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Research Reveals Long-Term Decline in Wild Bee Populations

Dan Environment, Pollinators, Pollinators, USDA-ARS

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In South Michigan, an Agricultural Research Service (ARS) scientist and her collaborators have used historical bee collections and advanced technology to uncover key ecological trends in pollinators. The findings could help shape new conservation efforts aimed at protecting bee diversity, which is vital for environmental stability and agricultural productivity.

Kelsey Graham, a scientist with the ARS Pollinating Insect Research Unit, co-led the study, which analyzed nearly a century of bee data from the E.S. George Reserve in collaboration with the University of Michigan. The research, spanning from 1921 to 2018, identified alarming trends in bee populations, including a decline in species richness and diversity. In the 1970s, 135 bee species were recorded, but recent surveys identified only 90 species, with just 58 species appearing in both time periods.

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The study found that bees with specialized traits, such as oligolectic bees (which gather pollen from only a few plants) and kleptoparasitic bees (which steal resources from others), are at higher risk of disappearing. In contrast, polylectic bees (which collect pollen from many plant types) and bees nesting in cavities are more resilient.

Graham noted that changes in bee populations are also linked to climate shifts, with contemporary bees showing a more southern distribution than their predecessors. She emphasized that using historical data with modern neural networks provides valuable insights into bee conservation strategies moving forward.