judging by the latin, Id say they are just after some mold you are growing.
are you in fabric pots too?
No I am using living soil in plastic autopots, thousands of them now. I am wiping the pots down with bleach and water to reduce the number as they are getting out of control. No harm to plants however I did see a few on the leaves. I did read this on biobest website about predator mite ABS System - which contains the predatory mite Amblyseius cucumeris, also contains the prey mite (Tyrophagus putrescentiae) as a food source.
Thinking of ordering some cucumeris to maybe reduce the amount of these? I have emailed Biobest to ask about this but have not heard back.