Re: sterilizing FF culture cups
Mites are fragile but mobile and they are easily eliminated from a surface even mechanically in hot soapy water. Its the ones that are not contacted, that happen to be located in a fissure of micro terrain wherever there is traction that gravitate back to resources to re infest. Especially the wayward gravid ladies.
Wiping down the area and floor has helped with other more ardent species.
Interesting anecdote I once looked at O. natricis under magnification on a brand new stainless steel table and found they could not locomote properly.