APA 7: TWs Editor. (2023, November 22). Honeybees Do Not Insulate Their Colonies Against Cold Naturally, Research Shows. PerEXP Teamworks. [News Link]
Derek Mitchell, a Ph.D. student at the University of Leeds, is advocating for an extended discourse on the ethical treatment of insects based on his research. His findings challenge the commonly held theory that bees respond to cold temperatures by creating layers of insulation. This idea has resulted in the construction of beehives with inadequate insulation compared to the bees’ natural habitat. Mitchell’s research prompts a reevaluation of the ethical considerations involved in beekeeping practices.
Published in the Journal of the Royal Society Interface, the research delves into honeybee “clusters” where the insects gather in dense disks between the combs, attempting to maintain a temperature above 18°C when faced with dropping external temperatures. Contrary to the longstanding belief that the outer layer of honeybees, known as the mantle, serves to insulate the cluster core—the bees at the center—this study reexamines and challenges this notion that has persisted for almost 120 years.
Applying methods akin to those employed in assessing heat loss from buildings, Mr. Mitchell, affiliated with the School of Mechanical Engineering, scrutinized the theory. Contrary to expectations, his analysis suggests that, rather than serving as insulation, the mantle functions more like a heat sink. Instead of preserving heat within the central area, the findings indicate that the mantle disperses heat away from the core. The paper articulates, “The cluster mantle fails to satisfy any of the four identified insulation criteria and fulfills all three criteria indicative of a heat sink.”
Mr. Mitchell noted that his findings are contentious, challenging a fundamental belief in beekeeping that the mantle serves as insulation for honeybees.
In his explanation, he details that as the external temperature decreases, the demand for heat to maintain a temperature above 18°C inside rises. If the bees are unable to generate sufficient heat, the area near the hive wall experiences a drop in temperature, leading the honeybees in that vicinity to become chilled. To counteract this, they reposition themselves closer to bees that can effectively generate heat. As they cluster together, their collective thermal conductivity rises, exacerbating the overall heat loss.
According to him, the recent research suggests that clustering, far from being a benign behavior, is a survival response to an imminent threat, leading to heightened stress caused by the cold and increased exertion. He emphasizes that, in anthropomorphic terms, clustering should not be likened to wrapping in a thick blanket for warmth but rather viewed as a desperate effort to huddle closer to the ‘fire’ in order to survive, potentially even resorting to extreme measures such as consuming their own offspring.
He expressed his intention to disseminate his research findings to increase awareness regarding welfare issues and to contribute to the education of beekeepers. His aim is to illuminate the intricate interplay between colony enclosure and thermofluids, encompassing factors such as heat, radiation, water vapor, and air, in conjunction with honeybee behavior and physiology.
Harvey M. Thompson, Professor of Computational Fluid Dynamics at the University of Leeds and supervisor of the recent research, expressed satisfaction in witnessing the application of mechanical engineering across diverse fields. He highlighted the potential utility of these findings in assisting beekeepers in the future.
The impetus for Mr. Mitchell’s research emerged when his wife ventured into beekeeping, drawing his attention to the continued use of beehives designed in the 1930s and 1940s.
He explained that the beehives utilized by beekeepers seemed incongruent with his understanding of heat transfer principles and the information he had received about honeybees. This discrepancy prompted him to explore the possibility of constructing improved hives. During his inquiry into the requirements of honeybees, he discovered a lack of engineering-sensible information, motivating him to delve further into the subject.
Having initially studied mechanical engineering as a student apprentice, he later revisited the discipline as a Ph.D. student. Employing engineering methods typically applied to address industrial challenges, his earlier research indicated that the heat loss in most manufactured hives surpasses that of natural nests by a factor of seven.
Mr. Mitchell, with a background in Physics (BSc) and Microelectronics (MSc), and experience in spacecraft ground control software, expressed his belief that misunderstandings regarding clustering had, to some extent, originated from observations primarily made in thin (19mm) wooden hives. These hives possess substantially different thermal properties compared to the honeybees’ natural habitat of thick-walled (150mm) tree hollows.
He noted that longstanding beliefs have fostered enforced clustering due to beekeepers predominantly utilizing what he terms “inadequately insulated hives,” coupled with the common use of refrigeration in North America. Despite these conditions of significant heat loss being viewed as natural or necessary within beekeeping and academic research, Mr. Mitchell highlights the need for reconsideration.
He advocates for an immediate exploration, research, and promotion of changes in beekeeping practices. Additionally, he emphasizes the necessity for extended discussions concerning the ethical treatment of honeybees and insects.
Resources
- ONLINE NEWS University of Leeds. (2023, November 22). Research challenges widespread belief that honeybees naturally insulate their colonies against cold. Phys.org. [Phys.org]
- JOURNAL Mitchell, D. (2023). Honeybee cluster—not insulation but stressful heat sink. Journal of the Royal Society Interface, 20(230), 4888. [Journal of the Royal Society Interface]
