Utilization of a Clark electrode device as a respirometer for small insects: a convincing test on ants allowing to detect discontinuous respiration

Respirometry provides a direct measure of an organism’s respiration, which is a significant component of its metabolic rate. Amongst ants, variations in lifespan between different social castes (such as workers and queens) can be substantial, varying according to the species. As metabolic rate is higher in short-living species, we aimed to establish how metabolic rate and longevity may have coevolved within ant’s casts. As a first methodological step, we validate here the use of a Clark electrode initially design for measuring mitochondrial respiration control pathways, for flow-through oxygen consumption in ant, by comparison with stop flow oxygen consumption and carbon dioxide production utilizing the indirect calorimetry methodology. The global aim is to provide a reliable methodology to conduct accurate comparisons of metabolic rates within and among ant species. As expected, using Clarck electrode entails high time resolution and revealed that queens and workers exhibited discontinuous respiration, with episodes of apnea up to 20 minutes.