Do you recognise this brood disease? Explain what you see.
- Banded brood associated with wax moth.
- American foulbrood, a bacterial brood disease.
- Healthy colony with regular brood.
- European foulbrood.
- Nosemosis affecting mainly adult bees.
- Deformed Wing Virus: DWV.
- Chalkbrood alone, a fungal brood disease.
Show answer
Correct answer: 4.
European foulbrood, with possible associated chalkbrood.
Why?
European foulbrood is a bacterial brood disease caused by Melissococcus plutonius. It mainly affects the larvae, often before capping, and can produce irregular or patchy brood.
The suggestive signs are flaccid larvae, yellowish to brownish, sometimes placed in abnormal positions in the cells. A sour or unpleasant odour may be present, but on its own it is not enough to make a diagnosis.
If the image also shows dried-out larvae that are whitish, greyish, or black, there may be an appearance of chalkbrood. This point must be interpreted with caution, because chalkbrood can be confused with other brood disorders.
What to understand
European foulbrood and chalkbrood do not belong to the same type of disease. European foulbrood is a contagious bacterial brood disease, whereas chalkbrood is a fungal disease linked to Ascosphaera apis.
In European foulbrood, the diseased larvae become soft, change colour, and may decompose in the cells. In chalkbrood, the larvae dry out and take on the appearance of small hard mummies, white and then sometimes grey or black.
In the field, the issue is not only to name the disease, but to avoid a poor decision. In case of suspected European foulbrood, handling should be limited, equipment should not be moved, and the apiary inspector should be contacted.
Key takeaways
The main diagnosis is European foulbrood, a bacterial brood disease. Chalkbrood may be an element to discuss if the image shows larval mummies.
The important signs of European foulbrood are patchy brood, flaccid larvae that are yellowish to brownish, abnormal larval positions, and sometimes a suspicious odour.
A suspicion of European foulbrood must be reported quickly to the apiary inspectorate. Suspect combs, colonies, or equipment must not be moved before competent advice.
Further reading
► Practical Guide: 2.2 European foulbrood
► Practical Guide: 2.4 Chalkbrood
