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Structure proof of (—)-myrtenol, 3-cyclopentenyl-1-methanol and 5-norbornene-2-endo-methanol has been obtained from their proton magnetic resonance spectra in carbon tetrachloride containing different added amounts of tris(dipivaloylmethanato)europium. For each alcohol, a 1:1 complex structure with Eu(dpm)3 could be computed, in which the calculated pseudocontact shift effects on all skeleton protons of the ring system were consistent with the observed shift effect values. A considerable contact contribution of opposite sign to that of the pseudocontact part of the effect could be estimated for the methylene protons of the CH2OH group.

Upon exposure to vapours of the host tree's monoterpene (-)-α-pinene, Ips acuminatus produces the terpene alcohol cis-verbenol which, besides ipsdienol and ipsenol, is a component of its aggregation pheromone. I. cembrae transforms the same monoterpene predominantly into myrtenol and trans-verbenol but little into cis-verbenol, which interrupts pheromone response under field conditions. On the other hand, I. cembrae releases, upon feeding in the bark, the terpene alcohol amitinol in major amounts. Amitinol significantly enhances field response to the aggregation pheromone that also includes ipsdienol, ipsenol, and 3-methyl-3-buten-1-ol. However, amitinol reduces pheromone response in I. acuminatus and I. erosus. Also, males of I. sexdentatus release amitinol which appears to increase response to its attractive principle pheromone component, racemic ipsdienol. There is some evidence that present knowledge of the chemical communication systems among European Ips spp. still lacks satisfactory explanation of the naturally occuring aggregation en masse, perhaps with the exception of I. erosus and I. typographus.

The volatile fraction of Otacanthus coeruleus Lindl. was investigated by GC-MS of the essential oil and of the headspace. About 50% of the oil consists of oxygen-containing substances. Out of more than 100 volatiles, 34 were identified by their Kovats indices and mass spectral data. The new copaene derivative β-copaen-4α-ol (II) was isolated. The plant and its oil have an agreeable, slightly floral, resinous smell. No character impact compound could be recognized. Major components of the oil were: trans-pinocarveol (13%), pinocarvone (12%), myrtenal (7%), myrtenol (ca 5%), α-copaene (ca 3%), α-humulene (ca 6%) and β-copaen-4α-ol (ca 7%).

The emission of species-specific odors byPristiphora erichsonii andP. wesmaeli is accompanied by a characteristic defensive behavior called "snap bending." When the larvae are disturbed, blends of volatile compounds are emitted from ventral glands. The odor ofP. erichsonii, a colonial species, is composed of bornyl acetate, borneol,trans-pinocarveol, myrtenol, benzaldehyde, and tetradecyl, hexadecyl, and octadecyl acetates, whereas that of the solitaryP. wesmaeli is composed of 3-carene-10-al, linalool, myrtenal, and benzaldehyde. The role of these compounds in the defensive behavior of the larvae is discussed.

Eight pheromones were collected as volatiles from living Dendroctonus beetles, and identified by GLC/MS. With Dendroctonus frontalis Zimmerman, in addition to earlier reported pheromones, the monoterpene ketone pinocarvone, and frontalin, were released by males, and the terpene alcohol myrtenol was released by both males and females. With D. ponderosae Hopkins, besides the previously known pheromones, endo -brevicomin and 3-methyl-2-cyc1ohexen-1-one (MCH) were released by males, and frontalin was collected from pairs of this species. Bioassay indicated that exo -brevicomin with D. ponderosae , and myrtenol as well as verbenone with D. frontalis , are multifunctional pheromones, since a small quantity (released by females) was synergistically attractive, and a larger quantity (released by males) was repressive and/or evoked “rivalry” behavior. For this latter effect, the male pheromones were designated antiaggregative-“rivalry” pheromones. With D. ponderosae , our data contradict the previous belief that this species releases no inhibitor and depends upon host-oleoresin effects to stop beetle aggregation. The identified male pheromones were released with males placed together, as well as with pairs, and the pheromones of fmale D. frontalis (though not of female D. ponderosae ) were also released with females placed together, as well as with pairs. Both intrasex and intersex stimuli and response must be important in pheromone release, and may help answer certain questions about bark beetle behavior of practical significance in attempts to utilize these pheromones in control.

