Structure-activity relationship observations oftrans-trimedlure enantiomers

tert-Butyl 4- (and 5-) chloro-trans-2-methylcyclohexane-1-carboxylate (TML), a mixture of four majortrans and four minorcis isomers, is used as an attractant for detecting and monitoring the male Mediterranean fruit fly (medfly),Ceratitis capitata (Wiedemann). The eight isomers (racemic mixtures) were isolated by HPLC, and their relative attractiveness in the field was determined. A quantitative structure-activity relationship (QSAR) was proposed that related a molecular measurement (ų) of the TML structure to male medfly captures. More recently, thetrans-TML enantiomers were synthesized in sufficient quantities for field testing. This paper reports the computer-aided molecular modeling, via Chem-X, of thetrans-TML enantiomers and the staggered and superimposed fitting with the most attractive isomer, (1S,2S,4R)-TML-C, to determine common volumes and surface areas from Van der Waals (VdW) maps. Observations of structure-activity relationships (SAR) are reported for the staggered fittings.     

Trans-ceralure isomers: Differences in attraction for mediterranean fruit fly,Ceratitis capitata (Wied.) (diptera: Tephritidae)

Differences in attractiveness of four individualtrans isomers of ceralure (CRL) [ethyl 4- (and 5-) iodo-trans-2-methylcyclohexane-1-carboxylate] for male Mediterranean fruit fly,Ceratitis capitata (Wiedemann), were investigated. One of the isomers, CRL-B1 (ethylcis-5-iodo-trans-2-methylcyclohexane-1-carboxylate) was significantly superior to the three othertrans-CRL isomers, CRL, trimedlure (TML) [1,1-dimethylethyl 4- (and 5-) chloro-trans-2-methylcyclohexane-1-carboxylate], and TML-C (1,1-dimethylethyl-cis-4-chloro-trans-2-methylcyclohexane-1-carboxylate) on an equal weight basis.     

Attraction of pea mothCydia nigricana F. (Lepidoptera: Tortricidae) to female sex pheromone (E,E)-8,10-dodecadien-1-YL acetate,is inhibited by geometric isomersE,Z, Z,E, andZ,Z

Field attraction ofCydia nigricana males to synthetic female sex pheromone (E,E)-8,10-dodecadien-1-yl acetate, formulated on red rubber septa, declined continuously during two weeks. This was due to isomerization of (E,E)-8,10-dodecadien-1-yl acetate: eight days after application of purifiedE,E isomer, the proportion ofE,Z;Z,E; andZ,Z isomers in rubber septa aged in the laboratory was 4%; a 5% addition of any one of these isomers to fresh lures of (E,E)-8,10-dodecadien-1-yl acetate significantly reduced male attraction. Stereospecific syntheses of (E,Z)-, (Z,E)-, and (Z,Z)-8,10-dodecadien-1-yl acetate are described. The pheromone gland ofCydia nigricana contains 0.8 ng/female of (E,E)-8,10-dodecadien-1-yl acetate, accompanied by three monounsaturated acetates, (E)-9-dodecen-1-yl acetate, (Z)-5-tetradecen-1-yl acetate, and (Z)-7-tetradecen-1-yl acetate (0.1 ng/female each). These compounds did not augment male trap catch when added to (E,E)-8,10-dodecadien-1-yl acetate.     

Efficacy of nonpheromone communication disruptants of codling moth (Cydia pomonella): Effect of pheromone isomers and of distance between calling females and dispensers

