Insect Pheromones Research Articles

A peculiar transition-metal-free cyclodimerization of propargylic alcohols to vinyl bicyclic ketals

Propargylic alcohols, alkylaryl(hetaryl)ethynyl carbinols, under transition-metal-free conditions (KOH/DMSO, 70–80 °C, 10–15 min) unexpectedly undergo stereoselective cyclodimerization to 7-methylene-6,8-dioxabicyclo[3.2.1]octanes having the scaffold of known insect pheromones and marine toxins. Under acetylenic pressure the yields of bicyclic ketals reach 80%. In all the cases, the cyclodimers are formed exclusively as one diastereomer.

New Insights into the Mechanism of Odorant Detection by the Malaria-transmitting Mosquito Anopheles gambiae

Anopheles gambiae mosquitoes that transmit Plasmodium falciparum malaria use a series of olfactory cues present in human sweat to locate their hosts for a blood meal. Recognition of these odor cues occurs through the interplay of odorant receptors and odorant-binding proteins (OBPs) that bind to odorant molecules and transport and present them to the receptors. Recent studies have implicated potential heterodimeric interactions between two OBPs, OBP1 and OBP4, as important for perception of indole by the mosquito (Biessmann, H., Andronopoulou, E., Biessmann, M. R., Douris, V., Dimitratos, S. D., Eliopoulos, E., Guerin, P. M., Iatrou, K., Justice, R. W., Kröber, T., Marinotti, O., Tsitoura, P., Woods, D. F., and Walter, M. F. (2010) PLoS ONE 5, e9471; Qiao, H., He, X., Schymura, D., Ban, L., Field, L., Dani, F. R., Michelucci, E., Caputo, B., della Torre, A., Iatrou, K., Zhou, J. J., Krieger, J., and Pelosi, P. (2011) Cell. Mol. Life Sci. 68, 1799-1813). Here we present the 2.0 Å crystal structure of the OBP4-indole complex, which adopts a classical odorant-binding protein fold, with indole bound at one end of a central hydrophobic cavity. Solution-based NMR studies reveal that OBP4 exists in a molten globule state and binding of indole induces a dramatic conformational shift to a well ordered structure, and this leads to the formation of the binding site for OBP1. Analysis of the OBP4-OBP1 interaction reveals a network of contacts between residues in the OBP1 binding site and the core of the protein and suggests how the interaction of the two proteins can alter the binding affinity for ligands. These studies provide evidence that conformational ordering plays a key role in regulating heteromeric interactions between OBPs.

Synthesis of grandisol, the sexual attracting insect pheromone

In this issue, Suh's group reported a new formal total synthesis of (±)-grandisol featuring a palladium-catalyzed 4-exo-trig cyclization. Grandisol's interesting cyclobutane structure has been a popular test model for various cyclization methods over the years. This report summarizes Suh's formal synthesis of grandisol along with a concise review of the four-membered ring cyclization strategies employed in the synthesis of grandisol.

The feasibility study of novel odor biosensor using dissociate neuronal culture expressing ion channel built-in odor receptors

The transport of hydrophobic insect pheromones through the aqueous medium surrounding their receptors is assisted by pheromone-binding proteins (PBPs). The protein from the silkworm moth Bombyx mori, BmorPBP, exhibits a pH-dependent conformational change postulated to trigger the release of the pheromone bombykol to its receptor. At low pH, an α-helix occupies the same binding pocket that houses the pheromone in the BmorPBP–bombykol complex at high pH. We have determined the crystal structure of apo BmorPBP at a resolution of 2.3 Å and pH 7.5, which has surprisingly a structure similar to the A-form. These data suggest that BmorPBP undergoes a ligand-dependent conformational change in addition to the previously described pH-dependent conformational change. Analysis of the α-helix occupying the binding pocket reveals an amphipathic helix with three acidic residues along one face that are conserved among lepidopteran PBPs and may be involved in a conformational transition of BmorPBP at the receptor membrane.

