Ireland lost almost a third of its honey bee colonies last winter, and the very mild weather may be partly to blame.
The University of Limerick, the National Apiculture Programme and Teagasc are working together to find out why Ireland has been losing so many bee colonies.
Ireland’s extremely high bee colony losses emerged from an international survey of beekeepers by the non-profit organisation Coloss (honey bee colony losses).
Coloss is composed of researchers from 69 countries, and Dr Frances Coffey, who heads the National Apiculture Programme at Teagasc is Ireland’s Coloss representative.
Honey bee colony losses have reached worrying proportions worldwide.
Disease, increased use of pesticides, climate change, and decreased floral diversity are all blamed for the bees’ disappearance.
Each year, Coloss issues a standard questionnaire to beekeepers in each country and the latest one covered losses of honey bee colonies in Ireland last winter.
This year, the survey was completed by 450 Irish beekeepers — about 15% of all beekeepers in the country.
Beekeepers generally agree that over-wintering colony losses of 15% are acceptable. However, last winter the national average loss for bee colonies in Ireland was almost double at 29.5%.
Bee colony losses in Ireland were the highest of all of the 29 countries covered by the Coloss network, with average colony losses of 11.9%.
Other significant colony losses were 28.2% in the North, 22.4% in Wales, and 22.1% in Spain.
Over-wintering colony losses are usually higher in Ireland than in other countries studied by Coloss researchers.
Losses during the past winter in Ireland were higher than in the two previous winters at 19.3% for the winter of 2014-2015 and 13% for the winter of 2013-2014. During the 2012-2013 winter, there was a very high level of losses of 37%.
Dr Coffey said the greatest losses of over 30% were in some parts of counties Cork, Kerry, and Kilkenny, but it was hard to isolate a single cause for these high losses.
“The National Apicultural Programme will contact some of the beekeepers involved to ask some extra questions to try to tease out possible causes for this high level of mortality,” she said.
Dr Coffey said beekeepers must remain vigilant and ensure that they carry out treatments for the honey bee parasite Varroa destructor consistently and promptly.
John Breen from the Department of Life Sciences at the University of Limerick said the Irish climate might be responsible for our high bee mortality rate.
“We just had a very mild winter, and that could be influencing the mortality as well,” said Prof Breen. “If there is warm weather the bees fly out and use up their stores of honey.
“In countries like Poland and other south-eastern countries where the winters are colder bees cluster longer and that might be contributing to the low mortality in those countries.”
However, importing bees into Ireland would be frowned upon, and there is also the danger of bringing in other diseases.
“The main thing is to control the Varroa destructor, and the beekeepers are doing that. There are natural products like thymol, obtained from oil from thyme and that causes the mite to fall off the bees.”
Prof Breen said people could also start to garden for their bees. “Not all flowers have food for bees. People should have gardens with lots of single rather than double flowers,” he said.
Double flowers have extra rows of petals instead of nectaries and so produce little or no nectar or pollen.
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