Aggregation pheromone components inDrosophila mulleri

Existence of an aggregation pheromone was demonstrated inDrosophila mulleri. Mature males produce at least two compounds that are lacking from females and newly emerged males and that attract both males and females in a wind-tunnel bioassay. These compounds are (S)-(+)-2-tridecanol acetate and (Z)-10-heptadecen-2-one. Both were synthesized, and the flies responded to the synthetic compounds as well as to fly-derived preparations. The flies also responded to racemic 2-tridecanol acetate but not to the pureR enantiomer. A more polar, very volatile attractant was also extracted from both sexes ofD. mulleri but was not identified.     

(Z)-10-Heptadecen-2-one and other 2-ketones in the aggregation pheromone blend ofDrosophila martensis,D. buzzatii,andD. serido

(Z)-10-Heptadecen-2-one was identified as the major aggregation pheromone component inDrosophila martensis, D. buzzatii, andD. serido. Aliphatic 2-ketones were not detected in newly eclosed males or in virgin females of any age. The amount of (Z)-10-heptadecen-2-one in the ejaculatory bulb and on the cuticle of males increased with age. Only trace quantities of (Z)-10-heptadecen-2-one were transferred to the female during mating. 2-Tridecanone was found in the ejaculatory bulb and on the cuticle of maleD. martensis andD. buzzatii, but notD. serido. The amount of 2-tridecanone increased with age. Unexpectedly,2-tridecanone inhibited the aggregation activity of (Z)-10-heptadecen-2-one inD. buzzatii. InD. martensis, 2-tridecanone was significantly less attractive than controls but did not decrease the attractiveness of one fly equivalent of (Z)-10-heptadecen-2-one.D. serido males did not have any 2-tridecanone and the activity of (Z)-10-heptadecen-2-one was not diminished inD. serido by the presence of 2-tridecanone.     

(Z)-11-Eicosenyl acetate,an aggregation pheromone inDrosophila malerkotliana

(Z)-11-Eicosenyl acetate (Z11–20:Ac) was identified as the aggregation pheromone inDrosophila malerkotliana. The pheromone (200–300 ng/fly) was isolated from hexane extracts of the ejaculatory bulb of sexually mature male flies. Males released very little, if any,Z11–20:Ac to the food at any time. During mating there was a transfer of ca. 100 ng ofZ11–20:Ac to the female's reproductive tract. The mated female fly transferred theZ11–20:Ac to the surrounding surfaces in just a few hours after mating. In bioassay in a wind-tunnel olfactometer,Z11–20:Ac was not attractive alone, but was synergistic with fermenting food or with acetone. AlthoughD. malerkotliana has no (Z)-11-octadecenyl acetate (Z11–18:Ac), it was as attracted toZ11–18:Ac as to an equal quantity ofZ11–20:Ac.D. melanogaster andD. simulans, however, responded to theZ11–18: Ac that they produced and did not respond toZ11–20:Ac.     

Biocatalytic synthesis of (S)-2-tridecanyl acetate and (S)-2-pentadecanyl acetate,aggregation pheromone components ofDrosophila mulleri andD. busckii,by enantioselective hydrolysis with lipase

The two chiral pheromone acetates, (S)-2-tridecanyl acetate and (S)-2-pentadecanyl acetate, were synthesized with an enantiomeric excess (e.e.) of almost 100% byPseudomonas cepacia lipase-catalyzed hydrolysis of their corresponding racemic acetates in an acetone-water solvent system.     

Aggregation pheromone ofDrosophila mauritiana,Drosophila yakuba,andDrosophila rajasekari

(Z)-11-Octadecenyl acetate (Z11–18Ac) was identified as the aggregation pheromone ofDrosophila mauritiana, D. yakuba, andD. rajasekari. The amount of pheromone in the ejaculatory bulb of male flies increased with age, reaching plateau levels of ca. 240, 800, and 1100 ng/fly forD. mauritiana, D. yakuba, andD. rajasekari, respectively. Thirty to 50% of the pheromone in the ejaculatory bulb was transferred to the female during mating, with the majority transferred to the female's reproductive tract. In the subsequent 6-hr period, over half the pheromone in the female's reproductive tract was transferred to the surroundings. In a wind-tunnel olfactometer,Z11–18Ac was attractive toD. yakuba andD. mauritiana; however,D. rajasekari required food or food odors in combination withZ11–18Ac to demonstrate aggregation activity.Z11–16Ac andZ11–20Ac were not attractive forD. mauritiana, D. yakuba, andD. rajasekari. For all three species, food was synergistic withZ11–18Ac and both sexes were attracted.     

