Losses of honey bee colonies over the 2013/14 winter

Preliminary results from an international study

The honey bee protection network COLOSS 1 has today announced the preliminary results of an international study to investigate honey bee winter colony losses. Data were collected from Israel and Algeria and 19 European countries. In total 17,135 respondents provided overwintering mortality and other data of their honey bee colonies. Collectively, all
responding beekeepers managed more than 376,754 colonies. A preliminary analysis of the data show that the mortality rate over the 2013-14 winter varied between countries, ranging from 6% in Norway to 14 % in Portugal, and there were also marked regional differences within most countries. The overall proportion of colonies lost was 9 %, the lowest since the
international working group started collecting data in 2007.

These figures compare with losses over the same period of 7.85% in England and Wales (provided by the UK
Food and Environment Research Agency: see attached spreadsheet for details). Losses of colonies in the USA
between Oct 1 2013 and April 1 2014 were also substantially lower.

The protocol used to collect this COLOSS data has been internationally standardized 2,3  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 later in the year.

Co-ordinator of the COLOSS Monitoring and Diagnosis Working Group Dr Romée van der Zee from the Dutch
Centre for Bee Research says: “The contribution of many factors which are correlated to colony losses seem
to be very dependent on weather conditions. Colonies built their brood nests late because of the relatively
cold spring in 2013. This may have decreased the number of reproductive cycles of the parasitic varroa mite,
producing fewer mites. Good weather in the summer then provided excellent foraging opportunities”.

Press release (PDF): COLOSS Press Release colony losses July 14.pdf

COLOSS Press Release colony losses July 14 Appendix.pdf
COLOSS Press Release colony losses July 14 Map.pdf
Supported by

Ricola Foundation


University of Bern

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