USDA pinpoints cause of recent mass honeybee collapse

Project Apis m., a honeybee research organization, determined the cause of the mass honeybee colony collapse earlier this year was virus-infected, miticide-resistant parasitic mites. The USDA’s Agricultural Research Service (ARS) Bee Research Laboratory found high levels of deformed wing virus A and B as well as acute bee paralysis in all recently USDA-sampled bees.² The USDA ARS also stated that these viruses are responsible for the recent honeybee colony collapses and losses across the country.

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"While viruses are a likely end-stage cause of colony death, other stressors such as nutritional stress and agrochemicals may have also played significant roles," the researchers wrote.³

The researchers also screened Varroa mites from the collapsed colonies, and they found signs of resistance to amitraz in “virtually all” collections, which highlights a need for new parasitic treatment strategies.

The colony collapse culminated in a loss of 1.7 million colonies, which represents more than 60% of commercial beekeeping colonies since the summer before. The USDA also estimates that the financial impact of the collapsed colonies is $600 million.¹

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“Our nation’s food supply thrives, and is sustained, by the work of our pollinators,” said Joon Park, Acting ARS Administrator, in a USDA release.² “USDA scientists continue to research major stressors and new parasite treatment strategies, which will help reduce the agricultural challenge presented by the Varroa mites in honey bee colonies.”

In January 2025, commercial beekeepers in the US started reporting mass honeybee die-offs. A month later ARS researchers collected bee and colony samples from California and other Western US states prior to almond pollination to analyze parasites and pathogens. Researchers found that in both pooled samples, viruses were indicated from the surviving colonies and individual bees were showing behavioral morbidities.

Project Apis m. conducted a survey that gathered data from 842 beekeepers, which represented about 1,956 million colonies, making up 72% of the honeybees in the US. The findings of the survey at the time it was conducted, between June 2024 and February 2025, found an average loss of 62%, which has surpassed historical trends.

“Initial survey results of colony losses suggest that commercial beekeepers may have lost in excess of 60% of their bees. The scale of these losses is completely unsustainable,” said Zac Browning, a fourth-generation commercial beekeeper and board chairman of Project Apis m., in a release from February 2025.⁴

“Honey bees are the backbone of our food system, pollinating the crops that feed our nation. If we continue to see losses at this rate, we simply won’t be able to sustain current food production. The industry must look inward and outward for solutions to chronic bee health failure.”

Reference

1. Won C. USDA identifies cause of recent mass honey bee collapse. American Veterinary Medical Association. Published September 15, 2025. Accessed September 17, 2025. https://www.avma.org/news/usda-identifies-cause-recent-mass-honey-bee-collapse?utm_source=delivra&utm_medium=email&utm_campaign=todays-headlines-news
2. USDA Researchers Find Viruses from Miticide Resistant Parasitic Mites are Cause of Recent Honey Bee Colony Collapses. News release. US Department of Agriculture. June 2, 2025. Accessed September 17, 2025. https://www.ars.usda.gov/news-events/news/research-news/2025/usda-researchers-find-viruses-from-miticide-resistant-parasitic-mites-are-cause-of-recent-honey-bee-colony-collapses
3. Lamas Z, Rinkevich F, Garavito A, et al. Viruses and vectors tied to honey bee colony losses. bioRxiv (Cold Spring Harbor Laboratory). Published online June 1, 2025. doi:https://doi.org/10.1101/2025.05.28.656706
4. Survey reveals over 1.1 million honey bee colonies lost, raising alarm for pollination and agriculture. News release. Honey Bee Health Coalition. February 20, 2025. Accessed April 24, 2025. https://honeybeehealthcoalition.org/survey-reveals-over-1-1-million-honey-bee-colonies-lost-raising-alarm-for-pollination-and-agriculture/