Application of Eucalyptus globulus Labill essential oil against confused flour beetle Tribolium confusum Jacquelin du Val

In the current study, the influence of time factors was investigated on application of Eucalyptus globulus Labill., essential oil against the adults of confused flour beetle Tribolium confusum Jacquelin du Val. The containers were treated with 205, 328, 460, 615 and 902 µl/L air of the essential oil and the adults were exposed 1, 2, 4, 8, 16 and 24 hours after treatment, for evaluating the effectiveness period of the essential oil. LC50 values were estimated in other experiments based on 1, 2, 4, 8 and 16 hours exposure times. Finally, the cumulative mortalities of the essential oil were recorded at 3, 6, 9, 12 and 24 hours after treatment. According to the obtained results, a delay more than 16 hours reduced the efficacy of the essential oil to the lowest level (0% mortality) in first assays. LC50 values of the second bioassays were 1384, 201.2, 131, 130.2 and 109 µl/L air, respectively. These values suggested that keeping closed the treating area as long as four hours was sufficient to access effective results. Gradual increasing of mortality was observed in cumulative assays and mortalities at concentrations of 90, 170, 340, 510, 680 and 850 µl/L air after 24 hours were calculated to be 41.6, 91.6, 100, 100, 100 and 100%, respectively. The last results demonstrated that the most proportion of mortality occured within the first three hours after treatment. Therefore, by considering the quick mortalities caused by the essential oil and rapid decreasing of its efficacy, the essential oil application time must be accurately selected to acquire its maximum efficiency.