Adverse weather conditions, natural disasters and unsolvable queen problems resulted in the loss of 16 per cent honeybee colonies in 36 countries in the winter of 2017-18, according to a study published in a scientific journal this week.

For the study, scientists used data voluntarily provided by over 25,000 beekeepers from 33 European countries and non-European countries such as Algeria, Israel and Mexico.

Of nearly 5,45,000 colonies managed in winter, 89,000 were lost due to a combination of circumstances, said the study, which appeared in the Journal of Apicultural Research.

The study was led by Alison Gray, a researcher with the Department of Mathematics and Statistics at the University of Strathclyde in the UK. Also involved were researchers in the colony-loss monitoring group of the international honey bee research association COLOSS, which is based in the Institute of Bee Health at the University of Bern in Switzerland.

Portugal, Northern Ireland, Italy and England experienced losses above 25 per cent, while Belarus, Israel and Serbia were among those with loss rates below 10 per cent. There were also significant regional variations within some countries, including Germany, Sweden and Greece, the study showed.

The total loss rate was down from 20.9 per cent in 2016-17 but was still higher than the 2015-16 figure of 12 per cent.

Relocation helped

In a departure from previous findings, beekeepers who moved their colonies in the foraging season to access other forage or for pollination, faced fewer losses than those who kept their bees in the same place. Smaller-scale beekeeping operations also had higher losses than larger ventures.

“The loss of honey bee colonies is a highly complex issue. It tends to be influenced less by overall climate than by specific weather patterns or a natural disaster affecting the colony. We observe colonies in winter, but what happens to the bees then can be partly determined by the conditions of the previous summer,” said Gray in a statement.

Many colonies are also lost when there are problems with a colony’s queen – for example, if she goes missing or doesn’t layfertilised eggs. Most colonies are also under attack from varroa mites, a parasitic mite, Gray said.

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