vTempDelta.m from Nectar, humidity, honey bees (Apis mellifera) and varroa in summer: a theoretical thermofluid analysis of the fate of water vapour from honey ripening and its implications on the control of Varroa destructor

This theoretical thermofluid analysis investigates the relationships between honey production rate, nectar concentration and the parameters of entrance size, nest thermal conductance, brood nest humidity and the temperatures needed for nectar to honey conversion. It quantifies and shows that nest humidity is positively related to the amount, and water content of the nectar being desiccated into honey and negatively with respect to nest thermal conductance and entrance size. It is highly likely that honeybees, in temperate climates and in their natural home, with much smaller thermal conductance and entrance, can achieve higher humidities more easily and more frequently than in man-made hives. As a consequence, it is possible that Varroa destructor, a parasite implicated in the spread of pathogenic viruses and colony collapse, which loses fecundity at absolute humidities of 4.3 kPa (approx. 30 gm−3) and above, is impacted by the more frequent occurrence of higher humidities in these low conductance, small entrance nests. This study provides the theoretical basis for new avenues of research into the control of varroa, via the modification of beekeeping practices to help maintain higher hive humidities.本理论热流体分析探讨了蜂蜜产率、花蜜浓度与蜂箱入口尺寸、蜂巢热导率、育蜂巢湿度以及花蜜转化为蜂蜜所需温度之间的关联。该研究量化并验证了：蜂巢湿度与待脱水制备蜂蜜的花蜜总量及含水量呈正相关，而与蜂巢热导率和入口尺寸呈负相关。在温带气候的自然蜂巢中，热导率更低、入口尺寸更小的蜂箱，相较于人工饲养蜂箱，能够更轻松且更频繁地实现更高湿度，这一现象具有较高可能性。据此可推测，瓦螨（Varroa destructor）——一种与致病性病毒传播及蜂群崩溃相关的寄生虫，在绝对湿度达到4.3 kPa（约30 g·m⁻³）及以上时会丧失繁殖能力——会受到这类低导热、小入口蜂巢中更频繁出现的高湿度环境的影响。本研究为通过调整养蜂实践以维持更高蜂箱湿度，进而开展瓦螨防控相关的新研究方向提供了理论依据。