Shape of brood

Healthy larvae


Healthy larvae and pupae are characteristically plump in shape. In healthy larvae at the prepupal stage, the circular lines of segmentation are clearly visible. In healthy pupae, the shape of all of the external body parts can be seen (Fig. 18).

 Figure 18: Healthy pupa 

Early signs of infection

When an AFB infection occurs, the first symptom is often a slight change in the colour of the prepupae or pupae (Fig. 19, 20 and 21).


Figure 19: Early stage AFB
infected pupa
Figure 20: A very early stage
AFB infected prepupa slumped
on the lower cell wall 
Figure 21: An early stage
AFB infected prepupa
slumped on the lower cell wall

Advanced infection of larvae

As the infection develops and the brood tissues are consumed, the remains slump down onto the lower wall of the cell. In diseased larvae in the prepupal stage, the lines of segmentation can no longer be determined easily (Fig. 16, 21 and 22).



Figure 16: Coffee coloured AFB

Figure 22: An AFB prepupa slumped on the
lower wall of a cell

Diseased pupae

In diseased pupae, the body parts lose most of their characteristic shape, although the tongue remains upright and prominent (Fig. 17 and 23).



Figure 17: Pupal scale with tongue
Figure 23: Infected pupa with tongue
stretched across the cell

Next >>