In your study VSH factor counting was done by dividing the number of cells opened by bees with the number of cells examined. This was done by comparing fotographs taken at 10 days versus 20 days brood age. The porpotion of opened cells together with infestation rate ( of donor colony?) was used to determine VSH factor.

This is not the usually used method to determine VSH factor. This does not take into account cells opened and again closed by the bees. Usually VSH factor is examined by opening for example 400 cells and dividing number of mites with offspring with the total number mites found in these 400 cells. Why did you not use the standard way to determine VSH factor?