the reason I'm interested is I started treating a couple of apiaries one year, the crawlers went down, the honey production went up(now I'll admit how do you know year to year with different flows different weather etc so its a judgement call), so I did a few more yard, and the honey production went up, until two years ago I was treating all yards except one, my control. now this hasn't been a really good year, but the one yard that is falling apart is the untreated yard, now how do you factor in that they leased the land out, they plowed under 150 acres of knapp weed, and all the golden rod in site. the only down side I've seen is that my swarming rate went up the year after treating(the bees feel good?),
I also use my partner as a test case, he doesn't treat or I should say didn't treat. My average honey production went up so much, while his has been going down, he started treating all his nucs, or new hives last year, now this year isn't much of a test, but we will see when we get a "normal" year next year. and no I gave up counting through a microscope.