Respiration of Rhyzopertha dominica (F.) at reduced oxygen concentrations
M. Emekcia, S. Navarrob,*, E. Donahayeb, M. Rindnerb, A. Azrielib
aDepartment of Plant Protection, Faculty of Agriculture, University of Ankara, Turkey
bDepartment of Stored Products, The Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
Accepted 15 May2002
Abstract: Developmental stages of Rhyzopertha dominica were exposed to atmospheres containing 1%, 2%, 3%, 5%, 10% or 15% oxygen (O2) in nitrogen at 30°C and 70% r.h. Respiration rates were determined with a gas chromatograph. The O2 intake and carbon dioxide (CO2) output byinsects 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 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 µl CO2/mg h, respectively. At reduced O2 levels respiration rates of eggs, larvae and pupae were proportional to the O2 levels. Adult respiration rates were high at 3% and 5% O2 levels almost reaching that of normal atmospheric air, and were 2.56 and 2.85 µl CO2/insect h, respectively. In adults, respiration quotient values for the same O2 levels were higher than at normal atmospheric O2 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 CO2/insect h, respectively, or 0.93 and 5.63 µl O2/insect h, respectively.
© 2002 Elsevier Science Ltd. All rights reserved.
Key words: Rhyzopertha dominica; Respiration; Reduced oxygen; Developmental stages
