Natural Pheromone Research Articles

Identification and field bioassays of the sex pheromone of Eurytoma maslovskii (Hymenoptera: Eurytomidae)

Long-range sex pheromones are generally considered to be a main cue for mate recognition in the order Hymenoptera. Although considerable attention has been given to the identification of semiochemicals in the superfamily Chalcidoidea, which comprises 19 families, no study has identified active components in a field bioassay. We herein report the sensitive and selective pheromone communication system of the Korean apricot wasp, Eurytoma maslovskii (Eurytomidae), whose larvae feed on Prunus mume seeds. Using gas chromatography coupled with electroantennographic detection (GC-EAD) and mass spectrometry (GC-MS), we detected 2,10-dimethyldodecyl propionate and 2,8-dimethyldecyl propionate in thoracic extracts of female E. maslovskii at a ratio of 8:2 as the active pheromone components. Field experiments showed that the attractive effect of the two compounds is highly enantioselective. Racemic 2,10-dimethyldodecyl propionate and 2,8-dimethyldecyl propionate were not attractive to E. maslovskii males. In bioassays with single enantiomers, the (2 S,10 R)-enantiomer was highly attractive to male wasps, and the (2 S,8 S)-enantiomer was also attractive, although to a lesser degree. No synergistic effect between (2 S,10 R)- and (2 S,8 S)-enantiomers was identified, and the (2 S,10 R)-enantiomer alone caught significantly more males than the natural pheromone extracts. The addition of other enantiomers to the (2 S,10 R)-isomer significantly decreased the attraction of conspecific males. In addition, a very low dose of synthetic pheromone attracted conspecific males, showing that both female signaling and male response traits may have evolved to contribute to species-specific sexual communication in this species.

Female-Produced Sex Pheromone of Tetrastichus planipennisi, a Parasitoid Introduced for Biological Control of the Invasive Emerald Ash Borer, Agrilus planipennis.

The Asian eulophid wasp Tetrastichus planipennisi is being released in North America as a biocontrol agent for the emerald ash borer (Agrilus planipennis), a very destructive invasive buprestid beetle that is devastating ash trees (Fraxinus spp.). We identified, synthesized, and tested a female-produced sex pheromone for the wasp. The key component eliciting behavioral responses from male wasps in flight tunnel bioassays was identified as (6S,10S)-(2E,4E,8E)-4,6,8,10-tetramethyltrideca-2,4,8-triene. Female specificity was demonstrated by gas chromatographic (GC) comparison of male and female volatile emissions and whole body extracts. The identification was aided by coupled gas chromatography/mass spectrometry analysis, microchemical reactions, NMR, GC analyses with a chiral stationary phase column, and matching GC retention times and mass spectra with those of synthetic standards. The tetramethyl-triene hydrocarbon was synthesized as a mixture of two enantiomeric pairs of diastereomers, and as the pure insect-produced stereoisomer. In flight-tunnel bioassays, males responded to both the natural pheromone and the chiral synthetic material by upwind flight and landing on the source. In contrast, the mixture of four stereoisomers was not attractive, indicating that one or more of the "unnatural" stereoisomers antagonized attraction. Field trials, using yellow pan traps baited with natural pheromone, captured significantly more male wasps than control traps over a four week trial. The identified pheromone could increase the efficiency and specificity of the current detection methods for Tetrastichus planipennisi and aid in the determination of parasitoid establishment at release sites.

Trail pheromone modulates subjective reward evaluation in Argentine ants.

The Argentine ant, Linepithema humile, is native to South America but has become one of the most invasive species in the world. These ants heavily rely on trail pheromones for foraging, and previous studies have focused on such signals to develop a strategy for chemical control. Here, we studied the effects of pre-exposure to the trail pheromone on sugar acceptance and olfactory learning in Argentine ants. We used the synthetic trail pheromone component (Z)-9-hexadecenal, which triggers the same attraction and trail-following behavior as the natural trail pheromone. We found that pre-exposure to (Z)-9-hexadecenal increases the acceptance of sucrose solutions of different concentrations, thus changing the ants' subjective evaluation of a food reward. However, although ants learned to associate an odor with a sucrose reward, pheromone pre-exposure affected neither the learning nor the mid-term memory of the odor-reward association. Taking into account the importance of the Argentine ant as a pest and invasive organism, our results highlight the importance of pheromonal cues in resource evaluation, a fact that could be useful in control strategies implemented for this species.

