Hygienic Workshop Materials

Hygienic Bees Workshop at the University of Sussex - Monday 23rd of May

by Stephen Whittaker

On Monday the 23rd of May I had the pleasure, along with Pam, Otto and Susan, and about twenty other beekeepers from as far afield as Wales and Northern Ireland, of attending a workshop at the Laboratory of Apiculture and Social Insects (LASI) at the University of Sussex on the subject of hygienic behaviour in honey bees, very ably taught by Francis Ratnieks, Karin Alton, Norman Carreck and Gianluigi Bigio (Italians have much better names than us, don't they). The theory of honey bee hygiene goes something like this...... Research has shown that hygienic behaviour (i.e. the prompt removal by the workers of dead or diseased larvae) reduces the spread of diseases such as foulbrood and chalkbrood within a colony and furthermore disrupts the breeding cycle of Varroa mites. This hygienic behaviour is a genetic trait, is therefore inherited, and can be bred for using normal breeding methods. Surprisingly, only about 10% of British colonies are classed as 'hygienic'; moreover, within a hygienic colony perhaps only about 10% of the workers actually perform the hygiene tasks, though this is enough to make that colony hygienic. Professor Ratnieks used the analogy of a student household, often a fairly 'unhygienic' environment. However, even if only one or two of the housemates start to perform housework, this may well be enough to render the household (relatively) 'hygienic'!

The workshop explained and demonstrated the techniques that LASI use to assess whether or not a colony is hygienic. There was also an explanation of how they establish, by patient and careful marking and observation, exactly which workers are doing the larva removal, and then use DNA techniques to make sure that the queens that are bred from that colony actually come from the same patriline (i.e. have the same father) as the hygienic workers. This makes the selective breeding process more efficient and rapid. The technique used for assessing the level of hygiene within a colony is fascinating - simple and elegant - and we were able to witness it at very close quarters. A frame containing a good solid patch of sealed worker brood is removed from the hive and taken to a suitable work area, where two metal cylinders (i.e. old food tins!) are carefully pushed into the wax so as to isolate two circular areas of brood. About 125ml of liquid nitrogen at -196 degrees C is then very carefully poured into each cylinder, which has the effect of immediately killing the brood within the area of the cylinder, but without causing any mechanical damage to the wax capping. The liquid nitrogen almost instantly evaporates and once the cylinders have warmed up a bit they are carefully removed. (It is worth mentioning at this point that LASI use plastic frames and plastic foundation, which, though it is not much liked by the bees, is thicker and more rigid than wax, and makes this process much easier whilst also better protecting the brood on the other side of the frame.) The frame is then replaced in the hive for 48 hours, after which it is examined to see what proportion of the killed brood has been removed, and thus, how hygienic the colony is.

The whole story is rather more complicated than this, since the level of hygiene within a colony varies not only through the day and through the year, but is also dependent upon such things as colony size, the weather and the abundance of forage at the time of the test. Thus, the test has to be repeated many times and then averaged, and enormous efforts have to be made to maximise consistency. Also, it must be remembered that these measures of ‘hygienicness’ must be regarded as relative, not absolute, and so for statistical reasons, this sort of assaying works best for apiaries with at least 30 or so colonies.

The workshop also included a presentation by a representative of BOC who explained the process for obtaining, storing, handling and using liquid nitrogen, should any of us be tempted to do our own testing. An interesting prospect for sure, but I personally think most individuals would probably tend to be rather put off by the complexities and not inconsiderable cost of obtaining and dealing with this exotic material. This was a really full and informative afternoon, and I could have written even more about it than I have, but I have tried to be reasonably concise!

All of the information was presented in an informal and relaxed way, but there was certainly no dumbing down. There was ample tea and biscuits (very important) and ample opportunity for questions and discussion, which certainly proved the old cliché that a group beekeepers that all agree with each other is about as rare as a herd of unicorns! Like all good research, the work at LASI provokes as many questions as it answers, and the workshop certainly sent us all away with plenty of food for thought. On a personal note, I felt very smug to be able, only hours after the workshop, to spot a glaring area in a TV programme, which described an industrial process where objects were ‘dipped in liquid nitrogen at -120 degrees C’. Difficult, as it boils at -196! There are more workshops planned over the next few months on other bee-related topics, and I for one will be putting my name down.

Courtesy of 'The Buzz', the Newsletter of the Central Sussex Beekeepers Association

 Photo's from the 2011 event at LASI on Flickr

Hygiene workshop handout [PDF 2.56MB]