Anatomical site of pheromone accumulation and temporal pattern of pheromone emission in the ambrosia beetle Megaplatypus mutatus

Abstract

Megaplatypus mutatus (Chapuis) is a native South American ambrosia beetle that attacks live hardwood trees (e.g. Populus spp.), causing important economic losses to commercial plantations. Male beetles release the main components of the sex pheromone, namely (+)-6-methyl-5-hepten-2-ol [(+)-sulcatol, or retusol] and 6-methyl-5-hepten-2-one (sulcatone), when colonizing suitable hosts. The hindgut is shown to be the anatomical site of pheromone accumulation within males, the enantiomeric composition of sulcatol in this tissue is 99%-(+) and sulcatol is first detectable in this tissue on days 1-2 after gallery initiation. Peak accumulation of sulcatol occurs on days 5-12 after gallery initiation. Trace quantities of sulcatone are also observed during the same period. Both pheromone components are present in male emissions from three host species (Populus×canadensis, Populus alba and Casuarina stricta) between days 2 and 12 after gallery initiation, although sulcatone is always present in low concentrations. The temporal patterns of sulcatol and sulcatone accumulation or storage in male M. mutatus correspond to the temporal patterns of emission.