Male-Produced Aggregation Pheromone of the Sloe Bug, Dolycoris baccarum L. (Hemiptera: Heteroptera: Pentatomidae).

The sloe bug, Dolycoris baccarum L. (Hemiptera: Heteroptera: Pentatomidae), is a Palearctic species and an important polyphagous pest. Previous studies have reported that male D. baccarum produce an aggregation pheromone, to which conspecific adults of both sexes respond. We used solid-phase microextraction (SPME) to collect volatiles released by sexually mature virgin males and females, and identified potential components of the male-produced aggregation pheromone. Analysis of the SPME samples by gas chromatography-mass spectrometry (GC-MS) revealed three male-specific components, α-bisabolol, trans-α-bergamotene, and β-bisabolene, at a ratio of 100:10:3. A field trapping experiment showed that (±)-α-bisabolol alone attracted D. baccarum adults, and it was synergized by trans-α-bergamotene, but not (S)-β-bisabolene. However, neither trans-α-bergamotene nor (S)-β-bisabolene was attractive individually. A binary blend of (±)-α-bisabolol and trans-α-bergamotene in a 10:1 ratio was less attractive than caged live males, suggesting that further study is necessary to determine the absolute configuration or steroisomeric composition of the natural pheromone components. This is the first report of α-bisabolol and trans-α-bergamotene as semiochemicals among Pentatomidae, and the first to identify α-bisabolol from insects.

Functional unification of sex pheromone-receptive glomeruli in the invasive Turkestan cockroach derived from the genus Periplaneta

Female Periplaneta americana cockroaches emit two cooperatively working pheromone components, periplanone-B (PB) as a long-range attractant and periplanone-A (PA) as a short-range arrestant, and males develop enlarged glomeruli for processing them separately in the first-order olfactory center. Using intracellular recordings and neuronal labelings, we found that the Turkestan cockroach, Blatta lateralis, which is phylogenetically close to P. americana but having adapted to inground habitats, has an extraordinary large glomerulus. This is caused by drastic enlargement of the PB-responsive glomerulus but not the PA-responsive glomerulus during the late nymphal stage. The output neuron from the macroglomerulus is sensitive to both PA and PB, at a dose of only 0.1 fg. Nevertheless, B. lateralis males never exhibited courtship rituals in response to the presentation of periplanones or natural sex pheromone but exhibited courtship rituals in response to antennal contact with females. Our findings indicate that the unique behavioral ecology and habitats of B. lateralis are related to the functional unification of the pheromone processing system, opposite to the functional differentiation that often underlies species diversification.

Pheromone synthesis. Part 264: Synthesis of the core 3-oxabicyclo[3.3.0]octane structures of gomadalactones A, B and C, the components of the contact sex pheromone of the white-spotted longicorn beetle, Anoplophora malasiaca

The core bicyclic cyclopentanelactone structures of gomadalactones A, B and C with α-hydroxyketone system were synthesized from (R)-pulegone, employing deconjugation of an α,β-unsaturated lactone as the key step. Comparison of the CD spectra of the synthetic compounds with those of the natural products confirmed the absolute configuration of the natural pheromone components as proposed in 2007. X-ray crystallographic analysis of the model compound of gomadalactone B core structure was carried out.

