Analyses of lepidopteran sex pheromones by mass spectrometry

Lepidoptera, including about 150,000 species in the world, comprise the second largest insect group, and sex pheromones have been identified from virgin female moths of more than 600 species. The chemical structures are simple, but diverse, because species-specific pheromones play an important role in the reproductive isolation of each species. The pheromone content in each female is quite low, and gas chromatography coupled to mass spectrometry (GC-MS) is most frequently utilized to reveal the chemical structure. Almost all pheromone components are straight-chain compounds and are classified into two major groups [i.e. unsaturated C₁₀-C₁₈ fatty alcohols and their derivatives (Type I) and C₁₇-C₂₃ polyenyl hydrocarbons and their epoxides (Type II)]. In addition to the unbranched compounds, some species secrete methyl-branched compounds (e.g., 2-ketones). For the identification of these compounds, determining the positions of the double bond, the epoxy ring, and the methyl group is an important key step. Copious spectral information measured by electron-impact ionization (70 eV) has been accumulated for these compounds. This review therefore deals with their spectral characteristics, namely, diagnostic ions, to apply them to pheromone studies on new target insects.     

Nonlinear Multivariate SAR of Lepidoptera Pheromones

Abstract

The combined use of the nonlinear mapping method with correspondence factor analysis allowed to derive interesting structure-chemoreception relationships in Lepidoptera. A chemotaxonomy of insects based on their responses to pheromones was also proposed.     

New synthesis of (Z)-5- and (Z)-7-monoene components of insect sex pheromones of the Lepidoptera order

A new procedure was developed for the synthesis of (Z)-5- and (Z)-7-monoene components of sex pheromones of Lepidoptera insects based on cometathesis of readily accessible cycloocta-1,5-diene and ethylene. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1304–1307, July, 2000.     

Mass spectrometrical analysis of bilin-binding protein from the wing of Hebomoia glaucippe (Linnaeus, 1758) (Lepidoptera: Pieridae)

Bilin-binding protein (BBP) is a member of the lipocalin superfamily and a pigment protein in Lepidoptera. It is binding to a series of lipidic compounds but its functions remain to be elucidated. Working on wing proteins in Hebomoia glaucippe, we observed this protein on gels and decided to characterize BBP. A gel-based mass spectrometrical method using two-dimensional gel electrophoresis followed by in-gel digestion of protein spots followed by nano-LC-ESI-MS/MS (ion trap, HCT) identification and characterization of proteins was applied. An antibody was generated against the protein and immunoblotting in the butterfly and mouse brain was carried out. Two spots were identified from the butterfly wing as BBP (P09464) with high sequence coverage. Nitrotyrosination (Y163; as aminotyrosine) was observed and nitration was verified using immunoblotting. Additional posttranslational modifications (PTMs) as hypusine, carboxylation, kynurenine, aminoadipic acid, were proposed. The presence of BBP-immunoreactive protein was also observed in mouse brain. The characterization of BBP showed high sequence similarity with mouse apolipoprotein D and the findings suggest a tentative function of BBP comparable to apolipoproteins. The role of the PTMs remains elusive but nitration, in analogy to nitration effects reported in literature, proposes a role for mechanoelastic proteins and protein-protein interactions.     

Cytopathology of the trachea of Bombyx mori (Lepidoptera: Bombycidae) to Bombyx mori nucleopolyhedrovirus

Bombyx mori is a holometabolous insect found only in germplasm banks and morphological data related of resistance and susceptibility to diseases is important when selecting hybrids for commercial and scientific interest. This study analyzed the cytopathology of B. mori trachea to BmNPV, isolated geographically in Paraná state, Brazil. Fifth instar larvae were divided into two groups, control and inoculated; the viral suspension used was 2.4 × 10⁷ polyhedral occlusion bodies/mL. From the second to the ninth day post-inoculation, segments of silkworm organs, containing the trachea, were processed for transmission electron microscopy. Analyses of fresh hemolymph were also performed to verify the susceptibility of the hemocytes. Signs of infection were initially detected in the hemocytes and in the tracheal cells on the second and fourth post-inoculation days, respectively. The cytopathology of the trachea showed all stages of the viral cycle, which was the same as in other tissues. Virions were detected in the basal lamina, which showed structural disorganization. So, the infection time of the hemocytes prior to trachea and the presence of virus in basal lamina, suggests that the trachea was a secondary target, infected by budded virus coming from the hemolymph.     

(5R,7R)-5-Methylheptadecan-7-ol: a novel sex pheromone component produced by a female lichen moth, Miltochrista calamina, in the family Arctiidae

A methyl-branched heptadecanol was found in the pheromone gland extract of a female lichen moth, Miltochrista calamina (Arctiidae, Lithosiinae). GC-MS analyses of the alcohol and a hydrocarbon derived from it by subsequent treatments with methanesulfonyl chloride and LiAlD₄ in microscale reactions indicated 5-methylheptadecan-7-ol (1) as one possible structure. The four stereoisomers of 1 in a ratio of 4:4:1:1 were prepared from (S)-β-citronellol with 60% ee, and were separated by a combination of achiral and chiral HPLC columns. The absolute configuration of each isomer was determined by the comparison with the chromatographic behaviors of other samples synthesized by a different scheme, which applied the Jacobsen hydrolytic kinetic resolution of racemic 1,2-epoxydodecane to fix the configuration of the 7-hydroxy group. Only the (5R,7R)-isomer attracted male moths; thus, we concluded that M. calamina females secrete (5R,7R)-1 as a sex pheromone, indicating a new chemical class of lepidopteran female sex pheromones.