Effects of Temperature and Termite' Substrate on Methane and Carbon Dioxide Emissions from Macrotermes bellicosus and Microcerotermes dubius Cultures

Termites are considered to be a potential natural source of greenhouse gas such as methane (CH ) 4 and carbon dioxide (CO ). Although it has been taken into account of termite diet in the estimation of termites' 2 contribution to the global greenhouse gas emission, the emission rates recorded widely varies. Indeed, the emission of gases can be influenced by ecological area and its environmental parameters which can, in return, induce a physiological change among the gut microbial communities. Macrotermes bellicosus, Microcerotermes dubius and their intestine microbial community were investigated in this study for CO and 2 CH production in vitro at 30°C and 37°C and on different substrates. 37°C appeared the optimal temperature 4 leading to more CO release with both species and 30°C the best temperature for CH production with M. 24 bellicosus. The highest productions of CH and CO were obtained in the presence of food substrates. The 42 maximum rate of CH emission was recorded on mango hull (1.62 ppm/termite/day), that of CO upon fungus 42 comb (29.28 ppm/termite/h) with M. bellicosus; but that of CO was recorded on millet stem (3.71 ppm/termite/h) 2 with M. dubius. A clear CH decrease was observed in the presence of termite mound soil from 11 days. The 4 gut homogenate microflora of both termite species widely exhibited CH upon formate at 30°C and CO upon 42 acetate at 37°C. In general, the best CH production was noted on formate after a long incubation period at 30°C. 4