sampled weekly from May to September 2022, via aerial netting along a 200m stretch of the embankment, which was seeded with 28 species of native plants in 2021, as well as a terraced area designed for growing crops. We predicted that bee diversity would increase with increases in floral diversity across the growing season. Furthermore, we hypothesized that the bee community in the terrace would represent a nested subset of the bees in the embankment.

We collected 391 bees across 14 different taxa. We also documented 88 species of wild flowering plants or domesticated crops. A preliminary survey of the same area conducted in 2019 (once a month from June to August) resulted in only three bee species. In general bee diversity correlated with floral diversity. The lowest bee diversity was observed in May (mean species richness = 3.8 ± 1.2) whereas the highest diversity was from mid July through mid August (7.8 ± 2.8). The most common bees were in the genus Megachilidae (n=112) followed by Bombus (n=110). Our results will help us understand relationships between native flowers and bee pollinators visitation in urban settings that traditionally have not been considered as potential suitable habitat. These findings may assist in conservation efforts and understanding human effects on plant-pollinator relationships.