Field response and gas-liquid chromatograph separation of optically active synthetic and natural pheromones in two sympatric diprionid sawflies,Neodiprion nanulus nanulus andNeodiprion sertifer (Hymenoptera: Diprionidae).

The male red pine sawflyNeodiprion nanulus nanulus Schedl responds mainly to the (2S,3S,7S)-3,7-dimethylpentadecan-2-yl acetate (2S,3S,7S-A) in the field. No other isomer is as effective by itself or syner-gizes 2S,3S, 7S-A in this species. ForNeodiprion sertifer (Geoffroy), however, we confirmed our earlier report that males responded significantly to a 5∶0.003 mixture of 2S,3S,7S-A and either 2S,3R,7R-A or 2S,3R,7R/S-A. The 2S,3S,7S-A isomer was separated from 2S,3R,7R-A by capillary gas-liquid chromatographic (GLC) analysis using Carbowax 20 M and DB-5 columns. The latter column also separated 2S,3S,7S-A from 2S,3R,7S-A. Only 2S,3S,7S-A was found in the natural pheromones ofN. n. nanulus andN. sertifer by GLC analysis.