Identification of Sex Pheromone Components of the Hessian Fly, <Emphasis Type="Italic">Mayetiola destructor</Emphasis>

Coupled gas chromatographic (GC)–electroantennographic detection (EAD) analyses of ovipositor extract of calling Hessian fly, Mayetiola destructor, females revealed that seven compounds elicited responses from male antennae. Four of the compounds—(2S)-tridec-2-yl acetate, (2S,10Z)-10-tridecen-2-yl acetate, (2S,10E)-10-tridecen-2-yl acetate, and (2S,10E)-10-tridecen-2-ol—were identified previously in female extracts. Two new EAD-active compounds, (2S,8Z,10E)-8,10-tridecadien-2-yl acetate and (2S,8E,10E)-8,10-tridecadien-2-yl acetate, were identified by GC–mass spectroscopy (MS) and the use of synthetic reference samples. In a Y-tube bioassay, a five-component blend (1 ng (2S)-tridec-2-yl acetate, 10 ng (2S,10E)-10-tridecen-2-yl acetate, 1 ng (2S,10E)-10-tridecen-2-ol, 1 ng (2S,8Z,10E)-8,10-tridecadien-2-yl acetate, and 1 ng (2S,8E,10E)-8,10-tridecadien-2-yl acetate) was as attractive to male Hessian flies as a similar amount of female extract (with respect to the main compound, (2S,10E)-10-tridecen-2-yl acetate). The five-component blend was more attractive to male flies than a three-component blend lacking the two dienes. Furthermore, the five-component blend was more attractive than a blend with the same compounds but that contained one tenth the concentration of (2S,8E,10E)-8,10-tridecadien-2-yl acetate (more accurately mimicking the ratios found in female extract). This suggests that the ratios emitted by females might deviate from those in gland extracts. In a field-trapping experiment, the five-component blend applied to polyethylene cap dispensers in a 100:10 μg ratio between the main component and each of the other blend components attracted a significant number of male Hessian flies. Also, a small-plot field test demonstrated the attractiveness of the five-component blend to male Hessian flies and suggests that this pheromone blend may be useful for monitoring and predicting Hessian fly outbreaks in agricultural systems.     

(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 g) or virgin female C. oregonensis suggested that synthetic pheromone baits could be developed for monitoring C. oregonensis populations in commercial Douglas-fir seed orchards.     

(2S,12Z)-2-Acetoxy-12-heptadecene: Major Sex Pheromone Component of Pistachio Twig Borer, Kermania pistaciella

The sex pheromone of the pistachio twig borer, Kermania pistaciella (Lepidoptera: Oinophilidae), one of the most important insect pests of pistachio, Pistacia vera, in Turkey and Iran, was identified. In gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric analyses of pheromone gland extracts of female K. pistaciella from Turkey, (2S,12Z)-2-acetoxy-12-heptadecene was identified as the major candidate pheromone component. In field experiments in Turkey, lures containing synthetic (2S,12Z)-2-acetoxy-12-heptadecene attracted large numbers of male moths. Its attractiveness was significantly reduced by the presence of the R-enantiomer or of either enantiomer of the corresponding alcohol. (2S,12Z)-2-Acetoxy-12-heptadecene is the first pheromone component identified in the Oinophilidae and the first secondary acetate pheromone component identified in the Lepidoptera. An erratum to this article can be found at     

Synthesis of the stereoisomers of the female sex pheromone of the Hessian fly,Mayetiola destructor

