I used Apivar in 30 hives this spring. Temps. were 30 to 50 degree days and 20 to 30 degree nights. The first fifteen days I was seeing mites but after that I didn't see any more even in the drone brood. I haven't done a roll test yet as they have only been out for two weeks. All of these hives have been split either coming out of the almonds or shortly after. All are booming now and might need to be split again. So far I don't see any queen issues from the Apivar and I feel like I got good results.