Reducing Honeybee Stress in the Winter
The art of beekeeping dates back to the Egyptians, where they kept honeybee colonies in pottery. It has evolved far from this through revolutionary science and innovation. However, new research suggests there is a common misconception about colonies and their hives that could be putting them at risk.
The misconception is that honeybees (Apis mellifera), huddle together in the hive when under cold temperatures to insulate the colony. In light of this, hives have been built with walls only 19mm thick compared to tree hollows, where natural nests are formed, that can be as thick as 150mm. Previous research found manufactured hives to have up to seven times more heat loss than those found in nature.
New findings from University of Leeds PhD student Derek Mitchell, propose that the bees are being subjected to thermal stress due to the poor insulation of manufactured hives. This evidence comes from studies on the clustering behaviour of bees and observing how heat interacts within the hive. The huddle of bees consists of an inner layer, called the cluster core, and the outer layer, known as the cluster mantle.
Using his background in mechanical engineering, Mr Mitchell discovered that the cluster mantle is acting more like a heat sink than an insulation mechanism. As “the cluster mantle does not meet any (of) the four insulation criteria identified and meets all three heat sink criteria”. This is because, as the bees on the outside of the cluster become cold, they migrate towards the centre and the warmth of the bees that can still produce heat. Consequently, thermal conductivity increases, leading to heat loss as heat moves out from the center of the huddle outwards. There is a complex relationship between the colony and thermo-fluids including heat, radiation, air and water vapour; this needs to be better understood to enable the proper care for domestic honeybees.
Therefore, it was concluded that the clustering behaviour is not a clever insulation mechanism from the colony but a survival reaction to the extreme cold. Mitchell described that “clustering is not a wrapping of a thick blanket to keep warm – but more like a desperate struggle to crowd closer to the fire or otherwise die”. Other survival techniques in bees include eating their own young. Behaviour such as this would want to be avoided as it can damage the colony and reduce the honey yield for the beekeeper. The inadequacy of man-made hives has lead to this behaviour amongst domesticated bees, therefore, efforts need to be made to increase the insulation efficiency of manufactured hives.
This research aims to contribute towards the debate on the ethical treatment of honeybees. With Mitchell aspiring to “raise awareness of the welfare issues and to help educate beekeepers about the complex interaction of the colony enclosure and thermo-fluids”. When buying honey, you can make more ethical choices based on how the honey has been produced.
Removing honey from the hive on a regular basis can lead to bee population decline. This anthropogenic focused, profit driven method of beekeeping is damaging to honeybees. When buying honey, smaller scale, bee focused companies are recommended for a more ethical choice. A bee centred approach includes more natural and balanced beekeeping which isn’t as stressful on the population.
There is an issue with certifying UK honey as ‘organic’ because it is uncertain whether the bees are visiting only organically grown flowers. Locally sourced honey can be a better choice if you are willing to contact the beekeeper about their practices. The website ‘Ethical Consumer’ contains a list of ethically approved honey brands that can help you make bee-friendly choices if you wish to include honey in your diet. The research paper entitled ‘Honeybee cluster – not insulation but stressful heat sink’ can be found online here.