Hawaii's bee virus story
Varroa destructor and DWV
In 2009-2010, in collaboration with Dr. Stephen J. Martin, we documented the changes associated with the introduction of Varroa to the Hawaiian islands. Our study showed that with exposure to the mite, the prevalence and viral load of deformed wing virus (DWV) greatly increased, while the strain diversity of the virus decreased. During this study, DWV was also detected in Varroa-free islands but a much lower levels and with a greater strain diversity. (Martin et al., 2012 -Science VOL 336)
Deformed Winged Beee by S. Nikaido
Varroa and DWV initial impact
The changes in the viral landscape of Oahu and Hawaii Island were dramatic. Feral colonies which provided pollination services to many growers were almost completely wiped-out. The beekeepers had to rely on chemical treatments against Varroa, sometimes up to 3 or 4 times per year, to reduce the impact of the fast growing mite populations and the associated viral disease.
DWV strains over time
The prevalence of DWV variants in the UK and in the US is changing, with the prevalence of the DWV-A strain declining and DWV-B strain increasing over time. In 2012, only the DWV-A variant was detected on the Hawaiian Islands. In 2021, ten years after the arrival of the mite, we found that the DWV population is changing and the dominant DWV-A variant is now not solely dominant, and that DWV-B is increasing in prevalence on Oahu and Hawaii Island (Grindrod et al., 2021).
We also found seasonal variation in both viral prevalence and load for DWV-B in individual colonies; a result that provides perspective on the dynamic nature of DWV master variants emerging in Hawaii (Zhang et al., 2024)
