Klingner R, Richter K, Schmolz E, Keller B
Wood Laboratory, EMPA-Swiss Federal Laboratories for Materials Testing and Research, 8600 Dübendorf, Switzerland.
Naturwissenschaften. 2005 Sep;92(9):427-30. doi: 10.1007/s00114-005-0012-y. Epub 2005 Oct 28.
Paper nests of social wasps are intriguing constructions for both, biologists and engineers. We demonstrate that moisture and latent heat significantly influence the thermal performance of the nest construction. Two colonies of the hornet Vespa crabro were investigated in order to clarify the relation of the temperature and the moisture regime inside the nest. Next to fairly stable nest temperatures the hornets maintain a high relative humidity inside the nest. We found that in consequence a partial vapor-pressure gradient between nest and ambient drives a constant vapor flux through the envelope. The vapor flux is limited by the diffusion resistance of the envelope. The driving force of vapor flux is heat, which is consumed through evaporation inside the nest. The colony has to compensate this loss with metabolic heat production in order to maintain a stable nest temperature. However, humidity fluctuations inside the nest induce circadian adsorption and desorption cycles, which stabilize the nest temperature and thus contribute significantly to temperature homeostasis. Our study demonstrates that both mechanisms influence nest thermoregulation and need to be considered to understand the thermodynamic behavior of nests of wasps and social insects in general.
社会性黄蜂的纸质巢穴对生物学家和工程师来说都是引人入胜的建筑。我们证明，湿度和潜热会显著影响巢穴建筑的热性能。为了阐明巢穴内部温度与湿度状况之间的关系，我们对大黄蜂（Vespa crabro）的两个蜂群进行了研究。除了巢穴温度相当稳定外，黄蜂还在巢穴内维持着较高的相对湿度。我们发现，因此巢穴与周围环境之间的部分蒸气压梯度驱动着恒定的蒸气流过巢穴外壳。蒸气流受到外壳扩散阻力的限制。蒸气流的驱动力是热量，这些热量在巢穴内部通过蒸发而消耗。蜂群必须用代谢产热来补偿这种损失，以维持巢穴温度的稳定。然而，巢穴内部的湿度波动会引发昼夜吸附和解吸循环，这会稳定巢穴温度，从而对温度稳态做出显著贡献。我们的研究表明，这两种机制都会影响巢穴的体温调节，为了理解黄蜂和一般社会性昆虫巢穴的热力学行为，都需要考虑这两种机制。
