Understanding Deformed Wing Virus (DWV): What Every Beginner Beekeeper Should Know
Deformed Wing Virus (DWV) is one of the most widespread and destructive viruses affecting honey bees (Apis mellifera). Once a minor pathogen, DWV became a global threat with the spread of the Varroa destructor mite. Today, DWV is found in nearly every bee colony where Varroa exists – and it’s often the silent driver behind colony losses.
What Is DWV?
DWV is a single-stranded RNA virus belonging to the Iflaviridae family. It’s named for one of its most visible symptoms – bees with shriveled, misshapen wings. These bees can’t fly and usually die within days, leaving the colony weakened. However, not all DWV infections are visible; many bees carry the virus without showing symptoms, acting as hidden reservoirs of infection.
The Varroa Connection
When Varroa mites feed on the haemolymph (bee “blood”) of developing pupae or adult bees, they inject DWV directly into the bee’s system. This bypasses the bee’s natural defenses, allowing the virus to multiply rapidly.
According to Martin et al. (2013), DWV was found in:
- Only 0.6% of non-infested brood, but
- A staggering 89% of brood invaded by Varroa mites.
In those infected pupae, DWV caused deformities, reduced lifespan, and sometimes death. Adults infected after emergence rarely showed symptoms but became virus carriers, spreading DWV to other bees.
This finding marked a turning point: DWV was no longer just a minor virus – it became a major agent of colony collapse once Varroa entered the picture.
The Evolution of DWV: A More Dangerous Virus
DWV isn’t a single virus -How Varroa Changes DWV Dynamics
In a groundbreaking 2014 study, Ryabov et al. demonstrated that Varroa doesn’t just transmit DWV — it selects for the most virulent strains. When bees were experimentally exposed to Varroa, a single dominant, virulent DWV variant emerged from an initially diverse viral population.
This variant replicates 1,000 to 10,000 times faster than typical DWV strains, overwhelming the bee’s immune system. In contrast, colonies without Varroa maintained a diverse mix of mild virus strains, with minimal visible disease.
In short:
Varroa acts as both syringe and selector – injecting DWV and amplifying the most harmful versions. it’s a group of closely related variants, commonly referred to as DWV-A, DWV-B, and DWV-C. Research shows that Varroa infestation has altered the balance among these variants.
- DWV-A is strongly associated with colony collapse.
- DWV-B (formerly known as Varroa destructor virus-1) can sometimes dominate colonies and may offer partial protection against DWV-A through a process called superinfection exclusion.
- DWV-C, discovered later, is often found at low levels but can contribute to colony losses when combined with other variants.
A large-scale 2019 survey by Kevill et al. found:
- DWV-B dominated colonies in the UK, correlating with low overwinter losses (6%).
- DWV-A dominated in the U.S., where overwinter losses reached up to 60%.
This suggests that the variant type and balance within colonies can influence their survival chances.
Recognizing DWV in the Hive
For beginner beekeepers, early recognition is key. Common DWV symptoms include:
- Bees with deformed or missing wings
- Discolored, bloated abdomens
- Bees crawling near the hive entrance
- Patchy brood patterns
- Reduced colony strength
However, as Stuart Spinx highlights in his Beekeeping Short and Sweet podcast, by the time you see deformed wings, “it usually means Varroa issues” – and intervention is urgently needed.
Managing DWV and Varroa Together
Because DWV and Varroa are inseparable, controlling Varroa mites is the only effective way to control DWV. Here’s what research and experience suggest:
1. Monitor Mite Levels Regularly
Use a sugar roll, alcohol wash, or sticky board to estimate Varroa populations. Early detection prevents DWV outbreaks.
2. Implement an Integrated Pest Management (IPM) Plan
Rotate between treatment methods to prevent mite resistance. Common strategies include:
- Organic acids (oxalic, formic)
- Thymol-based treatments
- Drone brood removal
- Using screened bottom boards
3. Requeen with Resistant Stock
Some bee strains show greater resistance to Varroa and DWV, often through improved hygienic behavior.
4. Avoid Stress
Poor nutrition, crowding, and pesticide exposure can suppress the bee immune system, making DWV more deadly.
5. Culling Heavily Infected Colonies
As hard as it is, collapsing colonies can spread DWV through robbing. Sometimes, it’s better to remove one to save the rest.
The Bigger Picture
Research over the last two decades shows that DWV has fundamentally reshaped modern beekeeping. What began as a low-level, benign infection has evolved – through Varroa’s global spread – into a pandemic virus driving colony losses worldwide. Yet, with knowledge and vigilant management, even beginner beekeepers can keep DWV in check.
Key Takeaway
Control Varroa = Control DWV.
Healthy bees begin with a healthy mite management plan.
A sustainable beekeeping twist on DWV and modern honey bee health emphasizes working with natural adaptation rather than against it. Sustainable beekeeping, as advocated by researchers like Tom Seeley, Dorian Pritchard, and the B4 Project, views DWV not only as a viral problem but as a symptom of deeper management issues – especially dependence on imported, non-local bees. Rather than relying solely on chemical Varroa treatments, sustainable beekeepers focus on natural selection, local breeding, and ecological harmony to build lasting resistance. Studies like Fries et al. (2006) on the Gotland “Bond bees” show that untreated colonies can co-adapt with Varroa and DWV over time, achieving equilibrium where both host and parasite survive. Similarly, Büchler et al. (2014) demonstrated that colonies with local genetic origins lived significantly longer – up to 83 days more on average – than imported stock. This supports the B4 Project’s stance against imports, as noted at the 2025 Sustainable Beekeeping Symposium, which warned that foreign queens introduce disease, dilute adaptation, and erode native Apis mellifera mellifera resilience. In practice, the sustainable twist means selecting for local survival traits, minimizing interference, and letting bees’ evolutionary instincts – honed over millions of years – guide their own recovery. As Seeley’s “Darwinian Beekeeping” reminds us, bees are master beekeepers themselves; our role is to provide the space and stability for nature to do its work.
Bibliography
- Martin, S. J., Ball, B. V., & Carreck, N. L. (2013). The role of deformed wing virus in the initial collapse of Varroa infested honey bee colonies in the UK. Journal of Apicultural Research, 52(5), 251–258. DOI: 10.3896/IBRA.1.52.5.12
- Ryabov, E. V., et al. (2014). A virulent strain of deformed wing virus of honeybees (Apis mellifera) prevails after Varroa destructor-mediated, or in vitro, transmission. PLoS Pathogens, 10(6), e1004230. DOI: 10.1371/journal.ppat.1004230
- Kevill, J. L., et al. (2019). DWV-A lethal to honey bees: A colony-level survey of DWV variants (A, B, and C) in England, Wales, and 32 states across the US. Viruses, 11(5), 426. DOI: 10.3390/v11050426
- Spinx, S. (2023). Beekeeping Short and Sweet Podcast, Episode 3177. Transcript retrieved from DWV.txt