The indiscriminate use of synthetic pesticides has given rise to many serious problems, including toxicity to nontarget organisms, development of pest resistance and resurgence and environmental contamination. So during past three decades, the scientists have looked for less persistent and biodegradable alternatives. Essential oils from aromatic plants are recognized as proper alternatives. In this experiment, toxicity of Zingiber officinale (Roscoe) essential oil that was isolated via hydrodistillation was investigated against adults of the red flour beetle, Tribolium castaneum (Herbst) and larvae of the Mediterranean flour moth, Ephestia kuehniella (Zell.) and Indianmeal moth, Plodia interpunctella (Hübner). Repellency of this oil on all the three pest species adults was also studied. In determination of fumigant toxicity, the LC50 value for T. castaneum was calculated 374.95 μL/L air after 48 hr of exposure. As well, LC50 for E. kuehniella and P. interpunctella after 9 hr were calculated 258.95 and 69.05 μL/L air, respectively. In contact toxicity assay, LC50 value for E. kuehniella and P. interpunctella were determined as 0.61 and 0.81 μL/cm2, respectively. Relationship between exposure time and oil concentration on mortality of all species indicated that mortality was increased by increasing of the oil concentration and exposure time. Repellency of this oil on all the insect species was significant.

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