Experts around the world have warned that bee population is declining. Now, a study reveals that the number of honey bee colonies dropped by almost 12 percent last winter.

An international team of researchers, including the University of Strathclyde and the University of Bern, found that 11.9 percent of the total 400,000 honey bee colonies in 29 countries did not survive winter. The team was also surprised to find that the number of colonies that died after problems involving their queen were higher than expected.

According to researcher Alison Gray of Strathclyde’s Department of Mathematics & Statistics, the loss rates vary between countries. The worst affected are Ireland, Northern Ireland, Wales and Spain.

From March 2015 to July of the same year, the temperatures in Scotland, Denmark, Norway and Ireland ranged from 12.8 degrees Celsius to 14.4 degrees Celsius. The research team believes that the temperature could have negatively impacted the development of honey bee colonies.

“The pattern of loss rates differs from last year, when higher mortality and loss rates were found in central Europe and countries to the east. This year, the higher loss rates tend to be in the west and northern countries, although Spain had high rates of loss in both years,” adds Gray. “All the loss rates quoted here include losses due to unresolvable queen problems after winter, as well as colonies that died over winter for various reasons. Losses due to queen problems were unexpectedly high in some countries, and this will be a matter for further investigation.

This problem can have implications to agriculture, economy and food security. Moreover, honey bees also play an important role in maintaining the environment and biodiversity by pollinating trees and flowering plants.

These findings were the result of the study by COLOSS, a honey bee research association based in the Institute of Bee Health at the University of Bern.