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Control of Ephestia Cautella with Low Levels of Methyl Bromide and Carbon Dioxide Gas Mixtures

G.Sabio, S.Navarro*, J.E.Donahaye, M.Rindner, A.Azrieli and R.Dias

²Dept. of Stored Products, Agricultural Research Organization, The Volcani Center, Bet Dagan 50-250, Israel [*e-mail:vtshlo@netvision.net.il]

Abstract: The potential application of low levels of methyl bromide (MB) in combination with CO₂ gas mixtures as a rapid disinfestation technique was evaluated under laboratory conditions at 30°C and 70% relative humidity (r.h.), using the tropical warehouse moth, Ephestia cautella as test insect. CO₂ concentrations of 0, 10 and 20% in air were examined when mixed with different MB concentrations. Eggs, larvae, pupae and adults were exposed to the various gas mixtures for periods ranging from 4 to 32 hours. The influence of CO₂ on reducing the MB concentration required for control was assessed by calculating products of concentration x time (CtP) as expressed in mg.h L⁻¹. CtPࠩࠩ values of MB in normal air for E. cautella eggs, larvae, pupae and adults were 25.4, 30.1, 50.2 and 16.6 mg.h L⁻¹, respectively. These values were markedly reduced as the CO₂ concentration was increased to 10 and to 20%. In the presence of 20% CO₂ the effective MB dose was reduced to 18.7, 20.3, 29.7 and 4.3 mg.h L⁻¹ in eggs, larvae, pupae and adults, respectively. The resistance of the developmental stages of E. cautella to MB was (in decreasing order): pupae, larvae, eggs and adults. In the presence of 20% CO₂ the CtPࠩࠩ of MB was decreased by 1.4 times in eggs, the least sensitive stage and by 3.8 times in adults, the most sensitive stage responding to the gas mixture. This work was carried out as part of a Ph.D. study of the first author, at the Hebrew University of Jerusalem, Israel.

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