Chalkbrood
Krankheiten
Chalkbrood is a fungal disease of the bee brood.
Chalkbrood is a fungal disease of the bee brood. It is caused by Ascosphaera apis, a spore-forming fungus whose spores enter the larva with the brood food. They germinate in the gut, the fungal mycelium grows through the larva and usually kills it after capping. The dead larva dries into a hard, chalk-white mummy. If the fungus forms fruiting bodies, the mummies turn grey to black.
In the colony, chalkbrood is recognized by a patchy brood nest and by mummies lying loose in the cells. If you shake the comb, you can hear them rattle in the cells, and once the cappings are opened they fall out. The edge brood and the drone brood are especially affected, because the temperature fluctuates there. A very reliable sign is mummies on the hive floor and in front of the entrance, where the bees have carried them out. A light infestation is often only noticed via a bottom board insert or during an inspection in the early morning.
Chalkbrood is a typical multifactorial disease. The fungus is widespread; the disease breaks out mainly at cool, damp sites, in hives that are too large, in weak colonies with poor temperature regulation, after nectar-flow stress, or where there is a hereditarily weak hygienic behavior. The colony often heals itself once it grows and the weather improves.
There is no approved medicine. Beekeeping management is what works: reducing the space occupied by the colony, providing a warm, sunny, and dry site, removing and melting down heavily affected brood combs, consistently renewing combs, and above all requeening with a young queen from a line with strong hygienic behavior. Breeding material should not be taken from colonies showing symptoms.
Moving affected combs into healthy colonies and reusing heavily moldy combs are to be avoided. There is no reporting or notification requirement in either Germany or Austria. Chalkbrood poses no risk to consumers of the honey; it is solely a problem of colony development.