European Foulbrood

Melissococcus plutonius

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Changed on: 04.06.2019
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European foulbrood (EFB) is a disease that infects the brood of the honey bee, caused by the bacterium Melissococcus plutonius. This bacterium (formerly known as Streptococcus pluton) forms a capsule. This capsule is less resistant in comparison to the spore produced by Paenibacillus larvae, the pathogen of the American foulbrood.

The larvae become infected by ingesting contaminated brood food and up to the maximum age of 48 hours. The bacterium reproduces in the larvae’s midgut and the brood usually dies in the larvae phase. The larvae turn brown-black in colour and transform into a pulp, sometimes watery-grainy pulp (with threads in rare cases), which consequently dries, becoming smooth, shiny, loose scales.
Should the larva survive, the hatching bee will be lower in size and weight. The infection ranges from mild to severe. The course of infection is affected by food conditions.

European foulbrood is a serious problem in some countries, such as Switzerland and the United Kingdom. Infections are seldom in Austria, though.

European foulbrood (EFB) is a disease that infects the brood of the honey bee, caused by the bacterium Melissococcus plutonius. This bacterium (formerly known as Streptococcus pluton) forms a capsule. This capsule is less resistant in comparison to the spore produced by Paenibacillus larvae, the pathogen of the American foulbrood.

The larvae become infected by ingesting contaminated brood food and up to the maximum age of 48 hours. The bacterium reproduces in the larvae’s midgut and the brood usually dies in the larvae phase. The larvae turn brown-black in colour and transform into a pulp, sometimes watery-grainy pulp (with threads in rare cases), which consequently dries, becoming smooth, shiny, loose scales.
Should the larva survive, the hatching bee will be lower in size and weight. The infection ranges from mild to severe. The course of infection is affected by food conditions.

European foulbrood is a serious problem in some countries, such as Switzerland and the United Kingdom. Infections are seldom in Austria, though.

Symptoms

Other bacteria, such as Streptococcus faecalis, Paenibacillus alvei and Achromobacter Eurydice, may also be responsible for some symptoms to a varying degree, depending on the case in question. As a result, the visual appearance and odour of the dead brood may vary.
Possible symptoms are a spotty brood pattern, dead brood in both open and capped cells.

Before capping: limp larvae, body segmentation barely visible; larvae slightly turned sideways in their cells. A dirty-yellow lump shines through the skin at the rear, blind end of the gut (can be removed by pulling the larvae skin apart with two pairs of tweezers); brown pulp (does not produce threads usually when tested with match).

After capping: cell cap is dented, often has holes, might even be missing partly or entirely; black, lacquer-like coat on the inner side of the cap containing vast numbers of bacteria; dried-out scale with smooth, shiny surface, lying loose on the floor of the cell (can be removed easily from cell with a pair of tweezers).

Transmission

There are vast numbers of capsules of Melissococcus plutonius in the dead larvae and the larvae excrement, which are spread throughout the hive or passed on to the brood via food by cleaner and nurse bees.

Transmission between colonies occurs through the bees themselves (landing at the wrong hive, robbery, and contact with bee excrement at watering stations, for example).

The disease can also be transmitted by beekeepers (purchase of contaminated comb materials and equipment, feeding third party pollen, exchange of combs between healthy and contaminated colonies, merging affected with healthy colonies).

 

 

Prevention

Possibilities are limited: be careful when acquiring colonies and equipment; keep strong colonies (weak hibernated colonies are more susceptible); adding additional feeding or pollen combs when EFB is suspected; additional feeding only with sugar or feeding syrup; do not feed honey; protect watering station from excrement; separate quarantine hives for caught natural swarms and newly purchased colonies. Good spring feeding sources are beneficial to the resistance and self restoration of a colony.

There are no drugs for a therapy available in Austria. Thus, the shakedown method is the preferred choice to combat this disease.

 

 


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