Which disease (C3) ?

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

Attracted by the smell of the combs, wax moths enter beehives or stored 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 destroying old, abandoned combs, which are potential sources of pathogens.

Tubular brood, also known as bald brood, is characterised by the construction of a rim of wax at the upper part of the cell, which is not capped. The pupa, of varying age, is visible inside. This condition is attributed to the larvae of the lesser wax moth (Achroea grisella), a lepidopteran belonging to the same family as the greater wax moth (Galleria mellonella), which infests combs in the larval stage. The larvae tunnel at the base of the cells, restricting the space available for the growth of bee larvae. As a result, the bee larvae are positioned higher and are not always capped.

Symptoms and field diagnosis:

• An infestation with wax moths is easily identified by the black droppings found on the supports placed at the bottom of comb storage cabinets or in movable-frame hives. In addition, several domed or open cappings of adjacent cells (tubular brood) indicate the presence of a tunnel dug by the wax moth.
• A rim of wax around cells that are not capped.
• When these pupae are removed from the cells, excrement of wax moth larvae (greyish rod-shaped pellets) is often found on their bodies.

Prevention and control

Only store honey frames without pollen that have never contained brood.

• Store feed frames and honey frames separately. Melt down, rather than store, frames that have contained brood. Brood frames that have come into contact with chemically synthesised varroacides must be discarded or may be used for candle production.
• Frame storage: cool (below +12 °C), in a well-ventilated, well-lit room
• Regularly melt down old frames
• Avoid weak colonies
• During storage, regularly check for wax moth droppings

What can the beekeeper do?

It is recommended to strengthen the bees’ natural defences against diseases by applying the principles of good beekeeping practice. Colonies are healthy when they develop well (adult bees and brood), show good hygienic behaviour and achieve 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:

• Location with good nectar flow conditions (continuous food supply) and a suitable local climate.
• Regular formation of young colonies and replacement of weak colonies.
• Selection of queens with sufficient vitality traits (colony development, hygienic behaviour).
• Regular renewal of frames.
• Varroa mite control in accordance with regulations – hygiene in the apiary.
• Caution when introducing bees from other locations (diseases!).
• Avoid any importation of bees from regions outside Europe.

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