Re: Why Treatment Free.
They still exist but as a heterogenous mixed population. AMM genetics show up in my area, easy to tell by the stinging behavior, honey produced, and spring buildup. There are no standard breeds that can out-compete AMM in an adapted range. That includes most of the Eastern U.S. Varroa brought AMM down because there was very little to no tolerance. AMM readily cross with drones from managed colonies which dilutes the genetics, but if isolated from managed colonies, the AMM genetics re-assert because they are better adapted to the climate. We had this discussion a few years ago with a couple of beekeepers saying there was no way AMM is still in my area, then when I told one of them where I live, he had an epiphany moment and realized he had recently seen a feral AMM colony less than 15 miles from here.
I think it had more to do with it being out competed by Italian and other standard breeds. They kept getting bred by the drones until they just weren't AMM anymore. That dying out and other stressors.
AMM in this area exhibit excessive swarming, a tendency to collect the blackest honey imaginable, extreme pollen collection with storing pollen in honey supers, and incredible spring buildup. I have had a single frame of AMM bees build up a March 20th split into a 2 story colony that produced 3 shallow supers of honey on the spring flow that ended 6 weeks later. No Italian or Carniolan I've ever seen could have done the same.
NW Alabama, 50 years, 20 colonies and growing, sideliner, treatment free since 2005, 14 frame square Dadant broodnest