Chalkbrood is normally a stress disease.
That stress can be bad temps, high humidity, weak genetics, poor population, or otherwise.
Relieve the stress and the contagious elements of sick brood frames and the disease will subside.
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I'm not convinced on the theory of "brood fever".
If there is failed brood in the hive, the colony is going to compensate by trying to produce more larvae to make up for the sick. The larger quantity of brood itself can induce a higher temp in the hive.
I can argue just as well that if I believe C/B to be an dampness issue, the bees maybe naturally more active to fan more moisture out of the hive. That instinct can raise the hive temperature just as well.
I could also argue that if there are sick larvae to be removed, there maybe less bees to regulate hive temp, as they act as mortuary bees.
I mean if this is really the answer, why don't we just put heating pads under chalkbrood hives until they get well?
My worse problem with this study is that it works with one frame of bees.
This is far from any normal construction of a colony.
A two frame observation hive has no where near the thermal dynamics of a 8 or 10 frame colony.
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