condensateTDu.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（thermofluid analysis）探究了蜂蜜产率、花蜜浓度与蜂箱入口尺寸、巢室热传导率、育雏巢湿度以及花蜜转化为蜂蜜所需温度之间的关联关系。该研究通过量化分析证实，巢室湿度与待脱水制备蜂蜜的花蜜总量及含水量呈正相关，而与巢室热传导率和入口尺寸呈负相关。研究表明，在温带气候的自然蜂巢中，由于其热传导率与入口尺寸更小，蜜蜂可比人工养殖蜂箱更轻松且更频繁地实现更高的巢室湿度，该现象具备较高可信度。据此，这类低热传导、小入口尺寸的蜂巢中更频繁出现的高湿度环境，可能会对狄斯瓦螨（Varroa destructor）产生影响——该寄生虫与致病性病毒传播及蜂群崩溃密切相关，其繁殖能力会在绝对湿度达到4.3 kPa（约30 g·m⁻³）及以上时出现下降。本研究为通过优化养蜂操作以维持更高蜂箱湿度，进而开展狄斯瓦螨防控相关的新型研究方向提供了理论基础。