Electrophysiological and behavioural responses of the Grapevine Moth to odours of Perilla frutescens

The Grapevine Moth Lobesia botrana is a major pest of grapes worldwide and its control still largely relies on insecticide applications. There is accordingly great interest in identifying attractant or repellent semiochemicals interfering efficiently with both male and female olfaction, in order to develop alternative control strategies. Host plant volatiles playing a relevant role in the plant selection process of this insect have been extensively studied but their effectiveness for control purposes is strongly negatively affected by the overlapping background odour in the vineyard. Finding of behaviourally active compounds emitted by non-host plants would represent an attractive target for the L. botrana control. Therefore, we studied the biological activity on L. botrana olfactory system of secondary metabolites isolated from the Asian food plant Perilla frutescens (L.). Interestingly, Perilla compounds were shown to activate a novel family of receptor, the Transient Receptor Potential (TRP) channels, expressed also in the antennae of lepidopterous species. The olfactory response of L. botrana females to Perilla extracts was preliminary tested adopting electroantennographic experiments (EAG). Antennal-active compounds were identified by a gas chromatograph equipped with a mass spectrometer (GC-MS). Moreover, gas-chromatography coupled with electroantennography (GC-EAD) allowed to detect several active compounds eliciting significant electrophysiological responses on female antennae. In a dual choice oviposition test based on olfactory cues, females showed a dose-dependent preference for the odours released by Perilla even in presence of the odour bouquet of the host plants. Future molecular, physiological and behavioural studies will focus on the activity of the single and blended Perilla compounds and on the role of TRP receptors in their perception with the aim to improve the current strategies for the management of pest populations.