5 minute read
Practical beekeeping – comb hygiene
Wolfgang Ritter, CVUA-Freiburg, Am Moos Weihez, D 79108, Freiburg, Germany
Keywords: American foulbrood, chalkbrood, Nosema, Varroa, wax cycle, wax moth
The third in the series from Dr Wolfang Ritter offering advice for Good Beekeeping Practice to ensure healthy bees with “fresh” comb and high quality honey.
Brood combs can become infested by pathogens including Nosema, chalkbrood and foulbrood spores. As each bee pupa moults, it leaves a cuticle which gradually narrows the width of each brood cell. This becomes critical when it prevents bees from developing to their full size. For these reasons it is therefore essential to replace brood combs regularly. In Good Beekeeping Practice, combs from the brood chamber never get into the honey chamber, because they may be contaminated by germs (pathogenic micro-organisms) and pollutants that may affect honey quality. Combs from the honey chamber are suitable and acceptable to replace those in the brood chamber.
Open wax cycle
In all frame hive management methods, old combs are produced every year. Small-scale beekeepers will give them away for wax processing in exchange for new foundation which should be certified pest and pollutant free. Large-scale beekeepers may process the wax themselves, but must test regularly for pollutants. A closed cycle – always using the same wax – is not recommended. An open system is much better where every year, at least one third of the wax (the oldest) is removed from the cycle, and used, for example, to produce candles. New, clean wax for the foundation can be obtained from the uncapping of honey combs when honey is harvested (uncapping wax). However, it is possible to modify one’s management method completely or partially by favouring natural comb construction. Never buy used combs – the risk of importing pests into the apiary is too high.
The decision to keep or to melt is not always as clear as shown here during comb hygiene training for veterinarians
PHOTO © W RITTER
Melting and disinfecting
Old combs are produced as a result of additional feeding and spring management. An appropriate management method consists of completely replacing the frame with the oldest combs (see illustration below). In spring any mouldy or fouled combs are removed. Bees would clean them but the combs could be germinfested and it would restrain the bees from accomplishing other important hygiene activities. Food combs of colonies killed by Nosema, apparently looking clean and bright, have to be disinfected. In case of the originally tropical Nosema ceranae (nowadays widespread), it is sufficient to deep-freeze the combs for a short time. Combs of colonies killed by Varroa are usually contaminated also by viruses. With infestation from chalkbrood or sacbrood, disinfecting with 60% acetic acid is necessary. This is also recommended as a preventive measure if colonies have died due to weakness or long-term queenlessness.
The dark combs (centre) appear bright and let light through, however those on the left must be destroyed. Comb on the right is in good condition and is ready to be used again
PHOTO © J SCHWENKEL
Although in comb construction terms still correct, this fouled comb from a Nosema colony must be melted
PHOTO © W RITTER
Wax moth control
Wax moths mainly feed on larvae cuticles, therefore combs that have had brood, and combs, must be stored separately. Sulphur application for moth control should be repeated after a few days, because the moths often survive the first treatment. Using Bacillus thuringiensis solution (available commercially in some countries) has a longer term effect and is non-hazardous for bees. Moth-proof receptacles can prevent new infestations. As Good Beekeeping Practice does not involve use of chemicals, or the use of bacteria, multiplication of moths can be avoided also by using a constant draught of air. This can be achieved by a chimney effect in the frame stack caused by a grid cover.
Exchange and store combs
Replacing combs:
If frames in the honey and brood chambers are of the same size, you can offer colonies an additional frame with food; put this on top of the stack containing combs from which honey has already been extracted. Therefore at the end of the breeding season (at harvest or in early spring), you can remove the brood frame with the oldest comb and melt the comb.
Melting comb:
Beeswax melts at 65°C and combs can be melted using several methods:
Water quench:
• Viruses and Nosema spores are killed with little technical effort.
Solar wax extractor:
• Without additional energy input more obstinate pathogens are killed at temperatures up to 120°C.
Steam wax extractor:
• Under pressure and at temperatures of up to 130°C several combs can be melted at the same time.
Oil-bath wax extracting by thermal oil heaters:
• Spores of American foulbrood cannot survive at 150°C for 40 minutes. After an outbreak of American foulbrood, sanitation must be carried out in compliance with any legal requirements.
Disinfecting combs:
120 ml of 60% acetic acid is sufficient to disinfect ten combs. Sponges or felt layers saturated with acid are placed between the stack of frames, or an open receptacle of the liquid is placed underneath.
Advantage: does not affect any metal parts, is cost-effective and is classified as food safe.
Disadvantage: short duration of effectiveness.
Killing wax moth
Sulphur:
• Advantage: cost- and time-effective.
• Disadvantage: hazardous to user’s health. Repeated treatment and airing of combs before re-use is necessary.
Bacillus thuringiensis:
• Advantage: long lasting effect, applicable within the colony, and non-hazardous to the user’s health.
• Disadvantage: expensive and involves using a time-consuming spray.
Air draught:
• Advantage: takes time, free of residues.
• Disadvantage: ventilator costs are high.
Frost or cold:
• Advantage: takes time, free of residues.
• Disadvantage: expense for deep-freezing respectively dependent on climatic conditions when stored outdoors.
Diagonal view of the comb clearly shows a covering of mould
PHOTO © J SCHWENKEL
Checklist for Good Beekeeping Practice
Combs with brood are not inserted into the honey chamber YES/NO
One third of uncontaminated wax introduced into wax cycle per year YES/NO
Combs from other apiaries are not introduced YES/NO
Mouldy or fouled combs are melted YES/NO
Combs of Nosema colonies are exposed to frost YES/NO
Combs of Varroa colonies are disinfected YES/NO
Combs that have had brood, and that have not had brood, are stored separately YES/NO
Combs are stored in moth-proof receptacles YES/NO
Only non-hazardous substances (sulphur, Bacillus thuringiensis) or physical methods (heat, cold, air draught) are applied to achieve moth-proof storage YES/NO
