Marco Moretti made a valid comment to the sugar shaker post. It doesn’t surprise me that Antonio Nanetti found checking mite populations besides a real treatment is unreliable. It is many factors making the results uncertain. Why beekeepers want to do this anyway is to get an idea when it’s time to treat against the mite.
If you do an oxalic dribble, or trickling, you make a real treatment. And that’s okey with me, if you choose to do that. Before making a real treatment the most reliable mite test is said to be alcohol washing like with the bee shaker described in this blog. The sugar shaker might do well for others. According to findings in USA described by Dennis van Engelsdorp those beekeepers that checked mite populations with alcohol wash, thus keeping track of the mite population had the lowest winter losses, of those beekeepers treating regularely.
John Harbo and his collegues at Baton Rouge lab found in the early 1990:s when they took help of a statistican to find out that checking mite population increase during a period of time was not a good way of testing mite resistance. That’s why they finally ended up checking infertility of the mites, which finally became the VSH method. (Information from Harbo)
That’s also one of the resons I don’t count mites. I check for virus problems in the hive before treating. The easiest virus and the one most common when mites are becoming many is Deformed Wing Virus (DWV). Maybe that’s too late normally to save the colony. I don’t know. But fortunately I don’t have ”normal” bees. Also a reason for me not counting mites, but looking for DWV, is that I want my bee stock to develop strong varroa (and virus) resistance.