Repellency of lavender oil and linalool against spot clothing wax cicada, Lycorma delicatula (Hemiptera: Fulgoridae) and their electrophysiological responses

This study was performed to investigate the repellent effect of 5 mu l doses of ten essential oils (bergamot, chamomile, clary sage, fennel, lavender, lemongrass, majoram, peanut, pennyroyal, and peppermint) against Lycorma delicatula 4th nymphs using an olfactometer. Only lavender oil exhibited significant repellency. We then tested 10, 5, 2.5, and 1 mu l doses of lavender oil against the nymphs and females of L delicatula. The oil showed significant repellency at 10 and 5 mu l, although the latter is less potent to 1st instar nymphs. At the lavender oil dose of 2.5 mu l, only 3rd and 4th instar nymphs and females were significantly affected. None of the stages tested were affected by 1 mu l. Chromatographic and mass spectrometric analyses of lavender oil detected linalool (42.2%), linalyl acetate (49.4%), terpinen-4-ol (5.0%), and caryophyllene oxide (3.4%). Among the four main components, only linalool showed repellency to all instar nymphs and females. No synergism was detected. Antennae of all instar nymphs and females showed electrophysiological responses only to linalool. In field studies using linalool, 4th nymphs and adults were highly repelled at a dose of 30 mu l of lavender oil. The effect differed according to test plot and treatment dose. (C) Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society, 2011. Published by Elsevier B.V. All rights reserved.