Hi to all,

This translated material was forwarded to me several days ago - Relating 
to the developing problems in various regions of the US, it makes 
interesting reading.

Peter

Nosema ceranae

Asian Nosema Disease Vector Confirmed – is this a new infestation or 
only now discovered?

Translated from the original German with the permission of Dr Wolfgang 
Ritter, Freiburg University by Eric McArthur MIL



Nosemosis(previously Nosematosis), which in acute cases causes diarrhoea 
and short lived bees, which exhibit agitated crawling around in front of 
the hive is a disease known to most beekeepers.   The cause of the 
disease is Nosema apis, which affects the mid gut of the Western 
honeybee, Apis mellifera spp., and which is wide spread in virtually all 
honeybee colonies.   The disease is aggravated by long confinement in 
the hive due to external unfavourable weather conditions, possible 
worsened by badly positioned hives, which forces the bees to defecate in 
the hive, which frequently results in heavy loss of bee life.



The Asian Variant

In 1996 a similar type of organism to N. apis was discovered on the 
Asian honey bee Apis cerana and subsequently named Nosema ceranae. 
Little is known at the present time about the symptoms and the course of 
the infection in Asia.  Until recently it was assumed that this disease 
vector was specific to the Eastern honeybee, A. cerana.  However in 2005 
Chinese researchers reported that N.ceranae had been discovered in the 
Western honeybee, A mellifera in Taiwan.  In the same year the Castilla 
– La Mancha Beekeeping Institute in Spain and the Veterinary Medicine 
University in Madrid demonstrated for the first time that the disease 
was present in European honeybee in Europe.  In Spain the cases of 
Nosemosis had risen constantly from 10% in 2000 to over 20% and 30% in 
the following years reaching 88% in 2004.  An important cause for the 
huge honeybee colony losses in Spain was therefore suspected as being a 
result of the N.ceranae infection, after it was discovered there.   A 
massive loss of adult bees was also observed in the apiaries (defined as 
absconding), similar to the symptoms of heavy Varroa mite infestation.



Discoveries also in Germany

The question as to whether particular colony losses in Germany could 
possibly be ascribed to N.ceranae is intended to be cleared up in 
collaboration with the Audit Laboratory of the University of  Freiburg 
and the Spanish institutes around the end of the year 2005/2006.  In the 
meantime using molecular-genetic methods (PCR) the new Nosemosis vector 
has been shown to be also present Germany in 8 of 10 tested apiaries.



Two apiaries in Baden – Württemburg, four in Bavaria and two in North 
Rhein- Westfalia.  The bees with the classic vector, N. apis came from 
Thüringen and Bavaria.



In all these apiaries, irrespective of the disease vectors confirmed 
later, severe problems occurred in spring, late summer and autumn of 
2005.  These problems lead to either to the death of most of the 
colonies  or of the whole apiary.  There was evidence of a moderate to 
severe Nosema infestation in all of the samples tested.



Clear symptoms of defecation and crawling were not present in all cases 
investigated, however a heavy bee mortality occurred in every case.



The Mechanism of  Infection Spread is Unclear

Both disease vectors, N. apis and N.ceranae cannot be differentiated 
using the present routine microscopic examination.  Only with the use of 
molecular genetic procedures is it possible to separate the two.



The following questions arise from this situation:

·         Where did N. ceranae originate?  Although this species carries 
the cerana name, because it was initially discovered on the Asian 
honeybee,  this is not necessarily a statement on its initial spread.

·         Was the disease only recently brought in does it actually 
cause high bee mortality, as the Spanish presume, due to its extreme 
virulence.

·         Or is it a long standing condition, which only now we have 
been able to differentiate from the traditional N. apis?

·         Is the actual course of the disease with the increase of 
Nosema infestation more severe because the colonies are weaker and more 
vulnerable due to the predations of the Varroa mite and other factors?



We have tested samples  from some 500 apiaries in Germany, Italy 
(Tirol), Austria and Switzerland since 2002, which suffered high or 
total losses.  Where residual bees were present, we were seldom able to 
confirm Nosemosis.  During the years 2002/03 where high winter losses 
occurred the disease level was 38%.  This year according to current 
tests the proportion appears to be higher.  Consequently we are able at 
this time to confirm the Spanish results only with regard to the 
increase in Nosemosis.



Over the past 2 to 3 years, however we have observed, that the course of 
Nosemosis has actually altered.   Contrary to the classic insidious form 
of Nosemosis, crawling and losses occur during the whole year. 
Furthermore it is being observed this winter that colonies are dying 
within a very short time scale  Beekeepers are finding contrary to 
typical Varroa infestation damage, hives full of dead bees. A further 
observation was made that this winter that colonies in many apiaries 
were undertaking relatively strong cleansing flights, even at 
temperatures as low as 4 C.    At this stage it is not possible to 
conclusively link these flights with the new form of Nosemosis.



There are still many questions which we are attempting to clarify with 
our on-going investigations.   According to our current assessment  the 
whole situation appears to be similar to the classic Nosemosis 
condition.  We are of the opinion therefore, that the usual preventative 
measures relative to Varroa treatment as well as the optimisation of the 
factors relating to apiary location should still play a dominant role in 
beekeeping management - in order to come to terms with the Nosemosis 
problem.

-- Visit www.honeybeeworld.com/bee-l for rules, FAQ and  other info ---