Beekeepers in Southern California are reporting that locally adapted hybrid honeybees are showing significantly lower Varroa mite infestations compared to commercial colonies.
How these bees resist mite infestations
Research from UC Riverside found that colonies led by locally raised hybrid queens carried about 68% fewer mites on average than those led by commercial queens. These bees were also more than five times less likely to reach mite levels requiring chemical treatment. The study tracked 236 colonies from 2019 through 2022 and is the first to demonstrate natural, sustained mite control in a locally adapted honeybee population.
What makes these hybrid bees different
The bees come from a naturally mixed population in Southern California, often originating from feral colonies in trees. Genetic analysis shows they combine traits from at least four honeybee lineages: African, Eastern European, Middle Eastern, and Western European bees. Unlike commercial breeding programs, this resistance emerged without human-directed selection.
Why this matters amid widespread colony losses
Beekeepers across the U.S. Reported losing up to 62% of managed honeybee colonies in 2025, with Varroa mites being a primary driver. The mites weaken bees by feeding on fat body tissue—critical for immunity and metabolism—and spread viruses like Deformed Wing Virus. Last year, similar losses prompted emergency surveys as beekeepers discovered sudden mass die-offs in January 2025, with causes still under investigation.
Are these bees completely resistant to Varroa mites?
No, the bees are not completely resistant but maintain significantly lower mite populations and require far fewer chemical interventions.
Where were these bees studied?
The bees were studied in Southern California, where they originate from feral colonies and a naturally mixed local population.