by Dewey M. Caron, Communications and Content Specialist for the Oregon Master Beekeeper Program
Are Langstroth style hives a stressor to overwintering bees?
US beekeepers largely keep honey bees in a Langstroth hive. The original Langstroth hive, designated (at least in the US) as the first practical movable comb hive incorporating bee space, has been called the best thing that has happened for beekeepers and the worst thing that has happened to honey bees. We actually use a ‘simplified’ Langstroth hive; Langstroth’s original hive was a double-walled insulated hive, with interior glass walls of the comb honey super.
In a series of studies, Derek Mitchell, a mechanical engineer and part-time beekeeper with his wife from northern England (Leeds), has challenged the widespread belief that honeybees naturally insulate their colonies against cold. His latest research published in the Journal of the Royal Society Interface (Mitchell, DM, 2023. Honeybee cluster-not insulation but stressful heat sink. https://doi.org/10.1098/rsif.2023.0488) faults the Langstroth hive as potentially subjecting bees to thermally-induced stress due to extremely poor insulation viz-a-viz their natural nest in bee trees. He further suggests we need a dialogue about the ethical treatment of honey bees, especially relative to our choice of colony domiciles.
Bees in a winter in a bee hive are responsive to the outside temperature. On warm days, honey bees can be observed distributed about the hive engaged in various hive activities. Some will fly and might return with some pollen, depending upon availability. On very cold days, the bees form into a spheroid cluster extending between frames of beeswax combs. The colder the outside (ambient) temperature, the more compact the cluster formation.
Bees forming the mantle of the cluster have to maintain a body temperature of around 50° F (10° C) to avoid falling from the cluster shell. As their body temperature falls, they move inward to where bees in the interior of the cluster generate heat from muscle activity due to movement and brood rearing. This gives the surface temperature of the cluster a lower limit of approximately 50°F.
In our management we are aware that survival of the wintering bee colony is reliant on having large populous colonies with elevated adult numbers and sufficient honey stores (roughly a full 2nd top box), to allow the bees to survive the winter. That 30% or more of colonies that do not survive winter can be attributed to both our failure to effectively insulate our hives and to control varroa mites. We need do more to relieve the stress of winter in our bee management practices.
Mitchell points out that research into the heat transfer of the honey bees within their nests has been limited to applying insulation to hives. He also believes there has not been adequate attention to top openings in the wintering hive (Mitchell D. 2017 Honey bee engineering: top ventilation and top entrances. Amer. Bee Jour. 157, 887–889 and Mitchell, DM 2019.Thermal Efficiency, May 2019. Bee Culture). This he says has led to an inability to make valid comparisons of the several different hive designs used by English and US beekeepers.
His latest publication faults our misconception about what a winter cluster can or cannot do overwinter as having led to our adoption of the use of the poorly insulated, highly-conductance Langstroth hive. He even says it is part of the rationale in the US to the newest tendency to use refrigeration as a wintering management. (https://www.projectapism.org/demographics-of-indoor-bee-storage.html).
I recommend you look at his latest open access publication and his earlier studies (which have been published in both Bee Culture and American Bee Journal) especially if you struggle with whether you are making the best decision of top insulation, top entrances, moisture trapping at the colony top and decisions on use of whole colony winter wrapping to overwinter colonies.
Bee MD review
At the Fall OSBA meeting I discussed the BEEMD program I have been working on the last couple of years. We are ready for a review. Do you have an interest in reviewing Bee MD?
The BeeMD provides identification support to help users diagnose symptoms of honey bee health issues, and was created for both beginning and experienced beekeepers. The previous The BeeMD website has been redesigned, updated, and expanded, and is now hosted as an identification tool on ITP’s idtools.org platform.
From reviewers I am looking forward to feedback on how this tool fits your needs as a beekeeper, about your experience navigating the website, ease in using the tool’s informational pages and its key, and also of course about the accuracy of tool content. Since this has a high visual quality I m also constantly looking for that perfect photo that illustrates the text.
The tool is ready for review now. We are running this beta review period for three weeks, from November 28th through December 19th. Please let me know if you are interested in participating. I will send you the review form and website access information. It is not necessary to be an expert or have experience with beekeeping or with our digital tools. In fact, a lack of familiarity of the subject matter or using ITP tools are just as valuable as those with some expertise or experience.
Beta reviews are extremely important and beneficial for increasing the value of The BeeMD for its users, so I appreciate your nterest and thank you for your time. I will be sure to let you know when the program is posted and how to access it once we conclude this final step of preparation (NOTE: this is meant to be evergreen so once posted we will be updating and adding to content as necessary to keep it current and relevant for users).
The organization Pollination protection P2 has supported this BeeMD development along with USDA APHIS since our initiation in 2014. For their latest annual report of P2 see https://www.pollinator.org/pollinator.org/assets/generalFiles/2023-Annual-Report-FINAL.pdf
You can view other USDA APHIS ID tools (such as updated Exotic bee ID, Bee mites, Hornet identification) at www.idtools.org.
24-Methylenecholesterol paper by OSU researchers
We are well aware that nectar supplies bees with energy, while pollen serves as the primary source of proteins, lipids, vitamins, and vital micronutrients. One such micronutrient, 24-Methylenecholesterol, is an essential phytosterol micronutrient that research by the OSU bee lab has shown makes up approximately 50% of the total sterols found in bee pupae. It is selectively transferred from nurse adult honey bees to the youngest larvae via the feeding of brood food. This steroid is used directly or as the starting material for other needed functional molecules including cell membranes and as a precursor to moulting hormones.
The OSU bee lab has demonstrated that bees are incapable of biosynthesizing 24-methylenecholesterol. When we feed supplemental protein (pollen patties) these diets lack critical phytosterols, especially 24-methylenecholesterol. This technical publication, a collaborative effort of the OSU bee lab and organic chemists developed a means of producing 24-Methylenecholesterol, not a naturally abundant sterol, in quantities suitable for further studies on honey bee dietary needs. (For additional background see also: Evaluating Effects of a Critical Micronutrient (24-Methylenecholesterol) on Honey Bee Physiology. Priyadarshini Chakrabarti, Hannah M Lucas and Ramesh R Sagili. 2020. Evaluating Effects of a Critical Micronutrient (24-Methylenecholesterol) on Honey Bee Physiology Annals of the Entomological Society of America, 113(3):176–182, https://doi.org/10.1093/aesa/saz067)
Quiroz, Eliseo with colleages of organic chemistry (Paul Blakemorea lab, OSU) (with Ramesh and Priya as coauthors). 2023. Synthesis of [28-13C]-24-methylenecholesterol using 1-tert-butyl-1H-tetrazol-5-yl [13C]-methyl sulfone to methylenate an isopropyl ketone intermediate. ARKIVOC 2024(2):10.24820/ark.5550190.p012.100