Hi There,
I'm currently studying the effects of Varroa mites on how a honey bee
colony functions for my Master's thesis at Simon Fraser University.  I've
sorted through the various literature on honey bee pathogens to come up
with some idea of how honey bee colonies respond to parasitism. Chalkbrood
appears to primarily infect brood that has become chilled shortly after
capping. Not to long ago, there was a short article on this topic in one
of the beekeeping magazines (I'm afraid I don't know which one, Sorry!  If
anyone wants a reference, I'll look through my files)
 
I've noticed this in my own work, in which I have taken recently
capped brood frames out of the colony to infest individual larvae with
varroa mites, only to find that several weeks later my work is lost to
chalkbrood.  I removed some 'control' frames that I did not inoculate with
Varroa, to see if there were similar losses to chalkbrood.  Chalkbrood
was a problem on these frames as well.
 
Chalkbrood appears to be a problem when there are not enough adult bees in
a colony to maintain the appropriate temperature in the brood nest.  If
adult populations in colonies are beginning to decrease, yet brood
production has not decreased, the brood may become
chilled and chalkbrood will result.
 
I spoke to a beekeeper from Alberta who would supplement his colonies with
pollen, only to find that chalkbrood became a problem.  I suspect that
the colonies responded to the addition of pollen by increasing brood
production above that which the adult bees could keep warm.  It's possible
that spores were present in the pollen, but I think that spores are
present in the colony at all times, and chalkbrood only becomes a problem
when the colony is compromised in some way.
 
That's my two bits worth.  I look forward to reading your replies!
 
Alida Janmaat
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Centre for Pest Management
Simon Fraser University
Burnaby, Canada
email: [log in to unmask]
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