The researchers that originally observed the process of RNAi (RNA interference) were recently given the Nobel prize.
RNAi has been used in multiple molecular biology techniques, mostly as diagnostic and research tools. Recently some researchers are focusing on therapeutic uses for the technology (antivirals, and vaccines). It looks like researchers are looking at RNAi for mite control.
RNAi are small single stranded oligos of RNA (ribo-nucleic acid, very similar to DNA) that range between 15-30 bases. RNAi works by specifically attaching to targeted mRNA molecules (mRNA contains the information to make protein). The RNAi oligo sequence can be made specific to only hybridize (bind to) to a specific mRNA. When an RNAi molecule binds to an mRNA molecule it sets in motion a chain of enzymatic events in the cell. The end result is the destruction of the mRNA molecule and therefore the protein the the mRNA codes for. This mRNA destruction pathway is one way the cell normally controls protein expression. Researchers can put the pathway into overdrive by providing additional RNAi to the cells (organism).
I figure the researchers would comb the apis and mite genomes (I think they are both finished now) looking for mRNA sequences that are divergent from each other in important genes needed for mite life. The trick is to find RNAi's that only recognize mite sequence and not bee sequence. Many important cellular genes are similar from organism to organism, but with the entire genome to compare I am positive differences will be found. Also another thing to consider is multiple targets. It would be feasible with RNAi to target multiple genes for protein expression knockdown. With multiple targets it is less likely that resistance will be generated in the mite population.
The down side is that RNA is easily degraded. So the half life would be low, but I guess for some that is a Plus.
If you have any other questions please ask. I am a molecular biologist, not that that means much, but I don't have my bees yet ( I hope to start two hives in April) so this is the only question I can answer on a bee forum site right now