Scientists at the U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS) believe they are a step closer to understanding honey bee colony collapse. Researchers have submitted a manuscript to a scientific journal for peer review based on research findings that identified high levels of deformed wing virus A and B and acute bee paralysis in all recently USDA-sampled bees.
The viruses are responsible for recent honey bee (Apis mellifera) colony collapses and losses across the US and are spread by parasitic Varroa destructor (Varroa) mites. Screening of mites from hives by ARS scientists showed signs of resistance to amitraz, a critical miticide used widely by American beekeepers.
This miticide resistance was found in virtually all collected Varroa, underscoring the need for new parasitic treatment strategies. In January 2025, commercial beekeepers in the United States began reporting severe losses in commercially managed operations. As losses unfolded, it was evident that more than 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, prior to almond pollination, with the samples analysed at their Bee Research Laboratory in Maryland.
“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,” explained ARS Research Leader Dr Judy Chen. ARS researchers said they 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.