The female-produced sex pheromone of the Hessian fly,Mayetiola destructor (Say) (Diptera: Cecidomyiidae), has been identified as (10E)-tridecen-2-yl acetate. A flexible synthetic route was developed which allowed access to the chiral and racemic forms of the pheromone, and to the 10Z stereoisomer of the pheromone. The natural compound was determined to have the 2S configuration by hydrolysis of the acetate function, derivatization of the resulting alcohol with (2S)-2-acetoxypropionyl chloride, and capillary gas Chromatographic comparison of the derivative with the corresponding derivatives prepared from the synthetic enantiomers. Trace amounts of the 10Z isomer of the pheromone have also been detected in extracts of female Hessian fly ovipositors, along with (10E)-tridecen-2-ol and 2-tridecanyl acetate. Due to the small quantities of these compounds available from ovipositor extracts, the chirality of the trace components has not yet been determined.     

Enantiomeric composition of grandisol and grandisal produced byPissodes strobi andP. nemorensis and their electroantennogram response to pure enantiomers

Grandisol (cis-2-isopropenyl-1-methylcyclobutaneethanol) and its corresponding aldehyde, grandisal, were previously isolated and identified as aggregation pheromone components forPissodes strobi (Peck) andP. nemorensis Germar, but the enantiomeric ratios produced by these insects were not previously determined. We isolated grandisol and grandisal from males of bothP. strobi andP. nemorensis. The insect-produced grandisol was derivatized with trifluoroacetic anhydride, and the enantiomeric composition was determined by gas chromatography on an optically active cyclodextrin glass capillary column. The insect-produced grandisal was first reduced to grandisol before derivatization.P. nemorensis produced nearly 100% (1R,2S)-grandisol and nearly 100% (1S,2R)-grandisal.P. strobi produced 99% (1R,2S)-grandisol and approximately 60% (lR,2S)-grandisal. In electroantennogram (EAG) studies with liveP. nemorensis andP. strobi, no significant differences were found between the responses of males and females to racemic grandisol, racemic grandisal, or the 1R,2S and 1S,2R enantiomers of grandisol and grandisal, which is consistent with previous assertions that these compounds are aggregation pheromones. Although no studies to date withP. strobi have demonstrated a behavioral response to grandisol and grandisal,P. strobi antennae detected all enantiomers of grandisol and grandisal tested in EAG tests. The antennae of P.nemorensis responded significantly more to (1R,2S) grandisal than to (1S,2R)-grandisal, despite producing only (1S,2R)-grandisal.Coleoptera: Curculionidae.     

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.     

Field attraction ofBiprorulus bibax Breddin (Hemiptera: Pentatomidae) to synthetic aggregation pheromone and (E)-2-hexenal,a pentatomid defense chemical

A synthetic blend of the aggregation pheromone [(3R,4S,1E)-3,4-bis(1-butenyl)tetrahydro-2-furanol, linalool, farnesol, and nerolidol] of the spined citrus bug,Biprorulus bibax, and the pentatomid defense chemical, (E)-2-hexenal, both attracted adultB. bibax to individual trees in citrus orchards. Lemon trees containing single glass vials with aggregation pheromone or (E)-2-hexenal were colonized by significantly greater numbers of reproductiveB. bibax than unbaited trees. There was no significant difference between the treatments and bug recruitment was not improved by using both treatments.B. bibax did not enter cylinder/funnel traps baited with aggregation pheromone but colonized trees containing the traps. Orange or lemon trees containing aggregation pheromone on orchard perimeters recruited significantly larger populations of emigrating, nonreproductiveB. bibax during fall than untreated trees. Nonreproductive bugs were not attracted to trees containing (E)-2-hexenal. The potential for using these semiochemicals as management tools forB. bibax is discussed.     

Structure-activity studies on aggregation pheromone components ofPityogenes chalcographus (Coleoptera: Scolytidae)

