Sex pheromone components of fall cankerworm moth,Alsophila pometaria : Synthesis and field trapping

Sex attractants for Geometrid and Noctuid moths : Field trapping and electroantennographic responses to triene hydrocarbons and monoepoxydiene derivatives

Male moths belonging to 17 species of Geometridae and nine species of Noctuidae were captured in traps baited with synthetic chemicals as part of a field screening program. The compounds tested were the C18-C22 homologs of: (1) (3Z,6Z,9Z)-triene hydrocarbons; (2) mixtures containing equal quantities of (3Z,6Z)-cis-9,10-expoxydienes, (3Z,92Z)-cis-6,7-epoxydienes, and (6Z,9Z)-cis-3,4-epoxydienes; (3) (3Z,6Z)-9S,10R-epoxydienes; (4) (3Z,6Z)-9R,10S-epoxydienes; and (5) (3Z,6Z,9Z,11E)-nonadecatetraene. Field captures and electroantennographic assays revealed a high degree of specificity in the responses of many species to the synthetic chemicals. In several species the ability of males to discriminate between the 9S,10R and 9R,10S enantiomers of the monoepoxydiene isomers was clearly shown. Synergists and inhibitors were discovered for several of the reported attractants, some of which were not previously known to have semiochemical activity. The geometrid moths captured includedEpirrhoe sperryi (Herbulot),Mesoleuca ruficillata (Guenée),Triphosa haesitata (Guenée),Metanema inatomaria (Guenée),Prochoerodes transversata (Drury),Cabera erythemaria (Guenée),Synaxis jubararia (Hulst),Dysstroma brunneata ethela (Hulst),Eulithes testata (Linnaeus),Sicya macularia (Harris),Xanthorhoe iduata (Guenée),X. abrasaria aquilonaria (Herrich-Schäffer),X. munitata (Hübner),Itame loricaria (Eversmann),Eupithecia annulata (Hulst),E. rovocastaliata (Packard) andE. satyrata dodata (Taylor). The noctuid moths captured includedBleptina caradrinalis (Guenée),Idia américalis (Guenée),I. aemula (Hübner),Rivula propinqualis (Guenée),Lomanaltes eductalis (Walker),Spargaloma sexpunctata (Grote),Caenurgina distincta (Neumuller),Euclidia cuspidea (Hübner), andZale duplicata (Bethune). Six of the nine noctuid species captured belong to three subfamilies for which sex attractants had not been reported previously. Details for the stereospecific synthesis of (3Z,6Z)-cis-9,10-epoxydienes are also reported.

Copulation releaser pheromone in body scales of female whitemarked tussock moth,Orgyia leucostigma (Lepidoptera: Lymantriidae): Identification and behavioral role

The copulatory behavior of the male whitemarked tussock moth,Orgyia leucostigma, was released by extracts of female body scales applied to rubber septum models baited with a female sex pheromone gland. The major compounds in the scale extracts were identified by GC-MS as a series ofn-alkanes from C-21 to C-29. Of these,n-tricosane,n-tetracosane,n-pentacosane, andn-heptacosane, applied at 10 ng/septum, caused significantly more males to attempt copulation than hexane-treated controls. Mixtures of then-alkanes, resembling the composition in the scale extracts, were no better than the two most active alkanes,n-tetracosane andn-pentacosane, alone. The releaser effect of then-alkanes was dose dependent. EAG responses to the identifiedn-alkanes were small suggesting, along with the behavioral observations, that their perception occurred at very close range. Other factors releasing male copulatory behavior are discussed.

Use of a sex attractant and an inhibitor for monitoring winter moth and bruce spanworm populations

A single sex pherormone component was isolated from abdominal tip extracts of female Bruce spanworm.Operophtera bruceata (Hulst). This was identified as (Z,Z,Z)-1,3,6,9-nonadecatetraene by capillary gas chromatography (GC), electroantennography, and mass spectrometry. In addition, hexane extracts of female abdominal tips from Bruce spanworm and the winter moth.O. brumata L., were analyzed by GC coupled to an electroantennographic detector (GC-EAD). The extracts ofO. bruceata andO. brumata females elicited only a single response, at the same retention time, from antennae of their conspecific and reciprocal males. In field tests conducted in Saskatchewan, traps baited with the synthetic tetraene captured Bruce spanworm males. In tests carried out on Vancouver Island, British Columbia, where the two species coexist, both Bruce spanworm and winter moth males were captured. The attractancy of lures containing the synthetic pheromone alone and in combination with several structurally related analogs was field tested at both locations. One of these, an isomer of the natural pheromone, (E,Z,Z)-1,3,6,9-nonadecatetraene, inhibited the capture of Bruce spanworm males but had no effect upon the number of winter moth males which were taken. Thus, populations of these two very similar species can be distinguished by employing traps baited with pheromone ± the inhibitor. Coneorifice Hara traps were found useful for field trapping males of both species.

