Do you recognise this brood disease? Explain what you see.
- Banded brood associated with wax moth.
- Chalkbrood of fungal origin.
- American foulbrood, a bacterial brood disease.
- Healthy colony with regular brood.
- European foulbrood, a bacterial brood disease.
- Deformed Wing Virus: DWV.
- Nosemosis affecting mainly adult bees.
Show answer
Correct answer: 5.
European foulbrood, a bacterial brood disease.
Why?
European foulbrood is a bacterial brood disease, caused by Melissococcus plutonius. It mainly affects the larvae, often before capping.
In the field, one typically observes patchy brood, larvae that lose their pearly appearance, turn yellowish to brownish, soften, and may be found in abnormal positions in the cells.
The odour may be sour or unpleasant, but on its own it is not a sufficient criterion. Diagnosis rests on the overall picture and, in case of doubt, on assessment by the apiary inspectorate.
What to understand
European foulbrood can remain inconspicuous as long as the bees quickly remove the affected larvae. The symptoms become visible when infection pressure increases or when cleaning behaviour is no longer sufficient.
It can be distinguished from American foulbrood by several indicators: the affected larvae often die before capping, the mass is generally little or not stringy in the ropiness test, and the dried residues detach more easily from the cell.
In Switzerland, a suspicion of foulbrood must be taken seriously. The beekeeper should not move any suspect combs, colonies, or equipment before having sought competent advice.
Key takeaways
European foulbrood is a contagious bacterial brood disease. It is not judged on a single isolated sign, but on a set of observations of the brood and the colony.
The warning signals are notably patchy brood, flaccid, yellowish or brownish larvae, abnormal larval positions, and sometimes a suspicious odour.
In case of doubt, the right reflex is to contact the apiary inspector rather than to intervene alone or move equipment.
Further reading
► Practical Guide: 2.2 European foulbrood
► Practical Guide: 2 Diseases and pests