we run 600-700 colonies. Our bees are mongrels,queens are from a breeder that started with 18 lines of hygenic bees.but they are the best performing bees i have seen in years. They produce honey( when there is a flow ) like the bees used to when we first started in the 80's. Still have to treat.Our best hives made 6 mediums of fall honey this year to harvest.We have tried most of the advertized resistant queens on the market over the years. they all die from the mite/virus loads if left untreated,sooner or later. We worked in a coop with jack Griffis and the Honeybee Improvement program in Mi. back in the 90's breeding from our untreated THRIVING 2 year survivors and AI breeding them with drones from the same program. We spent a lot of time(4 years) and money and still had dead bees. No silver bullet.
Mites are always an issue and need some type of treatment whether it is different styles of management, chems or organic acids etc. I may be going out on a limb, but there is really no such thing as a mite resistant bee.Some are more resistant to the viruses ie;russians,as they tend to last longer before the viruses kill them as opposed to other stocks.They still have plenty of mites and seem to manage them ( reduce the mite load) better by being a very swarmy bee.We ran 100 colonies of relatively pure russians a few years ago and this was my observation.
I spent some time in the mountains of Nepal 2 summers ago and worked apis cerana cerana and apis cerana indica with a missionary friend who lived in the remote village of Jumla in the mountains. The bees were kept in topbar/log hives and swarming was actually looked forward to. the hives usually only make 2-3 KG of honey per year surplus and the beeks were excited for swarms to increase production and hive numbers. At the time I was there we witnessed some colonies sucumbing to PMS and crashing, just like ours do when left untreated. This appeared to be due to the weather patterns and bloom, there was almost NO swarming for the normal period that swarms usually issue. We used apistan to try to save this farmers hives. Most of the commercial beeks there (50 colony ave.) kill all the queens after the flow and put in a sprig of artemesia plant( a relative of wormwood that contains essential oils that repel and kill mites). So the bees are treated for mites during a queenless /broodless period.
They also have an insect called a psudo-scorpion that lives in the crevices in a hive and you can actually see them eat mites. These bees do not propolize the cracks and the scorpions have a place to live.
My question is how can we say that this bee ( apis cerana) which, is the native host of varroa, is resistant to mites? It seems that the management( swarming) and the psudo scorpions normally control the mite populations. Why would the natives treat with artemesia and kill queens to reduce the mite populations it they were naturally resistant.
I am not against non treatment and would LOVE to not treat myself, but when your paycheck depends on your bees making honey, you hafta do what is necessary. Dead bees dont make honey. We use formic in early may,late july to have healthy bees going into fall so the winter bees are not heavily mite laden. A fall only treatment is too late as the bees raised in the early fall are already weakened and those need to survive till spring broodrearing.
lots to consider
Virgil NY _Not spring here yet