A search on mite treatments did not turn anything up on this TBH forum, though there are many references in other forums.
A friend has two TBHs with natural comb from a wooden center strip which were stocked with feral swarms last year. They have produced bumper crops of honey. Both hives swarmed this year, so there is a new queen in each, and each is full of honey again. These bees are productive....
The queens are atill laying eggs, the drones have not been kicked out yet, and the weather is mild enough to work the hives.
TBH/natural comb with small cell brood chambers are not supposed to have mite problems. Maybe the mite infestation was caused by drifters from failing hives, who knows, and now it has to be dealt with.
Using powdered sugar on the bars may work in a Langsworth but without a bee space that will not help a TBH.
How have other TBH beekeepers dealt with mites?
What was used and how was it applied?