Solitary bees provide a framework for pollinator conservation using status assessments

Numerous studies have reported declines in terrestrial insect abundances in recent decades and highlight the consequential impacts to ecosystems. Of particular concern are declines in insect pollinators. In a taxonomically diverse assessment of extinction risk in the U.S. and Canada, we assessed the conservation status of over 1500 pollinating bees, butterflies, flower flies, and macro moths using the NatureServe rank calculator. The NatureServe rank calculator provides a standardized method to use the best available data to establish a conservation rank for a species in the United States and Canada as well as states and provinces. We found that up to 20-29% of assessed insect pollinators have elevated risk of extinction and bees had the highest risk at around 40%. Solitary bees, particularly members of Megachile, Anthophora, and Habropoda, were the groups with the highest risk of extinction, nearing 50%. At risk bees were concentrated in the southwest and major threats included climate change, agriculture, and development with invasive species and disease posing more of a threat in the northeast. These results provide taxonomic, geographic, and threat priorities for local and regional conservation actions. Monitoring, data sharing, and identification at various levels can both contribute to and take from NatureServe solitary bee rankings for more effective pollinator conservation.