Although not very pleasant, Chalk brood is not the devastating plague in the
way that others are currently worrying us.
Len Heath, who recently retired as Professor of Biology at Plymouth
University, researched the life history of Chalk brood for almost 20 years.
In a recent article in Devon's magazine "BEEKEEPING"
Len compared the generally accepted understanding of the disease as it was
in 1975, with our present knowledge.  Much of the change is a result of
Len's discoveries.
 
From "BEEKEEPING"  Nov 1996
Chalk Brood is:
1975
An epidemic disease caused by the minute spores of a mould. It is common in
damp areas and affects drone brood more than worker brood.  The spores are
fed to brood in their food.  They germinate in the anaerobic conditions of
the larval gut.  If the brood is chilled then the mould grows all through
the larva and mummifies the body.  If both sexes of the fungus are present
then spores are formed and the mummy is black.  If only one sex of the
fungus is present then the mummy remains white.  Mummies are ejected by the
worker bees and the spores on them are wind or splash dispersed onto the
foliage and flowers where they are picked up by forager bees and infect
other colonies.
 
1996
An endemic disease caused by the minute spores of a mould.  It primarily
attacks genetically susceptible bees under various physiological stresses.
The spores are fed to larvae in their food.  They germinate in the contents
of the gut, stimulated to do so by the high carbon dioxide content  and the
fungus grows through the body tisues to form a "mummy".  Depending on the
exact conditions under which the mummy is formed, it may or may not produce
spores.  Mummies are ejected by worker bees which become covered in the
sticky spores and spread them to all contents of the hive.  Bees carry
spores on their bodies, so all new colonies are infected from day one.
 
End of quote.
 
I think these two accounts show how preconceived ideas are brought into
question and revised  by real scientific investigation.  Moreover, there are
obviously still many questions unanswered.  eg  "What are the physiological
stresses that induces attack?  What are the conditions that induce spore
formation?"  As knowledge develops I think that at least we start to ask
more relevant questions but there are always more that arise.
 
As a practical matter it seems wise to me to get rid of dubious queens and
rear new ones from selected stocks.  This is where bee clubs are so valuable
to beekeepers with only a few colonies; and ultimately to all.
 
Best Wishes,
 
Glyn Davies,  Ashburton, Devon UK