Effectiveness of sodium hypochlorite
Sodium hypochlorite is a commonly used sterilising agent, and is one of the few common disinfectants that is effective against AFB spores. Sodium hypochlorite is the active ingredient in household bleach (e.g., Janola®), and is present in such products at about 3% concentration. Research has shown that concentrations of 0.5% sodium hypochlorite in water will kill all AFB spores in 20 minutes.
What can be treated
Sodium hypochlorite is potentially useful to treat beekeeping equipment such as plastic or metal feeders and plastic frames. It is important to note that that sodium hypochlorite will only kill what it comes into contact with, so any material to be sterilised must be very clean before treatment.
Do not attempt to disinfect used plastic frames with sodium hypochlorite as it will not penetrate and kill spores covered by the adhering wax and propolis.
Care also needs to be taken with the types of materials being treated. Some plastics, metals, and especially leather, can degrade when put into sodium hypochlorite solutions. It is therefore worthwhile carrying out a small trial run before doing any major sterilisation of equipment.
What can't be treated
The material is not recommended as a disinfectant for gloves, hive tools, or smokers, since the 20 minute contact time is crucial to successful destruction of AFB spores.
Storage of sodium hypochlorite
Sodium hypochlorite solutions must be kept in the dark, since the chemical breaks down in sunlight. The solution should also not be kept for long periods, and must be disposed of safely after use.
Finally, a note of caution: the effects of bleach on clothing are well-known, so protective clothing should be worn when using the material. Eye protection is recommended. Some individuals also react adversely (dizziness, fainting) to the fumes of sodium hypochlorite, so extreme care is needed when using the material.
Soaking equipment in 0.5% sodium hypochlorite will only kill any AFB spores on the surface.
Beekeepers overseas use other methods to sterilise AFB infected equipment. These methods include scorching boxes and steam chests. None of these methods are legal for use in New Zealand as their effectiveness is too variable.
Do not use steam chests or scorch boxes to sterilise AFB infected equipment.