I do some sampling these days but not really much. From the mid 90's until a few years ago, i would sample all of the time, alcohol wash and sticky boards seemed to be my life. Just a couple of thoughts that may or may not apply for you---- queen age seemed to mean a lot relative to fall mite samples when it comes to just winter survival. it seemed that the vast majority of 1st year queens would survive even with a relatively high mite load. however, come spring other parts of the story sometimes unfolded. many of those colonies start to crash and never develop into a true production hive. while other hives go crazy, simply outrun the mites thru the summer, produce a large crop but then crash before the next fall even arrives; that seems to be the biggest percentage. and then there are those colonies that can go forward with a high mite load, survive the winter, maintain some level of acceptable productivity and not crash that fall. those are the interesting ones; imagine that is where we will see future work with virus resistance play. when we talk about queens heading into their second winter it was different ball game. high mite loads in the fall corresponded to plenty of them not making it thru winter. but as a side note i'll say that was at the stage when the stock for vsh was being selected. at this point in the game there should be way more bees holding a level of mite resistance than what we had to work with 15+ years agoI won't go on with this preliminary analysis, but suffice to say mite count is not tightly correlated with survival. Not for this group of hives. None the less I have a few nice low mite, nice spring cluster hives to work to make queens from this year.
I think at this point we can see how completely unnuanced world view we have about mite/bee/virus interactions. There is so much to learn from untreated bees.