Lippia gracilis against Tetranychus urticae and a natural enemy, Neoseiulus californicus, under greenhouse conditions]]>

摘要

The essential oil from the leaves of Lippia gracilis was investigated for fumigant and residual activity against Tetranychus urticae (Acari: Tetranychidae) and Neoseiulus californicus (Acari: Phytoseiidae). The results were compared to eugenol, Ortus_(?)and Azamax_(?), as positive controls. Gas chromatography (GC) and GC/mass spectrometry analysis enabled the identification of 28 compounds, accounting for 99.1?±?0.6% of the essential oil. The major constituents were carvacrol (61%), p -cymene (11%) and thymol (11%). Mites were more susceptible to the oil in fumigant tests than in residual tests. Among the components, thymol and β -caryophyllene had the greatest fumigant and residual toxicity against T. urticae , respectively. The role of selected constituents (carvacrol, p -cymene, thymol, limonene, β -pinene, 1,8-cineole, terpinolene and β -caryophyllene) in the acaricidal properties of the L. gracilis essential oil is also discussed. Fumigant and residual effects of Lippia oil were more selective than eugenol with regard to a natural enemy of T. urticae , Neoseiulus californicus . Experiments under greenhouse conditions demonstrated greater toxicity of the Lippia oil in comparison to the positive control at 24, 48 and 72?h after treatment. The results suggest that Lippia oil is a good candidate for the formulation of a botanical acaricide for the integrated management of T. urticae .