Hello Dee, I have contacts to a bee institute in Germany where they testing and breeding bees on 4.9mm cells for some years also.

Have you studied why your hives survive even if they’re mite infected?
Do you know exact the reason why this happen or is it a result of many different ways and you find it out by a lucky chance?

I’m not familiar with test on bees, queens and cells they made on the institute but there a few thinks they discovered why it can work and many times not.

One reason I heard that small bees producing much less pheromones on the 8th day than bigger bees and the Varroa goes by the smell from that pheromone on the 9th day into the cells. More pheromone, more interest to go into the cells.

On tests they neutralized the smell totally and no mite entered the cell.

A second reason the find is, that the Africanized bees breeding only 20 instead 21and most Varroa are not fully developed and can’t reproduce again.
I’m not a scientist that’s why I say it simple. A combination of both is a possibility why bees live and survive with the mites.

Do you have blood from Africanized bees in your colonies? What does happen in the long run when you sell queens or colonies to someone else and they breeding with non-Africanized drones? Have you any results?

The scientists say if breeding queens and they get fertilized with drones like this it will work, but if you’re a beekeeper on a different locality with other drones, it doesn’t work. After a few years the effect is gone and even the bees in 4.9mm cells have a hell of trouble to survive without a treatment.

Would be interesting to hear your experiences over the years.