Utilizing natural history collections and data mining to assess flower associations and phenology of North American bees in the genus Andrena (Hymenoptera: Andrenidae) subgenus Plastandrena

Even though bees are the most frequently discussed and important pollinators, most native species’ fundamental ecology including phenology and flower preferences is not known. This is especially true within the mega diverse bee genus Andrena Fabricius, 1775 where only a small percentage of species floral associations have been assessed. Here, using label data with associated floral records and collection event dates, the phenology and flower visitations of North American bees in the Andrena subgenus Plastandrena Heidicke, 1933 is assessed. Results of Shannon–Wiener index, Simpson’s diversity index, and occurrences on plant genera, families, and orders demonstrate Andrena argemonis, Andrena mellea are polylectic, while Andrena crataegi, Andrena fracta, and Andrena prunorum are broad polylectic. Plant-pollinator network analyses demonstrated the degree of polylecty within the subgenus, with Andrena argemonis being the most specialized towards Argemone and Andrena mellea being the most generalized. Collection event dates demonstrate all species phenology except A. mellea have a unimodal peak. However, the bimodal peaks in A. mellea may be due to geographic variation or sampling bias. Each species has peak records at varying times, showing some species are spring associated and others summer associated. This study provides an in-depth update of floral and phenological data of these understudied bee species, providing evidence that these bees may be important native pollinators that require more attention.