Grigori Khaskin

(Z,Z)-4,7-Tridecadien-(S)-2-yl Acetate: Sex Pheromone of Douglas-Fir Cone Gall Midge, Contarinia oregonensis

Our objectives were to identify and field test the sex pheromone of female Douglas-fir cone gall midge, Contarinia oregonensis (Diptera: Cecidomyiidae). Coupled gas chromatographic–electroantennographic detection (GC-EAD) analyses of pheromone extract revealed a single compound (A) that elicited responses from male antennae. Hydrogenation of pheromone extract, followed by renewed GC-EAD analysis, revealed a new EAD-active compound with chromatographic characteristics identical to those of tridecan-2-yl acetate on five fused silica columns (DB-5, DB-210, DB-23, SP-1000, and Cyclodex-B). Syntheses, chromatography, and retention index calculations of all possible tridecen-2-yl acetates suggested that the candidate pheromone A was a tridecadien-2-yl acetate with nonconjugated double bonds. Synthetic candidate pheromone component (Z,Z)-4,7-tridecadien-2-yl acetate (Z4Z7) cochromatographed with A on all analytical columns and elicited comparable antennal activity. In GC-EAD analyses that separated the enantiomers (Z,Z)-4,7-tridecadien-(S)-2-yl acetate (2S-Z4Z7) and (Z,Z)-4,7-tridecadien-(R)-2-yl acetate (2R-Z4Z7) with baseline resolution, only 2S-Z4Z7 as a component in a racemic standard or in pheromone extract elicited antennal responses. In Douglas-fir seed orchards, sticky traps baited with 2S-Z4Z7 captured male C. oregonensis, whereas 2R-Z4Z7 was behaviorally benign. Comparable catches of males in traps baited with racemic Z4Z7 (50 μg) or virgin female C. oregonensis suggested that synthetic pheromone baits could be developed for monitoring C. oregonensis populations in commercial Douglas-fir seed orchards.

Specificity of nun and gypsy moth sexual communication through multiple-component pheromone blends.

The nun moth [NM; Lymantria monacha (L.)] in Europe and the gypsy moth [GM; L. dispar (L.)] in Europe and North America are most important defoliators of coniferous and decidious forests, respectively [1, 2]. For sexual communication GM and NM females produce the pheromone disparlure [3-6] ; NM and GM males respond to the (+)-disparlure enantiomer [(7R, 8S)-cis-7,8-epoxy-2-methyloctadecane] as a single attractive but unspecific pheromone component [7-11] . Reanalysis of female NM sex pheromone extract by gas chromatographic-electroantennographic detection (GC-EAD [121; Fig. 1), and field tests of candidate pheromone components revealed a multiple-component NM sex pheromone. In the Czech Republic a ternary blend of (+)-disparlure, (7R, 8S)-cis-7,8-epoxy-octadecane [termed here (+)-monachalure] and 2-methyl-Z7-octadecene at a 10 :10 :1 ratio synergistically attracted NM males and was ten times more attractive than previously known (+)-disparlure (Fig. 2). Three epoxide [(-)-disparlure, (+)and (-)-monachalure] and two hydrocarbon volatile components [2-methyl-Z7-octadecene and Z7-octadecene] synergistically prevented crosS-attraction of coseasonal GM males and imparted specificity to NM sexual communication (Fig. 3). Identification of cis-7,8-epoxy-3-methylnonadecane as a second pheromone component in female GM, attracting GM but not NM males, provided the first evidence for species-specific pheromone components also in GM. Future use of multiple-component synthetic pheromone lures will allow highly sensitive and species-specific monitoring of NM and GM populations.

Sex pheromone of orange wheat blossom midge, Sitodiplosis mosellana.

Abstract Pheromone extract of the female orange wheat blossom midge, Sitodiplosis mosellana (Géhin) (SM) (Diptera: Cecidomyiidae), was analyzed by coupled gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometry (MS), employing fused silica columns coated with DB-5, DB-210, DB-23 or SP-1000. These analyses revealed a single, EAD-active candidate pheromone which was identified as 2,7-nonanediyl dibutyrate. In experiments in wheat fields in Saskatchewan, traps baited with (2S,7S)-2,7-nonanediyl dibutyrate attracted significant numbers of male SM. The presence of other stereoisomers did not adversely affect trap captures. Facile synthesis of stereoisomeric 2,7-nonanediyl dibutyrate will facilitate the development of pheromone-based monitoring or even control of SM populations.

