Dendroctonus pseudotsugae hopkins (Coleoptera: Scolytidae): Production of and response to enantiomers of 1-methylcyclohex-2-en-1-ol.

Female Douglas-fir beetles,Dendroctonus pseudotsugae, produced an average 45∶55 mixture of the (S)-(-)- and (R)-(+)-enantiomers of 1-methylcyclohex-2-en-1-ol (MCOL). The (S)-(-)∶(R)-(+) ratio of 3-methylcyclohex-2-en-1-ol (seudenol) produced by this population of females was 34∶66. Lindgren funnel traps baited with (R)-(+)-MCOL attracted significantly more males and females than (S)-(-)-MCOL-baited traps, which captured significantly more beetles than unbaited controls. The combined effect of the enantiomers was additive, rather than synergistic. Either enantiomer of MCOL increased catches by frontalin-baited traps. Racemic MCOL can be used for trapping Douglas-fir beetles in south-central British Columbia.