Losses of honey bee colonies over the 2012/13 winter - Preliminary results from an international study

The honey bee research network COLOSS 1 has today announced the preliminary results of an international
study to investigate winter colony losses. Data were collected from 19 countries from Europe, Israel and
Algeria. In total, more than 15,000 beekeepers provided overwintering mortality and other data of their
colonies. Collectively, they managed more than 280,000 colonies. A preliminary analysis of the data shows
that the mortality rate over the 2012-13 winter varied between countries, ranging from 6% in Israel to 37%
in Ireland, and there were also marked regional differences within some countries. These figures compare
with losses over the same period of 31% and 34% recently reported from the USA 2  and the UK 3 respectively.

The protocol used to collect this COLOSS data has been internationally standardized to allow comparisons and joint
analysis of the data. A more detailed analysis of risk factors calculated from the whole dataset , as well as further
colony loss data from other countries will be published in the peer-reviewed Journal of Apicultural Research 4 later in
the year. The data show that Poland and Finland have each year experienced losses of about 17%. Countries in south
eastern Europe (Slovakia, Bosnia Herzegovina, Croatia) have had average losses of less than 10%, but in 2012 losses
were slightly higher. In central Europe (Germany, Switzerland, Austria) losses rose to above 20% in 2012 but went back
to around 15% in 2013. In the neighbouring Netherlands, losses were above 20% for five years, but decreased in 2013
to a level comparable with Germany and Switzerland. Interestingly, we now see losses rising to substantially higher
levels in northern countries (Sweden, Denmark, Norway, Ireland, UK) whose losses were around the 15% in the
previous years.

Co-ordinator of the COLOSS Monitoring and Diagnosis Working Group Dr Romée van der Zee from the Dutch Centre
for Bee Research says: “We have observed an interesting pattern in honey bee colony losses over the last 3 years. These
results emphasise that losses in many countries remain greater than beekeepers consider are acceptable. We believe
that many factors including the weather are responsible for these losses, which show patterns over the years which are
not bound to administrative borders”. [Ends]

COLOSS Press Release July 2013.pdf