The Influence of Temperature on the Semitivity of Two Nitidulid Beetles to Low Oxygen Concentrations
J.E. Donahaye, S. Navarro and M.Rindner*
*Department of Stored Products, Agricultural Research Organization. P.O. Box 6, Bel Dagan. 50250 Israel.
Abstract: In laboratory experiments, Iarval, pupal, and adult stages of the nitidulid beetles Carpophilus hemipterus (L.) and Urophorus humeralis (F.) were exposed to simdated burner-gas concentrations at three temperatures of 26° 30°, and 35°C. The gas concentrations were l% O₂, 85% N₂, 14% CO₂; 2% O₂, 84.7% N₂, 13.3% CO₂; 3% O₂, 85% N₂, 12% CO₂ -- all at 75% relative humidity. For all insects submitted to the modified atmosphere (MA) containing 3% O₂ at 26°C, exposure time to produce 95% mortality was 196 hours. To obtain the same mortality level with the MA containing 1% O₂ at 35°C 60 hours was required. Comparison of exposure times required to produce 50% kill (LT₅₀) showed that the effect of temperam on treatment efficiecy was most pronounced at the 1% O₂ level where for the three stages of both species tested, values of LT₅₀ at 26°C were about half those at 35°C. However, at 3% O₂ and 35°C LT₅₀ levels were only marginally reduced.
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