Analysis of the volatile contents of hindguts from a Dendroctonus bark beetle in Guatemala indicated distinct differences from those of D. frontalis, which it resembles morphologically. The major compound in emergent males, most of which disappears during initial attack of host trees (Pinus maximinoi), was identified as 1-phenylethanol. During initial attack females produce frontalin and trans-verbenol, males produce myrtenol, and both sexes produce 1-heptanol and 2-heptanol. Synthetic frontalin attracted predominantly males to small traps, but the use of larger trapping surfaces increased the proportion of females caught. The heptanols, as well as 1-phenylethanol, apparently had some regulatory effect on the response to frontalin, but myrtenol and trans-verbenol were inactive. The results suggest that frontalin is the key compound responsible for the aggregation of this species, but the response-regulating mechanism differs from that of D. frontalis.

In field tests, mentha-1,8-dien-4-ol, a major oxidation product of d -limonene with selenium dioxide, greatly increased activity for the scolytid beetle, Taenoglyptes fulvus (Cryphalus fulvus auct. ). The attractant, however, does not seem to be contained in neutral host volatiles from fresh phloem of Pinus densiflora , and this suggests that it may be either a sort of pheromone of beetle origin or, if not, simply a mimic. Further detections of the oxidation products of pinenes, i.e. pinocarvone, trans-pinocarveol, and verbenone in the host volatiles, in addition to those of myrtenal and myrtenol are also described.

Oxygenated and hydrocarbon monoterpenes present in gallery walls in the phloem at different phases of an attack by Ips typographus and associated microorganisms on Norway spruce trees were quantified. The concentration of monoterpene hydrocarbons rose rapidly at the onset of beetle attack and reached a maximum in the phloem surrounding nuptial chambers that were recently prepared by males. Thereafter, amounts decreased rapidly and then increased again in late attack phases. During the attack, the variation in the amounts of monoterpene hydrocarbons in the gallery walls was partly reflected by some oxygenated monoterpenes, such as myrtenol, present in the same tissue. Borneol, verbenone, terpinene-4-ol, and α-terpineol were present in low quantities in the early phases of attack, but large amounts of these compounds were found in gallery walls during later phases. The bark beetle semiochemicals, cis- and trans-verbenol, had their concentration maxima in gallery walls of finished nuptial chambers. Results of the present study suggest that some bark beetle semiochemicals are produced extraneously to the beetle by microorganisms such as yeasts. A simple model for the production of oxygenated monoterpenes in early and late Ips typographus attack phases is presented.

Under field conditions, both bark beetles, Hylurgops palliatus Gyll. and Tomicus piniperda L. (Col., Scolytidae) preferred flight barrier traps baited with ethanol and oleoresin of their favoured host, Picea abies L., and Pinus sylvestris L., respectively, compared to traps baited with ethanol and various monoterpenes. However, replacing the host-specific oleoresin with β-pinene and the pine-characteristic terpinolene enhanced trap catches of both species. Response of H. palliatus increased with myrtenol, but decreased with (+)-trans-verbenol, while T. piniperda was attracted by both terpene alcohols. ZUSAMMENFASSUNG Die Signalwirkung wirtsspezifischer Terpenmuster auf die Borkenkafer Hylurgops palliatus und Tomicus piniperda Die Lockwirkung wirtsspezifischer Terpenmuster auf die sekundaren Rindenbruter Hylurgops palliatus und Tomicus piniperda wird im Freiland untersucht. Beide Arten fliegen bevorzugt Fallen an, die mit Ethanol und dem Rohharz ihrer Wirtsbaume, Picea abies bzw. Pinus sylvestris, bekodert sind. Der Ersatz der Rohharze durch eine Mischung aus β-Pinen und dem fur Kiefernharz charakteristischen Terpinolen erhoht die Fangzahlen beider Arten deutlich. Die Praferenzen fur Monoterpene deuten unterschiedlich enge Wirtsbindungen an: Bei breitem Wirtsspektrum bevorzugt H. palliatus wenig spezifische Terpene und hohe Ethanol-Konzentrationen, der zur Monophagie an Frischholz neigende Waldgartner T. piniperda jedoch geringe Ethanol-Konzentrationen und spezifische Terpenkombinationen. H. palliatus wird von dem Terpenalkohol (-)-Myrtenol deutlich angelockt, wahrend das von aggressiven Scolytiden bekannte Pheromon (+)-trans-Verbenol seinen Anflug im Gegensatz zu T. piniperda zu hemmen scheint.

