Recent findings by scientists of the USDA-ARS laboratories in Beltsville, Maryland and Baton Rouge, Louisiana provide important insights into the biological factors associated with the unusually high honey bee colony losses reported by U.S. commercial beekeepers earlier this year.1 The detection of elevated levels of Deformed Wing Virus (DWV-A and DWV-B) and Acute Bee Paralysis Virus (ABPV) in affected colonies confirms what many in the beekeeping community have long observed: honey bee health is under increasing pressure from multiple, interconnected stressors.
As the researchers point out in their publication, honey bees as a species have developed a remarkable resilience against significant population losses. Examples of this are the relatively short worker bee development time and ability to produce new queens when necessary. Despite these and other evolutionary advantages, managed honey bee colonies seem more vulnerable than ever with several local colony collapse events in the last few decades.1
While the presence of amitraz resistance markers in Varroa destructor mites sampled in the present study has sparked widespread discussion, it’s essential to recognize that viral infections, parasite pressure, pesticide exposure, poor nutrition, climatic extremes, and management practices all play a role in colony vitality. Even beekeeping operations that do not use amitraz, including organic systems, have reported substantial losses, further emphasizing that no single factor alone explains the severity of the situation.
Dr. Claudia Garrido, biologist and renown honey bee researcher, shares a similar view in a recent article published on her website bee-safe.eu.2 Mentioning the comparatively low sample size of mites tested for amitraz resistance in the original study, Dr. Garrido explains why loud calls for new treatments may not be the answer to the underlying problem: Beekeepers need to be better educated to implement good beekeeping practices such as treatment rotation, using the correct dose, and applying treatments at the right time.2
An interesting finding has been published earlier this year in a shared press release by Project Apis m., the Honey Bee Health Coalition, the Federal Beekeeping Association, and the American Honey Producers.3 In a nationwide survey for beekeepers with 842 respondents, commercial beekeepers reported an average colony loss rate of 62%, while hobbyist beekeepers reported 51% losses.3 While both loss rates are undoubtedly too high, it is a somewhat unusual result, as commercial beekeepers typically experience lower winter colony loss rates in their operations compared to hobbyist beekeepers4,5,6,7. Investigating which of those factors more commonly associated with commercial beekeeping operations than with hobbyist beekeepers could play a role in extreme colony losses, may be another promising lead to follow on the search for answers.
What these events illustrate is that beekeeping today requires a more balanced, proactive approach to colony health. Véto-pharma continues to promote and support Integrated Pest Management (IPM) as the foundation of efficient and sustainable mite control. IPM encourages rotation of authorized treatments, regular monitoring, and combining chemical, biological, and physical hive management methods to keep Varroa mite populations in check while minimizing the development of resistance.
Treatment rotation especially has been established as an effective tool against resistance development in several other species such as cattle ticks8, whiteflys9, or Asian citrus psyllids.10 And in varroa mites, similar observations have been made with regards to amitraz resistance.11 USDA researcher Dr. Frank Rinkevich has found a significant increase in the susceptibility towards amitraz of previously resistant mite populations. By applying Oxalic acid treatments on varroa populations that had been tested resistant against amitraz in 2020, susceptibility towards the active ingredient could be restored in those same populations just one year later, in 2021.11
These findings represent a strong indication that an efficient and sustainable implementation of authorized amitraz treatments in an IPM-based varroa treatment strategy is possible. 11,12 Data from other global regions such as New Zealand point in this direction as well.12 Beekeepers in New Zealand continue to use amitraz-based treatments successfully, incorporating them in a rotation strategy with other varroa treatments, based on different active ingredients.12
In a recent Science article, summarizing the report of the USDA-ARS researchers, the problematic consequences of using amitraz in (too) high doses are briefly mentioned, as a potentially relevant factor.13 “The study’s findings are “concerning,” says Aaron Gross, a toxicologist at the Virginia Polytechnic Institute and State University. Even a miticide like amitraz, widely considered one of the least toxic options to humans and bees alike, can weaken colonies when applied in high doses, says Gross, an expert in arthropod pesticide resistance who was not involved with the new work. Losing amitraz could be a major blow to beekeepers’ toolbox, he says, as many other miticides are either harsher or less effective.7
Véto-pharma has recently released updated tools for Varroa management, including an IPM guide on Varroa mite control and a handout explaining amitraz resistance, reflecting the latest science and field experience. These resources will provide practical strategies to maintain efficacy of available treatments, minimize stressors, and support long-term colony health.
