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Hydrological characteristics and functions of termite mounds in areas with clear dry and rainy seasons

Chen, Chunfeng, Wu, Junen, Zhu, Xiai, Jiang, Xiaojin, Liu, Wenjie, Zeng, Huanhuan, Meng, Fan-Rui
Agriculture, ecosystems & environment 2019 v.277 pp. 25-35
Isoptera, drainage systems, dry season, dyes, evaporation, fungi, fungivores, gas exchange, heat, humidity, insect colonies, microclimate, morphogenesis, rain, spatial distribution, spatial variation, temporal variation, termite mounds, water content, wet season, South Asia
Many species of fungus-feeding termites collectively build massive mound structures that enclose a network of broad tunnels to provide a controlled microclimate in which to raise fungus and brood by managing heat, humidity and respiratory gas exchange. However, the mechanisms by which termites regulate the water content inside the termite mounds are currently unknown in regions in southern Asia with distinctive dry and wet seasons. Here, we investigated the spatio-temporal variations in the water content in the mound structures of O. yunnanensis and then used the dye tracer infiltration method to determine how the existing mound structure and/or termite activities contribute to regulating the moisture inside the mounds. We found that the outer walls could act as a shield to prevent water infiltration into the mound, and the network of broad tunnels could act as a drainage system to eliminate excess water when the outer walls are compromised during heavy rainfall events in the rainy season. Furthermore, the termites could repair or reshape the mound to control water flows inside the mound. During the dry season, the high-density mound wall effectively reduced evaporation, and the termites could actively transport water to maintain favourable microclimatic conditions. Our results demonstrated the internal water spatio-temporal distribution in the mound and its regulation mechanisms and provided clues for understanding mound morphogenesis and the organization of insect societies.