Repellent activity of essential oils from two species of Citrus against Tetranychus urticae in the laboratory and greenhouse

• We evaluated the repellent effect of Citrus oils on cotton string against adult Tetranychus urticae.
• Both major and minor constituents of orange oils were responsible for the repellent effect.
• Prolonged repellent action of lima oil (>24 h) was confirmed in the greenhouse test.
• Lima oil prevented the movement of mites for up to one week in greenhouse tests.

Essential oils from fruit skins of laranja pera (Citrus sinensis Osbeck var. pera) and laranja lima (Citrus aurantium L.) obtained through water distillation were analyzed by GC-FID and GC-MS and their repellence to the twospotted spider mite, Tetranychus urticae Koch, on string was evaluated in laboratory bioassays and greenhouse experiments. Twenty-seven compounds were identified, representing 98.1% and 98.9% of the total constituents of the C. aurantium and C. sinensis var. pera oils, respectively. d-Limonene was the main constituent found in both Citrus species. Both of the natural oils and an artificial mixture of mono- and sesquiterpenes intended to mimic one of the oils showed repellent effects comparable to eugenol (a positive control) for up to 3 h in laboratory bioassays. Both major and minor constituents of the two oils were responsible for the repellent effect. Although both oils showed similar repellent effects, lima oil prevented the movement of mites between plants across oil-treated strings for one week. Lima oil has potential for development as a commercial repellent against spider mites and could prevent their spread in commercial greenhouses.

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