Looking forward, more comparative research is needed to understand why certain operations experienced disproportionately high losses, and which practices may have buffered others against the worst effects. Sharing this knowledge transparently will help all beekeepers make informed, evidence-based decisions, whether conventional or organic – commercial or hobbyist.
Ultimately, preserving bee health is a shared responsibility, between researchers, regulators, manufacturing companies, and most of all, beekeepers. It is only through collaboration, innovation, and continuous learning that we can rise to the evolving challenges facing pollinators today.
1. Lamas, Zachary, et al. “Viruses and vectors tied to honey bee colony losses.” bioRxiv (2025): 2025-05.
2. Garrido, Claudia. “Large colony losses in the USA – causes and consequences”. Bees-safe.eu: 2025. https://bee-safe.eu/articles/bee-thoughts-2/large-colony-losses/
3. Project Apis m., Honey Bee Health Coalition, American Beekeeping Federation, American Honey Producers, “New Data Confirm Catastrophic Honey Bee Colony Losses, Underscoring Urgent Need for Action” (April 3rd, 2025).
4. Steinhauer, Nathalie, and Claude Saegerman. “Prioritizing changes in management practices associated with reduced winter honey bee colony losses for US beekeepers.” Science of The Total Environment 753 (2021): 141629.
5. Kagiali, Evangelia, et al. “Four-year overview of winter colony losses in Greece: citizen science evidence that transitioning to organic beekeeping practices reduces colony losses.” Insects 14.2 (2023): 193.
6. Tang, Jiao, et al. “A national survey of managed honey bee colony winter losses (Apis mellifera) in China (2013–2017).” Diversity 12.9 (2020): 318.
7. Gray, Alison, et al. “Loss rates of honey bee colonies during winter 2017/18 in 36 countries participating in the COLOSS survey, including effects of forage sources.” Journal of Apicultural Research 58.4 (2019): 479-485.
8. Thullner, Friederike, Peter Willadsen, and David Kemp. “Acaricide rotation strategy for managing resistance in the tick Rhipicephalus (Boophilus) microplus (Acarina: Ixodidae): laboratory experiment with a field strain from Costa Rica.” Journal of Medical Entomology 44.5 (2007): 817-821.
9. Prabhaker, Nilima, Nick C. Toscano, and Thomas J. Henneberry. “Evaluation of insecticide rotations and mixtures as resistance management strategies for Bemisia argentifolii (Homoptera: Aleyrodidae).” Journal of Economic Entomology 91.4 (1998): 820-826.
10. Chen, Xue Dong, et al. “Insecticide rotation scheme restores insecticide susceptibility in thiamethoxam‐resistant field populations of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), in Florida.” Pest Management Science 77.1 (2021): 464-473.
11. Rinkevich, Frank. „Amitraz Resistance Test Results and Strategies to Manage Amitraz-Resistant Varroa.” (2024). YouTube: Michigan State University Beekeeping. Amitraz Resistance Test Results and Strategies to Manage Amitraz-Resistant Varroa – YouTube
12. Biosecurity New Zealand & Manaaki Whenua. “2024 New Zealand colony loss survey – data summary”. https://www.mpi.govt.nz/biosecurity/how-to-find-report-and-prevent-pests-and-diseases/bee-biosecurity/bee-colony-loss-survey/
13. Thompson, Joanna. „Scientists identify culprit behind biggest-ever U.S. honey bee die-off.” (2025) Science. https://www.science.org/content/article/scientists-identify-culprit-behind-biggest-ever-u-s-honeybee-die
by Juan Molina 
by Juan Molina 
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