In article <[log in to unmask]>,
[log in to unmask] writes
>Chalk brood is a fungus, and hence, not considered life threatening to bees
>resulting
>in little active scientific research.
Chalk brood is a funny thing which, in our experience is not the result
of any single factor.
We have noted it occur frequently in many colonies in spring when
perhaps they are struggling a bit to kept the rapidly expanding brood
nest warm enough, yet six weeks later in the same colony, with no change
of queen, no relocation, no new combs, it is gone. Only differences are
that the weather is warmer and the colony stronger.
Occasionally we get a colony (probably 1 out of 1700 every other year)
which is some kind of genetic runt whereby it is not able to prosper
because of chalk brood. The combs can almost rattle with it. In that
case we just kill the queen and unite to a healthy neighbouring colony
which soon tidies it up.
> I found that hives that had OLDER COMB, enjoyed the coolness of
>wooded
>shade and lack of direct sun, and close to water that might have elevated the
>humidity (dampness) were those most likely to exhibit CB mummies.
I would agree with all these factors except the old comb bit. We have
OFTEN noticed the worst chalk brood cycle being the first one on newly
drawn foundation, after which it gets tidied up and is fine. Most times
the new comb is fine but it is surprising how often chalk brood goes for
the first cycle only to fade away thereafter. We see no great
correlation between older combs and chalk brood.
>I don't expect any direct research on CB, but the research related
>to
>HYGIENIC bees might uncover a lot.
Genetic factors will have a large part to play in this, whether it is
hygienic behaviour or some other resistance mechanism. For example, any
bees we have had off the New World Carniolan have shown chalk brood only
rarely and I am certain this is not hygienic behaviour that is
responsible for this. Reason? No, or very few gap cells in the brood.
The 2" square test on an area of similar age brood shows few, and
occasionally zero, gaps. So there have not been the infected larvae
there to begin with. Other strains in the same apiaries can have
significant amounts of chalk brood and/or gaps (which could be CB or sex
allele related) present.
I would also disagree with whoever said that it is not an important
disease. It is definitely economically damaging, as raising that brood
which dies is an expenditure of energy and a loss of a percentage of
your foraging force two or three weeks later, a loss which is continuous
throughout the period chalk brood is active, and over a period can add
up to a measureable loss of crop. 'Clean' colonies noticeably out
perform, and accelerate away from, 'infected' ones.
Thus I would suggest that chalk problems are related to a number of
factors, which are detrimental to the bees ability to deal with the
underlying cause, fungal attack. Genetic factors are very important, but
mild chilling, dampness, and colony strength are also definite
contributory issues.
Finally, we have noticed for many years (long before varroa predation) a
particular tendency for chalk brood to attack areas of drone brood at
certain times of the year. We see worker brood on the same comb clean or
at least nearly so, and the drone a horrid mess with almost every cell
turned chalk. We cannot see any other factor at work here apart from the
longer development period of drone brood giving the fungus more time to
act at the critical point in the larval stage. If this is so we could
have another genetic factor at work not yet touch on, that some bees
exhibiting resistance have a relatively short infection window due to
variations (possibly only slight, but significant to the fungus) in the
duration of critical stages of brood development.
>Happy New Year!
And to you too George!
Murray
--
Murray McGregor
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