Beekeeping - European foul brood disease

European foul brood disease (EFB), a serious disease of honey bees in the eastern States of Australia, which as yet has not been detected in Western Australia.

Cause

European foul brood disease is caused by a bacterium Melissococcus pluton, (formerly called Streptococcus pluton), which invades the mid-gut of four to five day old larvae, multiplies rapidly in the mid-gut causing death.

Unlike American foul brood disease, which affects the larvae in sealed brood cells, European foul brood disease commonly affects larvae in open brood.

Signs

Infected larvae move about inside the cell instead of staying in the normal curled position. Unlike American foul brood disease, where the larvae consistently slump to the lower side of the cells, larvae infected with European foul brood disease appear twisted in different positions.

Infected larvae lose their pearly white sheen, turning creamy white through to yellowish brown and drying into loose brown scales.

In severely affected colonies, the capped brood may appear irregular, similar to a failing queen or to American foul brood disease. However, the brood cappings do not appear dark and sunken as with American foul brood disease.

The bacteria itself may not cause any odour in infected colonies. However, secondary invasion by other bacteria could result in a sour or foul smell. The secondary bacteria that flourish in dying larvae can cause variations in the classic signs of European foul brood disease.

Once the first signs appear, strong colonies can become non-productive within four weeks and the entire colony may die out if severely affected.

Spread

The bacterium M. pluton is a very robust organism. It can survive for months on contaminated equipment. It usually enters the colony through infected bees, equipment or honey introduced by the beekeeper. The organism can be present in a dormant form for some months before there are any visible signs of infection.

The infection can spread throughout the apiary during hive manipulation where infected combs are introduced to healthy colonies. Bees drifting from one hive to another and contamination of drinking water are other possible means of spread.

Control

European foul brood disease could possibly be eradicated if it occurred in an isolated area. Eradication may involve the total destruction of all colonies within the affected area.

Should the disease become widespread, eradication may not be possible and it may be necessary to adopt control measures using antibiotics. Antibiotics, combined with good management, have been shown to control but not eradicate the disease.

Hygiene is important in limiting or preventing the spread of the disease. Beekeepers should maintain good apiary hygiene, as follows:

• Avoid the introduction of bees and equipment from unknown sources.
• Avoid exposing honey combs or equipment to robbing. Store and fumigate spare equipment away from robber bees.
• Watch for signs of the disease.

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