Varroa Sensitive Hygiene VSH
The natural way to control mites and brood diseases
"In the middle of difficulty lies opportunity"Albert Einstein
It's not often in life that an idea comes along that is so good that it can change the world. The development of VSH bees which can reduce Varroa mite populations without chemical treatments is just such an idea. The result of over a decade of research by some of today's brightest honeybee scientists, VSH is making a difference in the apiaries and lives of beekeepers all across America.
The development of the VSH line of bees by the team of scientists at the USDA Bee Breeding Lab in Baton Rouge, is a true scientific success story. Through careful observation and experimentation, they painstakingly came to understand the natural defenses that the bees had hidden away in their genome. Selection for these beneficial genetic traits over many bee generations has resulted in not only resistance to Varroa mites, but also to American Foulbrood and Chalkbrood. The hygienic behavior of VSH bees, even extends to defense against wax moths and small hive beetles.
Queen rearing is one of those high leverage activities, where small actions can have large consequences. By carefully choosing the proper breeding stock to begin with, entire local populations of bees can be transformed into mite destroying armies, getting the upper hand on the many problems Varroa can cause. The development and use of VSH bees show that man and nature can work together for the mutual benefit of both.
What is VSH?
USDA ARS scientists Dr. John Harbo and Dr. Jeffrey Harris at the Honey Bee Breeding Laboratory in Baton Rouge, Louisiana, have defined and tested a trait of the honeybee which appeared to suppress mite reproduction (SMR). Recently it has been better defined as "varroa sensitive hygiene (VSH)." This is a form of behavior where adult bees remove pupae that have reproductive mites but do not disturb pupae that have mites that produce no progeny.
Recent research done under real world beekeeping conditions with Alabama beekeepers clearly show the value of VSH bees. The resistance to Varroa mites was significantly better than all other bees in the study without sacrificing honey production. These bees have proven their value to American beekeepers. The time has come for you to take advantage of this remarkable line of bees.
Dr. Harbo and Dr. Harris proved the effectiveness of the VSH trait by exchanging queens between resistant and susceptible colonies. Each time a resistant queen was put into a susceptible colony, the mite population went down. On the other hand, every time a susceptible queen was placed in the resistant colonies, the mite population increased.
Recent studies by Dr. Spivak and Dr. Harbo have shown that the SMR trait might be best described as a "varroa-sensitive hygienic behavior". VSH bees remove mites that have started to reproduce. The reproduction of mites triggers their removal by the bees. The only mites left in the cells are non reproductive or sterile. So there is evidence for selective removal of reproductive mites from brood cells.
A goal of the USDA SMR Project is to distribute the VSH trait for resistance to Varroa mites to queen breeders around the country. The object is to cross these bees with beekeeper's own well adapted stock. This will maintain the genetic diversity of American bees while enhancing this important trait. Once in the hives of beekeepers, further selection and improvement can be made for honey production, other disease resistance mechanisms, and other beneficial traits.
Recent tests have shown that VSH queens 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 pure VSH breeder queen so her daughters mate with your local drones.
The VSH trait has proven to be extremely effective at controlling Varroa. It holds great promise as a permanent solution, but the work is not yet finished. There is still considerable variation in crosses with different lines of bees, and so should still be thought of as as a work in progress. With the recent retirement of Dr. Harbo from the bee lab, Dr. Bob Danka , Dr. Jeffrey Harris and the team at the USDA Baton Rouge Bee Lab are carrying on the work.
Questions and Answers
How were VSH bees developed?Dr. Harbo and Dr. Harris have methodically worked on selecting bees for Varroa resistance since 1995. They first had to develop techniques for measuring populations of bees and mites and for measuring characteristics that are associated with resistance. Then they identified specific traits that are related to the growth of mite populations. These traits were analyzed statistically to determine the degree of heritability they had. The trait for suppressed mite reproduction SMR, now called VSH, was shown to be the most promising, so they began a selective breeding program to enhance it. Read about the VSH Project at the USDA ARS Honey Bee Breeding, Genetics & Physiology Laboratory website.Where did VSH bees come from?
VSH bees were originally selected from diverse domestic honeybee colonies in Louisiana and Michigan that showed some degree of mite resistance . They are all American bees.
