Varroa Research

Last night I attended the Suffolk Beekeepers Association AGM, which was as AGM’s tend to be, but had the added attraction of Ricarda (Ricky) Kathay, Phd student. Suffolk Beekeepers are part-funding the research project into varroa destructor that she is working on – and it’s fascinating stuff.

A little background about varroa: it is a parasitic mite that lives on honey bees and feeds on haemolymph (equivalent of blood) by making holes through the cuticle (skin). It stresses and weakens the bees making them susceptible to other pathogens. More specifically it sometimes transmits a virus that deforms their wings, thereby making them unviable. It breeds in sealed brood cells, feeding on the developing pupa, preferring the larger and longer developing drone brood.

And so to the research (extremely briefly): The initial question posed was ‘why don’t the honey bees seem to detect these relatively huge mites’. Bees recognise one another by sensing a chemical profile of hydrocarbons (alkanes and alkenes) and fatty acids secreted onto a waxy layer on their cuticle (skin). It is possible that the varroa mites mimic this bee ‘scent’ to go undetected, but as different colonies have different group profiles and bees with different roles also have different profiles, it raises the question of how the mite would successfully do this.

The first published piece of work from the project investigated the role specific (also age specific as role is age dependent) chemical profiles of bees; click on the title to read Task Group Differences in Cuticular Lipids in the Honey Bee Apis mellifera.

Interestingly, given the choice between a forager bee and a nurse bee varroa mites will choose the nurse bee – which has access to brood chambers – 90% of the time, showing they can recognise the particular elements of that profile. Freshly hatched bees have no particular ‘scent’ or profile for a few hours, allowing them to be transferred between colonies with no problems. A united hive (2 colonies forced together) will show altered colony profiles within a day.

Future research will look further into analysing chemical profiles of varroa mites in different situations, also as to whether varroa alters the behaviour of the honey bee to promote mite survival. There are also differences between honeybee species to investigate, for example the african honey bee has one particular extra chemical in it’s profile. Also interestingly, asian honeybees are more resistant to varroa mites, partly because their drone brood capping is so thick the drone bees can’t move around the mites to break out and hatch.

I for one feel my £5 contribution has been well spent and I look forward to hearing more in the future.

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