Effects of Surface Darkening on Cell Temperature in Paper Wasp Nests : Measurements Using Paper Model Nests

概要

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To estimate thermal effects of dark oral secretion applied on nest surface by adult paper wasps, we measured cell temperature of paper model nests. Paper models of Polistes nests, with the following five different solar radiation absorption rates, were made : 10% (absorption of white tissue), 40% (equivalent to the absorption rate at the lower part of natural vertical nest), 70% (upper part), 85% (dorsum) and 95% (absorption rate of pure black poster color). The mean difference between cell and ambient temperatures measured in the field between 1030 and 1300 on a sunny and calm summer day (solar radiation quantity (SRQ)=820.8W/m^2, ambient temperature (T_a)=30.0±0.1℃) was 6.2±0.1℃, 7.1±0.2℃, 7.9±0.2℃, 8.7±0.2℃ and 10.0±0.2℃ for white, 40%, 70%, 85% and black model nests, respectively. The temperature difference was significant for any pair. On a windy day (mean wind velocity=1.0 m/s), such a thermal effect was small in the painted nests, and the mean temperature excess in the daytime (1030-1300, SRQ=690.3 W/m^2, T_a=31.2±0.2℃) was 5.5±0.1℃, 6.8±0.3℃, 7.1±0.3℃, 7.3±0.3℃ and 7.1±0.3℃ for white, 40%, 70%, 85% and black model nests, respectively. The results suggest that the darkening of nest surface significantly increases the cell temperature when nests receive sunlight.
日本昆虫学会の論文
2001-06-25