Just curious, not a bee keeper, and won't be, but is there an effective mite treatment now?
Everything I've read is mites have gotten "immune" to the current treatments.
Yes, there are several effective treatments on the market and quite a few cultural techniques that can be implemented to reduce mite reproduction without the use of chemicals, plus stocks of bees that show resistance are being identified and used in breeding programs to spread resistance traits into the general population.
The key though for any treatment to be effective is the willingness to do it with effective mite monitoring to determine the most effective timing of treatment and most importantly that it is actually working.
The immunity you speak of is our fault as beekeepers in not doing the post treatment monitoring and assuming that treatments were still working. That and using the same treatment products and protocols over and over. Even the best of the treatments only kill 97-98 percent of mites under the very best of circumstances and if that 2-3 percent were to survive due to a genetic anomaly guess what the next generation of mites are going to look like?
That last is what's most bewildering as a keeper needs to use multiple different tools and be ever vigilant to stay ahead of the mites.
It's really not difficult just requires extra labor and a willingness to research the treatments available and fit the treatment to the need.
The big ugly truth in the room is the facts of mite reproduction. They can only reproduce and grow in numbers on bee brood, aka baby bees.
And the old beekeeping truism that in order to make honey you've got to make bees still holds true.
So every time your bees are making bees they are making mites as well.
The key to successful mite management is timing those periods of high brood production so you can treat to reduce mite numbers just before the brood production occurs.
Low mite numbers going in means lower mite numbers coming out.