Management to control and minimise impact of SHB
The prime aim is to reduce the number of beetles around the apiary and honey extracting plant and thereby reduce the level of infestation in hives. This is best achieved using strategies that interrupt the SHB life-cycle. The adoption of good beekeeping practices as described below will help to minimise the effect of SHB infestations.
The key management strategies are: maintain strong colonies and provide only sufficient combs in the hive that bees can cover and look after
extract combs of honey immediately after removal from the hive and protect stored combs and apiary products
avoid attracting adult beetles to apiaries and stored combs by practicing good apiary hygiene.
Combs not covered by bees are especially prone SHB damage. Supers of combs should only be added to hives when they are required. As a guide, only add a super when at least 70% of combs in the hive are filled with honey and/or brood. Excess combs are best removed from the hive and stored as described later.
Maintain strong colonies
Weak colonies are best united to form stronger ones. For example, colonies that have swarmed excessively or those with few field bees, as a result of nearby application of insecticide, are best united. Make sure colonies are free of American Foulbrood disease before uniting them. Avoid placing SHB infested combs and material onto colonies free of SHB as the infestation will soon spread throughout the entire hive. Weak colonies may be strengthened adding one or two combs of sealed brood from strong healthy colonies.
Extract combs of honey immediately after robbing
Although combs of honey appear free of infestation, they may already contain SHB eggs or very small larvae at the time of removal from the hive for extracting. Extract combs of honey immediately or, at least within a day or two of their removal from hives. SHB eggs hatch within 2-4 days and contamination of the honey combs will soon occur as larvae develop. The risk is greater if pollen and/or honey bee brood is present in the combs.
Beetles may lay eggs on combs awaiting extraction.
Studies in the USA have shown that hatching of SHB eggs is inhibited when relative humidity is below 50%. It was found that circulation of dry air through combs of honey awaiting extraction provided complete or almost complete protection from SHB damage. Extracted combs are also prone to SHB infestation and steps should be taken to protect combs as described below.
Minimise opening the hive
The combined odors of honey, pollen and adult bees attract adult SHB to apiaries. Beetles are more attracted to hives that have been opened. The opening of a hive and the manipulation of combs also appears to trigger female SHB adults already present in the hive to lay eggs, which results in a rapid increase of SHB larvae. While it is a recommendation that the opening of hives be kept to a minimum, it is still necessary to inspect brood throughout the season for signs of American Foulbrood disease.
Maintain good apiary hygiene
Discarded comb, beeswax scraps and slum gum left in the open around the apiary or honey extracting plant will attract adult beetles. These should be melted and processed without delay.
Protect beeswax cappings and bee collected pollen
Cappings should be melted and processed into cakes without delay to avoid infestation and damage by SHB. Pollen is also at high risk and can be protected by packaging into sealed containers and freezing as described below.
Avoid leaving honey combs above clearer boards
Combs of honey left above clearer boards are unprotected by bees and heat generated by the colony can provide a favorable environment for fast development of SHB larvae. It is best to remove the honey combs for extracting as soon as the bees clear the supers.
Avoid using untreated infested hive material
Infested hive components, including combs, should not be placed on hives with bees until the infested items have been treated to kill all SHB life-cycle stages. Combs which have no signs of damage caused by SHB larvae may harbor adults. These are best checked and frozen if adults are present.
Bees are unlikely to accept combs with slime and/or contaminated honey. The contaminated honey, which is not fit for human consumption, is best extracted and deep buried in soil. Some references suggest that after extracting, the combs be rinsed in water to make them more attractive to bees.
Trapping to reduce SHB numbers
The Florida Department of Agriculture and Consumer Services reported a method of in-hive trapping of adult beetles (reference 3 below). A hole is cut in the bottom board to hold the neck of a jar one-third filled with a mixture of irradiated honey and pollen. A square of perspex elevated by some washers is then fixed with bolts over the opening to allow just enough room (3 mm) for adult beetles, but not bees, to crawl under the perspex into the jar. To date, no trap has yet been developed that is capable of attracting 100% of beetles.
If SHB larvae are a problem in extracting plants, the use of fluorescent light sources at night, placed on or near the floor, will attract those larvae looking for soil in which to pupate. The larvae accumulate at the light and can be easily swept up and destroyed.