My understanding from reading is that it is a gene that create this activity. So bees either have it or they don’t.
When tested bees that clear 70% pupi affected with mites can be called vsh so that’s still 30% that can bread and build up. Whilst it’s possible to get 100% vsh queens by carful selection and breading ie when tested they removed 100% of infected pupi .however if the 100% queen is mated with Zero % mated drone the % of vsh drops . some sellers offer queens at say 85% vsh
+ the vsh is only a measure of infected pupi removed it doesn’t measure adult bees carrying the mite either not removed at pupi stage or picked up when forageing.
my view is that the British and European bee has been around for thousands of years but the mite only turned up in the last 20-40 years so we can help our bees by wiping out varrora, if my bees kill 85% of the mites in the pupi and I can get 90% of the mites on the workers etc with vape that has to be good for the bees.
I’m sure there are plenty of beks that will supply queens for free or very low cost to friends or members of a club etc but This year I payed £46 for queens with the vsh gene one of which was graded as 85% the other line hasn’t yet been graded or at least not advertised as such.
Hopeful i will see how they compare next year-with each other and with my home raised queen not scientific and different breads but unless someone who tells me they know tells me I shouldn’t treat, I intend to keep treating
See wiki
Cross-breedingEdit
Bees bred to have high levels of VSH can keep mite populations below thresholds recommended for varroa treatment including
miticides.
[7] Queens from such VSH breeding sources can be allowed to mate freely with non-VSH
drones, and the resulting
hybridcolonies from these
outcrosses will retain lower and variable but generally still useful resistance to V. destructor while retaining desirable
beekeepingtraits such as
honey production.
[8]