Repellent, antifeedent and toxic effects of three essential oils on the two spotted spider mite, Tetranychus urticae koch (Acari: Tetranychidae)

The direct toxicity of three essential oils to females of the two spotted spider mite, Tetranychus urticae Koch, was tested in the laboratory. Wheat germ oil (Triticum vulgare Vill) was the most toxic essential oil to females of T. urticae, while clove oil (Eugenia caryophyllata Thumberg) was the least toxic one (LC50=0.995 and 2.82%, LC90=3.08 and 16.66%), respectively. Leaf discs treated with increasing concentrations of eucalyptus (Eucalyptus glabulus Labill.) and wheat germ oils showed a high percentage of repellency (90–100%), respectively. The oviposition deterrent indices (ODI) of eucalyptus and wheat germ oils were ranged (22–100) for T. urticae at concentration (1–4%), while this value was between (5–35%) in case of clove oil at the same above concentrations. Females of T. urticae suffered a significantly depression in reproduction when fed on painted kidney bean leaves with (1–4%) concentrations of each oil used in our studies. In contrast, at 0.25 and 0.5% concentrations, no significant differences was recorded between the total number of eggs deposited on treated leaves and control ones. Also, a high percentage of T. urticae mortality was recorded for wheat germ and clove oils during 10 days