Repellent and Oviposition-Deterring Activity of Rosemary and Sweet Marjoram on the Spider Mites Tetranychus urticae and Eutetranychus orientalis (Acari: Tetranychidae)

The deterrent and toxic effect of two essential oils, Majorana hortensis. Moench and Rosma- rinus officinalis L. on the two tetranychid mites Tetranychus urticae Koch and Eutetranychus orientalis (Klein) were studied under laboratory conditions. Both materials used were more potent for E. orientalis than against T. urticae with a significant increase in repellency. Leaf discs treated with increasing concentrations of the two oils showed increased mortality of both spider mites and reduction in the total numbers of eggs laid. This result could be due to the oil of the higher oxygenated compounds content that was more effective in this respect