Biological activities of some essential oils towards Philaenus spumarius adults
Abstract: Philaenus spumarius (L.) is a highly polyphagous species recently found to be the main vector of Xylella fastidiosa Wells et al. involved in the “Olive Quick Decline Syndrome” in the Salento Peninsula. Essential oils (EOs) of aromatic plants were traditionally used against economically important pests due to their capability to interfere with many physiological and behavioral functions in insects. In the present study, the chemical composition of Lavandula officinalis Chaix, Citrus aurantium L. var. bergamia, Pelargonium graveolens L’Herit, Cymbopogon nardus Rendle, Helichrysum italicum (Roth) G. Don, and Thymus vulgaris L. EOs and the antennal sensitivity of both sexes of P. spumarius to the same EOs were investigated by gaschromatography-mass spectrometry (GC-MS) and electroantennography (EAG) respectively. Moreover, Y-tube olfactometer bioassays were carried out to evaluate the behavioural responses of adult spittlebugs to L. officinalis and C. aurantium EOs. Chemical analyses revealed high contents of monoterpenes in the six EOs which elicited dose-dependent EAG responses in male and female antennae. At certain concentrations, P. spumarius males were attracted by L. officinalis EO and repelled by the C. aurantium one whereas females were attracted by low concentrations of C. aurantium EO and repelled by high concentrations of the same EO. These results provide useful information in the perspective of EOs practical applications in control strategies towards P. spumarius.