Nelson Honey’s Queen Breeding to Reduce Varroa Mites
The Varroa Sensitive Hygiene (VSH) Trait Breeding Programme aims to create a self-sustaining bee population with the VSH trait in New Zealand. The intention is to create an alternative means to control Varroa mite and reduce the need for increased treatments as Varroa develop resistance to the synthetic products.
Nelson Honey & Marketing and its sister companies are committed to the development of the beekeeping industry in New Zealand. When the funding for the Plant and Food Research project ceased in 2012, Rainbow Honey did not want to see the VSH Trait Breeding Programme cease along with it. Despite financial and project risks, they have sought to develop the programme. Rainbow Honey has made a commitment to return a royalty of 5% of revenue to the New Zealand Beekeepers Association and Plant and Food Research. This NBA funding will be specifically tagged to streamline the process for genetic finger printing of the VSH trait.
Rainbow Honey continues to work with Plant and Food scientists Michelle Taylor and Dr Mark Goodwin and consults with Dr Susan Cobey of the Honey Bee Research Facility, UC Davis and Washington State University in USA and Dr Bob Danka, Honey Beekeepers Genetics Laboratory, US Department of Agriculture.
The purpose of the programme may be best described in the words of Dr Bob Danka, “The emphasis will be on the practical application of defining what VSH bees can and cannot do and working on distributing the technology”.
What is the VSH trait?
Varroa Sensitive Hygiene trait is a gene in bees which causes them to detect and remove bee pupae which have reproductive Varroa mites. VSH is a naturally occurring gene in the bee population.
What does the VSH trait do?
Bees with the VSH trait have been shown to suppress Varroa mite reproduction by removing the mites that reproduce. This results in selective removal of reproductive mites from brood cells. The mites left in the brood cells are non-reproductive or sterile.
Is the VSH gene dominant or recessive?
The gene is neither dominant nor recessive. It is an ‘additive’ gene which means that the more genes which are present, the more strongly the trait will be expressed. This works in favour of beekeepers since a queen with VSH genes can mate with any drones and potentially still have sufficient VSH trait to reduce the mite population within the colony.
Is this new?
Studies commenced in the USA in 1995. Artificial insemination of bees is a technique which is approximately 50 years old.
Plant and Food Research initiated the VSH Trait Breeding Programme in New Zealand with funding from the Ministry of Agriculture and Forestry and through the Sustainable Farming Fund. When the funding ceased in 2012, Rainbow Honey saw the future potential of the programme and volunteered to continue the project.
Why is the programme needed?
Although miticide treatments are being used to control Varroa mite, mites are already showing resistance to these. The treatments are costly to administer, both in terms of time and product.
Given enough time and in the absence of chemical treatment, bees would probably become adapted to Varroa by natural selection. The goal of this programme is to accelerate this process through artificial selection.
What are pure VSH breeder queens?
VSH breeder queens are queens mated with drones that carry the VSH trait, through a process of artificial insemination.
Where do VSH bees come from?
Plant and Food sourced 65 queens from queen breeding stock throughout New Zealand. These bees were tested for the VSH trait and placed in closed conditions on Great Mercury Island (off the Coromandel Coast). The most resistant bees were naturally out-crossed to create a greater gene pool. These bees were further tested and re-selected based on the presence of the VSH trait. These bees have now been passed to Rainbow Honey. None of the bees have been imported.
What is the process?
a) Breeder queens are selected following testing for the VSH trait. Other desirable traits are also selected including disease resistance, temperament and honey production.
b) Drones are also bred and raised according to desirable traits.
c) Semen is collected by syringe from approximately 20 drones at one time. The semen is allowed to naturally mix for 24 hours to ensure that each queen receives maximum genetic diversity. The semen will last for approximately 6 weeks.
d) The queens are subdued by CO2 and then artificially inseminated and the brood are tested for the VSH gene 4 weeks later.
e) Each step requires exact record keeping as timing is critical to ensure that the queens and drones achieve sexually maturity simultaneously.
Do we want to achieve 100% presence of the VSH trait?
No, it is important to maintain a high degree of genetic diversity and prevent the negative effects from inbreeding.
How long does it take to see a difference in the hives?
Mite fertility is reduced several weeks after introduction of VSH queens into non-selected colonies. Hives can be tested by using a microscope to enable counting of the number of mites within the bee brood.
Will the VSH trait only be effective in a closed population?
VSH breeder queens have been shown to retain an acceptable level of mite resistance when they are free mated to unselected drones. The best way to get the maximum amount of the trait into a line of bees is to begin with a VSH breeder queen so that her daughters mate with unselected drones. This maintains genetic diversity and speeds up the level of the VSH trait present within the bee population.
Bees bred to have high levels of the VSH trait tend to keep mite productions below thresholds recommended for pesticide treatments. Queens from such VSH breeding sources can be allowed to mate freely with non–VSH drones and the resulting hybrid colonies from these outcrosses will retain lower and variable, but generally still useful, resistance to Varroa while retaining desirable beekeeping traits such as honey production.
During the Plant and Food Research study, bees with the VSH trait were found to be genetically geared to uncapping brood and removing larvae infested with Varroa.
Studies in USA have also demonstrated the effectiveness of the VSH trait by exchanging queens between resistant and susceptible colonies. The VSH colonies with the highest degree of mite resistance also had good honey production.
You can listen to Rae Butler’s radio interview here.
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