The native snail shell–nesting bee Osmia conjuncta (Hymenoptera: Megachilidae) exploits a local abundance of exotic Cepaea snails (Stylommatophora: Helicidae), choosing empty shells by size, colour, and microhabitat

Abstract For solitary bees, nesting substrate availability may limit population growth. Here, we investigate the nesting of a locally abundant bee Osmia conjuncta Cresson (Hymenoptera: Megachilidae) in empty shells of exotic snails, Cepaea spp. Held (Stylommatophora: Helicidae), in Hamilton, Ontario, Canada. A literature review determined that O. conjuncta was sparsely distributed throughout its range, with a low relative abundance except for …