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Calorimetric evaluation of responses of Sitophilus oryzae and Tribolium confusum to elevated temperatures and controlled atmospheres
- Downes, C.J., Van Epenhuijsen, C.W., Lill, R.E., Downes, J.E., Carpenter, A., Brash, D.
- Journal of stored products research 2008 v.44 no.3 pp. 295-303
- food storage, storage conditions, storage temperature, controlled atmosphere storage, Sitophilus oryzae, Tribolium confusum, storage insects, species differences, insect physiology, calorimetry, analytical methods, thermogravimetry, developmental stages, anaerobic conditions, mortality
- Metabolic heat rates, determined by microcalorimetry, were used to measure the effect of controlled atmospheres (CAs) and elevated temperatures on the stored-product insects Sitophilus oryzae (rice weevil) and Tribolium confusum (confused flour beetle). Results for larval and adult stages in air, and in a range of low O2 and/or high CO2 CAs, at temperatures from 15 to 45 °C, showed the general effectiveness of such atmospheres in lowering the lethal temperatures relative to those in air. Effects on adult S. oryzae at 25 °C were explored in more detail in experiments using the following conditions: exposure to anoxic CAs for extended times; exposure to hypoxic CAs; and simulated hermetic storage. A simple scanning calorimetric method was developed for determining lethal temperatures and a combined thermo-gravimetric and differential thermal-analysis method was used to interpret the thermal events, due to loss of water, occurring at and above these temperatures.