Transcription factor fork head regulates the promoter of diapause hormone gene in the cotton bollworm, Helicoverpa armigera, and the modification of SUMOylation

The transcription factor fork head (FoxA) plays important roles in development and metabolism. Here, we cloned a fork head gene in Helicoverpa armigera, and found that the fork head protein is mainly located in the nucleus. This fork head gene belongs to the FoxA subfamily of the Fox transcription factors. The diapause hormone and pheromone biosynthesis-activating neuropeptide (DH-PBAN), which are two well-documented insect neuropeptides that regulate insect development and pheromone biosynthesis, are encoded by a single mRNA. In the present study, fork head was shown to bind strongly to the promoter of H. armigera DH-PBAN gene, and regulate its promoter activity. Furthermore, the effect of SUMOylation of the FH protein on the regulation of Har-DH-PBAN gene was investigated, and we show that the SUMO can modify Har-FH protein and cause down-regulation of DH-PBAN gene expression. These results suggest that SUMOylated FH plays a key role in insect diapause in H. armigera.

Nanogram-Scale Preparation and NMR Analysis for Mass-Limited Small Volatile Compounds

Semiochemicals are often produced in infinitesimally small quantities, so their isolation requires large amounts of starting material, not only requiring significant effort in sample preparation, but also resulting in a complex mixture of compounds from which the bioactive compound needs to be purified and identified. Often, compounds cannot be unambiguously identified by their mass spectra alone, and NMR analysis is required for absolute chemical identification, further exacerbating the situation because NMR is relatively insensitive and requires large amounts of pure analyte, generally more than several micrograms. We developed an integrated approach for purification and NMR analysis of <1 µg of material. Collections from high performance preparative gas-chromatography are directly eluted with minimal NMR solvent into capillary NMR tubes. With this technique, 1H-NMR spectra were obtained on 50 ng of geranyl acetate, which served as a model compound, and reasonable H-H COSY NMR spectra were obtained from 250 ng of geranyl acetate. This simple off-line integration of preparative GC and NMR will facilitate the purification and chemical identification of novel volatile compounds, such as insect pheromones and other semiochemicals, which occur in minute (sub-nanogram), and often limited, quantities.

CD36 as a lipid sensor

CD36 is a multifunctional protein homologous to the class B scavenger receptor SR-B1 mainly found in tissues with a sustained lipid metabolism and in several hematopoieic cells. CD36 is thought to be involved in various physiological and pathological processes like angiogenesis, thrombosis, atherogenesis, Alzheimer's disease or malaria. An additive emerging function for CD36 is a role as a lipid sensor. Location of CD36 and orthologue molecules in plasma membrane of cells in contact with the external environment (e.g. gustatory, intestinal or olfactory epithelia) allows the binding of exogenous-derived ligands including dietary lipids, diglycerides from bacterial wall in mammals and even a lipid-like pheromone in insects. Similar function might also exist in the brain in which a CD36-dependent sensing of fatty acids has been reported in ventromedial hypothalamic neurons in rodents. Specific recognition of lipid-related molecules by a receptor-like protein highly conserved throughout the evolution strongly suggests that lipid-sensing by CD36 is responsible for basic physiological functions in relation with behavior, energy balance and innate immunity.

Bioactive natural products and chirality

Mori's synthetic works on bioactive natural products in general and pheromones in particular started about 40 years ago to establish their absolute configurations and also to clarify their stereochemistry-bioactivity relationships. Results indicate that bioactive natural products are not always enantiomerically pure, and the stereochemistry-bioactivity relationships are not simple but complicated. For example, neither (R)- nor (S)-sulcatol, the aggregation pheromone of an ambrosia beetle, is behaviorally bioactive, whereas their mixture is active. In the case of olean, the sex pheromone of the olive fruit fly, its (R)-isomer is active against the males and the (S)-isomer is active against the females. Recent synthesis of two new insect pheromones is discussed to illustrate the modern methods in enantioselective synthesis.

多様な環状骨格構築法の開発と生物活性天然物合成への応用

In this article, the author outlines five total syntheses of structurally unique and biologically intriguing natural products, which were matters of attractive concern in the author’s group during these two decades. The following natural product syntheses are summarized in this article: (1) a mycotoxin, (+)-asteltoxin, (2) sex-attracting insect pheromones, (−)-anastrephin and (−)-epianastrephin, (3) a bisabolene-type sesquiterpenoid, (+)-paniculide B, (4) 17-memberd tetra- and pentacyclic antibiotics, (+)-macquarimicins, and (5) cytotoxic and immunosuppressive caryophyllene-type sesquiterpenoid, (+)-pestalotiopsin A and its (−)-enantiomer. In conjunction with these total syntheses, the multigram-scale access to two versatile and enantiomerically homogeneous building blocks from D-glucose is also described. The synthetic utility of the both building blocks was convincingly demonstrated through the total syntheses of the above three natural products.

