Do you recognise this brood disease? Explain what you see.
- European foulbrood, a bacterial brood disease.
- Chalkbrood, a fungal brood disease.
- Healthy colony with regular brood.
- American foulbrood, a bacterial brood disease.
- Banded brood associated with wax moth.
- Deformed Wing Virus: DWV.
- Nosemosis affecting mainly adult bees.
Show answer
Correct answer: 2.
Chalkbrood, a fungal brood disease.
Why?
Chalkbrood is a fungal brood disease, caused by the fungus Ascosphaera apis. It affects worker and drone larvae, which dry out and take on the appearance of small hard mummies.
In the expected image, one looks above all for dead, dry larvae that are whitish, greyish, or sometimes almost black. These mummies may be found in the cells, on the hive floor, in front of the entrance, or on the alighting board.
The brood may also appear patchy, with open or irregular cells. The mummies generally detach quite easily from their support, which distinguishes them from other brood conditions.
What to understand
Chalkbrood often appears when several factors combine: humidity, chilling of the brood, a weakened colony, stress, an unfavourable location, or insufficient hygienic behaviour.
The disease can sometimes regress if the colony is strong and conditions improve. Conversely, a weak colony, or one poorly suited to its volume, may leave more affected larvae in the combs.
Differential diagnosis remains important. Dead larvae or patchy brood are not enough on their own to draw a conclusion. In case of doubt with a foulbrood or another serious health problem, competent advice should be sought before moving combs, colonies, or equipment.
Key takeaways
The typical sign of chalkbrood is the presence of dry, hard larval mummies, white and then sometimes grey or black.
Prevention relies above all on strong colonies, good ventilation, a suitable location, a hive volume proportionate to the population, and regular comb renewal.
If the infestation is mild, the colony can sometimes recover with good conditions. If the infestation is heavy or repeated, the colony's management, the location, the queen, and the hygiene of the equipment must be reviewed.
Further reading
► Practical Guide: 2.4 Chalkbrood
► Practical Guide: 2 Diseases and pests