Researchers say they may have found an unexpected ally in the fight against the Varroa mite, a destructive parasite blamed for devastating honeybee colony losses nationwide.
A new study from the University of California, Riverside, found that a unique hybrid population of feral honeybees in Southern California is naturally resisting the mites without heavy chemical treatments, offering a potential breakthrough for an industry battered by historic losses.
The research comes as U.S. beekeepers continue grappling with severe colony collapses. Industry surveys found beekeepers lost as much as 62% of managed honeybee colonies in 2025, threatening pollination services critical to California agriculture, especially almonds.
Researchers monitored 236 colonies between 2019 and 2022 and found the California hybrid bees carried dramatically fewer mites than conventional commercial colonies. Colonies headed by locally adapted queens averaged about 68% fewer Varroa mites, according to the study published in the journal Scientific Reports.
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Lead author Genesis Chong-Echavez said researchers initially heard anecdotal reports from beekeepers that some unmanaged Southern California bees were surviving with “way fewer treatments.” The study sought to determine whether those observations held up scientifically.
The bees are not fully immune to Varroa destructor, a parasite that feeds on honeybees and spreads deadly viruses. But researchers found the hybrid population was significantly more resilient and less dependent on chemical mite controls.
Scientists said the bees’ genetic diversity may be key. The Southern California population contains a mix of Western European, Eastern European, Middle Eastern and African honeybee lineages that appear to have adapted over time to local conditions and parasite pressure.
The findings arrive as beekeepers warn that existing mite-control tools are losing effectiveness. Researchers at UC Davis and USDA recently reported that Varroa mites are developing resistance to amitraz, one of the industry’s most widely used pesticides.
California’s almond industry depends heavily on healthy bee populations for pollination each spring. Beekeepers say rising colony losses, high operating costs and weak honey prices are straining the industry economically even as demand for pollination remains strong.
Researchers cautioned that more work is needed before the resilient Southern California bees can be widely integrated into commercial operations. But the study offers rare optimism for an industry searching for ways to slow the ongoing collapse of honeybee colonies.
