VSH-Based Resistance to Varroa


Varroa Sensitive Hygiene, identified and researched at the USDA Bee Lab in Baton Rouge, is neither a line nor a breed of bee.  Rather, it is identified as a “trait.” Backcrossing suggests that the trait involves a small group of genes, perhaps only two.

While the VSH trait was first identified in honeybees in the U.S., current research supports the theory that the VSH alleles (alternate forms of genes) may occur in bee populations worldwide. Moreover, the VSH alleles can be bred into any honey bee population to produce VSH-based resistance.

In 1992, as varroa mites were becoming widespread in the United States, Dr. John Harbo at the USDA’s Honey Bee Laboratory in Baton Rouge was assigned the task of breeding bees for resistance to varroa. In 1995 he and Dr. Roger Hoopingarner at Michigan State University discovered the VSH trait. During the next ten years Dr. Harbo led USDA research to understand how this trait works and to evaluate its effectiveness in field colonies. The VSH trait was released to the beekeeping industry in 2001.


Valuable Feature


A valuable feature of VSH is that bees will express a high level of mite resistance when a colony contains as little as 50% of the alleles for VSH. A simple way to produce such a colony is to raise daughter queens from a VSH breeder and allow the daughters to naturally mate. This is good news for queen producers. They can rear VSH queens, mate them to any drones, and those queens will produce colonies that require no chemical control for varroa. Another benefit is that beekeepers can have mite resistant colonies without destroying their existing bee populations --populations which may be well adapted to certain locales or have desirable beekeeping qualities.