Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/1995
Publication Date: N/A
Interpretive Summary: The speed at which an insect breathes may be important to explain how insects cope with a hostile environment. The resting rate of breathing in insects may be influenced by many factors, among them: 1) the concentration of gases breathed; 2) the species' dependence on water (desert inhabitants breathe less to reduce water loss); and 3) the relative size of the individuals (larger individuals have a greater rate/mg). Termites are useful to evaluate these factors as they: live in sealed galleries with gas levels much different from ambient conditions; have a wide range of moisture requirements; and range widely in size. We found that the most important factor affecting termite breathing rates was carbon dioxide and oxygen gas levels. Previous bioassays of termites in in laboratory gas environments, where termites breathe much more rapidly, may provide misleading results. Moreover, termites may produce large quantities of the greenhouse gas methane that contributes to global warming. Previous estimates of termite contributions to the global methane budget were misleading as gross generalizations were made about their methane production potential. However, we found wide between-species and within-species variations.
Technical Abstract: Rates of oxygen consumption and production of carbon dioxide and methane were measured in thirteen Nearctic termite species periodically, for 48 h, at 25 C. Decreased respiration rates were observed in several species with decreasing oxygen and increasing carbon dioxide levels. Those species with apparently higher moisture requirements (i.e., subterranean termites) generally had lower respiration rates compared with the dampwood (highest rates) and drywood (intermediate rates) termites. Termite biomass significantly influenced respiration rates, with the largest species having the highest rates. Methane production occurred in seven of the thirteen species assayed. Of these apparently methanogenic species, only one of the eleven colonies of Incisitermes minor and one of the two colonies of Prorhinotermes simplex produced methane. The generally reduced respiration rates found at lower oxygen and higher carbon dioxide levels are considered more representative of the conditions encountered in termite galleries. Bioassays conducted under more natural atmospheric conditions may be more representative of termite responses in the field.