Zingiberenol, (1S,4R,1′S)-4-(1′,5′-Dimethylhex-4′-enyl)-1-methylcyclohex-2-en-1-ol, Identified as the Sex Pheromone Produced by Males of the Rice Stink Bug Oebalus poecilus (Heteroptera: Pentatomidae)

Abstract

Bioassays using an olfactometer showed that Oebalus poecilus males produce the sexual pheromone, and the chemical analysis demonstrated that this compound is zingiberenol. Two groups of isomers, each containing four diastereoisomers, (1RS,4RS,1′S)- and (1RS,4RS,1′R)-zingiberenol, were prepared. These diastereoisomers were not separated on a chiral GC column. Therefore, to determine the absolute configuration of the carbon 1, 4, and 1′ of zingiberenol produced by males, the following strategies were conducted. The extract containing males volatiles was submitted to dehydration microchemistry to produce zingiberene, in which the isomers are separated by chiral GC analysis, and by comparison with the natural zingiberene from ginger oil, the absolute stereochemistry of the carbons 4 and 1′ was determined to be R and S, respectively, and the carbon 1 was determined as R from the ¹³C NMR spectra of quercivorol. Finally, the bioassays showed that O. poecilus females responded to racemic mixture and to (1RS,4RS,1′S)-zingiberenol.