Biogenetic oxidations of α-pinene along three different routes in Scheme 1 were conducted in vitro, and the activities of the oxidation products in attraction of the pine beetle, Cryphalus fulvus, were compared in field tests. Oxidation with selenium dioxide along route A in Scheme 1, resulting in production of myrtenal and myrtenol, revealed increased activity compared to that of the parent hydrocarbon. A greater increase of activity was observed when β-pinene was oxidized with the same reagent. Detection of myrtenal and myrtenol in host volatiles revealed their contribution to host attraction, but the presence or absence of pinocarvone and trans-pinocarveol in the host remained uncertain.

Dendroctonus terebrans often cohabits the same host tree with D. frontalis. D. terebrans produces and responds to some of the same pheromones produced by D. frontalis. D. terebrans was significantly more responsive at the antennal olfactory level to the D. frontalis pheromones frontalin, endo-brevicomin and trans-verbenol than to southern pine turpentine. In behavioral assays in the laboratory, frontalin was significantly more attractive to males and endo-brevicomin was significantly more attractive to females. Differential response between males and females was not found for trans-verbenol and turpentine. However, in field bioassays both males and females were unresponsive to the pheromones unless turpentine was released at high rates in combination with the pheromones. Turpentine had a distinct synergistic effect on the attractiveness of frontalin to males and endo-brevicomin to females. Chemical analysis of D. terebrans-released volatiles revealed that males produce endo-brevicomin, exo-brevicomin, trans-verbenol and myrtenol. Females produce and release frontalin, trans-verbenol and myrtenol. The compounds appear to have a significant role in the intra- and interspecific olfactory communication of the species. Zusammenfassung Zum Kairomon-Pheromon-System des Schwarzen Riesenbastkafers, Dendroctonus terebrans (Ol.) Der Schwarze Riesenbastkafer, Dendroctonus terebrans, besiedelt oft dieselben Wirtsbaume wie D. frontalis. Hierbei werden beide Arten von den gleichen Duftstoffen angelockt. Im Elektro-Antennogramm zeigt D. terebrans starkere Reaktionen auf die D. frontalis Pheromone endo-Brevicomin und trans-Verbenol als auf die Terpene des Wirtsbaumes. Im Labortest und in Freilandversuchen lockte Frontalin signifikant mehr Mannchen an, endo-Brevicomin mehr Weibchen. Beide Geschlechter reagierten jedoch im Freiland nur dann auf die bicyclischen Acetale, wenn sie zusammen mit hohen Konzentrationen von Terpentin ausgebracht wurden. Das Terpentin hatte einen deutlichen synergistischen Effekt auf die Lockwirkung der Pheromone. Die chemische Analyse wies nach, das die Mannchen exo-Brevicomin, und Spuren von endo-Brevicomin abgeben, die Weibchen Frontalin. Daneben produzieren beide Geschlechter trans-Verbenol und grosere Mengen Myrtenol.

The quantities of trans- verbenol , myrtenol, and the pheromone, cis- verbenol , in the hindguts of males and females were found to increase in linear proportion following exposure to increasing concentrations of vapour of the host plant precursor, (−)-α-pinene. Males produced significantly more of these compounds than females. Differences between males and females in the ratios of compound production were indicated. The concentrations of myrcene, α-pinene, and other monoterpenes volatilized in male nuptial chambers in ponderosa pine were quantified as well as the amounts in phloem. Males do not appear to ingest sufficient phloem to obtain enough of the host plant precursor, myrcene, to account for production of the pheromones, ipsenol and ipsdienol, but they may consume additional amounts of myrcene in oleoresin/xylem. Comparisons of ipsenol, ipsdienol and cis- verbenol production in males when feeding or exposed to precursor vapours at various concentrations indicate that under natural conditions myrcene used in pheromone biosynthesis primarily enters the beetle via the digestive tract.

