Hi Alida and All:
 
>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)
 
Please post it to the list and I hope it initiates discussion.
 
<snip>  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!
 
That was a most fascinating posting Alida.  I got a compilation a few months
ago from Aaron Morris (our Sysam) of all the postings to the bee-l on
chalkbrood.  By the way that is a great project (to compile postings by
subject) and you should report Aaron on which subjects are now ready, and
which you need volunteers to work on.  The majority of the postings on
chalkbrood seemed to indicate that it was a combination of two housekeeping
behaviours (the ability to remove mummies, and the ability to recognize
early and uncap infected larvae) that was important in resistance to the
fungus (reducing spore load by getting rid of the mummies before they turned
black and "highly spore loaded).  Most people also seemed to agree that
chalkbrood responds fairly quickly to selection for bees which have these
behaviours.
 
Since I have a bad problem with chalkbrood (in the spring) I requeened many
of my colonies still showing a few mummies late in the summer.  They were
moderate sized and I split them into nucs. I used queen cells from
chalkbrood free colonies and from a neighbour beekeeper who has a lower
incidence.   I knew that chilling was a factor in chalkbrood, but I was
still surprised at how much it increased in the nucs.  I think they almost
all showed some,  and it was severe in several.
 
I find that drone cells are more likely to be infected than worker cells,
and it has been suggested that this is because of chilling, i.e. the drone
cells are more likely to be on the edge of the brood pattern.  But I even
find that drone cells are infected right in the middle of the cluster.  For
example in hives with a very low level of infestation I can still find
mummies in the drone cells that are sometimes built between the boxes or on
the bottoms of frames wherever my imperfect carpentry has allowed.  I wonder
if there might be any other reason besides chilling for this.
 
Regards, Stan in Prince Edward Island, still mite free we hope (45 N)