Fumigant toxicity of three plant essential oils against adults ofEphestia kuehniella Zeller (Lep.: Pyralidae)

Abstract: Recently, there has been a growing interest in research concerning the possible use ofplant extracts as alternatives to synthetic insecticides. Essential oils are among the best-knownsubstances tested against insects. These compounds may act as fumigants, contact insecticides,repellents and antifeedants. The objective of the present study was to test the possible propertiesof medicinal plants, Ferula gummosa Boiss (Apiaceae), Rosmarinus officinalis L. (Lamiaceae)and Mentha piperita (Lamiaceae) essential oil vapors against Ephestia kuehniella to elucidatetheir fumigant toxicity. The experiments were conducted at 27±1°C, 60 ± 5% R.H. and in darkcondition. The essential oils were obtained from resin of F. gummosa and dried leaves ofR. officinalis and M. piperita, and subjected to hydrodistillation using a modified Clevenger-typeapparatus. The mortality of adults was tested at different concentrations and different exposuretimes (1-24h). The results showed that the mortality increased with increases in concentrationand exposure time. After 12h, high increases in mortality were seen. Data probit analysisdemonstrated that lethal concentration to kill 50% of the population (LC50) for F. gummosa,R. officinalis and M. piperita was estimated as 44.26, 2.15 and 0.97μl/l air, respectively. Betweenthese essential oils, M. piperita was almost more toxic than R. officinalis and F. gummosa. Thepresent study suggests that essential oils from these medicinal plants may be potential grainprotectants as botanical alternative fumigants.