In a message dated 23/04/2007 18:17:28 GMT Standard Time,  
[log in to unmask] writes:

BTW, I  
have been told that as little as 10-15% TM detected prior to winter is  
more than enough to kill the colony.


"Field observations and experiments at Rothamsted from 1951 to 1960  
inclusive (Bailey 1958;1961) showed that, contrary to the received opinion,  A.woodi, 
[tracheal mite], whether in natural or experimental infestations, does  not 
cause any outward sign of disease. It is detectable only by dissection and  
microscopical examination of individual bees. Moreover, although it shortens the  
life of an infested bee, it does so only by a barely detectable amount, an  
observation independantly confirmed in N.America (Royce and Rossignol 1990).  
Only the relatively few colonies that have more than 30% of their bees infested  
are more likely to die than uninfested colonies - because of the slightly  
shortened lives of infested bees - and then only in late winter or early  
spring......"  Leslie Bailey 2002 , based on a lecture to the Central  Association 
of Beekeepers on 14th October 2000.
 
Chris



   

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