The female sex pheromone of Rhizoglyphus setosus Manson (Astigmata: Acaridae) was identified as S-isorobinal (4S-4-isopropenyl-3-oxo-1-cyclohexene-1-carboxyaldehyde), which stimulated males sexually and enhanced the frequency of the male's tapping and mounting behavior. Although the female hexane extract indicated no sign of sex pheromone activity against tested males, possibly due to the presence of the alarm pheromone neryl formate, an SiO2 column fraction containing isorobinal elicited sex pheromone activity at a dose of one female equivalent. The stereochemistry of natural isorobinal was identified as S by an HPLC using a chiral column. Both S- and R-isorobinals exhibited maximum activity at the same dose of 1 and 10 ng with a convex dose-response relationship. Amounts of S-isorobinal were determined to be 11.7 +/- 1.0 ng per female and 6.4 +/- 1.3 ng per male by GLC. This is the second example of two pheromones (the alarm pheromone neryl formate, and the sex pheromone S-isorobinal) demonstrated to be components of the same opisthonotal gland secretion.

The female sex pheromone of Rhizoglyphus robini Claparède (Astigmata: Acaridae) was identified as alpha-acaridial [2(E)-(4-methyl-3-pentenyl)-butenedial], which stimulated males sexually and enhanced the frequency of male mounting behavior. Although a hexane extract of females manifested alarm pheromone activity against tested males due to the presence of the alarm pheromone neryl formate, silica gel column fractions containing alpha-acaridial evoked increased mounting behavior by males at a dose of 0.1 female equivalent. Synthetic alpha-acaridial at a dose of 10 ng showed a peak of activity as a sex pheromone, with a convex dose-response relationship. Its content was determined to be 388 +/- 244 ng per female and 163 +/- 97 ng per male by GC. This is the first time that two pheromones (the alarm pheromone neryl formate, and the sex pheromone alpha-acaridial) have been demonstrated to be components of the same opisthonotal gland secretion in astigmatid mites. A mechanism for the appropriate expression of the two pheromones by the mites under different conditions is proposed.

A total of 88 compounds, classified into 27 compounds with monoterpenoid carbon skeletons, two sesquiterpenes, eight aromatics, and 24 aliphatic compounds (a ketone, aldehydes, fatty acid esters and alkyl formates) together with 27 aliphatic hydrocarbons have been demonstrated as components of the opisthonotal gland secretions from 61 species of mites belonging to ten families of Astigmata in Acari.1) Parts of the compounds are known to function either as an alarm pheromone, an aggregation pheromone or a sex pheromone in each corresponding species. Among 27 monoterpenoids, ten compounds were first isolated and identified from Astigmata, with the structures unequivocally confirmed by synthesis. 1)Isorobinal [4-isopropenyl-3-oxo-1-cyclohexene-1-carbaldehyde, 1], one of such novel cyclic monoterpenes, has been identified from the secretion of the astigmatid mite Rhizoglyphus sp. "oki"2) [its ITS-II (internal transcriptive spacer-II) region consists of 460 bps (code name RH 6, GenBank Accession Number: AB104931)].3) (S)-Isomer of 1 has been demonstrated as the female sex pheromone of the related mite, Rhizoglyphus setosus (Acari: Acaridae), 4) using both enantiomers of 1 prepared by a group from Tohoku University 5) and also by us. Herein we report the syntheses of both enantiomers to determine the stereochemistry and the natural distribution of 1 among Astigmata. Methods and Materials Analytical methodsGC/MS was carried out using a Hewlett Packard HP-5989B gas chromatograph/mass spectrometer operated at 70 eV in the split-less mode, with an HP-5 MS capillary column (0.25 mm in diameter ϫ30 m in length, 0.25 mm in film thickness). Helium was used as the carrier gas at 1.23 ml/min, at temperatures programmed from 60°C to 290°C at 10°C/min, with an initial 2-min hold at 60°C and then at 290°C for 5 min.1 Hand 13 C-NMR spectra were obtained with a Bruker AC300 instrument ( 1 H at 300 MHz, 13 C at 75 MHz) in CDCl 3 solution with TMS as an internal standard. UV spectra were measured with a Beckman DU-64 spectrophotometer. Optical rotation values were measured with a Jasco DIP-370 spectropolarimeter.J. Pestic. Sci., 31(3), 311-315 (2006) Synthesis of (؉)-(S)-isorobinal together with its antipod