Syntheses of all four Stereoisomers (2S,5S; 2S,5R;2R,5R; and2R,5S) of chalcogran, a major component of the aggregation pheromone ofPityogenes chalcographus, and of all four isomers (2Z,4Z; 2Z,4E; 2E,4E; and 2E,4Z) of methyl 2,4-decadienoate (MD), the second major pheromone component, are briefly described. Attraction responses of walking beetles of both sexes were tested to mixtures of the synergistic pheromone components or analogs. These bioassays showed that theE,Z isomer of MD is the most active when tested with chalcogran. When tested with (E,Z)-MD, (2S,5R)-chalcogran was the most active stereoisomer, while 2R,5R and 2R,5S isomers had intermediate activities, and the 2S,5S isomer was inactive. There was no evidence that the relatively less active Stereoisomers of chalcogran inhibited or promoted attraction to (2S,5R)-chalcogran with (E,Z)-MD. Male beetles only produce the activeE,Z isomer of MD (inactive alone) and their hindguts contain the most active (2S,5R)- and least active (2S,5S)-chalcogran. A mixture of all MD isomers with racemic chalcogran was not significantly different in attractivity compared to (E,Z)-MD with racemic chalcogran, indicating no synergistic or inhibitory effects of the inactive isomers of MD.     

Using Generic Pheromone Lures to Expedite Identification of Aggregation Pheromones for the Cerambycid Beetles Xylotrechus nauticus, Phymatodes lecontei, and Neoclytus modestus modestus

Males of several species of longhorned beetles in the subfamily Cerambycinae produce sex or aggregation pheromones consisting of 2,3-hexanediols and/or hydroxyhexanones. We tested the hypothesis that this diol/hydroxyketone pheromone motif is highly conserved within the subfamily, and the resulting prediction that multiple cerambycine species will be attracted to compounds of this type. We also tested the concept that live traps baited with generic blends of these compounds could be used as a source of live insects from which pheromones could be collected and identified. Traps placed in a mature oak woodland and baited with generic blends of racemic 2-hydroxyhexan-3-one and 3-hydroxyhexan-2-one captured adults of both sexes of three cerambycine species: Xylotrechus nauticus (Mannerheim), Phymatodes lecontei Linsley, and Phymatodes decussatus decussatus (LeConte). Odors collected from male X. nauticus contained a 9:1 ratio of two male-specific compounds, (R)- and (S)-3-hydroxyhexan-2-one. Field trials with synthetic compounds determined that traps baited with (R)-3-hydroxyhexan-2-one (94% ee), alone or in blends with other isomers, attracted similar numbers of X. nauticus of both sexes, whereas (S)-3-hydroxyhexan-2-one (94% ee) attracted significantly fewer beetles. Phymatodes lecontei and P. d. decussatus also were caught in traps baited with hydroxyhexanones, as well as a few specimens of two other cerambycine species, Neoclytus modestus modestus Fall (both sexes) and Brothylus gemmulatus LeConte (only females). Male N. m. modestus produced (R)-3-hydroxyhexan-2-one, which was not present in extracts from females. Neoclytus m. modestus of both sexes also responded to lures that included (R)-3-hydroxyhexan-2-one as one of the components. The only male-specific compound found in extracts from P. lecontei was (R)-2-methylbutan-1-ol, and adults of both sexes were attracted to racemic 2-methylbutan-1-ol in field bioassays. Surprisingly, P. lecontei of both sexes also were attracted to (R)- and (S)-3-hydroxyhexan-2-ones, although neither compound was detected in extracts from this species. Males of all five beetle species had gland pores on their prothoraces that were similar in structure to those that have been associated with volatile pheromone production in other cerambycine species. The attraction of multiple cerambycine species of two tribes to (R)-3-hydroxyhexan-2-one in this study, and in earlier studies with other cerambycine species, suggests that this compound is a widespread aggregation pheromone component in this large and diverse subfamily. Overall, the attraction of multiple species from different cerambycine tribes to this compound at a single field site supports the hypothesis that the hydroxyketone pheromone structural motif is highly conserved within this subfamily.     

Identification of a Male-produced Aggregation Pheromone in the Western Flower Thrips <Emphasis Type="Italic">Frankliniella occidentalis</Emphasis>

Two major components have been detected in the headspace volatiles of adult male Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) that are not present in the headspace volatiles of adult females. The compounds were identified as (R)-lavandulyl acetate and neryl (S)-2-methylbutanoate by comparison with synthetic standards using gas chromatography (GC), GC–mass spectrometry (MS), and chiral GC. Field trials were conducted with synthetic compounds in naturally infested crops of sweet pepper grown in large plastic greenhouses in Spain. The catch of adult females and males on blue sticky traps was increased by neryl (S)-2-methylbutanoate alone or by a 1:1 blend of (R)-lavandulyl acetate and neryl (S)-2-methylbutanoate, but (R)-lavandulyl acetate was not active alone. This is the first identification of an aggregation pheromone in the order Thysanoptera. The possible role of (R)-lavandulyl acetate is discussed.     

