I came upon this article earlier today, which states that VSH behavior is polygenic and revolves around approximately 7 additive genes. It goes on to say that ~50% VSH genes appears to be optimal, as 100% VSH bees tend to be overzealous (I assume) and therefore do not rear brood very well at all, thus requiring that the colony be sustained by foreign brood.

This all sounds nice, but it rises the question... how does one estimate the level of VSH genetics in a queen? How can one tell that the queen is 0%, 70%, 100%, etc.? And would I be correct in understanding that there are about 14 levels of VSH, from the total absence of VSH genetics to having the 7 responsible genes being homozygous?

Finally, are there any breeders that have 100% VSH queens to sell?