Deformed wing virus (DWV)-infected larvae may emerge as adults with deformed wings that have not expanded and are twisted, tattered, and non-functional. Immatures with DWV infections show no signs of it. Viral testing using genetic markers confirm infections.
DWV is considered the most harmful of bee viruses. In viral analysis by the Bee Informed Partnership, it is found in greater than 90% of samples. Some strains are more detrimental than others. DWV is an iflavirus related to sacbrood virus and slow bee paralysis virus. It is transmitted by varroa mites. High virus levels in brood results in adults (queen, worker, or drone) with deformed wings. Infected brood lack visible signs of infection. Varroa mites apparently transmit or enhance replication of this virus; the virus quickly reaches epidemic levels, resulting in sudden collapse of colony in late fall or failure of colony to successfully overwinter.
The wings may appear as missing, twisted, or tattered and are definitely not adequate for flight. Sometimes wings are also cloudy, which may be due to cloudy wing virus (CWV).
Parasitic mite syndrome; viral infections, though DWV is one of the few viral infections that readily exhibit distinctive outward signs.
Koziy RV, et al. 2019. Deformed Wing Virus Infection in Honey Bees (Apis mellifera L.). Veterinary Pathology 56(4): 636-641. https://doi.org/10.1177/0300985819834617
Moore PA, Wilson ME, and Skinner JA. 2019 update. Honey Bee Viruses, the Deadly Varroa Mite Associates. Bee Health. Accessed 2023. https://bee-health.extension.org/honey-bee-viruses-the-deadly-varroa-mite-associates/
Grozinger C, Underwood R, and Lόpez-Uribe M. 2020. Viruses in Honey Bees. PennState Extension. Accessed 2023. https://extension.psu.edu/viruses-in-honey-bees
