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.本理论热流体分析研究了蜂蜜产率、花蜜浓度与蜂箱入口尺寸、巢体热导率、育幼巢湿度以及花蜜转化为蜂蜜所需温度之间的关联关系。该研究量化并证实：巢体湿度与待脱水转化为蜂蜜的花蜜总量及含水量呈正相关，而与巢体热导率和入口尺寸呈负相关。据此推测，在温带气候环境下，相较于人工饲养的蜂箱，野生蜂群的巢体热导率与入口尺寸均更小，因此能够更轻松且更频繁地维持更高的巢内湿度。据此，有理由认为：作为与致病性病毒传播及蜂群崩溃相关的寄生虫，狄斯瓦螨（Varroa destructor）在绝对湿度达到4.3 kPa（约30 gm⁻³）及以上时会丧失繁殖能力，而这类低热导率、小入口的巢体更频繁出现的高湿度环境，会对其生存产生影响。本研究为通过优化养蜂实践以维持更高蜂箱湿度，进而开展狄斯瓦螨防控的新型研究方向提供了理论依据。