Description
DWV: Deformed Wing Virus-A (DWV-A), Deformed Wing Virus-B (DWV-B), Deformed Wing Virus-C (DWV-C)
DWV-A seems to be especially tied to mite parasitism. The virus can be found everywhere, it is like the “herpesvirus of bees”. DWV-A shows annual peaks in late summer or fall, with
lows in January through March or April. Prevalence of DWV-A continues to remain high with between 80 – 90% of hives infected (Traynor et al., 2016). DWV-A is not always a problem
due to the noticeable increase of incidence within the US, but if the bees become stressed (lack of food, pesticide exposure, and transportation) could lead to sickness and death. DWV-A
replicates in the Varroa mite, making it a biological as well as physical vector. Winter colony mortality is strongly associated with DWV-A presence (de Miranda et al., 2011). Varroa
infection should be reduced in a colony far in advance of producing overwintering bees, to ensure reduction in DWV viral load (de Miranda et al., 2011).
DWV-B or Varroa destructor virus-1 (VDV-1) was discovered by scientists in search for pathogens of the Varroa mite (Ongus et al., 2004). DWV-B is a species of RNA viruses under the
genus Iflavirus. Other Iflaviruses include Sacbrood virus, Slow Bee Paralysis virus and its closest relative, Deformed Wing Virus-A (Ongus et al., 2004). DWV-B has been known to cause
high rates of overwintering colony losses in Europe, but the correlation has not been made yet in the US. DWV-B and the closely related Deformed Wing Viruses are the most widespread
and the most prevalent viruses in honey bees, but are also likely the most significant in terms of their impact on honey bee colony health (Ryabov et al., 2017).
DWV-C is a variant that was first described in 2016 by Mordecai, et al. The effects of high DWV-C loads are still being considered, however, it has been hypothesized that this variant may
be the cause of increased overwintering colony losses (Mordecai, et al., 2016). Studies have shown that both DWV-A and DWV-C are responsible for declines in colony health during the
overwintering period (Kevill et al., 2017).
References
de Miranda, J., Gauthier, L., Ribière, M. & Chen, Y. P. 2011. Honey Bee Viruses and Their Effect on Bee and Colony Health. Honey Bee Colony Health: Challenges and Sustainable Solutions, 71-102.
Ongus, J. R., Peters, D., Bonmatin, J. M., Bengsch, E., Vlak, J. M. & van Oers, M. M. 2004. Complete sequence of a picorna-like virus of the genus Iflavirus replicating in the mite Varroa destructor. J Gen Virol, 85, 3747-3755.
Ryabov, E. V., Childers, A. K., Chen, Y., Madella, S., Nessa, A., vanEngelsdorp, D. & Evans, J. D. 2017. Recent spread of Varroa destructor virus-1, a honey bee pathogen, in the United States. Scientific Reports, 7, 17447.
Traynor, K. S., Rennich, K., Forsgren, E., Rose, R., Pettis, J., Kunkel, G., Madella, S., Evans, J., Lopez, D. & vanEngelsdorp, D. 2016. Multiyear survey targeting disease incidence in US honey bees. Apidologie, 47, 325-347.
Kevill, J. L., Highfield, A., Mordecai, G. J., Martin, S. J., & Schroeder, D. C. (2017). ABC Assay: Method Development and Application to Quantify the Role of Three DWV Master Variants in Overwinter Colony Losses of European Honey Bees. Viruses, 9.
Mordecai, G., Wilfert, L., Martin, S. et al. 2016. Diversity in a honey bee pathogen: first report of a third master variant of the Deformed Wing Virus quasispecies. ISME J 10, 1264–1273.
