Stonebrood disease - is caused by a fungus and is considered of minor importance, but should not be totally ignored by bee inspectors and beekeepers. It is rarely encountered, but should be differentiated from the other more serious brood diseases. Several fungi belong to the genus Aspergillus can cause the symptoms of stonebrood although the primary causative organism is Aspergillus flavus. It is not regarded as a serious disease in normal circumstances, its effects on the colony being only slight. It is generally present in the majority of colonies at some point in time and can be present in its spore stage without affecting the colony.
Note: This is a not a notifiable disease however any suspected incidence of Stonebrood should be remediated without delay, inform your local beekeeping association / community to alert them of its presence.
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Larvae mummified by stonebrood, look very similar to chalkbrood, but turn green and hard.
As in chalkbrood, stonebrood disease causes a mummification of brood. Larvae and pupae that are infected with Aspergillus flavus turn green in contrast to white or black in chalkbrood. The green growth is powdery and can be readily seen with the naked eye. Fungus spores are found most abundantly near the head of affected larvae and pupae. Stonebrood diseased larvae are solid mummies and not sponge-like as in chalkbrood.
Hive Examination - Examination of brood frames and floor debris is required especially in spring. Bees should be gently shaken from the frames to allow full inspection, abnormalities are then easily spotted. Stonebrood 'mummies' are easily seen and may even fall out of the cells during examination.
Monitoring - Vigilance is important with all honeybee diseases. Check all apiaries and colonies regularly for health and suspect any colonies that are not thriving where there is no already known reason. Colonies that are not performing well or die out should be examined thoroughly and sealed to prevent robbing and spread of any diseases present.
Presently there is no effective medical treatments for Stonebrood, and there is no specific treatment recommended for Stonebrood. The disease has only slight effect on healthy colonies but may have a more serious effect on weakened colonies. Prevention is the best method of controlling this disease by maintaining healthy, strong and vigorous colonies that display good hygienic traits. Good husbandry contributes greatly to overall colony behaviour and health, thereby avoiding the conditions in which stonebrood can flourish. Colonies that suffer excessively from Stonebrood may need to be re-queened. Prevention is best practice, maintain good apiary housekeeping and bee husbandry:
As with many honeybee related diseases, the beekeeper is the main vector in the spread of this disease by transferring, selling or exchanging frames and combs, honey or equipment which is infected. Robbing of infected and depleted hives and swarms from infected colonies also transmit the disease.