Reducing Honeybee Stress in the Winter

Rosie Bibby on 23 December 2023

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.

Image from a temple dated 2400BC evidencing beekeeping (ancient-origins.net)

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.

Image of hives in a cold landscape (Scott Hall)

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.

“Triple Star” Discovery Could Revolutionise Understanding of Stellar Evolution

Zoe Parker on 23 December 2023

Although star formation may be seen as trivial for stars like our sun, some types are more elusive than others. Massive Be type stars are one such example often found in binary systems, where two stars obit each other. “The best point of reference for that is if you’ve watched Star Wars, there are planets where they have two Suns” explains Johnathan Dodd, PhD student and collaborator on the research. However, not much is known about their formation.

A recent discovery was made by Professor René Oudmaijer, PhD student Johnathan Dodd along with PhD student Isaac Radley from the University of Leeds’ School of Physics and Astronomy and two former Leeds academics Dr Miguel Vioque of the ALMA Observatory in Chile and Dr Abigail Frost at the European Southern Observatory in Chile. It suggests that these stars may also exist in triplet systems (where there are three stars orbiting each other), as well as double. This may help to reveal the long-awaited mystery of their formation since their identification via their emission lines in 1866 by Angelo Secchi.

The “triple star” discovery by Professor Oudmaijer and his team was made by using European Space Agency’s Gaia satellite and could cause ripples of excitement in the astrophysics community. It may also aid our understanding of neutron stars, gravitational waves, and black holes.

Principal Investigator Professor Oudmaijer said “there’s a revolution going on in physics at the moment around gravitational waves. We have only been observing these gravitational waves for a few years now, and these have been found to be due to merging black holes.”  

“We know that these enigmatic objects – black holes and neutron stars – exist, but we don’t know much about the stars that would become them. Our findings provide a clue to understanding these gravitational wave sources.” 

He added that “over the last decade or so, astronomers have found that binarity is an incredibly important element in stellar evolution. We are now moving more towards the idea it is even more complex than that and that triple stars need to be considered.” 

“Indeed,” Oudmaijer said, “triples have become the new binaries”.

Video Credit: ESO/L. Calçada eso.org/public/archives/videos/hd_and_apple/eso2204b.m4v (Artist’s animation of what the system could look like)
New research using data from ESO’s Very Large Telescope and Very Large Telescope Interferometer has revealed that HR 6819, previously believed to be a triple system with a black hole, is in fact a system of two stars with no black hole. The scientists, a KU Leuven-ESO team, believe they have observed this binary system in a brief moment after one of the stars sucked the atmosphere off its companion, a phenomenon often referred to as “stellar vampirism”. This animation shows what the system might look like; it’s composed of an oblate star with a disc around it (a Be “vampire” star; foreground) and B-type star that has been stripped of its atmosphere (background).

Their research involved looking for further away secondary stars within various data sets to build a picture that at larger separations the number of companions stars is comparable between Herbig Be and B type stars.

“We observed the way the stars move across the night sky, over longer periods like 10 years, and shorter periods of around six months. If a star moves in a straight line, we know there’s just one star, but if there is more than one, we will see a slight wobble or, in the best case, a spiral.” Mr Dodd explained.

The two types of stars they were most interested in are B and Be; the former displays hydrogen emission lines and the latter are main sequence non-supergiant stars that have Balmer series emission lines.

“We applied this across the two groups of stars that we are looking at – the B stars and the Be stars – and what we found, confusingly, is that at first it looks like the Be stars have a lower rate of companions than the B stars. This is interesting because we’d expect them to have a higher rate” Mr Dodd added.

In a large proportion of the sample analysed had the inference that a third body was influencing the system, resulting in the Be star having a reduced distance from its companion. This causes mass transfer from the two stars as the Be star ‘sucks’ matter from the other. It’s been dubbed a “vampire” Be star and this behaviour forms the characteristic disc around the Be star.

Image credit: ESO/M. Kornmesser/S.E. de Mink (Artist’s impression of a vampire star and its victim | ESO)
Artist’s impression of a vampire star (left) stealing material from its victim: New research using data from ESO’s Very Large Telescope has revealed that the hottest and brightest stars, which are known as O stars, are often found in close pairs. Many of such binaries will at some point transfer mass from one star to another, a kind of stellar vampirism depicted in this artist’s impression.

A reason as to why the companion is hard to spot could be due to them being obscured by the disc and reduced so much by the Be star making them very small and faint.

Professor Oudmaijer said “the fact that we do not see them might be because they are now too faint to be detected.”

This breakthrough has opened up another area of exciting research.

Their paper entitled “Gaia uncovers difference in B and Be star binarity at small scales: evidence for mass transfer causing the Be phenomenon” was published on the 21st November and can be found here.