Structure-activity relationships for chain-shortened analogs of (Z)-5-decenyl acetate, a pheromone component of the turnip moth,Agrotis segetum

Structure-activity relationships for chain-shortened analogs of (Z)-5-decenyl acetate, a pheromone component of the turnip moth,Agrotis segetum, have been studied by electrophysiological single-sensillum technique and interpreted in terms of a previously reported receptor-interaction model. The results indicate that the terminal methyl group, as well as the acetate group, interacts with highly complementary receptor sites. The terminal alkyl chain is suggested to interact with a hydrophobic "pocket" extending over the two methylene groups closest to the terminal methyl group. The amounts of stimulus actually released from the odor source have been studied. The results demonstrate the necessity to take differences of volatility into account in comparisons of electrophysiological data for compounds of different chain lengths. It is shown that relative vapor pressures may to a good approximation be employed to estimate correction factors.

Hydrocarbons with a homoconjugated polyene system and their monoepoxy derivatives: Sex attractants of geometrid and noctuid moths distributed in Japan

Although several sex pheromones of the family Geometridae have been characterized, investigations on Japanese species are limited. In order to obtain more information, screening using known sex pheromones and their analogs was carried out. The (Z,Z,Z)-3,6,9-triunsaturated and (Z,Z)-6,9-diunsaturated hydrocarbons with straight C(19)-C(21) chains were synthesized by the Grignard coupling reaction as a key step starting from linolenic and linoleic acids, respectively. Oxidation of the homoconjugated trienes withm-chloroperoxybenzoic acid yielded a 1∶1∶1 mixture of three monoepoxy derivatives that could be separated by silica gel chromatography. The chemical structure of each positional isomer was confirmed using two-dimensional NMR techniques and MS measurements, which enabled characteristic fragment ions from the isomers to be identified. Field tests using lures incorporating only one of the above six hydrocarbons or nine epoxides were carried out in a forest in Tokyo. Consequently, attraction of male moths of 14 geometrid species in addition to four species in another family, the Noctuidae, was observed. It was concluded that hydrocarbons with a homoconjugated polyene system and the monoepoxy derivatives are important components of sex pheromones produced by Japanese lepidopterous insects, particularly the geometrid moths.

Pheromone differences between sibling taxaDiachrysia chrysitis (linnaeus, 1758) andD. tutti (Kostrowicki, 1961) (Lepidoptera: Noctuidae)

The noctuid sibling taxaDiachrysia chrysitis s. str. andD. tutti, of yet uncertain taxonomic status, have previously been shown to possess differences in morphology and to be attracted to different mixtures of the two presumed pheromone components (Z)-5-decenyl acetate and (Z)-7-decenyl acetate. TypicalD. tutti males (clearly broken forewing marking) are known to respond to a 2: 100 mixture of the two isomers, whereasD. chrysitis males (unbroken marking) are attracted to a 100: 10 mixture. We investigated female pheromone production and male electroantennographic (EAG) response inDiachrysia families raised in the laboratory from field-collected gravid females. Extracts of individual females from typicalD. tutti andD. chrysitis families were subjected to gas chromatography with simultaneous flame ionization and electroantennographic detection. All females produced mixtures of Z5- and Z7-10:OAc, but femaleD. chrysitis produced predominantly Z5-10:OAc and the antennae of their brothers responded more strongly to the Z5 peak than to the Z7-10:OAc peak, whereas the opposite was true forD. tutti families. The pheromone components were shown to be biosynthesized from hexadecanoic and tetradecanoic acid, respectively by Z11-desaturation followed by chain shortening, reduction, and acetylation. The EAG responses of males trapped with the typicalD. tutti andD. chrysitis blends, as well as with an intermediate blend, were investigated. Males trapped with theD. tutti mixture almost exclusively had a clearly broken wing marking and showed strongest EAG response to Z7-10:OAc. The intermediate blend and theD. chrysitis mixture gave more mixed catches, but with a prevalence of males with an unbroken (or almost unbroken) wing marking and with a higher mean response to Z5-10:OAc. Some males with typicalD. tutti EAG responses were attracted in the field to theD. chrysitis pheromone. In the flight tunnel someD. chrysitis males were attracted also to theD. tutti mixture. This indicates that cross attraction may take place between the two taxa under natural conditions.

