Chemical ecology of Monochamus galloprovincialis (Coleoptera: Cerambycidae),vector of pinewood nematode in Europe

Abstract: Pine wood nematode, Bursaphelenchus xylophilus, is an invasive pest causing afatal wilting disease in susceptible pine trees. Native to America, it was introduced from theFar East to Portugal in 1999. The nematode is vectored by cerambycid beetles of the genusMonochamus, and the only confirmed vector in Europe is Monochamus galloprovincialis,although related species are also potential vectors. As part of an EU project to restrict spreadof the nematode in Europe, aspects of the chemical ecology of the vector and potential vectorswere investigated to provide potential management tools for the nematode and the disease.The aggregation pheromone produced by male M. galloprovincialis was identified and itsattractiveness to both sexes was shown to be strongly synergised by host-plant volatiles andbark beetle kairomones. Traps baited with the attractant are being developed for measuringdispersal of the beetle and mass trapping around outbreaks of the nematode. The lures attractonly mature beetles and work is in progress in field and laboratory to develop an attractant forthe immature beetles. Cuticular compounds are involved in species and sex recognition inM. galloprovincialis, although key, non-hydrocarbon compounds produced by the males areresponsible for this rather than hydrocarbons in the female, as reported for other cerambycidbeetles. M. galloprovincialis beetles tend to colonise stressed pines, including those damagedby fire. Electrophysiological studies and field trapping tests indicate the beetles can detectvolatile compounds found in wood smoke and these may provide a new approach to attractionof the beetles. The chemical ecology of Monochamus spp. presents several intriguingquestions, not least how is species-specificity ensured with such parsimony of pheromonecomponents? How is the main pheromone component biosynthesised? Are we just scratchingthe surface of the interactions of beetle, host plants and other fauna? What does this mean forinvasive species?