Dear Beekeepers:

This is very encouraging, indeed!

Charles Frederic Andros
Linden Apiaries since 1973
Former NH/VT Apiary Inspector '78-'89
1 McLean Road
POB 165
Walpole, NH 03608-0165
603-756-9056
[log in to unmask]
Residence: Latitude 43° 04' 53" North, Longitude 72° 21' 13" West, Elevation 363 meters 
Keeper of 43 two-queen colonies for unheated honey, fresh-frozen pollen, propolis tincture, Bee Complex facial, pollination, nuclei, beeswax, candles, apitherapy, workshops, and supplies
"Learn, experiment, innovate, educate!" 




Malcolm T. Sanford

ApisApicultural Information and Issues

Florida Extension Beekeeping Newsletter

Volume 19, Number 4, April 2001

  
Smrd Honey Bees:  Breakthrough in Varroa Tolerance

 

Dr. Jeff Harris of the USDA Honey Bee Breeding Lab in Baton Rouge, Louisiana provided some exciting information at the latest meeting of the South Alabama Beekeepers' Association in Mobile.  It seems that suppression of mite reproduction is a genetically inherited trait that results in Varroa-tolerant bees.  This characteristic, called SMR, is just one of several found in Africanized honey bees that have potential use in selection programs <http://www.ifas.ufl.edu/~mts/apishtm/apis97/apmay97.htm#2>.  Fortunately, the trait is widespread in the U.S. honey bee population and so is readily available in the present gene pool.  However, in order to begin a selection program, there must be a technology to measure the trait.  A full description of the work done by Dr. Harris along with Dr. John Harbo appears in the May 2001 issue of Bee Culture (Vol. 129, No. 5, pp. 34-39) and on the ARS web site <http://msa.ars.usda.gov/la/btn/hbb/jwh/SMRD/SMRD.htm>.

 

According to the authors, all female Varroa in a bee colony do not attempt to reproduce at the same time.  Generally one-third of the mites can be found on adult bees and the rest in the brood cells.  And some fifteen to twenty five percent of mites that enter brood cells do not in fact reproduce.  These individuals may be mites that die before laying eggs, live but do not lay eggs, produce only a male and no females, and/or produce progeny too late to mature before bee emergence.  One or all of these categories may be found in any one honey bee colony.

 

The number of non-reproducing mites in a colony is measured by examining about 30 singly infested brood cells and recording the reproductive success of each female found there.  Several environmental variables affect the percentage of non-reproducing (NR%) mites.  These include temperature and humidity (increase NR%), season (higher NR% in summer) and climate (larger NR% in the tropics).  NR mites also often have no sperm (have not been mated) and in some cases, dead mites are found "entrapped by the pupal cocoon."  Over fifty percent of mites in colonies selected for NR have been found so entrapped.  Of passing interest is the fact that non-reproducing mites deposit their feces on the bee pupae rather than beside it. 

 

It takes about 6 weeks after requeening a colony with an SMR queen to see results.  This is called by the authors "delayed mite suppression" or SMRd.  Mite suppression also occurs immediately in some  populations, and is called SMRi.  To show how SMR queens affect change in a colony, the authors performed several queen exchanges between control and SMR colonies, and found that mite populations became more or less reproductive based on the queen received.  They conclude: "¼we are confident that honey bees will become resistant to Varroa mites."  More encouragingly, they say that in the future, "¼bees will need fewer chemical treatments to control mites.  Eventually they will need none." 

 

The Varroa Species Complex:  New Strategies to Control Varroa Destructor 

 

An article titled: "The Varroa Species Complex: Identifying Varroa destructor and New Strategies for Control" in American Bee Journal (Vol. 141, No. 3, pp. 194-196) by Susan Cobey <http://iris.biosci.ohio-state.edu/honeybee/personnel/Sue.html> at the Ohio State University discusses in some detail the implications surrounding renaming Varroa jacobsoni to Varroa destructor <http://www.ifas.ufl.edu/~mts/apishtm/apis_2000/apjul_2000.htm#3>.  A key finding, according to Ms. Cobey, is that the former mite reproduces only on the original Varroa host, Apis cerana, while Varroa destructor infests and reproduces on Apis mellifera. Thus, they are reproductively isolated.

 

It is instructive to look at reproductive variability within the context of the Varroa species complex. Many questions arise.  Is it possible, for example, that the SMR characteristic only functions with one or a few haplotypes of the mite?  If so, does this mean it is in fact a haplotype dependent trait?.  What happens should other haplotypes be introduced into this complex equation?  There is no answer to these yet, according to Dr. Harris, but fortunately DNA study appears to confirm that the haplotypes found in Louisiana are presently susceptible to SMR honey bees.  

 

Ms. Cobey Concludes:  "New discoveries are encouraging and lead us closer to the goal of being able to naturally maintain mites at insignificant levels.  The focus must be on selective breeding.  We now have the knowledge to move forward in this direction (editor's note:  SMR bees described above is one of the most hopeful signs).  To select and maintain mite resistant honey bee stocks is the beekeeper's biggest challenge, ever.  This will require the combined efforts of scientists and beekeepers.  Beekeepers must then take the responsibility to establish selective breeding programs and apply this knowledge in the field.  As we discover new strategies and achieve this goal, we must also remember not to become complacent.  Selective breeding is an on-going endeavor and subject to constant change.

 

Are Non-Hygienic Queens Now Passé?

 

I wrote back in September 1998 that Drs. Spivak and Gilliam, who co-authored an article on the subject in Bee World, have concluded. that hygienic behavior is eminently inheritable and thus it can be selected for.  Commercially available lines of hygienic stock would help many beekeepers overcome a multitude of problems, especially those associated with mites and disease.  This would reduce operating costs by minimizing use of chemicals, with their concomitant possibilities of bee, colony and product contamination. Finally, standard queen rearing and breeding techniques can be used to produce many hygienic queens from a few mothers using any race of honey bees <http://www.ifas.ufl.edu/~mts/apishtm/apis95/apjan95.htm#BP>.  

 

At the time I wrote the article referenced above, I asked why this trait was not more widely used in breeding programs.  Mr. Allen Dick in Canada now says in no uncertain terms: "Non-hygienic queens are now passé."  He stated this in a May 19, 2001 post to the Bee-L discussion list, concluding that nowadays nobody should have to put up with queens that lack this essential characteristic and the consequent economic losses that result from AFB and chalkbrood (Editor's note: The trait also appears to affect mites and small hive beetle).  The hygienic characteristic, he says, can be easily selected in any strain of bees in only a few generations.  Mr. Dick urges beekeepers to demand hygienic queens from suppliers and "don't take no for an answer."

 

In an effort to show how one might employ this technology, Mr. Dick has put up an article with many illustrations describing in great detail both the basis behind hygienic behavior and how to test for it <http://www.internode.net/HoneyBee/Misc/hygienic.htm>.  Originally developed by Steve Taber, the technique has been modified using liquid nitrogen to effectively kill a patch of brood, an innovation of Dr. Jerry Bromenshenk at the University of Montana <http://biology.dbs.umt.edu/bees/default.htm >.  It factilitates the process because brood comb does not have to be physically removed from a frame and then be reincorporated back into it as the original technique demanded.  It will now be up to beekeepers to take or leave Mr. Dick's advice.