A Plant-Bee Visitation Network for Plummers Island, MD

Abstract

Plummers Island is a small island located in the Potomac River in Montgomery Co., MD. Bees have been collected and cataloged from Plummers Island since 1909, but their floral associations have not been thoroughly described. As bees are important pollinators of natural and managed terrestrial ecosystems, monitoring their floral host choices is an important step towards proper land management and conservation practices. We collected bees from flowering plants on and adjacent to Plummers Island over two seasons and characterized their interactions using a bipartite plant-bee visitation network. Seven hundred and forty individual bees visited 30 species of flowering plants currently classified in 17 different genera. The resulting network was characterized by nested, asymmetrical interactions, but did not show strong evidence of either extreme generalization or specialization. The plant with highest interaction frequency score (species strength) was the invasive poison hemlock, Conium maculatum (Apiaceae), while the common sweat bee, Augochlora pura (Halictidae) had the highest interaction strength for the bees. We discuss these results considering species phenology and potential sampling biases and compare them to previous records for the island.