A lot of it's genetics over management in my experience. I've seen treatment-free colonies go multiple years with low mite numbers and treatment free yards over

A lot of it's genetics over management in my experience. I've seen treatment-free colonies go multiple years with low mite numbers and treatment free yards overwinter 75-100% of colonies. I've also seen heavily managed hives take losses anyways, or abscond after treatment. Including some that take 75-100% losses. Many times the same apiary can go from one extreme to the other in a year or two. The problem with the genetics is that it's extremely hard to maintain continuity of a colony beyond a few years because eventually they need to requeen. Those future queens are made from a variety of contributions of other gene lines due to the way the mating happens.