Field tests comparing the ability of codlemone, (E,E)-8,10-dodecadien-1-ol, and isomers of codlemone to disrupt pheromonal communication of codling moth were carried out. In a pear orchard, four nonisomerizing, gray septa dispensers were placed in the upper canopy of each tree containing a trap baited with 10 virgin female codling moths. The dispensers were at trap height and 70 cm from the edge of each trap. Trap catches of released male codling moths in three test areas were compared simultaneously when trees in each of the test areas contained unbaited dispensers, dispensers with 1 mg of codlemone containing 1% isomers, and dispensers with 1 mg of a test communication disruptant. When the test disruptant was an equilibrium mixture of codlemone and its isomers (61% codlemone, 39% isomers), the percent communication disruption was 86.8% compared to 68.7% for codlemone (P < 0.001). When the disruptant was (E,Z)-8,10-dodecadien-1-ol (94%EZ, 3%EE), the percentage disruption was 86.4% compared to 62.7% for codlemone (P < 0.002). These results show that the previously reported superior disruptant potency (relative to codlemone) of compositions containing codlemone with a high percentage of isomers was not a result of the proximity of the dispensers to the traps. The percent disruption of compositions of codlemone with 10 and 20% isomers was also determined. A plot of percentage disruption versus logarithm of percentage of nonpheromone isomers in the mixture from 1% to 97% gave a straight line withR ²=0.93.     

Catalytic hydrogenation of linoleic acid over platinum-group metals supported on alumina

Catalytic activity and selectivity for hydrogenation of linoleic acid (cis-9,cis-12 18:2) were studied on Pt, Pd, Ru, and Ir supported on Al₂O₃. Stearic acid (18:0) and 10 different octadecenoic isomers (18:1) in the products could be separated completely by using a new capillary column coated by isocyanopropyl trisilphenylene siloxane for gas-liquid chromatography. The monoenoic acid isomers and dienoic acid isomers in the products on the various catalysts showed different distributions. The catalysts exhibited nearly equal selectivity for stearic acid formation. The 12-position double bond in linoleic acid has higher reactivity than the 9-position double bond in catalytic hydrogenation on platinum-group metal catalysts. In addition to hydrogenation products of linoleic acid, geometrical and positional dienoic acid isomers (trans-9,trans-12; trans-8,cis-12; cis-9,trans-13; trans-9,cis-13; cis-9,trans-12 18:2), due to isomerization of linoleic acid during hydrogenation, were contained in the reaction products. Ru/Al₂O₃ exhibited the highest activity for isomerization of linoleic acid with the noble metal catalysts. Conjugated octadecadienoic acid isomers have been observed in products of the reaction on Pt/Al₂O₃, Ru/Al₂O₃, and Ir/Al₂O₃. Catalytic activities of noble metals for positional and geometric isomerization of linoleic acid during hydrogenation decreased in the sequence of Ru ≥ Pt > Ir » Pd.     

Analysis ofcis- andtrans-fatty acid isomers in hydrogenated and refined vegetable oils by capillary gas-liquid chromatography

For quantitation ofcis- andtrans-fatty acid isomers, infrared (IR) spectroscopy, gas-liquid chromatography (GLC) on highly polar stationary phases or the combination (GLC-IR) may be used. IR offers the advantage of simplicity and speed, but the lower determination limit of 5% and the lack of detailed information limit its use. Detailed fatty acid information, required for, e.g., food-labeling purposes, can only be obtained with GLC methods. Most of the GLC methods are optimized for partially hydrogenated samples. AOCS Official Method Ce 1c-89 prescribes a single, highly polar stationary phase, SP2340, but underestimates the amount oftrans isomers due to 18∶1 positional isomer overlap. The combined GLC-IR method may circumvent this problem but at the cost of time, effort, and precision.Trans isomers in refined (deodorized or stripped) oils are different in type and levels from isomers in partially hydrogenated oils; theirtrans isomers are mono-trans trienoic and dienoic isomers, occurring at levels up to about 1–3%. GLC conditions for hydrogenated samples are often not suitable for refined oils because of overlap problems, but this time in the 18∶3 region. Through careful selection of stationary phase and temperature program optimization (Drylab^®GC), we have developed a single method that is suitable for hydrogenated, as well as refined, processed oils. The accuracy was checked withcis andtrans fatty acid fractions isolated by silverion exchange high-performance liquid chromatography. Thetrans values obtained with the optimized method are in good agreement with the results obtained for the isolated fractions. We propose that recommended methods describe GLC conditions in terms of separation criteria rather than recommending only a fixed combination of stationary phase and temperature program.     

