From http://www.biosecurity.govt.nz/pests/nosema-ceranae

*Nosema ceranae* and *Nosema apis* - are there differences in impact and
consequences?

Experts disagree on whether the two species of Nosema differ in their impact
on bees. *Nosema ceranae* has been in Europe since at least 1998 (as shown
by testing of stored samples), although it was not identified until the mid
2000s. Spain was the first country in Europe to detect *Noseam ceranae*, and
researchers there suggested it was more pathogenic than *N. apis* and was
responsible for colony losses. Once other countries began testing for *Nosema
ceranae*, it became clear that the species had been widespread in Europe for
many years, and there is no clear link to hive losses. ,For example, .*Nosema
ceranae* is widespread in the United Kingdom, and so far any difference in
impact appears marginal.

*Nosema ceranae* levels are higher in southern Europe than in northern
Europe, and many researchers consider it likely that *Nosema ceranae* is
better adapted to warm climates. *Nosema ceranae* has been present in the
USA since at least 1995, and it has been found in all states where it has
been looked for. In the United States it is commonly found together with *N.
apis*, but whether it is replacing *N. apis* or not is unclear. Although
there was initially some speculation that *N. ceranae* was implicated in
Colony Collapse Disorder, more recent research has failed to confirm a link.
A 2007 study of over-wintering sites in Florida and California found *N.
ceranae* was more common than *N. apis* in both healthy and unhealthy hives.
In 2009, researchers found around half of all hives tested contained *Nosema
ceranae*, irrespective of whether the hive was affected by colony collapse
disorder or not. While *Nosema ceranae* is found in hives suffering from
Colony Collapse Disorder, researchers in the US have concluded that it is
not the primary cause of this disorder.

In 2008 *Nosema ceranae* was found in all Eastern states of Australia, with
levels highest in Queensland and lowest in South Australia. This lends some
support to the theory proposed by European researchers that *Nosema
ceranae*is better adapted to warm conditions, while
*Nosema apis* is more tolerant of cold climates. *Nosema ceranae* has not
been identified in Tasmania or Western Australia, but only limited testing
has been carried out.

In Uruguay, where *Nosema ceranae* has been present since prior to 1990, its
presence "is not associated with an increase of Nosemosis and its role in
colony losses seems to be irrelevant". Reports of nosema disease in Uruguay
since 1964 do not suggest that it has become more prevalent or more serious
since 1990. Uruguay lies slightly to the north of New Zealand, and generally
has a warmer climate. If the suggested preference of *Nosema ceranae* for
warmer temperatures is proven correct, the impacts of *Nosema ceranae* in
New Zealand are unlikely to be more severe than those experienced in
Uruguay.

-- 
Juanse Barros J.
APIZUR S.A.
Carrera 695
Gorbea - CHILE
+56-45-271693
08-3613310
http://apiaraucania.blogspot.com/
[log in to unmask]

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html

Guidelines for posting to BEE-L can be found at:
http://honeybeeworld.com/bee-l/guidelines.htm