With the Varroa incursion in NSW many beekeepers are asking how we can breed Varroa resistant bees.
The United States Department of Agriculture (USDA) imported bees from the Primorsky region of Russia in 1997 because the stock had a long exposure to Varroa and had developed resistance to the mite.
Russian honey bees www.russianbreeder.org
The imported stock was kept on an island for testing, with only superior stock being introduced to the mainland. Varroa resistance is the main criteria for selection, but honey production, tracheal mite resistance, and chalkbrood resistance are also considered.
Varroa resistance breeding in this program is based on mite population growth.
Mite population growth is measured by taking a sample of approximately 300 bees at the first inspection in spring and determining the infection rate with a soap or alcohol wash. This is then compared with a sample taken at the end of the selection period.
Comparisons with control stock showed that Russian stock has lower proportions of infested brood, fewer brood cells infested with multiple mites, and a higher proportion of damaged mites on bottom boards. All the control stock died.
American foulbrood, chalkbrood and sacbrood are uncommon in the Russian stock, and they are resistant to small hive beetle and potentially to Deformed Wing Virus.
Rinderer and Coy list the following traits as contributing to Varroa resistance: suppression of population growth rate, Varroa Sensitive Hygiene, grooming, reduced mite reproduction, extended phoretic period (the mites spend a longer time on adult bees, exposing them to grooming), less attractive to mites, low proportion of infested brood, fewer cells with multiple foundress mites, timing of brood production.
The stock was released to industry management starting in 2000, with the Russian Honey Bee Breeders Association established in 2007. Honey production is considered indicative of colony health, but mite population growth is given double weighting in selection.
Each line is held by at least two members, to ensure that lines are not lost. Queens are exchanged between members so that they can be evaluated and as sources for drones. Members must operate at least 200 colonies, only of Russian stock, and be certified annually. Genetic testing is used to ensure that the stock remains pure.
Podcast: It’s all about the Russians (Russian honey bees, that is) – Dan Conlon, President of the Russian Honey Bee Breeders Association
Advantages of selecting for low mite population growth or low infestation levels
- Quick and easy protocol. While in the Russian program they use a soap or alcohol wash, you can determine infestation levels by:
- a Sugar shake
- Alcohol/soapy water wash
- Brood uncapping (brood cells should continue to be opened until you have found 30-40 infested cells, or until 500 cells have been examined)
- Sticky bottom boards placed for a set time
- Any trait that contributes to low population growth is selected for, including Varroa Sensitive Hygiene (VSH)
- You do not need to have colonies with high mite numbers on hand for use in your protocol, as you do for VSH. Keeping such colonies will increase mite numbers in surrounding colonies through bee drift
- There is a strong link between infestation levels and colony survival, something that hasn’t been established for all targets for selection of Varroa resistance
- Keeping track of Varroa numbers will help you to decide when to treat your bees
SmartBees (Europe) and several programs in Canada consider this trait. It’s time effective and it works.
Acknowledgements:
- Buchler, Kovacic, Buchegger, Puskadija, Hoppe & Brascamp (2020) Evaluation of traits for the selection of Apis mellifera for resistance against Varroa destructor. Insects 11: 618
- de Guzman, Rinderer & Frake (2007) Growth of Varroa destructor (Acari: Varroidae) populations in Russian honey bee (Hymenoptera: Apidae) colonies. Annals of the Entomological Society of America 100: 187-195
- Rinderer & Coy (2020) Russian Honey Bees. Salmon Bayou Press
- http://www.russianbreeder.org/
- This article was peer-reviewed by John Roberts and Elizabeth Frost
