Sex pheromone components of the giant looper,Boarmia selenaria schiff. (Lepidoptera: Geometridae): Identification, synthesis, electrophysiological evaluation, and behavioral activity

Functional characterization of the epoxidase gene, Li_epo1 (CYP341B14), involved in generation of epoxyalkene pheromones in the mulberry tiger moth Lemyra imparilis

Epoxidation of alkenes derived from essential fatty acids is a key step in the biosynthesis of sex pheromones in moth species that utilize alkenyl sex pheromones. The position of the epoxy ring in the pheromone molecule differs depending on the species, thereby conferring diversities on sex pheromones. To date, only one pheromone gland (PG)-specific epoxidase, Hc_epo1 (CYP341B14), has been reported. Hc_epo1, which was identified from an arctiid moth Hyphantria cunea, catalyzes the epoxidation of a double bond at position 9 of the triene, Z3,Z6,Z9-21:H. In the present study, we investigated the PG-specific epoxidase from another arctiid, the mulberry tiger moth Lemyra imparilis, in order to verify whether cytochrome P450 in the CYP341B subfamily, to which Hc_epo1 belongs to, is responsible for the epoxidation of pheromone precursors at position 9 in moths other than H. cunea. A fragment of the Hc_epo1 homolog was amplified from cDNA prepared from the PG of L. imparilis by PCR with degenerate primers. The deduced amino acid sequence of the subsequently cloned homolog, Li_epo1, showed 88.5% identity to Hc_epo1. A functional assay using the Sf9 insect cell line-baculovirus expression system showed that Li_epo1 exhibited epoxidase activity with high selectivity to the double bond at position 9 of two trienes, Z3,Z6,Z9-21:H and Z3,Z6,Z9-23:H, precursors of epoxy diene sex pheromone components in L. imparilis.

3Z,6Z,9Z-Trienes and unsaturated epoxides as sex attractants for geometrid moths

Sex attractants for three species of geometrid moths were discovered during field screening of 3Z,6Z,9Z-trienes, and the racemic monoepoxydienes derived therefrom. MaleProbole amicaria moths were attracted to lure blends containing 6Z,9Z-cis-3,4-epoxy-nonadecadiene (6Z,9Z-cis-3,4-epoxy-19∶H) with 3Z,9Z-cis-6,7-epoxy-19∶H. 3Z,6Z,9Z-19∶H was positively identified and 6Z,9Z-cis-3,4-epoxy-19∶H was tentatively identified in extracts of female pheromone glands by coupled gas chromatography-electroantennogram detection (GC-EAD) and gas chromatography-mass spectrometry (GC-MS).Sicya macularia male moths were attracted by blends of 3Z,6Z,9Z-19∶H and 6Z,9Z-cis-3,4-epoxy-19∶H. The attractive response was strongly antagonized by small amounts of 3Z,9Z-cis-6,7-epoxy-19∶H, or by larger amounts of 3Z,6Z-cis-9,10-epoxy-19∶H.Lomographa semiclarata male moths were attracted by a variety of lures containing 3Z,6Z,9Z-17∶H as a major component. 3Z,6Z,9Z-17∶H was tentatively identified in a female pheromone gland extract by GC-EAD.

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.

Identification of a sex pheromone component of the geometrid moth Milionia basalis pryeri

A single component in extracts of virgin female Milionia basalis pryeri moths elicited responses from male moth antennae. This compound (ca. 7 ng/female) was identified as (Z,Z)-(3S,4R)-3,4-epoxynonadeca-6,9-diene by GC-MS and NMR analyses, microchemical reactions, and comparative chiral HPLC. In a field test, synthetic (Z,Z)-(3S,4R)-3,4-epoxynonadeca-6,9-diene attracted male moths. The opposite enantiomer, the racemic mixture, and virgin female moths held in small cages attracted no more moths than the solvent controls.

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.