DARVEAU, C.-A.*; SUAREZ, R. K.; HOCHACHKA, P. W.: Evolution of energy metabolism: The case of hovering insects

Hovering insects possess the highest mass-specific metabolic rate ever measured and are therefore an excellent model to study the evolution of metabolic pathways involved in energy production. We conducted a survey of the maximal activity of several enzymes as indicators of glycolytic capacity (Hexokinase, Phosphofructokinase), redox balance (Glycerol 3-phosphate dehydrogenase), and mitochondrial metabolism (Citrate synthase, Cytochrome c oxidase) in 19 species (4 genera) of Euglossine bees of varying size (varying from 50 mg to 1 g). A strong negative allometric relationship was observed for the activity of Hexokinase. The slope was similar to that of the oxygen consumption rate previously published for 9 species of Euglossine bees, which highlights the importance (maybe high control coefficient) of Hexokinase in these insects. Citrate synthase activity was also related to body mass, however, other factors (e.g. phylogeny) influenced the relationship. We analyzed data using phylogeneticaly independent contrasts and discuss the metabolic and evolutionary implications of these results.