Synthesis of insect pheromones: Improved method for the preparation of queen substance and royal jelly of honeybees Apis mellifera

The biological activity of pheromones stems from various applications, especially in the area of pest control and insect monitoring; however, the quantity of pure pheromones available from natural sources is often extremely limited, because individual insects contain only minute amounts of pheromone. As our contribution to the field of pheromone synthesis, here we present a novel approach for the preparation of two known pheromones, namely queen substance and royal jelly of honeybees Apis mellifera. Our method is based on the original applications of lithiated α-alkenylphosphoramido anions as excellent synthetic equivalents of homoenolate anions.

Intramolecular iodoetherification of ene or diene ketals: facile synthesis of spiroketals

A novel and rapid approach to chiral mono- or di-substituted spiroketals based on remote asymmetric induction by intramolecular iodoetherification of ene or diene ketals has been developed. This strategy concisely offers 5,5- and 5,6-spiroketals including the natural insect pheromone of the wasp.

Evolution of insect pheromones and their role in reproductive isolation and speciation

The importance for reproductive isolation of a change in the pheromone biosynthetic pathway, resulting in a different pheromone blend, is discussed in Lepidoptera and Diptera. The different sites of pheromone production and the biosynthetic enzymes are briefly reviewed. Two examples of a modification in the pheromone blend leading to reproductive isolation in Lepidoptera are taken as examples: the first, in Ostrinia nubilalis, is involved in the formation of two different populations showing reproductive isolation; the second, in the genus Ostrinia, might be at the origin of the formation of two different species. In both examples, a modification in the function of a desaturase involved in pheromone biosynthesis brings about change in the pheromone blend. In the fruitfly, Drosophila melanogaster, a mutation at a desaturase locus leads to the formation of two populations which differ in their pheromone mixtures and have developed premating isolation. The closely related species, D. melanogaster and D. simulans, differ in their female pheromonal cuticular hydrocarbons. This pheromonal difference is due to two species- and female-specific genes, desatF and eloF. The activity of desatF could account for an effective barrier between these species. All these examples show that a birth and death process of desaturases is at the origin of major shifts in the pheromone blend leading to sexual isolation and speciation.

First Report ofHecatera dysodea(Denis and Schiffermüller) (Noctuidae) in the Pacific Northwest of the United States

ABSTRACT. New geographic records are reported for the noctuid moth Hecatera dysodea (Denis & Schiffermuller). It is a Palearctic species, but is now found in a broadly contiguous area of Oregon and Washington in the United States. This area is comprised of 7 counties across much of the north of Oregon and into 4 counties of southern Washington. Moths were captured in several types of survey traps baited with insect pheromones and feeding attractants, as well as blacklight traps, from 2003 to 2009. Larvae were collected on flower stalks of prickly lettuce, Lactuca serriola L. (Asteraceae), from June into September, suggesting multivoltinism. Collection records over time indicate a possibly rapidly expanding distribution of the species.

Pheromone Detection by a Pheromone Emitter: A Small Sex Pheromone-Specific Processing System in the Female American Cockroach

Many animals depend on pheromone communication for successful mating. Sex pheromone in insects is usually released by females to attract males. In American cockroaches, the largest glomerulus (B-glomerulus) in the male antennal lobe (first-order olfactory center) processes the major component of sex pheromone. Using intracellular recordings combined with fine neuroanatomical techniques, we provide evidence that the female homolog of the male B-glomerulus also acts as a sex pheromone-specific detector. Whereas ordinary glomeruli that process normal environmental odors are innervated by single projection neurons (PNs), the B-glomerulus in both sexes is innervated by multiple PNs, one of which possesses a thicker axon, termed here B-PN. Both soma size and axon diameter were smaller on B-PNs from females compared with B-PNs from males. The female B-PNs also produce fewer terminal arborizations in the protocerebrum than male B-PNs. Termination fields in the lateral protocerebrum of the female B-PN are mostly segregated from those formed by other uniglomerular PNs innervating ordinary glomeruli. Female B-PN activity was greatest in response to sex pheromone but lower than that in the male B-PN. This specific detection system suggests that sex pheromone affects the behavior and/or endocrine system of female cockroaches.

