>What do we know, though, about the survival of these mites in the post varroa time frame.

Again, just an opinion from Nancy Ostiguy in the same talk with no reference to known facts, she believed they had mostly been wiped out by the acaracides. I know the bee louse (which is not really a louse or a mite but part of the fauna of the hive) is almost unheard of now and used to be fairly common. Most of those mites are microscopic so I'm sure no one noticed if they were or were not missing unless they were seriously looking. Scientists usually don't keep track of the "bystanders."