How do you control varroa in your hives ? Do you use formic acid ?
My IPM approach involves natural triggers, an understanding of nature, equipment options, genetic selection, and a management approach that gives the bees the best chance at handling mites themselves.
Without writing a book, I'll mention one or two items.
Bees requeen almost every year. Without beekeeper intervention, bees will swarm in feral colonies, or manged hives, at a rate of 90% of all hives every year. As a beekeeper, I want to "control" my swarming so as too maximize my honey production, or do it without losing a bunch of bees. So like many beekeepers, I use good swarm prevention techniques.
But what benefits are you losing by not allowing your hives to swarm, and then having older queens in the hives from year to year? Studies have shown that younger queens outproduce, overwinter better, and deal with disease better. A first year queen also swarms less than a second year queen due. Not for the mere fact that all queens will be replaced anyways in nature. But by beekeeper control, the bees are driven to replace older queens at a higher desire, as you have older queens.
So by delaying this swarming and using splitting, requeening, brood breaks, later in the season, you can still reap the benefits what they normally do anyways, just later in the year, when it is much more beneficial.
Simply put....by stopping a natural thing such as swarming, you lose other natural benefits that gives bees an advantage in having the best chance possible for survival. It's not about not controlling your swarming, it's about understanding the benefits that nature shows you, then using these benefits.
Another area is using the right genetics for your area and climate. If you look at a bee map of where different bees originated, why are there so many types of bees? Why are bees not all the same? Because each region had different climates and demands on the bees. But here in the U.S., we just assume that any bee should be good anywhere we desire to ship them. That is not what nature does. Nature developed different bees in different areas, based on many factors. We as beekeepers ship them all over the place then stand back and wonder why some bees do lousy. Pure ignorance to me. Italians could be used many years ago with no problems. They were very adaptable. But with the problems we have today, using the best bees for your area is a big advantage. And we are not ever going back to the "pre-varroa" days that some still dream about, while they ponder the next new treatment coming out on the market for you to buy.
As you can see, my approach is not about what treatment I will use this year. And no, I don't use acid treatments, or any other mite treatment. You don't have to be fanatic about bees. It's about simply things like understanding the benefits of swarming and realizing some bees do better than others in certain areas around the country. Yes, you will quickly hear other suggest they keep "Italians" in such far off places as Finland, but also realize how much they treat also, while claiming all bees are the same. Its a little deeper than that.