Respiration of Rhyzopertha dominica (F.) at reduced oxygen concentrations

Abstract

Developmental stages of Rhyzopertha dominica were exposed to atmospheres containing 1%, 2%, 3%, 5%, 10% or 15% oxygen (O 2) in nitrogen at 30°C and 70% r.h. Respiration rates were determined with a gas chromatograph. The O 2 intake and carbon dioxide (CO 2) output by insects were expressed in μl/insect h or μl/mg h. Respiration of eggs, young and old larvae, pupae, and adults at normal atmospheric air were at rates of 0.0029, 0.41, 2.52, 0.82, and 2.86 μl CO 2/insect h, respectively. Respiration rates of the same stages in terms of insect weight were 0.14, 4.83, 1.98, 0.64 and, 2.58 μl CO 2/mg h, respectively. At reduced O 2 levels respiration rates of eggs, larvae and pupae were proportional to the O 2 levels. Adult respiration rates were high at 3% and 5% O 2 levels almost reaching that of normal atmospheric air, and were 2.56 and 2.85 μl CO 2/insect h, respectively. In adults, respiration quotient values for the same O 2 levels were higher than at normal atmospheric O 2 and were 1.5 and 1.02, respectively. Respiration of adults in normal air between 20°C and 35°C increased with temperature and gas values varied between 0.89 and 6.82 μl CO 2/insect h, respectively, or 0.93 and 5.63 μl O 2/insect h, respectively.