DANKA, R. G. and J. D. VILLA. 2000. A survey of tracheal mite resistance levels in U.S. commercial 
queen breeder colonies. American Bee Journal 140: 405-407.

Almost a decade old but still useful a reference for unexplained winter losses.  Looks like a roll of 
the dice if you are buying queens.   

see link for graph 

http://www.ars.usda.gov/Services/docs.htm?docid=2744&page=12


A Survey of Tracheal Mite Resistance Levels in U.S. Commercial Queen Breeder Colonies  

"Research has shown that honey bee strains having genetic resistance to tracheal mites (Acarapis 
woodi) can be used to help to solve the problems resulting from parasitism by this mite. Colonies 
of resistant bees tend to withstand challenge from tracheal mites and remain productive without 
treatment, while susceptible colonies tend to become infested at damaging levels.

Resistance to tracheal mites is of interest to bee breeders who are trying to improve stock quality. 
Identifying the level of resistance in breeding colonies should be a critical part of such breeding 
efforts. However, little is currently known about the resistance in the commercial breeding 
population used to supply queens for the U.S. beekeeping industry. Our objectives were to 
measure the range of resistance in a sample of U.S. commercial breeder colonies, and enable 
participating queen breeders to improve the quality of their stock by providing selection guidance.

Eight commercial queen producers from five states submitted brood from 6 to 19 breeder colonies 
each so that emerging bees could be evaluated for relative resistance to tracheal mites. Young, 
uninfested bees from each colony of an individual queen producer, and also from colonies of two 
reference stocks (one known to be resistant to tracheal mites and one known to be susceptible), 
were marked and then simultaneously exposed to mites in infested colonies. They were retrieved 
after 4-6 days and dissected to determine resulting mite infestations. Results for the breeder 
colonies were adjusted to the average results of the resistant and susceptible reference colonies 
with which they were tested.

The 83 breeder colonies varied widely in their responses to tracheal mites. About two-thirds were 
statistically similar to the resistant reference and one-fourth were similar to the susceptible 
reference. Three queen producers had 30 of 31 breeder colonies that were classified as resistant. 
The other five queen producers had breeder colonies that were very variable and of which 40% 
were susceptible.


The most striking result of this survey was the variability in levels of tracheal mite resistance 
among colonies of U.S. commercial breeding stock. This breeding population can be expected to 
yield propagated queens that range widely in quality: some queens will be useful in improving 
stock by imparting resistance, while others will predispose their colonies to damaging mite 
infestations. In the absence of knowledge about the resistance levels of individual breeder 
colonies, the performance (vis-vis tracheal mites) of production colonies headed by commercial 
queens becomes largely a matter of the chance associated with a queen producer=s random 
selection of a grafting source from  among his or her breeder colonies.  

Fortunately, the majority of colonies we tested had useful resistance to tracheal mites. However, 
queens propagated from susceptible colonies and then widely distributed through commercial 
sales may contribute to the lingering problems associated with tracheal mites across the country. 
The findings from this survey emphasize the value of testing in enabling effective selection for 
resistance to tracheal mites.  Through testing, susceptible colonies are easily identified and can be 
eliminated.  Several of the queen breeders who participated in this survey reported that 
susceptible colonies were removed from their breeding programs soon after they received the test 
results.  "



The russian lines  were very resistant when looked at in the late 1990's
http://www.ars.usda.gov/Services/docs.htm?docid=2744&page=8

are they resistant to nosema ceranae also?  

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