Control of Tetranychus urticae Koch by extracts of three essential oils of chamomile,marjoram and Eucalyptus

Objective:To evaluate the acaricidal activity of extracts of three essential oils of chamomile,marjoram and Eucalyptwi against Tetranychus urtiaie(T.urticae.)Koch.Methods:Extracts of three essential oils of chamomile,marjoram and Eucalyptus with different concentrations(0.5%,1.0%,2.0%,3.0%and 4.0%)were used to control T.urticae Koch.Results:The results showed that chamomile(Chamomilla recutita)represented the most potent efficient acaricidal agent against Tetranychus followed by marjoram(Marjorana hortensis)and Eucalyptus.The LC50values of chamomile,marjoram and Eucalyptus for adults were 0.65,1.84 and 2.18,respectively and for eggs 1.17,6.26 and 7.33,respectively.Activities of enzymes including glutathione-Stxansferase,esterase(α-esterase andβ-esterase)and alkaline phosphatase in susceptible mites were determined and activities of enzymes involved in the resistance of acaricides were proved.Protease enzyme was significantly decreased at LC50of both chamomile and marjoram compared with positive control.Gas chromatography-mass spectrometer(CC-MS)proved that the major compositions of Chamomilla recutita areα-bisabolol oxide A(35.251%),and trans-3-farersene(7.758%),while the main components of Marjorana hortensis are terpincne-4-ol(23.860%),p-cymene(23.404%)and sabinene(10.904%).Conclusions:It can be concluded that extracts of three essential oils of chamomile,marjoram and Eucalyptus possess acaricidal activity against T.urticae.