European foulbrood
European foulbrood (EFB) is a brood disease of honeybees caused by the bacterium Melissococcus pluton. The disease is endemic throughout eastern Australia, but is not known to occur in Western Australia.
Worker, drone and queen bee larvae are all susceptible to EFB infection. Larvae are most susceptible to infection when they are less than 48 hours old, and usually die while still in the coiled state.
Poor nutrition and severe stress, e.g. insecticide poisoning, often cause this disease to break out. The larvae first turn yellow then brown. In old larval remains, a secondary invading bacterium, Bacillus alvei is also commonly present. The disease is usually noticed in early spring, and to a lesser extent in autumn.
Multiplication and spread
The bacteria multiply vigorously in the gut of larval bees which have been given food contaminated with M. pluton. If larvae survive and pupate, the bacteria are discharged with faeces and deposited in the bases and cappings of cells. Some of these bacteria find their way to other larvae. As with American foulbrood, EFB can also be spread by:
- robbing infected hives
- transferring infected honey supers and combs to clean hives
- using contaminated beekeeping equipment
- feeding infected honey and pollen.
Clinical signs
- brood has a pepperbox appearance (that is, combs with many uncapped cells mixed with normal capped cells)
- cappings, which are concave and sometimes punctured
- young unsealed larvae (three to five days of age) in a 'C' shape around the cell walls
- dead larvae which are watery and pasty in appearance, and are yellow or brown/black in colour
- ropy brood (in old infections)
- a slightly sour or sometimes rotten faecal odour
Diagnosis
The Biosecurity Sciences Laboratory in Brisbane provides a brood-disease identification service. This service is free of charge. To use this service simply:
- cut a piece of brood comb approximately 10 cm x 10 cm square containing suspect larvae, or
- place a matchstick in the cell of suspect larva, and obtain larval material on one end of the stick. Place the matchstick in a small vial ready to send to the laboratory.
Wrap the comb or vial sample in paper (not plastic) and place in a padded postal bag or small box. Forward the specimen to:
Biosecurity Sciences Laboratory
Health and Food Sciences Precinct
Specimen receipt
Loading Block 12
39 Kessells Road
Coopers Plains Qld 4108
Include a completed Specimen advice sheet: Form A (PDF, 78KB) with the sample.
Treatment
When EFB infection is light, treatment is usually not required as the disease often disappears during a good nectar flow. Re-queening the hive is also advocated as a treatment. Stress is also an important factor in the control of EFB. Stress can result from:
- poor nutrition
- working winter honey flows
- excess movements of hives
- insecticide poisoning
- sudden expansion of the brood, resulting in insufficient nurse bees.
Antibiotics will be prescribed only after a positive laboratory diagnosis of EFB has been made. When 20% of hives are infected, it is advisable to treat all hives. Consult with Biosecurity Queensland apiary staff when antibiotic application is sought.
Management
- prevent robbing
- replace at least three brood combs each year
- re-queen annually using a strain of queen with good hygienic behaviour
- maintain good nutrition for the bees.
