European foulbrood

European foulbrood is a major infectious disease affecting honey bee larvae, caused by the bacterium Melissococcus plutonius. This disease specifically targets the open brood stage, leading to a significant population decline and the overall collapse of the colony if left untreated.

The pathogen is a gram-positive, non-spore-forming bacterium that multiplies rapidly in the midgut of the larvae. While it is not a plant disease, it is of paramount importance to the agricultural industry, as managed honey bees are vital for the pollination of numerous crops across the globe.

Clinical signs include a disorganized brood pattern, where infected larvae shift from their typical curled position to irregular orientations. As the disease progresses, the larvae turn yellow and then brown, often exhibiting a sour smell. The remains eventually dry into easily removable scales within the wax cells.

The spread of the infection is heavily influenced by environmental stressors. Factors such as nutritional deficiencies, severe temperature fluctuations, and poor hive sanitation provide the ideal conditions for the bacteria to thrive. Rapid transmission occurs through contaminated honey, pollen, and infected equipment handled by beekeepers.

Effective management requires a combination of robust biosecurity measures and colony health monitoring. Beekeepers must focus on replacing older combs, ensuring adequate protein nutrition for the bees, and conducting regular inspections. In severe outbreaks, isolation of infected colonies and professional veterinary intervention are necessary to curb the disease.