A Peter Borst snip followed by my comments..

 This diagnosis is all over the map but for openers, Nosema ceranae doesn't
"cause" winter mortality

"Seasonality of Nosema ceranae Infections and Their Relationship with
Honey Bee Populations, Food Stores, and Survivorship in a North American
Region"

>I must guess this depends on the degree to which any malady can be interpreted as 'cause'.  imho even the most insignificant malady can lead to a hive performing at a level where mortality is almost inevitable. from a practical matter some maladies response to beekeeper treatment and some do not... nosema C. from my own experience seems to fall into the not category. 

>Classical symptoms of nosema are weak bees that appear to be starving and who will fly at sub optimal temperature.  In places where it get even somewhat cold this means they die some feet from the front entrance to the hive.

>In my own operation I have seen nosema C. show up in the fall of the year and without intervention the hive will not live till spring.  the typically winter here is mild with occasional short term periods hovering around freezing. sadly when treatment end the hive goes back into decline and very slowly perishes.

>in very cold location any decline in bee population beyond a certain level almost insure the hive will perish.

Gene... temporarily hanging out on the left coast
 

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html