It's not just the honey bee that evolves to avoid losses due to Varroa: the viruses do also!
Here in the UK a very experienced beekeeper, Ron Hoskins, together with other beekeepers in his locality, have gone without treating their bees against Varroa for many years and it was assumed that they/Darwin had successfully selected a resistant strain of bee although Varroa were still present. Now it appears that the usual strain of Deformed Wing Virus (Type A) has been replaced by a less virulent Type B. A third type (C) has also been discovered elsewhere.
Chris
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