Chalkbrood

 

Causal agent

Ascosphaera apis  - Fungus

Other names

Chalk

Age group

Egg

Larvae

Pupae

Adult - worker

Drone

Queen

No

Yes

 

 

 

 

Clinical signs

Season

Commonly occurs in wet springs

Outside

The chalk mummies are often deposited on the landing board or on the ground surrounding the hive

Odour

None

Brood

Examination of the brood nest reveals chalk brood mainly at the bottom

Cappings

Almost no torn caps.  May be sealed and unsealed cells.

Larvae appearance

The larvae die and become hard and white or black.  Occurs after capping.  Larvae are upright in cell.  The mucelia grow to fill the cell.

Scales (larvae)

White-grey and hard, rattle in cell.  Does not adhere to cell wall.

Other

Problems tend to occur in older colonies – 3rd season plus

Hive tend to raise less Drone bees which may affect fertility

Often seen in association with Sacbrood.

Chalkbrood mummies are removed from the hive by the house bees and found on the ground by the hive

The chalkbrood in the brood nest.  They will rattle when you move the frame.  If the “chalk” has black spots this indicates spores being produced.

Infectivity

 

Fungus is in the honey and fed to the larvae.   Spores resistant for 15 years.

Transmission

 

Drifting and robbing moves the fungus between hives

Post-mortem Lesions

 

Appearance of larvae

Diagnosis

 

Appearance of larvae – become covered by fluffy cotton-like mycelia.

Culture

Treatment

 

Increase ventilation though the hive

Clean frames

 

Enhance biosecurity

 

Spontaneous recovering in warm weather

Control

Do not move infected frames

Common differentials

 

 

Zoonosis

None