Notes 5.2

5.0 DISEASES, POISONING AND PESTS

The candidate will be:

5.2 able to describe the signs of the bacterial diseases American Foul Brood (AFB) and European Foul Brood (EFB) and the fungal disease Chalk Brood and describe their effects upon the colony;

NOTES

AFB becomes apparent after cells are capped. The cell cappings become sunken and perforated and may appear greasy and darker in colour. The larvae in the cells die and become discoloured brown. A diagnostic test is to insert a matchstick into the cell – if it draws out a brown mucus like “rope” this is definitive of AFB. There may be an unpleasant smell. Eventually the larval remains shrink to a dark brown scale coating on the side of the cell. As the disease progresses, the brood pattern will appear patchy – a “pepper pot” pattern.

AFB is a very serious disease of honeybees as the bacterial spores can remain viable for many years. The bacteria will spread to most of the brood so that fewer and fewer adult bees remain and the colony will starve.

AFB is a notifiable disease that must be reported to the government bee inspectors. There is no treatment for AFB.

EFB affects larvae before cells are capped. The larvae move into different positions from the normal curled position. They become distorted, likened to being “melted” and turn discoloured brown. The cells may be capped after infection and become sunken and perforated, but these will not exhibit the ‘ropiness’ of AFB. The remains dry up to leave a brown scale. There may or may not be an unpleasant smell, depending on secondary infections. The brood pattern can become patchy and erratic.

The effect on the colony is to have brood loss over a period of months or years, depending on the level of infection. When the brood loss becomes unsustainable the colony will die.

EFB is also a notifiable disease but it is possible to treat infected colonies.

Chalk brood appears as shrunken, “mummified”, chalky white larvae. The mummies may later turn black when the fungus fruits. These may be seen in the cell or if they have been removed by the workers will fall to the floor or through the varroa mesh.

The chalk brood fungus is probably present in most hives and may only becomes noticeable when the colony is under stress.

The effect on the colony will not be noticeable.