A survey of bees (Hymenoptera, Apoidea) in the Bear River Mountains in northern Utah.

BACKGROUND: Bees provide critical pollination services to a diversity of flowering plants, facilitating the function of terrestrial ecosystems and global food production. Here, we present a checklist of bee species collected in conjunction with a larger systematic study in the Bear River Mountains of northern Utah, United States, over the course of three consecutive summers (2020-2022). The survey was conducted on public lands managed by the United States Forest Service. We collected 8,500 bee specimens using pan traps, hand nets and trap nests, representing at least 199 bee species belonging to 33 genera across five families. The checklist produced in this survey is critical for land managers and other stakeholders in developing pollinator management and conservation strategies, especially on public lands. NEW INFORMATION: We present the first published checklist of bees in the Bear River Mountains of northern Utah and document five new species that have not been recorded in Utah before: Ceratina sequoiae, Coelioxys alternata, Hoplitis pilosifrons, Megachile campanulae and Stelis holocyanea. Notably, this survey did not detect the presence of Osmia cornifrons, a non-native solitary bee species that is known from lower elevations in the adjacent Cache Valley. However, two non-native species, Megachile rotundata and Anthidium manicatum were each represented by an occurrence during our three year survey. Early detection of non-native species provides a baseline for potential range expansion.