What's special about these bees?Recent studies by Dr. Spivak and Dr. Harbo have shown that the VSH trait might be best described as a "varroa sensitive hygienic behavior". VSH bees remove mites that have started to reproduce. The reproduction of mites triggers their removal by the bees. The only mites left in the cells are non reproductive or sterile. So there is evidence that bees with the VSH trait selectively remove reproductive mites from brood cells.
Are VSH bees related to the USDA Russian bees?No. Though coming out of the same USDA ARS research laboratory as the Russians, they are not related. VSH bees are not imported, they originated from domestic American colonies.
What is the VSH project?A goal of the USDA ARS VSH Project is to distribute this mite resistance trait to queen breeders around the country. The object is to cross these bees with beekeeper's own well adapted stock, thus maintaining the genetic diversity of American bees while introducing this important trait. Once in the hives of beekeepers, further selection and improvement can be made for honey production, other disease resistance mechanisms, and other traits.
Are the genes for suppressed mite reproduction dominant or recessive?
The VSH trait is thought to be controlled by more than one gene, just how many is uncertain at this point. These genes are neither dominant nor recessive. They are what is called "additive" which simply means that the more of them that are present, the more strongly the trait will be expressed. This works in favor of beekeepers since a queen with VSH genes can mate to any drones and still have the trait expressed in her colony enough to reduce the mite population. So naturally mated queens produced from pure VSH breeders are mite resistant.
Who should buy pure VSH breeder queens?Pure VSH breeder queens should be used for queen rearing purposes. The best way to get the maximum amount of the trait into a line of bees is to begin with a pure VSH breeder queen so her daughters mate with your local drones. Daughter queens of pure VSH breeders who are out crossed by natural mating have good brood production and an acceptable level of mite resistance. The naturally mated daughters of these breeder queens should be used for production hives. Naturally mated queens containing 50% of the VSH trait can be purchased from various queen producers.
How do you know VSH bees are mite resistant?
In a recent published study Dr. Harris and Dr. Harbo proved the effectiveness of the VSH trait by exchanging queens between resistant and susceptible colonies. Each time a resistant queen was put into a susceptible colony, the mite population went down. On the other hand, every time a susceptible queen was placed in the resistant colonies, the mite population increased.In another study by Dr. Marla Spivak at the University of Minnesota, bees of several strains were compared. The VSH colonies showed the highest degree of mite resistance, and also had good honey production.
What is the difference between VSH and SMR bees?This line was originally called SMR for Suppressed Mite Reproduction because that was the apparent cause of the resistance to varroa mites. However after further research, it was learned that the real cause was a type of hygienic behavior that was sensitive to the presence of reproductive varroa mites. With this clarification of the mode of resistance, SMR was renamed VSH for Varroa Sensitive Hygiene to be more accurate.bee Further reading on VSH bees:
If there is one good thing about varroa mites, it is that they are large enough to see fairly easily. With a magnifying glass, a flashlight, and a little time to look, the VSH trait can be observed in any stock of bees. The USDA maintains a web site on Varroa mite reproduction which has an excellent display of pictures and descriptions of mites, both reproductive and non-reproductive. Your time will be well repaid by studying this site before you begin your own observations.
Materials needed:
What to look for:
- 2x-4x Magnification - visor magnifying glass works well or low power stereo microscope is best.
- Lighting - a bright handheld penlight
- Forceps or tweezers- fine enough to uncap and pull out pupae
- Record sheet - a simple tally of reproductive and non-reproductive mites.
- Brood comb containing mites - from colonies not recently treated with miticides.
- Time to look- allow at least an hour per comb
1. Uncap purple eyed pupae with tan body color.
2. Remove and inspect pupae for white fecal deposit- bright white powder.
3. Check pupae for varroa mites. They may colored brown or white depending on age.
4. Check cell wall for white fecal deposit, usually on the upper cell wall.
5. Check cell interior for mites.
6. Identify the reddish brown mother mite.
7. Identify lighter or smaller offspring mites.
8. Inspect 20 infested cells containing a single mother mite.
9. Record number of reproducing and non-reproducing mites.
10. Compare colonies to select the best breeders.
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