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.
Chalkbrood is recognized in the colony by a patchy brood nest and by mummies lying loose in the cells. Shaking the comb makes them rattle in the cells, and after opening the cappings they fall out. The edge brood and drone brood are especially affected, because temperatures fluctuate 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 weak infestation is often only noticed via a bottom board insert or during an inspection in the early morning.
Chalkbrood is a typical factor-related disease. The fungus is widespread; the disease breaks out mainly at cool, damp locations, in hives that are too large, in weak colonies with poor temperature regulation, after nectar-flow stress, or with a hereditarily weak grooming instinct. Self-healing often occurs once the colony grows and the weather improves.
There is no approved medication. Beekeeping measures are effective: reducing the space occupied by the colony, providing a warm, sunny, and dry location, removing and melting down heavily affected brood combs, consistently renewing combs, and above all requeening with a young queen from a line with good hygienic behavior. Breeding material should not be taken from conspicuous colonies.
Moving affected combs into healthy colonies and continuing to use heavily moldy combs should be avoided. There is no reporting or notification requirement in either Germany or Austria. Chalkbrood poses no consumption risk for the honey; it is exclusively a problem of colony development.