Scientists at the U.S. Department of Agriculture’s Agricultural Research Service (USDA/ARS) are helping American beekeepers solve the mystery behind widespread honey bee colony collapses and the debilitating effects this has on U.S. agriculture. Researchers have submitted a manuscript to a scientific journal for peer review based on findings that identified high levels of deformed wing virus A and B and acute bee paralysis in all recently USDA-sampled bees.
These viruses are responsible for recent honey bee colony collapses and losses across the United States. Since the viruses are known to be spread by parasitic Varroa destructor mites, ARS scientists screened the mites from collapsed colonies and found signs of resistance to amitraz, a critical miticide used widely by beekeepers. This miticide resistance was found in virtually all collected Varroa mites, underscoring the need for new parasitic treatment strategies.
“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.”
In January 2025, beekeepers began reporting severe losses in commercially managed operations. As losses unfolded, it was evident that over 60% of commercial beekeeping colonies had been lost since the prior summer, representing 1.7 million colonies and an estimated financial impact of $600 million.
ARS scientists collected colony and bee samples from across California and other western states in February 2025. The USDA-ARS Bee Research Laboratory in Mayland analyzed the parasites and pathogens from all samples and focused on individual bees exhibiting behavior known to precede death by minutes or hours. Viruses were indicated in pooled samples from surviving colonies and in individual bees showing behavioral morbidities.
“While viruses are a likely end-stage cause of colony death, these results do not rule out the importance of other long-known challenges to honey bees,” said ARS Research Leader Judy Chen.
The primary managed pollinator, Apis mellifera, is an integral component of agriculture, providing key pollination services for a wide variety of crops and over one-third of U.S. produce. The value of crops that require bee pollination is estimated to be more than $20 billion annually in the United States and $387 billion globally.
ARS researchers will continue to screen honey bees and their colonies for other known stressors and determine the best way to mitigate these stressors, mite infection and subsequent colony loss.
Source: USDA/ARS
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