Samuel Ramsey spoke at a VSBA training event this weekend that I attended in Virginia Beach. His full presentation is summarized by him in three minutes in the video below. As noted in this UMD article "For nearly 50 years, researchers have believed that the mite fed on the hemolymph (the “blood”) of the honey bee. Ramsey’s research establishes that the mites are primarily feeding on the honey bee’s fat body tissue—an organ in insects that serves a similar role to the human liver. Since several existing systemic pesticides were formulated assuming that mites fed on hemolymph, this discovery explains why these pesticides were never successful in controlling the mites. The mites will never ingest enough to kill them, but frequent exposure may contribute to future resistance." In his lecture he went into great detail on all the negative impacts Varroa have by feeding on this fat body tissue. Essentially, the fat body tissue is a critical to a number of life cycle functions and its destruction contributes to multiple mortal impacts on honey bees.
This was one of the most fascinating bee lectures I've sat through in a long time. His research will change the entire approach we take to control Varroa mites and their negative impact on Honey Bees. In fact, he hinted that a major company has already approached him to leverage his research! His work is now going through peer review and so is not fully published. I did capture his conclusion slide and it is worth repeating here: