Non-host plant essential oil volatiles with potential for a "push-pull' strategy to control the tea green leafhopper, Empoasca vitis

The tea green leafhopper, Empoasca vitis Gothe (Hemiptera: Cicadellidae), is an economically important pest of tea crops, Camellia sinensis (L.) O. Kuntze (Theaceae), in China. The use of non-host plant essential oils for manipulation of E.vitis was investigated for potential incorporation into a push-pull' control strategy for this pest. The effectiveness of 14 plant essential oils in repelling E.vitis was investigated in laboratory assays. Rosemary oil, geranium oil, lavender oil, cinnamon oil, and basil oil repelled leafhoppers in a Y-shaped olfactometer. We also compared the efficacy of these five plant essential oils to repel E.vitis in the presence of a host plant volatile-based leafhopper attractant, (Z)-3-hexenyl acetate, in a tea plantation. In the treatment combination, four plates (north, south, east, and west) treated with an essential oil surrounded a central sticky plate treated with (Z)-3-hexenyl acetate. Fewer E.vitis were found on the plates treated with rosemary oil (12.5% reduction) than on the four water-sprayed control treatment plates surrounding a central plate with (Z)-3-hexenyl acetate. We compared the distribution of E.vitis on the plates, and the relative numbers of E.vitis on each plate were compared with similar plates in the control treatment. When four plates treated with rosemary oil surrounded a central (Z)-3-hexenyl acetate-treated plate, the distribution of E.vitis on the different plates changed significantly compared with that of the control. Relatively fewer E.vitis were found on the east (13.0% reduction) rosemary oil-treated plates and more E.vitis (11.3% increase) were found on the central attractant-treated plate. Our findings indicate that rosemary oil is a promising leafhopper repellent that should be tested further in a push-pull' strategy for control of E.vitis.