“It’s obvious you don’t like these mites, but I want to try anyway. Do you have any suggestions?”
Well, I have some ideas, as long as you keep in mind that I have never actually done this . . .
These little mites are fragile. Most suppliers want to ship them overnight or two-day mail. Some say to use them immediately, although at least one place says you have up to 14 days. In any case, I recommend using them as soon as you get them because you lose some percentage every hour that you delay.
Don’t use the Stratiolaelaps mites in a hive where you’ve used acaricides in the recent past. We know these pesticides persist in the wax combs for long periods, and there is no reason to assume the predatory mites have any resistance whatsoever. Be wary of the “hard” pesticides as well as soft preparations such as thymol and formic, oxalic, and hop beta acids. Also keep them away from essential oils such as wintergreen.
The mites and the substrate, whether it be vermiculite, peat, or bran is a make-work project for the bees. Besides the live mites, the substrate will also contain dead mites, other arthropods supplied as a temporary food source, and feces. Whether you spread it on paper or shake it between the frames, a certain amount of it will land in open brood cells or honey cells, and the bees will not be content until they clean it up. This work will slow production, at least until it is complete.
What is best for honey production is not best for your predatory mites. According to EvergreenGrowers.com, the mites prefer cool, damp soil at 60-72° F. Good top ventilation speeds the curing of honey, but it may make the hive too dry for the mites. If you decrease the top ventilation you can preserve moisture, but you will slow the curing of the honey and perhaps make the hive too hot for the mites. So, if you want the mites to thrive, you will have to optimize conditions for them, rather than optimizing for honey or brood production.
Someone mentioned the possibility of maintaining a breeding bed of soil on the bottom board. Even if you could control the temperature and moisture of the breeding area, I don’t know what you would do about sunlight. In nature, these creatures live with diurnal fluctuations of sunlight. Can they live and breed in total darkness? I don’t know, but I wouldn’t bet on it.
In addition, part of their diet is made of algae and plant debris, neither of which are found in areas with no sunlight. Are these vital to the health of Stratiolaelaps? I don’t know that either.
Furthermore, even if they could breed in the dark, there is no evidence that they would crawl up into the hive to feed. Apparently, they prefer to spend their entire lives on the soil surface. Even if some ventured up into the hive, it probably would not be enough to have an impact on Varroa populations.
I have tried to find information on the techniques currently being used to raise these mites for sale, but I came up empty. Nevertheless, I’m more convinced than ever that this is not the right creature for the job. If you have answers to any of these issues, I will gladly post them.