Do you recognise this brood disease? Explain what you see.
- Banded brood associated with wax moth.
- European foulbrood, a bacterial brood disease.
- Chalkbrood of fungal origin.
- Healthy colony with regular brood.
- Deformed Wing Virus: DWV.
- American foulbrood, a bacterial brood disease.
- Nosemosis affecting mainly adult bees.
Show answer
Correct answer: 6.
American foulbrood, a bacterial brood disease.
Why?
American foulbrood is a highly contagious bacterial brood disease, caused by Paenibacillus larvae. It affects bee larvae and can remain barely visible as long as the workers efficiently remove the diseased brood.
In the expected image, the signs to look for are above all patchy brood, cappings that are dark, sunken, depressed, or perforated, as well as cells from which the bees do not emerge normally.
When the disease is advanced, the ropiness test may show a brownish, stringy mass under the capping. Dark brown to black scales, flat and strongly adherent to the bottom or lower edge of the cells, are also an important sign.
What to understand
American foulbrood is a notifiable disease. In case of suspicion, no combs, colonies, comb pieces, or equipment should be moved before having contacted the apiary inspector.
The distinction from European foulbrood is essential. In American foulbrood, the larvae often die after capping, the cappings become dark and sunken, the mass may be markedly stringy, and the scales remain strongly adherent to the cell.
A strong colony can temporarily mask the symptoms through its hygienic behaviour. The absence of spectacular signs is therefore not always enough to rule out a health problem, especially if the brood becomes irregular or suspicious.
Key takeaways
American foulbrood is a serious bacterial brood disease. It must be taken seriously from the suspicion stage onward.
The warning signs are patchy brood, dark, perforated, or sunken cappings, a stringy larval mass, and dark, adherent scales.
The right response is not to intervene alone, but to secure the situation: limit handling, move nothing, and quickly contact the apiary inspectorate.
Further reading
► Practical Guide: 2.1 American foulbrood
► Practical Guide: 2 Diseases and pests