Study of Some Experimental Parameters in the Synthesis of Triacylglycerols with CLA Isomers and Structural Analysis

The present research deals with the synthesis of structured triacylglycerols (TAG) by enzymatic treatment of sn-1,3-diacylglycerol (sn-1,3-DAG) with conjugated linoleic acid (CLA) isomers using the immobilized lipase from Rhizomucor miehei (Lipozyme^® IM) under different experimental conditions. In particular, the influence of reaction parameters, such as temperature, enzymatic load, reaction time and DAG/CLA ratio has been evaluated using an experimental design software with a screening objective. Two responses have been selected, they are the percentage of CLA isomers in total TAG and in the sn-2- position and a three-level-4-factor fractional factorial experimental design was used to screen the variables. The results showed that the selected experimental variables have an influence on the enzymatic reaction, in particular, the DAG/CLA substrate ratio and the temperature, both of which inversely correlated with CLA incorporation, but also the enzymatic load and the reaction time, both directly correlated with CLA incorporation. The best results for CLA isomer % content both in total TAG (46.3%) and in the sn-2- position (52.2%) were obtained at 40 °C for 96 h, with 20% enzymatic load and a 0.5 reactive ratio.     

Sex Pheromone of the Persimmon Fruit Moth, Stathmopoda masinissa: Identification and Laboratory Bioassay of (4E, 6Z)-4,6-Hexadecadien-1-ol Derivatives

Three electroantennogram (EAG)-active components were detected by gas chromatography coupled to an electroantennographic detector (GC–EAD) analysis of a hexane extract of the pheromone glands of the persimmon fruit moth, Stathmopoda masinissa. These compounds were identified as (4E,6Z)-4,6-hexadecadienal (E4,Z6-16:Ald) and the corresponding acetate (E4,Z6-16: OAc) and alcohol (E4,Z6-16:OH) by mass spectral, GC retention time (RT), and microchemical test data. The characteristic base peak of the aldehyde at m/z 84 provided a crucial piece of information suggesting the possibility of a 4,6-diene structure. The (4E,6Z)-isomer elicited the strongest EAG responses among the four geometrical isomers of each synthetic 4,6-hexadecadienyl compound. In a laboratory bioassay, only E4,Z6-16:OAc elicited male moth behavioral activity significantly different from the control; the activity of the acetate was not affected by addition of the aldehyde and alcohol. A preliminary field trial confirmed that E4,Z6-16:OAc as a single component attracted male moths. The possible roles of E4,Z6-16:Ald and E4,Z6-16:OH as components of lures for field use remain to be determined.     

Responses of Japanese Giant Looper Male Moth to Synthetic Sex Pheromone and Related Compounds

The Japanese giant looper, Ascotis selenaria cretacea, is a serious defoliator of tea gardens in Japan. In Mie Prefecture male moths were dose-dependently attracted to rubber septa baited with 0.1–10.0 mg of the sex pheromone component (Z,Z)-6,9-cis-3,4-epoxynonadecadiene. Monitoring by pheromone traps showed three flight periods (June, July, and August–September). A septum with a 1-mg dose was still active after exposure for over three months in the field, but the number of males captured by the old lure was one fifth of that captured by a fresh lure. The parent 3,6,9-triene, a minor pheromonal component, showed a synergistic effect on male attraction when mixed with the pheromonal epoxydiene at a very low ratio, but the 1:1 mixture hardly captured any male moths. Attraction was also effectively inhibited by the positional isomers (6,7- and 9,10-epoxydienes), which exhibited rather strong electrophysiological activities on the male antennae. When these related compounds were placed around a trap baited with the synthetic pheromone, the number of captured moths remarkably decreased, which indicates the possibility of using the compounds as a disruptant.     

