Respiration of Tribolium castaneum (Herbst) at reduced oxygen concentrations

Abstract Adults, eggs, young and old larvae and pupae of Tribolium castaneum (Herbst) were exposed to atmospheres containing 1%, 2%, 3%, 5%, 10%, and 15% oxygen in nitrogen at 30°C and 70% r.h. Respiration rates were determined with a gas chromatograph. The oxygen intake and carbon dioxide output by insects were expressed in μl/insect/h or μl/mg/h. Adults exposed to 21% oxygen required an initial acclimatization period of at least 5 h, after which the respiration rate remained stable. Based on this finding, all the respiration measurements were carried out after an initial adaptation of insects to the respirometer conditions for 24 h. Respiration of eggs, young and old larvae, pupae, and adults at 30°C in normal atmospheric air was at rates of 0.0121, 9.25, 8.45, 1.45, and 4.67 μl CO 2 /insect/h, respectively. Respiration rates of the same stages in terms of insect weight were 0.32, 29.08, 3.33, 0.59 and 2.37 μl CO 2 /mg insect/h, respectively. At reduced oxygen levels respiration rates of eggs, larvae and pupae were proportional to the oxygen levels. Adult respiration was higher for 3% and 5% oxygen than for normal atmospheric air with rates of 4.77 and 4.98 μl CO 2 /insect/h, respectively. In adults, RQ values for the same oxygen levels were also higher than for normal atmospheric oxygen and were 1.07 and 1.18, respectively.