Steps in the biosynthesis of fuscumol in the longhorn beetles Tetropium fuscum (F.) and Tetropium cinnamopterum Kirby

Nondestructive characterization gender of chicken eggs by odor using SPME/GC-MS coupled with chemometrics

It's a difficult task for researchers to identify the gender of chicken eggs by nondestructive approach in the early of incubation, which not only could reduce the cost of incubation, but also could improve the welfare of chicks. Therefore, SPME/GC-MS has been applied to investigate its potential as a nondestructive tool for characterizing the differences of odor between male and female chicken eggs during early of incubation and even before hatch. The results showed that more volatiles were found in female White leghorn eggs during early of incubation and 6,10-dimethyl-5,9-undecadien-2-one, 6-methyl-5-hepten-2-one, nonanal, decanal, octanal, 2-nonen-1-ol, etc. were important for the distinction of male and female White leghorn eggs during E₁-E₉ of incubation. 2-ethyl-1-hexanol; octanal, nonanal, 2,2,4-trimethyl-3-carboxyisopropyl pentanoic acid isobutyl ester; 2-nonen-1-ol, cyclopropanecarboxamide, heptadecane were correlated with gender of unhatched White leghorn, Hy-line brown and Jing fen eggs, respectively. Moreover, sex-related volatiles have been strongly influenced by incubation process and egg breed, and to be related to steroid hormone biosynthesis. What's more, this study enables us to develop a new visual for ovo sexing of chicken eggs and advances our understanding of the biological significance behind volatiles emitted from chicken eggs.

A male-produced aggregation-sex pheromone of the beetle Arhopalus rusticus (Coleoptera: Cerambycidae, Spondylinae) may be useful in managing this invasive species

The longhorned beetle Arhopalus rusticus (Coleoptera: Cerambycidae, Spondylinae) is a common species in conifer forests of the Northern Hemisphere, but with global trade, it has invaded and become established in New Zealand, Australia, and South America. Arhopalus rusticus is a suspected vector of the phytopathogenic nematode, Bursaphelenchus xylophilus, the causative agent of pine wilt disease, which is a major threat to pine forests worldwide. Here, we report the identification of a volatile, male-produced aggregation-sex pheromone for this species. Headspace odours from males contained a major male-specific compound, identified as (2 S, 5E)-6,10-dimethyl-5,9-undecadien-2-ol (common name (S)-fuscumol), and a minor component (E)-6,10-dimethyl-5,9-undecadien-2-one (geranylacetone). Both compounds are known pheromone components for species in the same subfamily. In field trials in its native range in Slovenia, (S)-fuscumol was significantly more attractive to beetles of both sexes, than racemic fuscumol and a blend of host plant volatiles commonly used as an attractant for this species. Fuscumol-baited traps also caught significant numbers of another spondylidine species, Spondylis buprestoides (L.), and a rare click beetle, Stenagostus rufus (De Geer). The pheromone can be exploited as a cost-effective and environmentally safe tool for detection and monitoring of this invasive species at ports of entry, and for monitoring the beetle's distribution and population trends in both endemic and invasive populations.

Both farnesyl diphosphate synthase genes are involved in the production of alarm pheromone in the green peach aphid Myzus persicae

Farnesyl diphosphate synthase (FPPS) catalyzes the formation of FPP, providing the precursor for the biosynthesis of (E)-β-farnesene (EβF) in plants, but it is unknown if FPPS supplies the precursor for the biosynthesis of EβF, the major component of aphid alarm pheromone, though our previous studies support the hypothesis that EβF is synthesized by the aphid itself. Here, we used two cohorts of the green peach aphid Myzus persicae separately, reared on pepper plant and artificial diet to test the correlations among droplet emission, EβF quantity, and FPPS gene expression. It was found that the proportion of aphids emitting cornicle droplets and the quantity of EβF per milligram of aphid were both significantly different between the two cohorts, which were positively correlated with the expression of the two FPPS genes ( MpFPPS1/ 2) in M. persicae. These results were further confirmed by RNAi-mediated knockdown of MpFPPS1/ 2. Specifically, knockdown of MpFPPS1/ 2 imposed no significant cost on the survival of aphid but remarkably increased the number of offspring per aphid; most importantly, knockdown of MpFPPS1/ 2 significantly reduced the proportion of aphids emitting droplets and the quantity of EβF calculated as per the weight of aphid. Our results suggest that both FPPS genes are involved in the production of EβF in M. persicae and cornicle droplet emission is closely associated with the EβF release in the aphid.

Fuscumol and Geranylacetone as Pheromone Components of Californian Longhorn Beetles (Coleoptera: Cerambycidae) in the Subfamily Spondylidinae

In field trials testing attraction of cerambycid beetles to a blend of known pheromone components plus host plant volatiles, several species in the subfamily Spondylidinae were attracted to baited traps, suggesting that one or more components of the blend might constitute their pheromones. Here, we describe laboratory and field experiments aimed at identifying the actual pheromone components produced by these species. Analysis of headspace odors collected from male Tetropium abietis (Fall) (Coleoptera: Cerambycidae) contained (S)-fuscumol as a single component, whereas Asemum nitidum (LeConte) (Coleoptera: Cerambycidae) males produced both (S)-fuscumol and geranylacetone, and Asemum caseyi (Linsley) (Coleoptera: Cerambycidae) produced only geranylacetone. In field trials testing fuscumol, fuscumol acetate, and geranylacetone as individual components or in blends, in combination with host plant volatiles, A. nitidum were attracted to blends of fuscumol and geranylacetone, T. abietis were attracted to fuscumol alone, and A. caseyi were attracted to geranylacetone alone. Fuscumol acetate did not appear to be either attractive or inhibitory. These results, along with previous catches of spondylidine species in traps baited with fuscumol, provide evidence that fuscumol and geranylacetone are likely to be relatively common pheromone structures for species in the subfamily Spondylidinae.

