Sacbrood
Krankheiten
Sacbrood is caused by the sacbrood virus, SBV for short, and is one of the most widespread bee viruses.
Sacbrood is caused by the sacbrood virus, SBV for short, and is one of the most widespread bee viruses. Symptoms appear only in the brood. Adult bees show no visible illness but carry the virus in their hypopharyngeal glands and pass it on to the young larvae when feeding them. Cleaning bees pick up the virus while cleaning the cells and thus become part of the cycle within the colony.
The larva dies as a stretched larva before its first pupal molt. Because the outer skin remains intact and fluid collects underneath, the larva takes on the characteristic sac-like shape when pulled out of the cell. When it dries, a dark, boat-shaped scale remains that can easily be lifted out of the cell. In the colony you see a patchy brood nest, cells opened by the bees, and perforated or sunken cappings.
The most important task in the field is distinguishing it from foulbrood. With sacbrood, the mass does not form threads, and the scale does not stick firmly to the cell wall. In any case of doubt, especially with ropy contents, the bee inspector or the veterinary office must be called in, because then there is a suspicion of the notifiable American foulbrood.
There is no medicine. Beekeeping measures are effective: removing and melting down heavily affected brood combs, since the virus is sensitive to heat, supplying the colony well with food and pollen, ensuring a continuous nectar flow, reducing the Varroa infestation, and requeening with a young queen from a line with good hygienic behavior. A strong colony often heals sacbrood by itself once conditions improve.
Moving affected brood combs into healthy colonies is to be avoided. There is no reporting or notification requirement in Germany or Austria, but sacbrood is recorded as part of monitoring projects.