Assessment of synthetic chemicals for disruption of Rhynchophorus ferrugineus attraction in an urban environment

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. Aim of this work was to discover repellent semiochemicals for RPW population management in urban environments. For this purpose we conducted electroantennographic (EAG) screenings of 17 commercially available synthetic compounds, representing three groups of plant volatiles (isoprenoids, phenyl propanoid derivatives and fatty acid derivatives) known for their repellent effects toward insects. EAG bioassays results showed positive dose-dependent responses to 13 of the 17 synthetic chemicals on RPW antennae of both sexes. These tests were followed by trap-based screenings of EAG-active menthone, α- pinene methyl salicylate, 1-octen-3-ol and citronellol, singly and in combination, under urban conditions. These trapping experiments were conducted in the city of Palermo, Italy during 2010, 2011 and 2012 to test the behavioural effect on the RPW adults. Experiments were carried out by placing the tested chemicals inside the pheromone baited traps and assessing a possible reduction in the adult captures. In particular were tested: in 2010 α-pinene and methyl salicylate, in 2011 α-pinene and menthone, in 2012 α-pinene, 1-octen-3-ol and citronellol. The results of trap tests showed that some of the compound tested significantly reduce the number of RPW captures in the traps.