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

Developmental stages of Rhyzopertha dominica were exposed to atmospheres containing 1%, 2%, 3%, 5%, 10% or 15% oxygen (O-2) in nitrogen at 30degreesC and 70% r.h. Respiration rates were determined with a gas chromatograph. The O-2 intake and carbon dioxide (CO2) output by insects were expressed in mul/insect h or mul/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 mul CO2/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 mul CO2/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% 02 levels almost reaching that of normal atmospheric air, and were 2.56 and 2.85 mul CO2/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 20degreesC and 35degreesC increased with temperature and gas values varied between 0.89 and 6.82 mul CO2/insect h, respectively, or 0.93 and 5.63 mul O-2/insect h, respectively. (C) 2002 Elsevier Science Ltd. All rights reserved.