New findings from the USDA’s Agricultural Research Service offer crucial insights into the dramatic honeybee colony losses seen among commercial beekeepers this year. The research identifies widespread viral infections—transmitted by Varroa mites with genetic resistance to standard treatments—as a major factor behind the die-offs.
The study examined samples from six large-scale beekeeping operations, all of which reported catastrophic losses averaging more than 60 percent of their colonies. These losses occurred just ahead of the critical almond pollination season in California, underscoring the economic and ecological impact.
Researchers found that all the Varroa mites sampled carried a genetic marker for resistance to Amitraz, a widely used miticide in commercial beekeeping. This marks the most detailed evidence to date linking treatment-resistant mites with heightened viral infection and colony collapse.
“We can’t keep relying on a single line of defense against Varroa mites, which are quickly evolving,” said Patty Sundberg, President of the American Beekeeping Federation.
The report raises urgent questions about the sustainability of current mite treatment strategies and highlights the need for integrated pest management approaches that include genetic, chemical, and biological controls.
