Assessment of synthetic chemicals for disruption of Rhynchophorus ferrugineus attraction

The red palm weevil (RPW), Rhynchophorus ferrugineus, Olivier (Coleoptera: Curculionidae), is currently one of the most severe pests of Canary palms in urban areas of Mediterranean countries and Date palms in cultivated areas of the Middle East. RPW aggregation pheromone can be implemented for both monitoring and mass trapping, however risks of RPW "spillover" onto palms is of great concern. Aiming to discover repellent semiochemicals for safer RPW population management, we conducted electroantennographic (EAG) screenings of 17 commercially available synthetic compounds. These compounds represent three groups of plant volatiles (isoprenoids, phenyl propanoid derivatives and fatty acid derivatives) and known for their repellent effects toward insects. These tests were followed by behavioral tests in olfactometer and field trap-based screenings of EAG-active compounds. In particular, menthone, α-pinene and methyl salicylate, singly and in combination, were selected for field studies under urban conditions using pheromone baited traps. RPW antennae of both sexes showed positive dosedependent responses to 13 of the 17 synthetic chemicals in EAG bioassays. In field trapping experiments, conducted in the city of Palermo, Italy from weeks 31 to 38 in 2010 and 2011, α-pinene, tested singly or in combination with methyl salicylate (2010) or menthone (2011), found to significantly interfered with the attraction of both sexes of RPW to its aggregation pheromone reducing catches in pheromone and kairomone baited trap by about 30 to 40%. When tested alone methyl salicylate and menthone alone did not affect the number of adults captured compared to the control. These results indicate α-pinene as promising RPW repellent that could be included in semiochemical-based strategies of this pest, such as the "push and pull" techniques.