The Hilo Bee program has roots in 25 years of selection to improve Varroa resistance in honey bees.
Selection for resistance has been based on “Varroa Sensitive Hygiene” (VSH), a trait of adult bees to remove reproductive mites. Read this history in the Oct 2020 ABJ, and find more references on the research at this USDA website.
Development of VSH Bees
The scientific story of VSH bees began with discovery of Varroa resistance in 1995, at the USDA bee lab in Louisiana. Here are some key milestones, with links to related scientific reports.
The factor most strongly associated with low population growth was a high frequency of non-reproducing female mites. Bees that resisted Varroa in this way were described as having a trait that caused “suppressed mite reproduction” (SMR).
SMR was shown to be heritable and became the focus of selective breeding for Varroa resistance. SMR bees were released to U.S. bee breeders in 2001.
Subsequent tests showed that SMR was the result of bees removing mite-infested brood, leaving high proportions of non-reproducing mites seen in SMR colonies. In 2007, the SMR trait was renamed VSH to emphasize the removal mechanism that confers high mite resistance.
Crossing VSH bees with commercial stocks and selecting for better productivity yielded a stock called Pol-line Bees.
VSH and Pol-line bees have been used only to a limited extent by commercial beekeepers, due in part to lack of large numbers of pure-mated queens.
VSH In Hawaii
Varroa was not detected on the island of Hawaii until 2008. This allowed a unique window to observe Hawaii's commercial and feral bees' initial response to mites.
Commercial bees from the Big Island of Hawaii were tested proactively before Varroa arrived on the island by USDA scientists, and were found to belargely susceptible. This finding led to initial imports of VSH semen to Hawaii, which became foundation for breeding to enrich mite resistance. Comparing various levels of VSH genetics showed that resistance required 75% VSH genes, but these bees would need additional traits for commercial use. Breeding toward this goal was initiated in 2010 near Hilo by the Hawaii Apiary Program, (D. Downey) and was expanded significantly when Hawaii Island Honey Company (D. Thomas) became involved in 2012. This effort continued through 2014, and led to the current Hilo Bee breeding program with the goals of stabilizing the mite resistance and productivity of the bees, and scaling up production to deliver commercial quantities of queens to beekeepers. Development continues with feedback from these beekeepers.
Hilo Bee Milestones:
2015 Hilo program formalizes with four partners. Laboratory and beekeeping infrastructure established in East Hawaii. 2016 Apiary technicians hired to conduct breeding, enabling rapid scaling up of testing and selection for mite resistance. 2017 Breeding progress continued. First field trial of Hilo Bees conducted in a commercial operation in North Dakota. 2018-2019 Breeding continued and field trials expanded to commercial beekeepers in ND, SD, LA. Initial release of 2000 queens to a limited number of beekeepers for the bees to be evaluated when used in production. 2020 Approximately 30,000 production queens distributed for use and evaluation by ~20 commercial beekeepers. Independent field trials conducted in 5 commercial operations, assessed by the Bee Informed Partnership. With mite resistance well established, the breeding program shifted from intense selection to a semi-closed population.