Carbon Dioxide and Methane Emissions from Different-Sized Groups of Eastern Subterranean Termites

Metabolic gas emissions released into the environment from termites contribute to overall soil and air gaseous composition. However, because subterranean termites are not evenly distributed in soil, it is difficult to understand their contribution of gases to the environment. The research presented here includes a method to measure baseline metabolic gas concentrations from subterranean termites in relation to increasing group sizes over time. Metabolic gas emissions were determined from defined numbers (group sizes) of the eastern subterranean termite, Reticulitermes flavipes (Kollar), foraging in laboratory test arenas. Four groups, each with 0, 50, 100, 150, 200, 250, or 300 R. flavipes workers previously collected from three field colonies were analyzed for CO2 and CH4 emissions over time. CO2 and CH4 concentrations in air samples increased linearly as group size increased across all sampling events. CO2 emissions from as few as 50 termites ranged from 442.6 to 660.9 ppm, a net increase of 33% between time zero and 60-minute sampling events. Fifty termites emitted similar increases in CH4, from 2.6 to 5.7 ppm during 60 minutes, a 55% net increase. Within each size group, cumulative gas emissions by termites increased linearly over time. This trend also was evident when different-sized groups were compared. Gas chromatograph measurements indicated significant differences in CO2 and CH4 emissions between different-sized groups of termites. Results showed that both time and group size influence metabolic gas emissions by termites.