These things are cleared out in Europe 5-7 years ago. I do not know what USA seach. Italian Nanetti is key person in these studies.
one of the reasons they did not recommend PS as a hive control was that the mites could return to the bees.
In theory that is good idea, but in practice it has been found that it does not work in practice.
with the advent of the screened bottom board, the mites are dislodged from bees and drop through the screen.
Goo idea, but i does not work in practice. It has been revieled out many times even in Canada.
while i would not use the powdered sugar as my only treatment, i do think it is useful mid season as a way to reduce mite infestation. the more live bees, the more work done. the fewer mites, the less chance of mite related disease.The key point is that mite level must keep so small that after summer mite population does not violate wintering bees. When last bees will over winter, all mites concentrate themselves into last brood.
If mite level is high, you take honey off and soon after that you give some vapour treatment like thymol or formic acid.
As I have written, PS is not recomended in Europe. It is laborous and ineffective method.
Kathyp, you live quite in cold climate and it is most easy to kill mites with one treatment. It takes 30 seconds per hive.
You have brood brake there and it makes it easy. http://pix.epodunk.com/locatorMaps/or/OR_15184.gif
You may keep your mind out and take what ever system into use, but just now, open your eyes and take into use best method: trickling. - But after that you have not so much talk about mites because hey are so hard to find.
If you have open mind, it cannot mean that you are 10 years after those who has closed mind. That is not purpose 8-)