Which disease (B2) ?

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Correct answer: 1 (Tubular brood – lesser wax moth)

Attracted by the odor of combs, wax moths enter hives or stores of old combs and lay their eggs there. The larvae that hatch feed on pollen residues and cocoon remains left at the bottom of the cells. In nature, wax moths play an important role by breaking down abandoned old combs, which can be sources of pathogens.

Tubular brood, also known as “bald brood,” is characterized by the formation of a rim of wax at the upper part of the cell that is not capped. The more or less developed pupa is visible inside. This condition is attributed to larvae of the lesser wax moth (Achroea grisella), a lepidopteran of the same family as the greater wax moth (Galleria mellonella), which infests wax combs in the larval stage. The larvae excavate galleries at the base of the cells, restricting the space available for the growth of bee larvae. As a result, the larvae sit higher in the cell and are not always capped.

Field symptoms and diagnosis:

• Wax moth infestation is easily identified by black fecal deposits found on supports placed at the bottom of comb cabinets or in modular hives. In addition, several bulging or open cappings of adjacent cells (tubular brood) indicate the presence of a gallery excavated by wax moth larvae.
• Rim of wax around cells that are not capped.
• When these pupae are removed from the cells, moth larval droppings (grayish pellets) are often found on their bodies.

Prevention and control

Store only honey combs without pollen that have never contained brood.

• Store feed combs and honey combs separately. Melt down brood combs rather than storing them. Brood combs that have come into contact with synthetic varroacides must be discarded or may be used for candle making.
• Comb storage: cool (below +12 °C), in a well-ventilated, light room.
• Regularly melt down old combs.
• Avoid weak colonies.
• During storage, regularly check for wax moth droppings.

What can the beekeeper do?

It is recommended to strengthen bees’ natural defenses against disease by applying the principles of good beekeeping practice. Colonies are healthy when they develop well (adult bees and brood), display good hygienic behavior, and produce good yields. In practice, these are referred to as strong or vital colonies (see cover image). Colony vitality depends on many factors. Beekeepers mainly have the following levers of influence:

• Apiary locations with good nectar flows (continuous food supply) and a suitable local climate.
• Regular creation of young colonies and replacement of weak colonies.
• Selection of queens with sufficient vitality traits (colony development, hygienic behavior).
• Regular renewal of combs.
• Varroa mite control in accordance with regulations – hygiene in the apiary.
• Caution when taking over bees from other locations (diseases!).
• Avoid any importation of bees from regions outside Europe.

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