Substrate specificity of acetyltransferase and reductase enzyme systems used in pheromone biosynthesis by Asian corn borer,Ostrinia furnacalis

The substrate specificity of the acetyltransferase and the reductase enzyme systems used byOstrinia furnacalis (Lepidoptera: Pyralidae) in pheromone biosynthesis was studied in vivo by topical application of precursors to pheromone glands. Each of the tetradecenols, varying in double bond position (from 7 to 13) and geometry of the double bond, was converted to the corresponding acetate by the acetyltransferase. The similarity in the conversion rates of all tested fatty alcohols indicated that the acetyltransferase has a low substrate specificity. Most of the corresponding tetradecenoic acids could also be converted to the respective acetates. However, very different conversion rates among the tested fatty acids demonstrated that the reductase system has a higher substrate specificity than the acetyltransferase. The conversion rates of mostE isomers were higher than those of the correspondingZ isomers, except for the (Δ)-11-tetradecenoic acids, in which much moreZ isomer was converted to the product. Saturated tetradecanoic acid was converted to the corresponding acetate at a high rate; the shorter homolog, tridecanoic acid, was converted at a lower rate (56%), and conversion to the respective acetates of the longer homolog, pentadecanoic and hexadecanoic acids, was insignificant (<5%). The results from the present study showed that specificity of pheromone production is to a large extent controlled by the pheromone gland reductase system.

Novel components of the sex pheromones produced by emerald moths: identification, synthesis, and field evaluation

The subfamily Geometrinae (Lepidoptera: Geometridae) includes many species called emerald moths. Based on our recent finding of novel polyenyl compounds, including a double bond at the 12-position from two geometrine species, Hemithea tritonaria and Thalassodes immissaria intaminata, (6Z,9Z,12Z)-6,9,12-trienes and (3Z,6Z,9Z,12Z)-3,6,9,12-tetraenes with a C(17)-C(20) straight chain were synthesized and analyzed by GC-MS. The 6,9,12-trienes, which were prepared by a double Wittig reaction between two alkanals and an ylide derived from (Z)-1,6-diiodo-3-hexene, characteristically produced fragment ions at m/z 79, 150, and M-98. The 3,6,9,12-tetraenes, which were prepared by a coupling between (Z)-3-alkenal and an ylide derived from (3Z,6Z)-1-iodo-3,6-nonadiene, showed fragment ions at m/z 79, 148, and M-96. These diagnostic ions were useful to distinguish these compounds from other known polyenyl pheromones, such as 4,6,9- and 6,9,11-trienes and 1,3,6,9-tetraenes. With reference to the GC-MS data, pheromone extracts of other species in Geometrinae inhabiting the Iriomote Islands were analyzed, and the 6,9,12-trienes were identified in the pheromone gland extracts of Pamphlebia rubrolimbraria rubrolimbraria and Maxates versicauda microptera. Furthermore, a field evaluation of the synthetic polyenes in a mixed forest of Tokyo revealed the following new male attractants for emerald moths: Idiochlora ussuriaria by a C(17) 6,9,12-triene and Jodis lactearia by a C(20) 3,6,9,12-tetraene, indicating the characteristic chemical structures of Geometrinae pheromones. On the other hand, through reexamination of the pheromone extract of H. tritonaria, (3E,6E)-α-farnesene was identified as an electrophysiologically active component in addition to the C(17) 6,9,12-triene. The binary mixture attracted more males than the single component lure baited with the triene in the Iriomote Islands.

Synthesis and chemical characterization of hydrocarbons with a 6,9,11-, 3,6,9,11-, or 1,3,6,9-polyene system, pheromone candidates in Lepidoptera

