Study on the role of olfaction in host plant detection of Scaphoideus titanus (Hemiptera: Cicadellidae) nymphs.

The American grapevine leafhopper, Scaphoideus titanus Ball (Hemiptera: Cicadellidae), is the vector of the phytoplasma that causes Flavescence dorée, one of the most threatening grapevine yellows disease. The role of olfaction in host plant detection of this species is still unknown. In this study, the attractiveness of a host plant, the grapevine rootstock Vitis riparia x rupestris 101/14, to nymphs was verified through behavioral bioassays in a vertical glass Y-olfactometer. Furthermore, the olfactory sensitivity to odors extracted from grapevine organs headspace and the external morphology of the antennae were studied by electroantennography (EAG) and scanning electron microscopy (SEM), respectively. Headspace collections were made from fresh apical shoots and leaves. Concentrated extracts were analyzed by coupled gas chromatography and mass spectrometry (GC-MS) to identify volatile compounds. In EAG experiments, weak responses to plant odors were recorded. SEM observations indicated the presence of few antennal sensilla, potentially associated with olfaction. Our results suggest that olfactory cues may play a role in the host plant detection of S. titanus nymphs.

Control of Cydia pomonella L. and Cydia molesta (Busck) (Lepidoptera Tortricidae) in pome-fruit orchards with Ecodian sex pheromone dispensers.

A mating disruption approach using high densities of pheromone dispensers, has been recently proposed for codling moth, Cydia pomonella (L.), and oriental fruit moth, Cydia molesta (Busck.), (Lepidoptera Tortricidae), control. Ecodian Star dispensers, made of low-cost biodegradable material and easy to apply, were formulated with 10 mg of codlemone (E8,E10-12OH) and 10 mg of grapamone (Z8-12OH) and placed at a rate of 1,400-2,000 dispensers/ha. The pheromone release rates from new and field aged dispensers were evaluated by hexane extraction of the residual attractant (indirectly) and gas-chromatographic analysis. The release rate of field-aged dispensers decreased over time with a good linearity; they released a significant amount of synthetic sex pheromones over the entire season. Dispensers elicited close-range approaches of codling moth males in wind tunnel irrespective of their age. Field trials carried out from 2003 to 2004 confirmed the efficacy of Ecodian Star dispensers for codling moth and oriental fruit moth control, regardless the size of the treated area. Our results demonstrate that Ecodian dispensers achieved a good level of activity and longevity over the season. The potential of this strategy for the control of the moths is discussed.