Thermoregulation of termite mounds: what role does ambient temperature andmetabolism of the colony play?

Termites are well known for their ability to regulate the environment of th eir nest such as temperature and humidity. The influence of fluctuating amb ient temperature and mound characteristics on mean nest temperature and dai ly fluctuation of nest temperature was analysed quantitatively in the fungu s-cultivating, mound-building termite Macrotermes bellicosus (Macrotermitin ae) in the savanna of the Comoe National Park (Cote d'Ivoire). Additionally , the nest temperatures of inhabited and uninhabited mounds were compared t o analyse the contribution of ambient temperature to nest temperature in re lation to metabolic heat production of the termites and their fungi. Mound structure alone resulted in a relatively constant nest temperature. Abiotic heat production via solar radiation alone yielded nest temperatures that c orresponded to mean ambient temperatures. However, only the production of m etabolic heat by the termites and the fungi increased these temperatures to the actual nest temperature. Therefore, and due to the high heat capacitie s of the mounds, large colonies (mound height above 2.0 m) had higher nest temperatures than smaller ones. Only large colonies attain constant nest te mperatures of 30 degreesC that are largely independent from ambient tempera tures and optimal for the growth and development of the termites and their fungi.