Ascosphaerosis

Ascosphaerosis, widely known as chalkbrood, is a fungal disease caused by the pathogen Ascosphaera apis. While primarily an issue within the apiary sector, it is highly significant for agriculture as it impacts the health of pollinators, which are vital for the successful production of various field and horticultural crops.

The fungus is a specialized parasite that targets honey bee larvae. The infection process begins when larvae ingest fungal spores via contaminated food. Once inside the larval gut, the spores germinate, and the mycelium grows to encompass the entire body of the larva, eventually leading to death and mummification of the host.

Symptoms of an infection are quite distinct. Beekeepers typically observe hardened, chalk-like mummies at the hive entrance or on the bottom board. Initially, these mummies are white due to the mycelial growth; however, they eventually turn grey or black as the fungus produces its fruiting bodies, known as ascocarps.

The disease thrives in specific environmental conditions, most notably high humidity and fluctuating temperatures. Poor ventilation within the hive is a major factor that encourages the germination and spread of spores. Stressed or weak colonies, often resulting from poor nutrition or chemical exposure, are significantly more susceptible to outbreaks of chalkbrood.

Effective management and protection strategies are crucial to minimize losses. Key measures include:

• Ensuring proper hive ventilation and keeping the interior dry;
• Regularly replacing old or contaminated frames and comb;
• Maintaining strong and healthy bee colonies through good nutrition;
• Implementing chemical or biological treatments approved for apiary use;
• Sanitizing beekeeping equipment to prevent cross-contamination between colonies.