Respiration of Tribolium castaneum (Herbst) at reduced oxygen concentrations

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 30degreesC and 70% r.h. Respiration rates were determined with a gas chromatograph. The oxygen intake and carbon dioxide output by insects were expressed in mul/insect/h or mul/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 24h. Respiration of eggs, young and old larvae, pupae, and adults at 30degreesC in normal atmospheric air was at rates of 0.0121, 9.25, 8.45, 1.45, and 4.67 mul CO2/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 mul CO2/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 mul CO2/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. (C) 2002 Elsevier Science Ltd. All rights reserved.