EUROPEAN FOULBROOD DISEASE OF THE HONEY BEE
- Cause: Melissococcus pluton, a bacterium.
- Effect: European foulbrood is most common in the spring when brood
rearing is at its height, though usually the earliest reared brood is not
affected. Sometimes the disease appears suddenly and spreads rapidly within
infected colonies; at other times it spreads slowly and does little damage. As
a rule, it subsides by mid- summer, but occasionally it continues to be active
during summer and fall or may reappear in the fall. A good honey flow seems to
- Symptoms: Combs containing larvae infected with European foulbrood
usually present a rather uniform appearance because the cells are not sealed.
Larvae diseased by European foulbrood move restlessly within their cells and,
therefore, when they die, are usually twisted in the cells or die while in the
"C" stage at the bottom of the cell. However, some larvae may be
stretched out lengthwise from the mouth to the base. In some cases, the larva
collapses as though it had been melted, turns yellowish brown, and eventually
dries to form a loosely attached brown scale. The consistency of recently dead
larvae varies but it is not ropy. The odor of the larval remains also varies.
The scale remains of larva dead from European foulbrood disease can be removed
Transmission: The organism becomes mixed with the brood food fed to
the young larva by the nurse bees, multiplies rapidly within the gut of the
larva, and causes death within about 4 days after egg hatch. House bees
cleaning out the dead larvae from the cells distribute the organism
throughout the hive. Since the honey of infected colonies and the
beekeeper's equipment are undoubtedly contaminated, subsequent spread of the
disease is accomplished by robber bees, exposure of contaminated honey by
the beekeeper, interchange of contaminated equipment among colonies, and
perhaps, to some extent, by drifting bees.