Chalk brood has been studied quite extensively by Prof Len Heath and a
series of PhD students at the University of Plymouth in the UK.
He wrote about this in a rather broader context in the magazine BEEKEEPING
last November. It is difficult to summarise but some points of interest
are:
hives in damp areas are not more susceptible;
drone brood is not more susceptible;
chilling brood is one of a number of physiological stresses which make
larvae more susceptible;
spores are almost everywhere where there are bees, they are fed to the
larvae and may develop in the gut and grow through the body tissues;
spores may or may not be formed depending on the conditions, but it is
nothing to do with having two types of spores present;
apart from the stress factor some bees are genetically more susceptible.
I hope these points, based on research results, are of interest.
Brian Gant
Buckfast, UK
Editor of BEEKEEPING