For the successful treatment-free beekeepers - Do you see a lot of mites in your colonies? Do you think your bees have a high tolerance to varroa and can coexist with high infestation rates or do you think they have adapted to keep mite populations low?
I am currently practicing IPM. Testing my colonies for mites this week I see a wide range of infestation rates >1% to 10%. While some of the colonies with a high infestation rate were poorer performers, others were some of my best colonies production-wise.
I see mites in them. Not just in dronebrood, sometimes walking on the bees. Very often in the microscope, when getting sperm from drones.
I used to see them on the hive bottoms, but not any more, for some reason I cannot imagine.
They must do both, tolerate and keep the numbers low, to survive in practical beekeeping environment. You cannot keep bees so, that they cannot get loads of mites from some other hives, sometimes. Sometimes advises are given to take all the suffering hives to their own yards, but in practise that is impossible.
Infestation levels vary, from almost 0 to well over 10%, they usually are getting high in some time during the summer, I suppose because bees get angry. Some of them change their queen to survive, but not very many. Usually they just calm down, and in the end of the summer they are normal again. Sometimes I reconed that 5% is the acceptable limit, but nowdays I don´t really know, I don´t care, how much they have mites. More or less, what does it matter!
In recent years I have not experienced any unexpected crashes, bees dying in mid summer or in autumn. This happend earlier, in the beginning of this breeding project.