Nomia melanderi, the world's only intensively managed ground-nesting bee, plays a vital role in pollinating alfalfa (Medicago sativa) for seed production in Washington state. Since the 1950s, active management of alkali bees by alfalfa seed growers has been crucial for sustaining alfalfa seed production. However, recent census work indicates a troubling decline in managed alkali bee populations in the Columbia basin. Alfalfa ranks third in production value among crops in the United States, with over 15 million acres harvested in 2021. The decline of alkali bees poses a significant threat to alfalfa seed production in the Columbia basin. This study investigates the factors contributing to the decline of managed alkali bees in the Columbia basin, focusing on genetic diversity. Through sampling nine bee beds and wild populations, we calculated three genetic diversity metrics—percent polymorphic loci, allelic richness, and heterozygosity. Our results reveal exceptionally low genetic diversity in the studied bee beds, with the collective genetic diversity of the wild population being higher than managed bee beds. This genetic diversity decline may facilitate inbreeding, ultimately jeopardizing the resilience and sustainability of managed alkali bee populations and, consequently, alfalfa seed production in the Columbia basin.
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