Moth Scale-Derived Kairomones Used by Egg–Larval Parasitoid Ascogaster quadridentata to Locate Eggs of Its Host, Cydia pomonella

We determined that location of host (Cydia pomonella) eggs by Ascogaster quadridentata is mediated by kairomones, investigated potential sources of the kairomones and identified a blend of kairomones from the source that was attractive to A. quadridentata. In Y-tube olfactometer bioassays, female A. quadridentata were attracted to Porapak Q-collected volatiles from female C. pomonella scales and eggs, but not to C. pomonella sex pheromone. Scales of C. pomonella were also attractive to male A. quadridentata. Coupled gas chromatographic–electroantennographic detection analysis of scale volatile extracts revealed numerous compounds that elicited responses from male or female A. quadridentata antennae, including heptanal, octanal, nonanal, decanal, undecan-2-one, dodecanal, pentadecan-2-one, (Z)-6-pentadecen-2-one, (Z)-9-hexadecenal, (Z)-6-heptadecen-2-one, and 3,7,11-trimethyl-2E,6E,10-dodecatrien-1-ol acetate. A synthetic blend of these compounds at quantities and ratios equivalent to Porapak Q scale volatile extract was attractive to female A. quadridentata in a Y-tube olfactometer bioassay.

Sex pheromone components of male Tirathaba mundella (Lepidoptera: Pyralidae)

Summary. During peak calling activity by male oil palm bunch moths, Tirathaba mundella Walker (Lepidoptera: Pyralidae), their hairpencils, wings or entire body were extracted in hexane. Gas chromatographic-electroantennographic detection (GC-EAD) analyses of hair pencil extracts revealed four compounds that consistently elicited responses from female antennae. The NMR spectrum of isolated compound 1, and mass spectra and retention indices of compounds 1–4 suggested that they were (3S,6S)-2,2,6-trimethyl-6-vinyl-tetrahydro-pyran-3-ol (1), 4-hydroxy-3-methoxy-benzaldehyde (2, vanillin), 6,10,14-trimethyl-2-pentadecanone (3), and 6,10,14-trimethyl-2-pentadecanol (4). Comparative GC and GC-MS analyses of hair pencils extract and synthetic standards confirmed these structural assignments. Moreover, comparative chromatography of synthetic and hairpencil-isolated 1 on a Cyclodex-B column (which separated the four stereoisomers with baseline resolution) revealed that male T. mundella produce the SS-stereoisomer (SS-1). In field cage bioassay experiments in Palembang, Indonesia, synthetic SS-1 and vanillin in combination, but not singly, attracted female T. mundella. SS-1 plus vanillin were as effective as male T. mundella in attracting females. Compounds 3 and 4 did not enhance the blends attractiveness.

(2R, 7S)-diacetoxytridecane: Sex pheromone of the aphidophagous gall midge, Aphidoletes aphidimyza

In a recent study, evidence was presented that females of the aphidophagous midge Aphidoletes aphidimyza (Rondi) (Diptera: Cecidomyiidae) release a sex pheromone to attract mates. Our objectives were to identify and bioassay the pheromone. Coupled gas chromatographic–electroantenno- graphicDetection (GC-EAD) analyses of untreated and hydrogenated pheromone extract on three fused-silica columns (DB-5, DB-23, DB-210) revealed a single compound that elicited responses from male antennae. Retention index calculations of this candidate pheromone (CP) suggested that it was a di-acetate. Considering that most of the presently identified cecidomyiid pheromones consist of a 13-carbon chain with (at least) one acetate group in C2, we synthesized 2,6-, 2,7-, 2,8-, 2,9-, 2,10-, 2,11-, and 2,12-diacetoxytridecane. In GC analyses of these compounds, only 2,7-diacetoxytridecane cochomatographed with CP on all columns. In laboratory two-choice experiments with stereospecifically synthesized stereoisomers, only (2R,7S)-diacetoxytridecane elicited significant anemotatic responses by male A.aphidimyza. In trapping experiments in greenhouse compartments, only traps baited with (2R,7S)-diacetoxytridecane captured significant numbers of male A. aphidimyza, clearly revealing the absolute configuration of the pheromone. Failure of the stereoisomeric mixture (containing all four stereoisomers including the pheromone) to attract males is due to inhibitory characteristics of the (2R,7R)- and (2S,7R)-stereoisomers. The pheromone of zoophagous A. aphidimyza resembles those from phytophagous cecidomyiid midges, suggesting a common, diet-independent pathway for pheromone biosyntheses.

Enantiomers of (Z,Z)-6,9-Heneicosadien-11-OL: Sex Pheromone Components of Orgyia detrita

Abstract(6Z,9Z,11S)-6,9-Heneicosadien-11-ol (Z6Z9-11S-ol-C21) and (6Z,9Z,11R)-6,9-heneicosadien-11-ol (Z6Z9-11R-ol-C21) were identified as major sex pheromone components of female tussock moths, Orgyia detritaGuérin-Méneville (Lepidoptera: Lymantriidae), on the basis of (1) analyses of pheromone gland extracts of female O. detrita by coupled gas chromatographic-electroantennographic detection (GC-EAD) and GC mass spectrometry, and (2) field trapping experiments with synthetic standards. Z6Z9-11S-ol-C21 and Z6Z9-11R-ol-C21 in combination, but not singly, attracted significant numbers of male moths. Racemic Z6Z9-11-ol-C21 was more attractive than the 1:3.5 (R:S) blend ratio found in pheromone gland extracts from female moths. Lower and higher homologues of Z6Z9-11-ol-C21 were also detected in GC-EAD recordings of pheromone extracts, and the racemic compounds enhanced attractiveness of Z6Z9-11-ol-C21 in field experiments. Because of trace amounts of these homologues in extracts, their enantiomeric composition could not be determined. This is the first report of secondary alcohols as pheromone components in the ditrysian (advanced) Lepidoptera.