Six compounds previously identified from hindguts of unmated maleIps typographus (L.) during host colonization: 2-methyl-3-buten-2-ol (MB),cis-verbenol (cV),trans-verbenol (tV), myrtenol (Mt),trans-myrtanol (tM), and 2-phenylethanol (PE), were tested for their attractivity in the field with a subtractive method. The amounts of MB and cV released from a pipe trap were similar to those given off from the commercial bait Ipslure as well as that from a Norway spruce tree,Picea abies (L.) Karst., under mass attack. The blend of the compounds became nonattractive when either MB or cV was subtracted, while subtraction of any of the other four compounds had no effect. Addition of ipsdienol (Id) to the blend did not significantly increase the attraction. In a second comparative test, the addition of three compounds as a group (tV + Mt + PE) to MB + cV again had no effect on the attraction, but the addition of Id increased the catch somewhat. Addition of host logs to a bait releasing MB + cV at a rate lower than in previous experiments did not influence the attraction to pipe traps. Sticky traps containing natural pheromone sources (50 males in a log), which released 1-5 mg/day of MB as determined by aerations with deuterated MB as internal standard, were less attractive than a synthetic source releasing similar amounts of MB.

Pheromones and metabolites of host (ponderosa pine) compounds were found in association with the hindgut of both naturally fed and of non-fed, host vapour-exposed bark beetles, Ips paraconfusus and Dendroctonus brevicomis . Much smaller amounts were found in the corresponding heads and mid guts. Sex-specific differences in content of pheromones were observed as in earlier studies. Exposure of I. paraconfusus to vapours of a pheromone component, ipsenol and other monoterpene alcohols resulted in their accumulation in the hindgut but relatively very low amounts in the head. The possible sites of pheromone biosynthesis are discussed. Exposure of male I. paraconfusus to vapours of host compounds, myrcene and α-pinene, revealed that immature adults do not produce the pheromone components, ipsenol and ipsdienol, as mature adults do while both immature and mature sexes produced another pheromone component, cis -verbenol, as well as trans -verbenol and myrtenol. Immature D. brevicomis adults did not contain pheromones until their exposure to vapours of (−)-α-pinene which caused production of trans -verbenol but only about 10% that of mature adults treated similarly. Verbenone, a male-produced inhibitory pheromone of D. brevicomis , apparently was not synthesized from (−)-α-pinene in females nor was its synthesis in males enhanced by exposure to this host compound.

Bark beetles exposed to vapours of terpene hydrocarbons produce alcohols and ketones, apparently by oxidation at allylic positions. The predictability of such oxidations has now been extended to include non-terpenoid hydrocarbons. Exposure of Dendroctonus frontalis to 1-methyl-1-cyclohexene resulted in the production of seudenol (3-methyl-2-cyclohexen-1-o1), a pheromone of D. pseudotsugae, along with the corresponding ketone and other alcohols. The most abundant of these was identified as 1-cyclohexenemethanol. A rearrangement product of seudenol, also believed to be present in D. pseudotsugae hindguts, was identified as 1-methyl-2-cyclohexen-1-o1. A similar rearrangement was detected upon exposure of D. frontalis females to α-pinene. In addition to cis- and trans- verbenol , cis-3- pinen -2-o1 was found in the hindguts. A general mechanism of oxidation and rearrangement is suggested, as further exemplified by the production of trans- pinocarveol and myrtenol by beetles exposed to β-pinene.

Ips typographus beetles were collected in the field, separated into eight attack phases (from beetles walking on the trunk of a tree under attack to those excavating gallery systems with a mother gallery longer than 4 cm), and immediately frozen in liquid nitrogen. 2-Methyl-3-buten-2-ol,cis- andtrans-verbenol, verbenone, myrtenol, trans-myrtanol, ipsenol, ipsdienol, and 2-phenylethanol were quantified from excised hindguts against an internal standard, heptyl acetate, in the extraction solvent. Methylbutenol, the pinene alcohols, and 2-phenylethanol showed the same pattern of variation between attack phases in males, with the largest amounts present before accepting females and then a fast decline. Ipsenol and ipsdienol were not detected in males before the females were accepted, and the amounts increased when the females start their egg laying. Verbenone occurred only in trace amounts. The beetles were sampled from five Norway spruce trees (Picea abies) of differing resin flow. The correlations between the nine pheromone components and five major host monoterpenes in the gut showed that the variation in the amount of methyl-butenol, ipsenol, and ipsdienol could not be explained by the variation in the amounts of host monoterpenes. In contrast over 80% of the quantitative variation ofcis-verbenol,trans-verbenol, and myrtenol was explained by the amount of α-pinene. The nine pheromone components from 36 individual males were also quantified. Both methylbutenol andcis-verbenol showed a large variation in both amounts and proportions. Females containedtrans-verbenol and traces of most other components found in males. When accepted by the male, they also contained a female-specific compound, β-isophorone. Behavioral and biosynthetic implications of the results are discussed.

