Honey bees colonies maintain CO2 temperature regimes in spite of change in hive characteristics

Authors: Meikle, William; BARG, A. - Tufts University; Weiss, Milagra

Submitted to: Apidologie
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2022
Publication Date: 8/18/2022
Citation: Meikle, W.G., Barg, A., Weiss, M. 2022. Honey bees colonies maintain CO2 temperature regimes in spite of change in hive characteristics. Apidologie. 53. Article 51. https://doi.org/10.1007/s13592-022-00954-1.
DOI: https://doi.org/10.1007/s13592-022-00954-1

Interpretive Summary: Honey bee colonies need to maintain certain conditions within the bee hive for the colony to thrive. That bee colonies warm the inside of the hive, particularly near the larval bees, is well known. Because bee colonies live in a confined space, bees must also ventilate the hive to get rid of CO2. Researchers have found large swings in the concentration of CO2 within hives during the day. Whether high concentrations are a by-product due to bees simply ventilating less and allowing CO2 to build up, or whether the peaks are actually something the bees want, is not clear. One way to test that is to increase ventilation in the hive and see if bees take advantage of that to lower CO2. We put screened bottom boards under half of the hives, allowing CO2, which is heavier than air, to sink down and out from the hive. We found that average CO2 concentration increased when ventilation increased, which suggests bee colonies desire the CO2 peaks. We also put a sensor near the entrance to see if the bee colony brought in air every 20-150 seconds (like breathing) but we found no such air cycles.

Technical Abstract: Regulation of CO2 within the honey bee colony is an important colony function but comparatively little studied. We measured CO2 concentrations at 1 second intervals to observe changes in CO2 as ventilation characteristics of the hive were changed. In hives with screened bottom boards (higher ventilation) average CO2 concentrations, and average temperature, were significantly higher relative to hives with solid bottom boards (lower ventilation). With CO2 sensors placed both at the top of frames and underneath frames, resting on a solid bottom boards, average CO2 concentrations were higher on the bottom board compared to the top of the hive, which was expected due to the higher density of CO2 relative to air. A periodogram analysis did not detect reported cycles of air movement, with periods of 20 to 150 seconds, within the hive. Bee colonies maintained strong daily cycles of CO2 concentration even when maintenance of those concentrations required more effort.