Abstract
The pine sawfly pheromone precursor 3,7-dimethyl-2-pentadecanol (diprionol) was quantified by gas chromatography in different body parts of virgin female Neodiprion sertifer. About one-third of the total amount (approx. 10 ng per female) was found in each of head + thorax, abdominal segments 1-3, and the remaining abdomen. Diprionol was also found in the respective parts of pupae, but in lower amounts. This suggests that at least the final steps of the pheromone biosynthesis take place in many parts of the body, possibly in the cuticle. The diprionol content remained relatively constant over the whole lifetime of virgin females. By using coupled gas chromatography-electroantennogram detection three active compounds in the acetylated female extract were observed. These corresponded to the pheromone, (2S,3S,7S)-diprionyl acetate, and its homologues with the chain shortened by one and two carbons respectively, as determined by gas chromatography-mass spectrometry. In addition, the homologue having a chain elongated by one carbon was found. The homologues occurred in amounts of 2-5% of the diprionyl acetate. When synthetic homologues were tested in the field, alone or in combination with diprionyl acetate, they were not behaviourally active to male sawflies, despite their electroantennogram activity. A threo-isomer of diprionol, most likely (2S,3R,7R), was present in the females in amounts less than 0.5% of the (2S,3S,7S)-content. The acetate of this threo-isomer is known as both synergist and inhibitor to the (2S,3S,7S)-isomer. trans-Perillenal was found in the abdominal segments 1-3 of both males and females and its possible biosynthetic relationship to diprionol is discussed.