The neutral fraction of the oleoresin from Pinus taiwanensis contained 89%. of monoterpene hydrocarbons (α-pinene, camphene, β-pinene, myrcene, limonene, β-phellandrene, p -cymene), 8.6% of sesquiterpene hydrocarbons (longicyclene, longifolene and caryophyllene) and 2.4% of oxygenated compounds (bornyl acetate, 4-terpineol, myrtenal, trans -pinocarveol, trans -verbenol, verbenone, myrtenol, caryophyllene oxide, 13-epimanoyl oxide, longiborneol and methyl dehydroabietate). Two diterpene hydrocarbons [pimara-8(14),15-diene, dehydroabietane], three norterpenoids [nopinone, longicamphenylone and 18-norpimara-8(14),15-dien-4-ol] and 13 n -alkanes (C 22 C 34 ) were also identified. The norterpenoids appear to be formed by autoxidation of hydrocarbons during the isolation process and the results of autoxidation of β-pinene and longifolene supported this view. The main constituent of the acidic part of the oleoresin was abietic acid (90%).

The reaction of 2- and 2(10)-pinene oxides, [1] and [2], in polar aprotic solvents or chloroacetic acids in the presence of synthetic zeolites was studied. In DMF, trans-carveol [8] was obtained as a principal component from [1] in 85% selectivity. In SF, myrtenol [6] was obtained from [2] in high selectivity (97%). Perillye alcohol [11] was obtained from [2] in 84% selectivity by the reaction with trichloroacetic acid in the presence of A-4zeolite.

The oxidation reaction of 2-pinene (1) and 2 (10) -pinene (2) in the presence on plasma irradiation of oxygen was investigated.(2 R) - (-) -cis-3-pinene-2-ol (4) and trans-verbenol (5) were obtained mainly from the oxidation reaction of (1). (-) -Myrtenol (1) and (-) -myrtenal (11) were the two main products from (2).

From myrtenol (6, 6-dimethyl-bicyclo [3, 1, 1] -2-heptane- 2-methanol) (7) as a starting material, 1-apocamphane-carboxylic acid (6) was synthesized. When the acetate (8) of (7) was chlorinated in ethylene dichloride with dried hydrogen chloride, 2-chloro-apocamphane-methylacetate (9) was obtained.(6) was obtained by the chromic acid anhydride oxidation of 1-apocamphane-methanol (11), which was obtained from dechlorination of the product of saponificaticn of (9) [i.e., 2-chloroapocamphane-methanol (10)] Ester of (6), which is derived from saturated lower alcohol, has a mild woodlike odor.

Pheromones of Dendroctonus brevicomis released variously during inter- and intra-sex response (including stridulation by both sexes) were the known pheromones exo-brevicomin, endo-brevicomin, frontalin and verbenone, and substances identified as pinocarvone, trans-pinocarveol, and myrtenol. These substances are present in emergent beetles and thus attack of a host tree is not essential for their initial production.

Three aspects of the relationship beween the coniferous host tree and bark beetles of the family Scolytidae are analyzed, and recent results are summarized. 1) Host-plant-terpenes serve in the host-recognition mechanism by attracting or repelling certain species and by synergizing or enhancing insect pheromones. 2) Proposed biosynthetic pathways for bark beetle pheromones produced from host-plant substances include 3-methyl-2-cyclohexen-l-one from the monoterpene terpinolene through piperitenone followed by cleavage of the isopropylidene side chain, and the analog alcohol 3-methyl-2-cyclohexen-l-ol from reduction of the ketone. Also, trans-verbenol, verbenone, and myrtenol are believed to result from oxidation of alpha-pinene, and similarly pinocarvone by oxidation of beta-pinene. However, the suggestion that certain kinds of pheromone production occur only on the freshly attacked host-tree is not supported by evidence that newly emerged beetles already release the same pheromones. 3) The host-plant also serves as the dense medium or substrate for sonic communication by those bark beetles that produce sound signals — an aspect that has received no study. In various Dendroctonus species it is established that the acoustic and chemical signals function as both stimulus and response in host-finding and colonization behavior.

