Frontalin in the male mountain pine beetle

Frontalin andexo-brevicomin were identified by GC-MS in air drawn over maleDendroclonus ponderosae Hopk. (MPB) from Oregon that had joined females for 1-2 days in the bark of lodgepole and ponderosa pine logs. Unfed males releasedexo- andendo-brevicomin but not frontalin. These three compounds were not detected in either unfed or fed females. Arrestment of males bytrans-verbenol and terpenes in an olfactory walkway was reduced by the addition of racemic frontalin; production of attractant chirps also diminished. Racemic frontalin also strongly reduced the aggregation of MPB in lodgepole and ponderosa pine stands to sticky traps baited with the aggregation pheromonetrans-verbenol and host terpenes; however, the function of the natural enantiomer of frontalin in MPB is unknown.