Decadienoates: Sex Pheromone Components of Nettle Caterpillars Darna trima and D. bradleyi

This study was undertaken to identify sex pheromone components of nettle caterpillars Darna trima and Darna bradleyi (Lepidoptera: Limacodidae) whose larvae defoliate oil palm, Elaeis guineensis, in southeast Asia. Coupled gas chromatographic–electroantennographic detection (GCEAD) analyses of pheromone gland extracts revealed two antennally active compounds produced by female D. trima and two by female D. bradleyi. Molecular structures of these candidate pheromone components were identified by electron-impact and chemical-ionization mass spectrometry; retention-index calculations on DB-5, DB-23, and DB-210 columns; microanalytical treatments, as well as syntheses of "auxilliary" compounds that facilitated identification of the compounds. The compounds from D. trima were 2-methylbutyl (E)-7,9-decadienoate (A) and (E)-2-hexenyl (E)-7,9decadienoate (B); from D. bradleyi we identified methyl (E)-7,9-decadienoate (C), and isobutyl (E)-7,9-decadienoate (D). In field experiments in Malaysia, (S)-2-methylbutyl (E)-7,9-decadienoate (SA) in combination with B proved to be essential and synergistic pheromone components for attraction of male D. trima. (R)-2-Methylbutyl (E)-7,9-decadienoate (RA) had no behavioral activity. Compound D singly attracted male D. bradleyi, but addition of C to D at a 1 : 10 ratio significantly enhanced attractiveness of the bait. Synthetic pheromone blends were more effective trap baits than unmated female moths and could be developed for monitoring populations of D. trima and D. bradleyi in Asian oil palm plantations.     

Role of sex pheromone components in behavioral reproductive isolation betweenAutographa gamma (L.) and eitherTrichoplusia ni (Hübner) ORChrysodeixis chalcites (Esp.) (Lepidoptera: Noctuidae: Plusiinae)

The composition of theAutographa gamma sex pheromone was reexamined and only (Z)-7-dodecenyl acetate and (Z)-7-dodecenol were identified by capillary GC, GC-MS, and dimethyl disulfide derivatization and subsequent GC-MS analysis. The fatty acid content of the pheromone glands was also studied, and a series of saturated and unsaturated acids was identified. However, most of the related pheromonal compounds were not detected. The male response to the pheromone components was studied in a flight tunnel and compared with the response to calling females. The best synthetic baits evoked a response similar to that observed to the virgin females, but males spent significantly more time at calling females than at the synthetic baits. The preferred synthetic baits consisted of (Z)-7-dodecenyl acetate alone or of a blend with 5% (Z)-7-dodecenol. Increasing the relative amount of the alcohol caused a gradual reduction in male response, particularly in the last steps of the courtship sequence. The addition of the minor sex pheromone components of the sympatric Plusiinae species,Trichoplusia ni andChrysodeixis chalcites, to theA. gamma pheromone was also investigated in the flight tunnel. Some of these components exhibited a significantly antagonistic effect on theA. gamma male courtship behavior. The most potent antagonists were (Z)-5-dodecenyl acetate and (Z)-9-tetradecenyl acetate. The response ofA. gamma andT. ni males to conspecific and heterospecific females was also compared in the flight tunnel. WhereasA. gamma males were attracted only to their conspecific females, a small percentage ofT. ni males were also attracted toA. gamma females and 11% performed the whole courtship sequence.Contribution from the Agricultural Research Organization (ARO), No. 3459-E, 1992 series.     