Controlled infestation ofDendroctonus terebrans (Olivier) on bolts of slash pine,Pinus ellionii Engelm. var.elliottii, elicited greater attraction of wild conspecifics than uninfested bolts. Secondary attraction was not apparent, however, to standing slash pines that had received volunteer attacks, when compared with attraction to unattacked but susceptible trees. Hindguts from in-flight or attacking femaleD. terebrans contained frontalin, and those from in-flight or attacking males containedexo-brevicomin.Trans-pinocarveol,cis-verbenol,trans-verbenol, myrtenal, verbenone, myrtenol, and other compounds were produced by both sexes during gallery construction in host trees. Synthetic frontalin, when deployed with a standard host odor mixture of turpentine and ethanol, was very attractive to maleD. terebrans in field-trapping experiments. The addition of eitherexo-brevicomin orendo-brevicomin to the frontalin-turpentine combination negated the attractive effect of frontalin for males.Trans-verbenol, myrtenol, and verbenone had little effect onD. terebrans behavior. Responses of females did not differ among treatments in any of the 11 field experiments.

The most prominent beetle-produced volatiles identified in the abdominal extracts of maleDryocoetes confusus Swaine after they had bored for 24 hr in logs of subalpine fir,Abies lasiocarpa (Hook.) Nutt. were:exo andendo-brevicomin,trans-verbenol, verbenone, myrtenol,trans-pinocarveol,cis- andtrans-p-menthen-7-ol, 3-caren-10-ol, and several monoterpenes and sesquiterpenes. Myrtenol was the only conspicuous compound in extracts from males that had been exposed toA.lasiocarpa resin volatiles for 24 hr. Laboratory bioassays indicated that both (−)- and (+)-exo-brevicomin were attractive to femaleD. confusus, and that the (−) enantiomer did not inhibit response to its antipode. Results from field trapping experiments indicated that bothero-brevicomin and myrtenol are aggregation pheromones forD. confusus.exo-Brevicomin baits were effective in causing attack byD. confusus on baited and surrounding trees, suggesting that this pheromone may have utility in manipulating populations of the beetle.

Scope: GABAA receptors are modulated by Sideritis extracts. The aim of this study was to identify single substances from Sideritis extracts responsible for GABAA receptor modulation. Methodsandresults: SinglevolatilesubstancesidentifiedbyGChavebeentestedintwoexpression systems, Xenopus oocytes and human embryonic kidney cells. Some of these substances, especially carvacrol, were highly potent on GABAA receptors composed of 1 2a nd122 subunits.Alleffectsmeasuredwereindependentfromthepresenceofthe2subunit.AsSideritisextracts contain a high amount of terpenes, 13 terpenes with similar structure elements were testedinthesameway.Followingaprescreeningon12GABAA receptors,ahigh-throughput method was used for identification of the most effective terpenoid substances on GABA-affinity of 122 receptors expressed in transfected cell lines. Isopulegol, pinocarveol, verbenol, and myrtenol were the most potent modifiers of GABAA receptor function. Conclusion: Comparing the chemical structures, the action of terpenes on GABAA receptors is most probably due to the presence of hydroxyl groups and a bicyclic character of the substances tested. We propose an allosteric modulation independent from the 2 subunit and similar to the action of alcohols and anesthetics.

The structure of a new, optically pure 2-hydroxytetrahydrofuran tricyclic compound resulting from the hydroformylation of (1R )-(−)-myrtenol was resolved by one- and two-dimensional 1H and 13C NMR. The configurations of the three new asymmetric centres are discussed on the basis of J(H,H) coupling constants, NOE measurements and molecular modelling. Copyright © 1999 John Wiley & Sons, Ltd.

The steam-volatile leaf oil of Zieria aspalathoides A. Cunn, ex Benth. contains (-)-car-3-en-2-one as its major component. Minor amounts of α-phellandrene, car-3-ene, terpinolene, limonene, 1,8-cineole, myrtenol, β-trans-ocimene, α-thujone and caryophyllene were tentatively identified by g.1.c. co-chromatography.