Lepidopteran Type II sex pheromones are mainly composed of 6,9-dienes, 3,6,9-trienes, and their epoxy derivatives, which are biosynthesized from linoleic and linolenic acids by the species in some families of higher Lepidoptera. To investigate further structural modifications on this theme, we synthesized polyunsaturated hydrocarbons with a C(17)-C(21) chain, which included an extra double bond. Using the Wittig reaction, (Z,Z,E)-6,9,11-trienes and (Z,Z,Z,E)-3,6,9,11-tetraenes were synthesized from (E)-2-alkenals with appropriate carbon chains, and (Z,Z,Z)-1,3,6,9-tetraenes were synthesized from 3-hexyn-1,6-diol. The gas chromatography-mass spectrometry (GC-MS) analysis of each synthetic polyene, whose chemical structure was confirmed by (1)H NMR and (13)C NMR, revealed some characteristic fragment ions reflecting the positions of the double bonds, i.e., m/z 79, 110, 163, and M-85 of the 6,9,11-trienes, m/z 79, 108, and M-82 of the 3,6,9,11-tetraenes, and m/z 79, 91, 106, and M-54 of the 1,3,6,9-tetraenes. Because the determination of the unsaturated positions is difficult to accomplish by chemical derivatization with a limited amount of natural pheromones, these diagnostic ions found in authentic samples would help identify the hydrocarbons in a pheromone extract. Furthermore, we carried out field screening tests of these polyenes in forests in Japan, and documented the attraction of four geometrid species in Tokyo and one noctuid species in the Iriomote Islands.

Sex pheromone of browntail moth, Euproctis chrysorrhea (L.): synthesis and field deployment

The browntail moth, Euproctis chrysorrhea (L.), is native to Eurasia, where periodic outbreaks result in defoliation of forest, shade, and ornamental trees. In addition to the damage caused by defoliation, human contact with larval urticating hairs often results in severe dermatitis. Hence, tools for monitoring and controlling the moth populations are desirable. The female-produced sex pheromone of the browntail moth was identified previously, but the synthesis had not been published. This paper reports the synthesis of the pheromone of the browntail moth, (7Z,13Z,16Z,19Z)-docosatetraenyl isobutyrate, using in a key step a Wittig olefination of (6Z)-13-(tetrahydo-2H-pyran-2-yloxy)tridecenal. Field trapping studies were conducted with rubber septa and string formulations of the pheromone and included dose-response, pheromone purity, and dispenser-aging trials. It was found that traps baited with 250 microg of pheromone of 91-94% isomeric purity (main impurity presumably being the 13E isomer) on rubber septa are suitable for monitoring moth populations during the entire flight season.

Identification of the sex pheromone of the currant shoot borer Lampronia capitella

Under an artificial light:dark cycle, females of Lampronia capitella were observed calling, with extended terminal abdominal segments, during the first 2 hr of the photoperiod. Extracts of terminal abdominal segments from females elicited large electroantennographic responses from male antennae. Gas chromatography with electroantennographic detection revealed three active peaks. Based on comparison of retention times and mass spectra of synthetic standards, these compounds were identified as (Z,Z)-9,11-tetradecadienol and the corresponding acetate and aldehyde. The electroantennographic activity of the four geometric isomers of all three compounds was investigated, and the respective (Z,Z)-isomer was found to be the most active in all cases. Aldehydes generally elicited larger antennal responses than alcohols, whereas acetates were the least active compounds. A subtractive trapping assay in the field, based on a 13:26:100 micrograms mixture of (Z,Z)-9,11-tetradecadienal, (Z,Z)-9,11-tetradecadienyl acetate, and (Z,Z)-9,11-tetradecadienol confirmed that all three compounds are pheromone components. Subtraction of (Z,Z)-9,11-tetradecadienol from the blend completely eliminated its attractiveness, whereas the other two-component blends showed reduced activity. This is the first pheromone identification from the monotrysian superfamily Incurvarioidea, confirming that the common pheromones among ditrysian moths (long-chain fatty acid derivatives comprising alcohols, acetates, and aldehydes with one or more double bonds) is not an autapomorphy of Ditrysia, but a synapomorphy of the more advanced heteroneuran lineages.

Polyene hydrocarbons and epoxides: a second major class of lepidopteran sex attractant pheromones

Polyene hydrocarbons and epoxides are used as pheromone components and sex attractants by four macrolepidopteran families: the Geometridae, Noctuidae, Arctiidae, and Lymantriidae. They constitute a second major class of lepidopteran pheromones, different from the C10-C18 acetates, alcohols, and aldehydes commonly found in other species. They are biosynthesized from diet-derived linoleic or linolenic acids and are characterized by C17-C23 straight chains, 1-3 cis double bonds separated by methylene groups, and 0, 1, or 2 epoxide functions. Pheromone blends are created from components with different chain lengths, numbers of double bonds, and functional groups, or from mixtures of epoxide regioisomers or enantiomers, with several examples of synergism between enantiomers. Behavioral antagonists also limit interspecific attraction, with numerous examples of antagonism by enantiomers. This review summarizes the taxonomic distribution, mechanisms used to generate unique pheromone blends, and the identification, synthesis, and biosynthesis of these compounds.