Synthesis of Functionalized 3,4‐Dihydropyrans via Rearrangement of the Products of a One‐Pot Diastereoselective Assembly of Ketones and Acetylene

AbstractThe products of the one‐pot assembly of ketones and acetylene, 7‐methylene‐6,8‐dioxabicyclo[3.2.1]octanes, congeners of an insect pheromone frontalin, undergo an acid‐catalyzed rearrangement to diastereomerically pure 2‐acetyl‐3,4‐dihydropyrans in excellent yields. The synthesis is realizable in a one‐pot manner procedure directly from ketones and acetylene.

Modelling pheromone anemotaxis for biosecurity surveillance: Moth movement patterns reveal a downwind component of anemotaxis

Insect pheromone traps are becoming an increasingly important tool in biosecurity and pest surveillance, alerting managers to the presence of unwanted organisms. To expand the role of these traps beyond their present sentinel role, it is necessary to develop reliable operational models of local insect dispersal. Following the detection of an insect incursion using a pheromone trap, such models could simulate the dispersal of the insect from its emergence site to the point of detection, enabling biosecurity managers to estimate the most likely proximal source of the incursion. An individual-based moth movement model was developed to simulate observed patterns of moth movement in response to the presence or absence of a pheromone. Using parameters derived from a genetic algorithm, it was possible to fit a model based on the three behavioural components (upwind, upwind with zigzags and casting) described in insect anemotaxis theory to a subset of observed movement patterns (0–135° to the wind), but not to the whole spectrum of movement patterns. It appears that current insect anemotaxis theory is missing a downwind flight component. Whilst the frequency of downwind movements is small; their ground speed could lead to significant downwind displacement, having a disproportionately strong influence on a moth movement model, and hence projections of the likely source or target locations.

Scent chemistry and pollinator attraction in the deceptive trap flowers of Ceropegia dolichophylla

Ceropegia species (Apocynaceae, Asclepiadoideae) have pitfall flowers and are pollinated by small flies through deception. It has been suggested that these flies are attracted by floral scent. However, the scent that is emitted from Ceropegia flowers has not been studied using headspace and gas chromatography mass spectrometry methods. It has also been unclear whether or not the flowers are mimics of particular models that attract flies. In the present study, we determined the composition as well as the spatial and temporal patterns of floral scent emitted by C. dolichophylla. Furthermore, we determined the pollinators in the native (China) and non-native (Germany) range of this species, and tested the capability of the floral scent to attract flies in the non-native range. Our data demonstrate that the floral scent, which is emitted from morning until evening, primarily from the tips of the corolla lobes, consists mainly of spiroacetals and aliphatic compounds. Milichiid flies were common visitors/pollinators in the native as well as non-native range, and were attracted by floral scent in bioassays performed in the non-native range. The compounds emitted by C. dolichophylla are unusual for flowers, but are well known from insect pheromones and occur in the glandular secretions of insects. The milichiid flies that visit and pollinate the flowers are kleptoparasites that feed on the prey (haemolymph or other secretions) of predatory arthropods, e.g. spiders, to which they are attracted by scent. Our data thus suggest that the floral scent of C. dolichophylla mimics the feeding sites of kleptoparasitic flies.

BIOENGINEERING Chemical detection linked to live cells and robotic mannequin

Researchers in Japan have built what is arguably the most eccentric chemical sensor to date: a living cell whose membrane is embedded with insect pheromone receptors. When activated by a whiff of pheromone, the receptors produce a current that causes a robotic mannequin to shake its head ( Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.1004334107). Equipped with different receptors, this biorobotic sensor prototype could one day have applications in environmental and health monitoring. The proof-of-principle apparatus, which includes a frog oocyte (egg) containing silkworm, fruit fly, or moth odorant receptors, was developed by a team of researchers led by Shoji Takeuchi, a bioengineer at the University of Tokyo. The sensor—which delivers an electrical current that is used for data readout and also, in a bit of fun, to control a mannequin—can detect a handful of molecules present in only parts per billion in a solution. It can also distinguish slight differences in double-bond isomerism or ...

ChemInform Abstract: Acetylcyclopropane as a Five-Carbon Building Block in the Synthesis of Some Acetogenin Insect Pheromones.

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ChemInform Abstract: Synthesis of (Z)-2-Nonenyl Propionate (IV), an Erroneously Identified Insect Pheromone Component of Flour Beetle, Tribolium castaneum.

ChemInform Abstract: Synthesis of (Z)-2-Nonenyl Propionate (IV), an Erroneously Identified Insect Pheromone Component of Flour Beetle, Tribolium castaneum.