Continuous hive weight, temperature and CO2 under varying conditions of hive ventilation

CO2, a byproduct of respiration, is toxic at high concentrations so regulation of CO2 within the honey bee hive is an important colony function. In this study, we measured hive CO2 concentrations at 1-s intervals while ventilation characteristics of the hive were changed every few days, and we analyzed the data for effects of increased ventilation on colony behavior and thermoregulation. Average CO2 concentrations were significantly higher, by > 200 ppm, when hives had screened bottom boards (higher ventilation) compared to hives with solid bottom boards (lower ventilation) at the same time. Daily CO2 concentration amplitudes, hourly temperature, daily temperature amplitudes, nor hourly hive weight changes were not significantly affected by the changes in hive ventilation. In a second experiment, we found average CO2 concentrations at the top center of the upper hive box, on top of the frames, were significantly lower than concentrations at the center of a solid bottom board underneath frames, which was expected due to the higher density of CO2 relative to air. Bee colonies have been reported to cycle air, with shorter periods of 20 to 150 s and longer periods of 42–80 min, but a periodogram analysis of the CO2 concentration data found no evidence of important CO2 cycle periods other than a strong 24-h period. Bee colonies maintained strong daily cycles of CO2 concentration, with average maximum concentrations > 11,000 ppm, even in conditions of increased ventilation, indicating that managing CO2 concentration is a complex colony behavior.二氧化碳（CO2）作为呼吸作用的副产物，在高浓度下具有毒性，因此调控蜜蜂蜂箱内的二氧化碳浓度是蜂群的一项重要群体功能。本研究以1秒间隔监测蜂箱内二氧化碳浓度，同时每隔数日调整蜂箱的通风特性，并分析数据以探究通风量提升对蜂群行为与体温调节的影响。在相同环境条件下，配备筛网底板（通风量更高）的蜂箱，其平均二氧化碳浓度较配备实心底板（通风量更低）的蜂箱高出200 ppm以上，差异具有统计学显著性。蜂箱通风量的变化并未显著影响每日二氧化碳浓度波动幅度、每小时温度、每日温度波动幅度，以及每小时蜂箱重量变化。在第二项实验中，我们发现位于巢框上方的上蜂箱顶部中央位置的平均二氧化碳浓度，显著低于巢框下方实心底板中央处的浓度——这一结果符合预期，因为二氧化碳密度高于空气。已有研究表明，蜂群会进行空气循环，其循环周期短则20至150秒，长则42至80分钟，但对二氧化碳浓度数据进行周期图分析后发现，除了显著的24小时周期外，未发现其他具有重要意义的二氧化碳循环周期。即便在通风量提升的环境中，蜂群仍维持着强烈的二氧化碳浓度日循环模式，其平均最高浓度超过11000 ppm，这表明调控二氧化碳浓度是一项复杂的蜂群行为。