Structure,chirality, and field testing of a male-produced aggregation pheromone of Asian palm weevilRhynchophorus bilineatus (Montr.) (Coleoptera: Curculionidae)

4-Methyl-5-nonanol is a male-produced aggregation pheromone of the Asian palm weevil,Rhynchophorus bilineatus (Montr.). The pheromone was identified by coupled gas chromatographic-electroantennographic detection (GC-EAD) and coupled GC-mass spectrometric (MS) analyses of male-and female-produced volatiles. Analyses by GC-EAD and GC-MS of weevil-produced and stereoselectively synthesized isomers of 4-methyl-5-nonanol on a Cyclodex B column, which separated isomers with baseline resolution, revealed that only (4S,5S)-4-methyl-5-nonanol is EAD active and produced by the males. In field experiments in Papua New Guinea, (4S,5S)-4-methyl-5-nonanol and a racemic mixture of disatereoisomers of it enhanced attraction of male and female weevils to sugarcane-baited traps. (4S,5S)-4-Methyl-5-nonanol is also an aggregation pheromone of two other Asian palm weevils.R. ferrugineus (Oliv.) andR. vulneratus (Panz.). The stereoisomeric mixture of 4-methyl-5-nonanol is currently used to manage populations ofR. bilineatus in Papua New Guinea.     

Isolation and identification of benzoquinolines in natural and synthetic crude oils

Using a sequential h.p.l.c. technique, the levels of each of the eight benzoquinoline isomers were estimated for two petroleum crude oils, several coal liquids shale oils and a coal gasifier tar. Significant concentrations (5–420 ppm) of phenanthridine, acridine, benzo(h)quinoline and benzo(f)quinoline were found in all coal-derived materials with the former two isomers being most abundant. In contrast, benzo(g)quinoline, benz(g)isoquinoline, benz(h)isoquinoline and benz(f)isoquinoline were seldom present at levels above 1 ppm. None or trace quantities of the eight isomers were detected in two petroleum crude oil samples. Major benzoquinoline isomers from one coal liquid were individually isolated and the presence of phenanthridine, benzo(h)quinoline and benzo(f)quinoline was unequivocally confirmed by matching infrared spectra.     

Response to pheromone traps and disruption of pheromone communication in the lesser peachtree borer and the peachtree borer (Lepidoptera: Sesiidae)

The sex pheromone communication of the lesser peachtree borer,Synanthedon pictipes (Grote and Robinson), and the peachtree borer,Sanninoidea exitiosa (Say), can be disrupted by permeation of the atmosphere with their respective sex pheromones, (E,Z)- and (Z,Z)-3,13-octadecadien-1-ol acetate. The two isomers seemed equally effective against both species. Disruption was greatest when the pheromone was evaporated from the tops of the peach trees; also, pheromone traps placed in the tree tops captured significantly more males than did traps placed lower in the trees. Neither the color nor the directional placement in a tree (NE, NW, SE, SW) of pheromone-baited traps influenced captures of male lesser peachtree borers.Mention of a commercial or proprietary product in this paper does not constitute a recommendation or an endorsement of that product by the USDA.     

Trans-18:1 acid content and profile in human milk lipids. Critical survey of data in connection with analytical methods

This study presents an in-depth, critical survey of the current knowledge about trans- 18:1 acid content and profile in human milk lipids. Emphasis is placed on the analytical methods employed to quantitate trans- 18:1 acids, most of which lead to imprecise quantitative data. It is demonstrated that data obtained by single gas-liquid chromatography (GLC) on polar capillary columns are underestimates by 25–40%. Several experiments indicate that the total content of trans-18:1 acids in human milk is directly related to the quantities ingested the previous day(s), provided no gross weight loss occurs during breast-milk feeding. Equations have been proposed to describe this relationship, and apparently the percentage of trans-18:1 isomers, relative to total fatty acids, is approximately three-fourths the quantity (in g) ingested by lactating mothers. That is, the determination of the trans-18:1 acid percentage in human milk is a convenient means to estimate trans-18:1 acid consumption by corresponding populations. Adapted methods (i.e., silver-ion thin-layer chromatography, coupled with GLC on long polar capillary columns) allow accurate quantitation of most individual trans- 18:1 acids, more particularly of the trans-Δ16 isomer. This determination, along with a knowledge of the distribution of individual isomers in ruminant fats and partially hydrogenated oils, is a convenient means to estimate the relative contribution of these two dietary sources to the distribution of individual trans-18:1 isomers in human milk lipids. A comparison of human milk and infant formulas is made with regard to trans-18:1 acid content and profile. Important differences are noted between data from European countries and from North America.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

