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Physiological Differences Between Strains of Tribolium Castaneum Selected for Resistance to Hypoxia and Hypercarbia, and the Unselected Strain


Department of Stored Products, Agricultural Research Organization, Bet Dagan, Israel

Abstract: The metabolic rates, as expressed by oxygen (O₂) consumption, carbon dioxide (CO₂) production, and losses in wet and dry weights, were examined for adults of three strains of the red flour beetle Tribolium castaneum (Herbst), during exposure to two modified atmospheres (MAS). Exposure of a strain selected for resistance over twenty-one generations to an atmosphere of 65% CO₂, 20% O₂ and the balance nitrogen (N₂),te rmed a high carbon dioxide concentration atmosphere (HCC) and exposure of an unselected strain to HCC, showed considerable levels of aerobic metabolism during exposure. For the unselected strain water loss and mobilization of energy reserves were rapid and mortality was followed by rapid desiccation. For the HCC-resistant strain water balance was maintained and energy reserves were utilized more slowly over a prolonged period. Exposure of a strain selected for resistance over twenty-one generations to a low oxygen concentration atmosphere (LOC) of 0.5% O₂ in N₂, and an unselected strain to LOC, revealed that even at 0.5% O₂, metabolism was largely aerobic in both strains. Maintenance of water balance was not a major factor causing mortality of either strain during exposure to LOG. In air, metabolic rates of both the resistant strains were lower than that of the unselected strain.

Key Words: Tribolium, flour beetle, resistance, hypoxia, hypercarbia.

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