(Z)6, (E)8-Heneicosadien-11-One: Synergistic Sex Pheromone Component of Douglas-Fir Tussock Moth, Orgyia pseudotsugata (McDunnough) (Lepidoptera: Lymantriidae)

Three candidate sex pheromone components, (Z)6,(Z)9-, (Z)6,(E)8-, and (Z)6,(E)9-heneicosadien-11-one (Z6Z9, Z6E8, and Z6E9) were identified in pheromone gland extracts of female Douglas-fir tussock moths (DFTM), Orgyia pseudotsugata (McDunnough). Their occurrence in subnanogram quantities in extracts and structural conversion during analytical procedures and bioassays complicated chemical identifications. Complete identification required comparative analyses of stereoselectively synthesized and female-produced dienones by coupled gas chromatographic–electroantennographic detection (GC-EAD), high-performance liquid chromatography (HPLC) and coupled GC–mass spectrometry (MS). Determination of the pheromone component was contingent upon an experimental design that minimized structural rearrangement of dienones before and during the field test. In a 40-min field experiment, acetonitrile solutions of each of the above dienones were carried on Dry Ice to traps and were syringed onto cotton release devices below trap lids. In combination with the previously known sex pheromone component of DFTM, (Z)6-heneicosen-11-one (Z6), Z6E8 was the only synergistic dienone and the mixture was highly attractive. Because Z6 by itself attracts seven species of tussock moths (two sympatric with DFTM), a blend of Z6 and Z6E8 may impart specificity to DFTM pheromone communication. In commercial lures, this binary blend may facilitate species-specific, sensitive monitoring and efficacious control by mating disruption of this important forest defoliator.

3,13-dimethylheptadecane: major sex pheromone component of the western false hemlock looper, Nepytia freemani Munroe (Lepidoptera: Geometridae)

Abstract3,13-Dimethylheptadecane (3,13-dime-17Hy) is the major sex pheromone component of the western false hemlock looper (WFHL),Nepytia freemani Munroe. It was identified in extracts of female pheromone glands by coupled gas chromatographic-electroantennographic detection (GC-EAD) and coupled GC-mass spectroscopy (GC-MS). Traps baited with 100μg of 3,13-dime-17Hy attracted large numbers of male WFHL. Of five additional candidate pheromone dimethylated hydrocarbons, only 3,13-dimethylhexadecane attracted male WFHL. However, neither 3,13-dime-16Hy nor the other four compounds enhanced attraction to 3,13-dime-17Hy when tested in binary or ternary combination at respective ratios of 100∶10, 100∶1, or 100∶1∶1. Identification of the complete WFHL sex pheromone requires structural elucidation of all 12 EAD-active components in gland extracts, determination of their chirality, and field testing of antennally active isomers in appropriate combinations and ratios. Stereoisomeric 3,13-dime-17Hy as trap bait may already be used to monitor WFHL populations.

( S , S )-2,12-, ( S , S )-2,13-, and ( S , S )-2,14-Diacetoxyheptadecanes: Sex Pheromone Components of Red Cedar Cone Midge, Mayetiola thujae

We identified, synthesized, and field-tested the sex pheromone of female red cedar cone midge Mayetiola thujae (Hedlin) (Diptera: Cecidomyiidae), a pest insect in red cedar Thuja plicata seed orchards. Coupled gas chromatographic (GC)–electroantennographic detection analyses of pheromone extract revealed three components (A, B, C) that elicited responses from antennae of males, all of which occurred below the detection threshold of the mass spectrometer and thus had to be identified without spectroscopic data. Taking into account (1) their retention indices (RI) on three GC columns (DB-5, DB-23, and DB-210), (2) intercolumn RI differentials, and (3) the molecular structures of known cecidomyiid pheromones, we synthesized seven candidate pheromone components: 2,10-, 2,11-, 2,12-, 2,13-, 2,14-, 2,15- and 2,16-diacetoxyheptadecanes. Of these, 2,12-, 2,13-, and 2,14-diacetoxyheptadecane had RIs on all columns consistent with those of A, B, and C and elicited strong antennal responses when tested at picogram levels. In field experiments with the twelve stereoselectively synthesized stereoisomers, only the SS-stereoisomers of 2,12-, 2,13-, and 2,14-diacetoxyheptadecane attracted male M. thujae. The three-component SS-stereoisomer blend was more attractive than the 12-component blend of all stereoisomers, suggesting that one or several nonnatural stereoisomers are inhibitory. One-, two-, and three-component lures of the SS-stereoisomers were equally effective in attracting male M. thujae, indicating redundancy in the pheromone. Identification of the M. thujae sex pheromone will allow development of pheromone-based monitoring, and possibly control, of M. thujae populations in T. plicata seed orchards.