USDA researchers submitted a manuscript to bioRxiv about the high U.S. colony losses in the United States in 2025 caused by the parasitic varroa mites, calling for new control strategies for the parasite.

Earlier this year, the country suffered severe bee colony losses; average reported losses since the preceding spring exceeded 60%, representing 1.7 million colonies and an estimated financial impact of $600 million.

In January 2025, when many colonies were still actively collapsing, ARS scientists collected colony and bee samples from across California and other western states in February 2025, before to almond pollination. 

In individual bees exhibiting shaking behaviors and morbidity, they found deformed wing virus strains A and B, along with Acute bee paralysis virus at unusually high levels.

The researchers also screened collapsed colonies for resistance to amitraz, a miticide used widely by beekeepers, and found that all collected varroa-infected colonies were miticide resistant. 

Bees are an integral component of agriculture. The value of crops that require bee pollination is estimated to be more than $20 billion annually in the U.S. and $387 billion globally. 

 “Our nation’s food supply thrives, and is sustained, by the work of our pollinators,” said Acting ARS Administrator Joon Park. “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.”