Varroa Sensitive Hygiene (VSH) is a behavioural trait of honeybees proven to assist bees in becoming resistant to varroa mites (Varroa destructor).
VSH colonies can offer the opportunity to delay the need for varroa treatments because the colony is able to keep the mite population below the need to take action threshold with varroa treatments.
In VSH bee colonies, the bees reduce the mite population by uncapping and removing brood that is infested by varroa mites. High VSH colonies can also recap the cell after releasing mites. The uncapping process causes disruption of the mite’s reproductive cycle and will reduce the fertility of the remaining mites, which has a snow ball effect of reducing the number of varroa mites in the colony.
There are indicators that a colony may have a certain level of VSH, but to reliably measure VSH the colony has to demonstrate the ability to lower infestation and maintain infertile varroa mites.
Ironically, to accurately measure for VSH the test hives need to have or be subjected to high levels of varroa. Breeding for varroa is not a desirable practice when the goal is to eliminate it.
Due to their complexity, the more reliable VSH tests take a huge amount of time, labour and resources.
There are simpler versions of the complex VSH tests that are less reliable but can be utilized collectively for the initial screening of VSH traits in beehive colonies. To confidently claim these tests are accurate extensive research in the field are required.
VSH can be used as another tool in an Integrated Pest Management Plan tool box to help combat varroa. Varroa is becoming resistant to the hard-chemical treatments creating a need for reliable alternative treatments.
To utilise the VSH trait within colonies there is still a lot of unanswered questions such as trait heritability, testing protocol and industry approval.
Research has been done on the complex measuring of the VSH trait but due to the genetic makeup it is still unknown what the breeding value of the VSH trait is. High VSH mothers do not necessarily produce high VSH daughters even in closed population mating programmes. The VSH levels are variable and require measuring.
High VSH colonies do not necessarily produce profit producing bees but can be crossed with the genetics of commercially popular bees.
Bee Smart Breeding propose to provide pure VSH breeding material, cross breeding options and provide good monitoring protocol to ascertain at what point treatment levels can be set.
There are two breeding programmes for the queens raised from these breeder colonies:
- ‘Hybrid VSH Queens’ outcrossed to produce production queens
- ‘Pol-line Queens’ closed population of out crossed VSH queens with commercially productive germplasm
Queens grafted from VSH breeders are outcrossed in cooperating beekeeping operations. Colonies are put through an annual cycle and after one year the best are retrieved. The colonies are tested using the simpler VSH testing assays to ascertain if the population retain enough varroa resistance to serve as breeder colonies for a new generation.
Regional monitoring will help ascertain the breeding value of VSH, reliability of VSH, productivity of outcrossed VSH and practicality of VSH tests.
Beekeeper cooperation is vital by providing the best preforming VSH colonies back to Bee Smart Breeding for developmental research.
Bee Smart Breeding has been utilising published research on the methodology of VSH testing to establish the VSH breeding programme.
The technology transfer has been refined it now requires gaining credibility within the industry. To gain industry credibility the reliability the VSH trait and the way it is tested out in the field within commercial beekeeping businesses needs to be proven thus requiring further research.
Bee Smart Breeding require assistance to expand the VSH breeding programme to encompass creating a robust data input analogy and is looking for cooperating beekeeping operations.