American Foulbrood

Causative Agent: Bacillus larvae (Bacteria)

Range: Worldwide

Life cycle:

• Young larvae can be fed as few as 10 spores to be infected.
• As larvae become older they have to consume more spores to be infected. Full grown larvae rarely become infected.
• Death occurs after the cell is capped.
• The larva or pupae within the capped cell will decay in place and the tongue is often left attached to the top of the cell.
• Progression of color: white→light brown→coffee brown→dark brown/black.
• Cadaver, including the head, deflates uniformly, dries into a “scale” and strongly adheres to the bottom of the cell.
• Consistency of dead brood is soft and becomes sticky and stringy
• A single dead pupa can produce approximately 2.5 billion spores.
• Spores can remain viable for up to 50 years.

Management:

• Frequent inspections of the hives often reveal this disease before it becomes damaging.
• When the infestation is low uncapping infected individuals will result in the hive removing the infected material.
• Treatment with Oxytetracycline can kill this disease but several precautions must be taken to prevent the contamination of honey and other products.

Misconceptions:

Odor is not a reliable method of distinguishing this disease.

Irregular brood pattern can be a sign of a problem (but not necessarily American Foulbrood)

Other Useful Sites:

Information and Pictures of American, European and Sac brood Diseases

Mid-Atlantic Apiculture Research & Extension Consortium Disease Control

References used:

Root, A. I. (1990) The ABC & XYZ of bee culture 40 th ed. A.I Root Co. Medina, OH.

Morse, R.A. & R. Nowogrodzki (eds). 1990. Honey bee pests, predators and diseases . Cornell University Press Ithaca , NY .

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