Volatile Organic Compounds Emitted by Fungal Associates of Conifer Bark Beetles and their Potential in Bark Beetle Control

Conifer bark beetles attack and kill mature spruce and pine trees, especially during hot and dry conditions. These beetles are closely associated with ophiostomatoid fungi of the Ascomycetes, including the genera Ophiostoma, Grosmannia, and Endoconidiophora, which enhance beetle success by improving nutrition and modifying their substrate, but also have negative impacts on beetles by attracting predators and parasites. A survey of the literature and our own data revealed that ophiostomatoid fungi emit a variety of volatile organic compounds under laboratory conditions including fusel alcohols, terpenoids, aromatic compounds, and aliphatic alcohols. Many of these compounds already have been shown to elicit behavioral responses from bark beetles, functioning as attractants or repellents, often as synergists to compounds currently used in bark beetle control. Thus, these compounds could serve as valuable new agents for bark beetle management. However, bark beetle associations with fungi are very complex. Beetle behavior varies with the species of fungus, the stage of the beetle life cycle, the host tree quality, and probably with changes in the emission rate of fungal volatiles. Additional research on bark beetles and their symbiotic associates is necessary before the basic significance of ophiostomatoid fungal volatiles can be understood and their applied potential realized.

Sex and Aggregation-Sex Pheromones of Cerambycid Beetles: Basic Science and Practical Applications

Research since 2004 has shown that the use of volatile attractants and pheromones is widespread in the large beetle family Cerambycidae, with pheromones now identified from more than 100 species, and likely pheromones for many more. The pheromones identified to date from species in the subfamilies Cerambycinae, Spondylidinae, and Lamiinae are all male-produced aggregation-sex pheromones that attract both sexes, whereas all known examples for species in the subfamilies Prioninae and Lepturinae are female-produced sex pheromones that attract only males. Here, we summarize the chemistry of the known pheromones, and the optimal methods for their collection, analysis, and synthesis. Attraction of cerambycids to host plant volatiles, interactions between their pheromones and host plant volatiles, and the implications of pheromone chemistry for invasion biology are discussed. We also describe optimized traps, lures, and operational parameters for practical applications of the pheromones in detection, sampling, and management of cerambycids.

Carbonyl reduction in the biosynthesis of a male sex pheromone secreted by the grape borer Xylotrechus pyrrhoderus

Males of the cerambycid beetle Xylotrechus pyrrhoderus release a mixture of (S)-2-hydroxy-3-octanone [(S)-1] and (2S,3S)-2,3-octanediol [(2S,3S)-2] as a sex pheromone that attracts conspecific females. The chemical structures of these pheromone components include a common motif and are assumed to be biosynthetically related. Here, we show that deuterated (S)-1, applied on the cuticle of a pronotal pheromone gland, was converted into (2S,3S)-2, that included deuterium atoms, but a reverse conversion did not take place. These results reveal a carbonyl reductase to be active in the pheromone gland, and that the ketol is a biosynthetic precursor of the diol. Males did not produce (R)-1; however, deuterated (R)-1 was converted into (2R,3R)-2, indicating an attack of the enzyme from the opposite side of the hydroxyl group at the 2-position. Furthermore, to understand the substrate specificity of the enzyme, racemates of 2-hydroxy-3-hexanone and 2-hydroxy-3-decanone were synthesized and applied to the gland. Their conversion into the corresponding diols suggests that the enzyme reduces the carbonyl group at the 3-position, regardless of the chain length.

Circadian release of male-specific components of the greater date moth, Aphomia (Arenipses) sabella, using sequential SPME/GC/MS analysis

The greater date moth (GDM), Aphomia sabella Hampson (Lepidoptera: Pyralidae: Galleriinae), is a serious pest of date palms, Phoenix dactylifera. The release of volatiles from both males and females was investigated using sequential SPME/GC/MS analysis. Males release a complex mixture of compounds in a circadian rhythm during the night between 03:00 and 05:00 hr. Six compounds were identified: benzaldehyde, sulcatol (6-methyl-5-hepten-2-ol), geranyl acetone [(E)-6,10-dimethyl-5,9-undecadien-2-one], phenylacetaldehyde, 2-phenylpropenal, and (R)-fuscumol [(R)-(E)-6, 10-dimethyl-5, 9-undecadien-2-ol]. Benzaldehyde, sulcatol, and geranyl acetone were found only in trace amounts. These compounds were in glands located in the forewing of males only. Small amounts of acetoin and 2,3-butanediol were found sporadically in the SPME/GC/MS analyses of volatiles from females, and these compounds probably originate from microorganisms. This is the first finding of a circadian release of male-specific compounds in moths. GC/EAD analyses with synthetic standards of compounds released by males showed that the female antenna is stimulated by all six compounds, while the male antenna responded only to phenylacetaldehyde. A possible pheromonal role for the male-specific compounds is suggested by the circadian rhythm of their release and the EAD response of females to them. However, trapping tests with the main male-specific compounds in screen cages in the laboratory or in the field did not reveal any significant behavioral responses from females or males. Copulation in the laboratory was observed only in the presence of date palm tissue, thus suggesting that sexual communication and mating of GDM moths probably occurs in the crown of date palms.