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The Combined Influence of Temperature and Modified Atmospheres on Tribolium Castaneum (Herbst) (Coleoptera: Tenebrionidae)


Department of Stored Products, Agricultural Research Organization, The Volcani Center, P.O.B. 6, Bet Dagan, Israel

Abstract: In laboratory experiments, egg, larval, pupal, and adult stages of the red flour beetle Tribolium castaneum (Herbst) were exposed to three low oxygen concentrations realistically obtainable under hermetic storage oonditions, at three temperatures of 26, 30, and 35°C. The gas concentrations were: 1% O₂, 85% N₂, 14% CO₂; 2% O₂, 84.7% N₂, 13.3% CO₂; 3% O₂, 85% N₂, 12% CO₂ (all at 75% relative humidity). When exposed to the 3% 0₂ level at 26°C, adults were most tolerant with a mortality of 70.5% when exposed for 10 d. To obtain 99% mortality at 3S°C with the atmosphere containing 1% 0₂ a maximum of only 44 h was required for the most tolerant stage, namely the polpa. Comparison of exposure times required to produce 50% kill (LT₅₀) showed that the effect of temperature on mortality rates was pronounced at all three levels of 0₂; for all the insect stages, values of LT₅₀ at 35°C ranged between 0.16 and 0.5 times those at 26°C. The insects were also submitted to a gas mixture containing 1% 0₂ in 99% N₂ representing a mixture obtainable by N₂ flushing techniques. At the higher temperatures, differences in mortality from those obtained on exposure to 1% 0₂; 85% N₂ 14% CO₂ were not significant. However, at 26°C, mortality levels of insects exposed to this mixture were lower, particularly for adults and eggs.

Copyright © 1996 Published by Elsevier Science Ltd.

Key words: Tribolium castaneum, hypoxia, temperature, hermetic storage, modified atmospheres

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