(Z)-11-octadecenyl acetate,an aggregation pheromone inDrosophila simulans

Existence of a male-produced pheromone, which attracts both males and females in a wind-tunnel olfactometer, has been demonstrated inDrosophila simulans (Sturtevant). A pheromone component was identified as (Z)-11-octadecenyl acetate (Z11-18: Ac), also known ascis-vaccenyl acetate. The pheromone is synergized by food volatiles. In bioassay ca. 1/1000 of a mature male equivalent of Z11-18: Ac is attractive and activity increases with increased amounts of Z11-18: Ac. Flies do not begin responding to Z11-18: Ac until after they have been away from food for at least 2 hr. Z11-18: Ac is transferred from the male to the female during mating, and the female emits the majority of the transferred Z11-18: Ac within 6 hr after mating.     

(<Emphasis Type="Italic">S</Emphasis>)-2-Acetoxy-5-Undecanone,Female Sex Pheromone of the Raspberry Cane Midge, <Emphasis Type="Italic">Resseliella theobaldi</Emphasis> (Barnes)

The raspberry cane midge, Resseliella theobaldi, is a widespread pest of cultivated red raspberry in Europe. Pheromone-baited traps could provide a much-needed, accurate means to monitor the pest. Volatiles collected separately from virgin female and male midges were analyzed by gas chromatography (GC) coupled to mass spectrometry (MS) to reveal four female-specific components. In analyses by GC coupled to electroantennographic (EAG) recording from the antennae of a male midge, at least three of these components elicited responses. Based on its GC retention indices and mass spectrum, we propose that the major component is 2-acetoxy-5-undecanone and confirm this by synthesis of the racemic compound in seven steps and 63% yield from 4-pentenoic acid. The three minor components were each present at approximately 30% of the major component and were identified as 2-undecanone, (S)-2-acetoxyundecane, and (S)-2-undecanol by comparison of GC retention times and mass spectra with those of synthetic standards. GC analyses of the female-produced volatiles on an enantioselective column showed that only one enantiomer of 2-acetoxy-5-undecanone was present, and this was found to be the S-enantiomer by hydrolytic kinetic resolution of an epoxide intermediate in the synthesis and also by enantioselective hydrolysis of the racemic acetate with a lipase enzyme. The two enantiomers were also separated by high-performance liquid chromatography on an enantioselective column for field tests. In two field trapping tests, (S)-2-acetoxy-5-undecanone was highly attractive to male R. theobaldi; the R-enantiomer was not attractive. The racemic compound was just as attractive as the S-enantiomer, and addition of the three minor components in racemic form at two different loads did not affect catches. The pheromone could be dispensed from both rubber septa and polyethylene vials for at least 1 month under field conditions, but the former was preferred as it gave more uniform release. 2-Acetoxy-5-undecanone belongs to a new group of pheromone structures in the Cecidomyiidae, most others being mono- or diesters.     

Kairomonal Effects of Sawfly Sex Pheromones on Egg Parasitoids

The response of the two eulophid egg parasitoid species Chrysonotomyia ruforum and Dipriocampe diprioni to sex pheromones of their sawfly hosts Diprion pini and Neodiprion sertifer was studied in olfactometer bioassays. Females of C. ruforum were arrested when exposed to odor of the tested major sex pheromone components of Diprion pini [acetate and propionate of (2S,3R,7R)-3,7–dimethyl-2–tridecanol] or Neodiprion sertifer [(2S,3S,7S)-3,7–dimethyl-2–pentadecyl acetate]. This behavioral response of C. ruforum was observed whether (1) parasitoid females had oviposition experience with D. pini eggs or not, (2) parasitoid females emerged from D. pini eggs of a French population or from N. sertifer eggs of a Finnish population, and (3) the tested sex pheromone concentration was low (1 ng/l hexane) or high (100 ng/l hexane). However, C. ruforum did not behaviorally respond to a stereoisomer of the major sex pheromone component of N. sertifer, which is known to act as a sex pheromone antagonist [antagonist = (2S,3R,7R)-3,7–dimethyl-2–pentadecyl acetate]. Thus, C. ruforum responded stereospecifically to the S,S,S configured pheromone of N. sertifer, but not to the S,R,R configuration. Females of the parasitoid D. diprioni were also arrested by the tested major sex pheromone components of the host D. pini. The kairomonal effects of diprionid host sex pheromones on these egg parasitoids are compared to known responses of egg parasitoids to lepidopteran sex pheromones.