Ascosphaera apis causes a fungal disease that infests the gut of the larvae. The fungus competes with them for food, ultimately causing them to starve. The fungus then goes on to consume the rest of the larval bodies, causing them to appear white and “chalky.”
Chalkbrood (ascosphaerosis larvae apium) is most commonly visible during wet springs. Hives with chalkbrood can generally be recovered by increasing the ventilation through the hive.
The causative agent of chalkbrood disease is Ascosphaera apis, a fungus that affects 3-4 day old larvae and is spread through the ingestion of spores.
Spores germinate within the gut of the larva and rapidly produce mycelium. The fungus eventually kills its host through direct competition for nutrients, most frequently when the larvae are within the upright position.
Infected larvae are soon covered within the white cotton-like mycelium which will fill the whole brood cell. The mycelium will begin to harden and in some cases, darken to grey or black.
These “mummies” are often found in sealed and unsealed cells. If enough are present under cappings, the frame will rattle when shaken.
Cases of chalkbrood are often seen in springtime, or when conditions are cool and damp and thus favorable for fungal growth.
Spread and Control
Chalkbrood is usually considered to be a secondary pest, spread by drifting bees. Keeping strong, healthy colonies is that the best sort of prevention.
If populations are adequate, adult honey bees are ready to remove the chalkbrood mummies to attenuate the spread of the disease. Chalkbrood mummies are often found on rock bottom board and hive entrance.
There are currently no chemical controls on the marketplace for use against chalkbrood. during a more serious case of chalkbrood, requeen with more resistance stock or for more hygienic behaviors.
Stonebrood (aspergillosis larvae apium) is a fungal disease caused by Aspergillus fumigatus, A. flavus, and A. niger. It causes mummification of the brood of a honey bee colony.
The fungi are common soil inhabitants and are also pathogenic to other insects, birds, and mammals. The disease is difficult to identify in the early stages of infection. The spores of the different species have different colours and can also cause respiratory damage to humans and other animals.
When bee larvae take in spores, they may hatch in the gut, growing rapidly to form a collar-like ring near the larval heads. After death, the larvae turn black and become difficult to crush, hence the name stonebrood.
Eventually, the fungus erupts from the integument of the larvae and forms a false skin. In this stage, the larvae are covered with powdery fungal spores.
Worker bees clean out the infected brood and the hive may recover depending on factors such as the strength of the colony, the level of infection, and hygienic habits of the strain of bees (variation in the trait occurs among different subspecies).
The larvae die from aflatoxins (toxins) produced by the fungus within the capped cell before they start to pupate. Spores germinate within the larvae’s guts and therefore the mycelium rapidly grows through the whole larvae’s bodies.
Once the mycelium reaches the surface, it begins to supply fruiting bodies. Even adult bees can ingest fungal spores with their food and therefore the mycelium will develop during a similar thanks to that within the larvae.
Broods: hard larvae bodies, the body surfaces of the affected larvae appear yellow-green when infested with Aspergillus flavus, and grey-green when infested by Aspergillus fumigatus . The mummies are attached tightly to the cell membrane , and therefore the larvae can’t be removed by the worker bees because the mycelium also grows through the cell walls to some extent. Instead, the cell walls are covered in propolis or are gnawed down by the bees.
Adult bees: the fungus grows out of the abdominal segments and produces spores. Hard abdomens, crawling bees ahead of the hive. Infections in adult bees often remain undetected, as they die outside the hive.
The spores can cause inflammation within the nose, eyes, throats and lungs of humans.