From Ray Bayless...
I could tell the difference in mite load between my Italian and Russian hives this year. I didn't do a sugar shake but the only hive I had come down with deformed wings were Itallian. I don't think Russian bees are mite free but they are supposed to be resistant to both trachea and varroa mites. Have you seen a difference?"
I really can't say quite yet. Again I'm a first year beek and I've only had my Russians since June. I will say this...I was under the (incorrect) assumption that new hives rarely get heavy mite loads during their first year. As I said before, I have 2 Italians and 2 Russians and they are all grouped within a few feet of each other. Just for the heck of it I slid in the white grid IPM sticky boards under all the hives and then pulled them 3 days later. No sugar dusting or anything. 1 Italian and 1 Russian hive had huge mite drops. The other 2 had practically none. The Italian with mites showed some DWV, but the Russian did not.
So...as far as I can tell so far, I don't see a lot of difference between the two breeds as to how they deal with mites. I'm pretty sure that if I had not treated them, the mites would have won. Maybe after I keep them another year I will have a better feel for their differences. Hope this helps.