NOSEMA MONITORING IN DEVON - 2009-2011


We started detailed testing colonies for nosema in Spring 2009.  For three years this was organised as a DBKA project at two centres each year in different locations around the county. These were full day events on consecutive Saturdays and Sundays in April.  Members from nearby DBKA branches were invited to bring 30 flying bees from everyone of their colonies. 844 samples were examined over three years.  The aim was to monitor all local bees for the presence of nosema so potentially we could (should) have tested 12,000!   Around 7%


The idealistic and still continuing ambition is that every year, every colony in Devon will be tested for  the presence of this debilitating infection.  There is increasing evidence that nosemosis will weaken the ability of honeybees to resist other infections, environmental stresses from weather extremes or even the feared modern pesticides.  If we know the extent of nosema infection in every colony we have then we are in an informed position to manage them accordingly.  Active management can only be applied in the active season so it makes sense that the test should be carried out at the earliest opportunity in each Spring.  Nosemosis, which is accentuated by confinement of the bees, has been shown to be at least loosely correlated with CCD in USA and seems increasingly common in UK and Europe. There is no evidence so far that Nosema apis or Nosema ceranae could be the direct or only causative agent for the current plight of honeybees in either continent but they are often present in CCD or other weak colonies especially N. ceranae.


Nigel Lawrance, Newton Abbot Branch, analysed the incidence of Nosema in the years 2009-2011. His findings were the basis of the report published in the January 2013 edition of Beekeeping.   Based on a total of 844 samples the infection rate was as illustrated in Fig 1.

Over the three years covering six events in six different areas of the county, the incidence and level of infection was fairly consistent.  Since then Branches have organised their own Nosema testing events.  As methods used have varied somewhat it is difficult and not sensible to have a combined set of results.  Some groups have even chosen to test colonies in the Autumn.  This was useful to give an indication as to whether Fumidil B, the traditional additive to autumn feed, was necessary.  However, as an antibiotic, this medicant has been deregistered for use and is no longer available.  There are several herbal-type products appearing in bee equipment catalogues and journal advertisements but their efficacy has yet to be established through experience.    


This year (2013) the winter has been very long and even in May the temperature is persistently just making 13-14C.  This follows the exceptional wet summer of 2012. So bees have been confined for long periods now over 12 months.  Some branches cancelled their planned nosema monitoring day in April as it was impossible even to open hives for inspection and flying times were rare.  May is little better.  However, Newton Abbot branch managed to obtain 44 samples from their members' hives and the incidence of nosema has increased considerably over the past year.  


One branch was advised not to differentiate between the high, medium and low levels of infection.  The suggestion being that if nosema is present then deal with it.  This is a serious loss of opportunity in my view.  A high level of infection certainly suggests a complete comb change for that colony is needed.  This is a cumbersome and certainly expensive operation which can itself bring problems.  It must therefore be done as carefully and as efficiently as possible.  Knowing precisely which colonies to target must be essential and sensible information.


What about the low and medium levels?  The information itself  is very reassuring when compared to guessing.   The extent of brood comb replacement with fresh foundation whenever convenient should be a decision every beekeeper should make all through the active season considering each colony individually.  So the concept of "monitoring'' every colony for its level of nosema infection should be considered as vital as monitoring the level of varroa infestation.  I see no difference in principle.


In recent years several Devon beekeepers have become qualified BBKA microscopists. In addition, our regular nosema days revealed several DBKA members who use a microscope professionally and are willing to apply their specialist skills to identifying and classifying nosema samples at their local branch event.  So DBKA now has the resources and expertise for full nosema monitoring of every hive of bees every year.  That's about 4000 per year!  Or about 400 per branch.  Can we do it?  It would be a great stride forward to improved bee health in Devon.  There is some basic DBKA equipment from the centrally organised events.  However, none of it is expensive and each branch should plan to have their own apparatus and so freely choose the time and system to suit themselves.  The value of say ten consecutive years of consistent nosema testing will be enormous and very revealing about the progress of bee health in each local area.


NOSEMA SURVEY RESULTS ANALYSIS 2009-2011

NOSEMA  SLIDES IN PDF

PRESENTATION to TAVISTOCK & NEWTON ABBOT