Sex Attractant Pheromone from the Rice Stalk Stink Bug, Tibraca limbativentris Stal

The male-produced sex pheromone from the Brazilian rice stalk stink bug Tibraca limbativentris is reported. Olfactometer bioassays with sexually mature males and females showed that males attracted females, which suggests that males release a sex pheromone. Males were not attracted to either sex, nor were females attractive to conspecific females. Attraction of the females to males was highest at night. The headspace volatiles collected from male and female bugs were analyzed by gas chromatography (GC) and GC–mass spectrometry. Two male-specific compounds were identified as isomers of 1′S-zingiberenol, whereas a series of defensive compounds were identified in extracts from both sexes. Zingiberenol has three chiral centers, and the nonselective syntheses used produced two groups of isomers, zingiberenol I containing four isomers, namely (1RS,4RS,1′R)-4-(1′,5′-dimethylhex-4′-enyl)-1-methylcyclohex-2-en-1-ol, and zingiberenol II containing the other four isomers, namely (1RS,4RS,1′S)-4-(1′,5′-dimethylhex-4′-enyl)-1-methylcyclohex-2-en-1-ol. Both groups of stereoisomers were more attractive than hexane controls. The absolute configuration of the insect-produced pheromonal components remains to be elucidated, but the 1′S stereochemistry was established for at least one of the isomers.     

Electroantennogram responses of grape borerXylotrechus pyrrhoderus bates (Coleoptera: Cerambycidae) to its male sex pheromone components

Electroantennograms were recorded from the grape borerXylotrechus pyrrhoderus in response to serial dilutions of male sex pheromone components, (2S,3S)-octanediol and (2S)-hydroxy-3-octanone, and to 100 g of their optical isomers and host plant substances. Female antennae always responded more strongly than male antennae. Antennae of both sexes were highly sensitive to (2S)-hydroxy-3-octanone. F/M ratio (female to male EAG value) was greater for male sex pheromone components, especially (2S,3S)-octanediol, and their optical isomers than plant substances. Antennal sensitivity to optical isomers (2R,3R-octanediol and 2S,3R-octanediol) was lower than true pheromone components.     

Analysis of sn-1(3)- and sn-2-short-chain acyl isomers of triacylglycerols in butteroil by gas-liquid chromatography

The aim of the study was to determine major triacylglycerols (TG), and sn-1(3) and sn-2 isomers of butyryl and caproyl TG in butteroil (BO) and interesterified butteroil (IBO) by gas-liquid chromatography (GLC) and silver ion column chromatography. Altogether, 112 molecular species of TG were synthesized by interesterification and their retention indices were determined. Molar empirical correction factors for TG were determined using linear calibration. Retention indices showed that sn-1(3) and sn-2 isomers of the TG containing one short-chain acyl (butyrate, caproate) and two long-chain acyls (lauroate, myristate, palmitate, stearate, and oleate) were separated on a phenyl (65%) methylsilicone column. The difference between retention indices of 1(3)- and 2-short-chain acyl isomers ranged from 14 to 19, and from 9 to 16 for butyrates and caproates, respectively. The proportion of sn-2 isomers of butyrates averaged 1.4%, but only traces of sn-2 isomers of caproates were detected in butteroil. The ratio of sn-1(3)- to sn-2-butyrates and caproates in interesterified butteroil averaged 2.0:1. The most abundant molecular species of mono-short-chain TG in butteroil were BPP + BMS (5.6 mol%), BPO + BSPo (4.8 mol%), BMP + BLaS (3.4 mol%), BMO + BPPo (2.7 mol%), BPS (2.5 mol%), and CoPP + CoMS (2.3 mol%).     

