Fumigation toxicity of four plant essential oils on adults of Tribolium castaneum (Herbst) and T. confosum (Du val)

The effects of four plant essential oils of Mentha longifolia, Thymus deanensis, Achillea wilhelmsii and Artemisia hausskenechtii were investigated on adult stage of Tribolium castaneum and T. confusum. The essential oils were prepared using water distillation method. Essential oils were used in five concentrations and five replications. The concentration selected based on primary experiment for each essential oil. Mortality rate of insects were recorded after 3, 6, 24, 48 and 72 hours. Results showed that the longer exposure of insect to essential oil and the higher concentration of essential oil, increased mortality of the two beetle species in all treatments. There was significant difference among mortality effect of the essential oils. The LC50 value of M.longifolia after 24 hours for T. castaneum and T. confosum were 11.59 and 10.67 μl/lair respectively, while the values of LC50 were 89.21 and 99.79 for T. daenensis, 55.40 and 98.71 for A. wilhelmsii and 60.64 and 62.25 μl/lair for A. hausskenechtii, respectively. The least LT50 recorded was in A. hausskenechtii essential oil with 23.10 and 21.10 hours against T. castaneum and T. confusun, respectively. Results showed that these essential oils can be as safe botanical pesticides for control of storage pests.