Agriculture Reference
In-Depth Information
is high. Most beekeepers don't notice it mainly because it affects a small percentage
of larvae only. Adult bees detect and remove infected larvae very quickly and so, if
the beekeeper does notice the problem, this is usually because it has progressed to a
stage where the workers can no longer control it. Therefore, by the time the beekeeper
observes the symptoms, the disease may be too severe for the adult worker population
to handle.
Both worker and drone larvae are affected. Pupae may be killed occasionally, but adult
bees are immune to it. Dead brood is often scattered among healthy brood. Nurse bees
are suspected of transmitting the disease by carrying the virus from cell to cell. It is also
believed that robber bees spread the disease by taking contaminated honey from one
colony to another. The spread of this disease is another reason why drifting and robbing
should be prevented.
Fig. 26.
Sacbrood larvae: typical position
Identifying sacbrood
The following are the signs of a sacbrood infestation:
If the cells have been capped, the cappings may be perforated (if so, also check for
AFB/EFB).
If the cells are open, identification is easier. The larva's head, the first part of the
body to change colour, becomes dark brown to black. If lifted from the cell, the
abdomen is bloated, resembling a watery sack.
Death usually occurs after the cell is sealed and the larva has spun its cocoon.
