There has been some discussion this winter about the use of bee repellents to remove honey from colonies. It appears that this has been initiated as a result of concerns over recent changes to European honey regulations. There is some concern that we will find some non-tariff barriers being developed to prevent North American honey entering the European market. Apart from concerns over honey from genetically modified crops, there are concerns about residues of butyric acid in honey. The current bee repellents that are used contain butyric anhydride. It has always been thought that this was a safe product to use since one of the breakdown products is butyric acid and this is naturally found in honey. However, there is some concern that the Europeans may establish upper levels of butyric acid and that these levels may be indiscriminately chosen and not necessarily reflect the level of butyric acid that may be found naturally in different types of honey.
Secondly, there is some concern that if misused, products such as BeeGo and Honey Robber, which contain butyric anhydride, may cause artificially high levels of butyric acid.
So far, there have not been any problems. However, as with all such issues, it is best to be careful and prudent and try to anticipate any potential problems rather than having to deal with them after the fact. To this end, I would like to suggest some measures that could be followed to minimize the use of butyric anhydride and minimize the risk of increasing butyric acid levels in honey.
1. Avoid using such products. Many beekeepers have started using the set-aside method for taking off honey, particularly for the first round and perhaps even for the second, if weather conditions permit. This simply involves removing the honey boxes and setting them to the side and allowing the bees to find their way back to the parent hive. The boxes can be set on top of the hive or they can be set to the side of the hive.
Care must be taken to ensure that no brood is in the honey boxes otherwise the bees will not leave. Many producers use queen excluders with this method but this method can be used even without queen excluders if care is taken to ensure there is no brood in the boxes that are removed. Within three to four hours the bees will vacate the honey boxes and return the parent hive. This method allows for honey removal without the use of bee repellents. It works well for commercial operators who might not be inclined to use devices such bee escape boards.
For the smaller operator a bee escape board is another alternate solution. This involves the use of a one-way bee escape or usually, four or five of them placed in a division board to allow the bees to leave the honey boxes and return to the brood area. Once they have left they cannot return. Such devices take about two days to operate but they can be quite handy for a person having only one or two hives.
The one draw back with such devices is that the equipment needs to be absolutely bee tight particularly at the end of the year. At such times, once the honey flow is diminishing or has stopped, as fast as the bees are migrating out of the supers back to the brood, new bees are entering into the supers to try to rob the honey and take it elsewhere.
2. Butyric acid levels will increase if the honey that is removed is uncapped. Uncapped, as opposed to honey that is completely capped, will expose the honey to the fumes of the butyric anhydride and more of the butyric anhydride will be absorbed into the honey. While this may be an opportunity to minimize the butyric anhydride levels, it is not necessarily practical, particularly on a commercial scale, since under our conditions we can remove honey from the hive before it is totally capped and still have it below 17.8% moisture. However, this issue is mentioned here because it will have an impact on butyric acid levels.
Acid boards should have high rims. If the acid board is not built very deep and the cloth is not taunt then there is the risk of the butyric anhydride coming in contact with burr comb on the top of the honey box and this may hasten the absorption of butyric acid into the extracted honey.
Amount used. Clearly the more butyric anhydride that is used the more risk of butyric acid residues being higher in the honey. Butyric acid works well to chase bees out of boxes when the temperatures are warm. When temperatures have cooled, the bees tend not to want to leave as quickly and so the temptation is to put more butyric acid onto the acid boards. Perhaps a better solution would be to blow the bees out of the supers.
Some beekeepers have reported using the set-aside method later in the season even after the honey flow is finished by removing the last honey boxes late in the day, just before dark, and coming back to the yard early in the morning to remove the honey boxes before the bees begin to fly. I have never tried this personally so I am not able to corroborate this information but have no reason to suspect that it is not true.
I suspect the largest problem with residues stems from too many acid boards being used. I personally am not able to keep up with more than four acid boards in my small operation. I suspect that a ratio of four acid boards or five acid boards per person on the crew is probably more than sufficient to operate at maximum efficiency. However, I have heard of people using eight to ten acid boards per person in the crew. This makes me believe that there will be acid boards sitting on some boxes for well in excess of ten minutes. If this is happening on days when the bees have moved out of the boxes within a minute or two then there is a great deal of unnecessary, increased exposure which may be causing the higher butyric acid residue levels. Perhaps the best opportunity to lower the levels is to lower the number of acid boards used in a yard so that the empty honey super is taken away immediately after the bees have cleared the super.
On those days that acid boards work well or even on those where the weather may be marginal, I have found that a puff or three of smoke applied to the top before the acid board is placed on top helps to get the bees going in the right direction. On real hot days it will help to drive the bees down before the acid board is placed onto the stack so that they do not become disoriented. On marginal days a few puffs of smoke will get them going in the right direction and this may help the acid boards to work a little better.
All beekeepers are advised to review their system of removing honey, particularly if they are using product containing butyric anhydride. While these products continue to be registered for use, it behooves all of us to minimize their use as best we can to minimize butyric acid residue levels.
From Beelines, from Saskatchewan Agriculture and Food, May 1999