Honey bees with a genetic trait that enables them to search out and kill Varroa mites are being developed by the Agricultural Research Service (ARS) in America. The 'Varroa-sensitive hygiene' (VSH) trait, which is a trait that can be bred into any bee population, is responsible for a form of genetic behaviour that causes bees to remove mite infected bee pupae from the hive, preventing the mites from reproducing and harming the colony.
Varroa mites are a major threat to honey bees, causing blood loss when they feed on adults. These parasites can also cause deformities in bees when they invade brood cells where the bee pupae develop. If left untreated, the mites can destroy an entire colony in less than two years. Chemical miticides are currently the most common form of treatment available for bee keepers, but the mites are becoming increasingly resistant.