Here are links to the USDA Bee Lab findings on Varroa-Sensitive Hygiene in honey bees
Varroa Sensitive Hygiene (VSH) Publications
VSH is an important mechanism of resistance to varroa mites. VSH is very similar or the same as hygienic behavior that honey bees use to combat American foulbrood, chalkbrood, and the eggs and larvae of wax moths and small hive beetles.
Another characteristic of VSH bees is a reduced fertility of mites, when compared to non-VSH bees. In a colony, mite fertility is reduced several weeks after introduction of VSH queens into non-selected colonies. This led to the original name of the trait, Suppressed Mite Reproduction (SMR). This name describes the trait (or traits) selected in the experimental population of bees. The name of the trait was later replaced by Varroa Sensitive Hygiene (VSH). This is due to the finding that the primary mechanism of the trait is the removal of infested pupae from capped brood cells.
Below is a clip of VSH bees removing mites from an infested cell