trans-Polyunsaturated fatty acids in French edible rapeseed and soybean oils

The fatty acid compositions of rapeseed and soybean oils marketed in France have been determined by gas liquid chromatography on a fused-silica capillary column coated with a 100% cyanopropyl polysiloxane stationary phase. Under the operating conditions employed, methyl esters of linolenic acid geometrical isomers could be separated and quantitated easily without any other complementary technique. With only one exception, all samples under study (eight salad oils and five food samples) contain geometrical isomers of linolenic acid in measurable, although variable, amounts. Totaltrans-18:3 acids may account for up to 3% of total fatty acids. This value corresponds to a degree of isomerization (percentage oftrans isomers relative to total octadecatrienoic acids) of 30%. Examination of our data indicates that the distribution pattern of linolenic acid geometrical isomers does not depend on the degree of isomerization. The two main isomers always have thec,c,t and thet,c,c configurations. These isomers occur in the almost invariable relative proportions of 47.8±1.7% and 41.1±1.0%, respectively. The third mono-trans isomer is present in lower amounts−6.5±0.7%. The only di-trans isomer that can be quantitated with sufficient accuracy is thet,c,t isomer (4.9±1.5%). Mono-trans isomers of linoleic acid are also present in these oils. However, their maximum percentages are lower than those determined for linolenic acid geometrical isomers. In the oils showing the highest degrees of isomerization,trans isomers of linoleic acid account for 0.5% (rapeseed oils) and 1% (soybean oils) of total fatty acids. Taking into account all data, it would appear that the probability of isomerization of linolenic acid is about 13–14 times that of linoleic acid.     

Electroantennogram responses of mediterranean fruit fly,Ceratitis capitata (Diptera: Tephritidae) to trimedlure and itstrans isomers

Electroantennograms (EAGs) of unmated laboratory-reared male and femaleCeratitis capitata (Wiedemann) were recorded in response to the attractant trimedlure [tert-butyl 4(and 5)-chloro-trans-2-methylcyclohexane-1-carboxylate] and its fourtrans isomers. For both sexes, the magnitude of the EAG response was relatively low as compared to other previously tested compounds (i.e., plant volatiles). Dosage-response curves generated for all TML isomers revealed that flies responded to increasing dosages over a relatively narrow range (two to three log steps). Responses for both sexes peaked at ca. 10 μg dose for all isomers. Antennal response in males was greatest to the C isomer followed by the B₁, A, and B₂ isomers, while responses of females were greatest for the A isomer followed by B₁, C, and B₂. Both sexes exhibited a long recovery period for the response potential to return to baseline at doses above 1 μg for all of the isomers tested, except for B₂. The low EAG sensitivity to trimedlure and the apparent EAG selectivity to the C isomer in males are discussed in relation to the known field attractancy of males to the C, A, B₁, and B₂ isomers.     

Optical isomers of 3,13-dimethylheptadecane: Sex pheromone components of the western false hemlock looper,Nepytia freemani (Lepidoptera: Geometridae)

(3S, 13R)-3, 13-Dimethylheptadecane [(3S, 13R)-3, 13-dime-17Hy] is the major pheromone component of the western false hemlock looper (WFHL),Nepytia freemani. In comparative gas chromotographic-electroantennographic detection (GC-EAD) analyses of stereoselectively synthesized isomers, 1 pg of (3S, 13R)-dime-17Hy elicited significantly stronger electrophysiological responses by male WFHL antennae than did 1 pg of separately injected (3R, 13R)-, (3R, 13S)- or (3S, 13S)-3, 13-dime-17Hy. In field experiments with individually tested stereoisomers. (3S, 13R)-3, 13-dime-17Hy was the only stereoisomer to attract males, but the four-stereoisomer blend was 3.6 times more attractive. Quaternary and all binary combinations of (3S, 13R)-3, 13-dime-17Hy with the other stereoisomers were equally attractive, suggesting that synergisytic behavioral activity in WFHL resided with either one of (3R, 13R)-, (3R, 13S)-, or (3S, 13S)-3, 13-dime-17Hy. Because optical isomers of (di)methylhydrocarbons do not separate on currently available columns, it remains unknown whether female WFHL also produce a four-stereoisomer pheromone blend. Substitutionality of pheromone stereoisomers without loss of behavioural activity has not previously been reported, but favorably compares with the concept of pheromone redundancy that was first suggested for the multiple pheromone component blend of the cabbage looper moth,Trichoplusia ni.