The Effect of Female Pheromone on the Functional State of Young Men

Introduction. Modern studies show that the presentation of smell of female mice before male mice infection with the influenza virus activates non-specific immune response which protects male mice from infection of the upper respiratory tract and reducing their mortality. However the researches have not studied the adaptive effect of female sexual pheromone on men.The aim of this work was to study the effect of odor of synthetic analogue of natural female pheromone (Osmopherine) on the functional state of young men often suffering from acute respiratory infections (ARI) and allergic diseases.Materials and methods. We studied four-week effect of Osmopherine on the psycho-emotional state, the concentration of hormones (testosterone, cortisol) and immunoglobulins (sIgA, total IgG), the percentage of leukocytes in the blood and the individual smell of young men, who have ARI more than 4 times a year or an allergic disease. The study involved 117 boys aged 19–23 years. Olfactory testing of individual odor samples of young men was carried out by young women (n = 32) aged 18–22 years.Results. It was found that female pheromone has a positive effect on the functional state of men with different immune systems. However its effect is caused by the pathogenesis of the disease. Application of Osmopherine in men with reduced immunity causes an increased activity, improved mood, reduced anxiety and stabilized testosterone level. Men with allergic diseases did not have the same effect. A significant 2 times decrease in the content of eosinophils was found, which indirectly indicates the decrease in the activity of the delayed phase of allergic reactions of immediate type.Conclusion. The immune system functions according to its internal laws and programs. However its activity for the benefit of the whole body is integrated and regulated by the nervous and endocrine systems. Therefore modulating effect on the functioning of the immune system can be mediated through the presentation of pheromones.

Mg-Catalyzed OPPenauer Oxidation—Application to the Flow Synthesis of a Natural Pheromone

The so-called OPPenauer oxidation is well known for its ability to oxidize valuable alcohols into their corresponding aldehydes or ketones. In particular, it has proven to be extremely successful in the oxidation of sterols. On the other hand, its application—in the original formulation—to the obtainment of ketones outside the field of steroids met a more limited success because of less favorable thermodynamics and side reactions. To circumvent these issues, the first example of magnesium-catalyzed OPPenauer oxidation is described. The oxidation of primary and secondary alcohol was performed using pivaldehyde or bromaldehyde as the oxidant and cheap magnesium tert-butoxide as catalyst. Decent to excellent yields were obtained using reasonable catalytic charge. The synthesis of a pheromone stemming from the Rhynchophorus ferrugineus was obtained by tandem addition-oxidation of 2-methylpentanal and the process was successfully applied to continuous flow on a multigram scale.

Capture of Prionus laticollis (Drury, 1773) (Coleoptera: Cerambycidae) in New York, U.S.A., in traps baited with the sex pheromone of Prionus californicus Motschulsky, 1845

Prionus laticollis (Drury, 1773) (Coleoptera: Cerambycidae), the broad necked root borer, is a known pest of numerous woody plant species. Larvae feed on and can severely damage roots and lower trunks, causing decline or structural weakness. It has been documented infesting commercial apple plantings in New York and New England, notably in recent years when infestations caused tree decline and death in an established orchard in Northport, New York. As with other Prionus species found in the U.S.A., males are attracted to all four isomers of 3,5-dimethyldodecanoic acid, the female-produced sex pheromone of the related species, P. californicus Motschulsky, 1845. We conducted field trials using a commercial mix of this pheromone to monitor occurrence, phenology and abundance of P. laticollis in several orchard and mixed hardwood habitats in New York from 2010–2015. Male beetles were readily captured in all locations using pitfall traps baited with a commercial synthetic pheromone blend of all possible isomers, with maximum seasonal totals of 112–145 beetles per site. The first beetles were captured from 19 June to 4 July, corresponding to 436–691 degree-days (base 10°C) from 1 January, depending on year and location. A 2012 lure comparison between the single-isomer natural pheromone and the four-isomer blend showed no significant differences in numbers of beetles captured. Beetle catch generally peaked within two weeks of initial flight each year, with most activity occurring throughout July. A distinct decrease in beetle numbers was noted at the Geneva location over the course of repeated annual trapping trials, possibly reflecting a negative impact on the local population.

Attraction Pheromone of The Benthic Diatom Seminavis robusta: Studies on Structure-Activity Relationships.

Recently the first pheromone of a marine diatom was identified to be the diketopiperazine (S,S)-diproline. This compound facilitates attraction between mating partners in the benthic diatom Seminavis robusta. Interestingly, sexualized S. robusta cells are attracted to both the natural pheromone (S,S)-diproline as well as to its enantiomer (R,R)-diproline. Usually stereospecificity is a prerequisite for successful substrate-receptor interactions, and especially pheromone perception is often highly enantioselective. Here we introduce a structure-activity relationship study, to learn more about the principles of pheromone reception in diatoms. We analyzed the activity of nine different diketopiperazines in attraction and interference assays. The pheromone diproline itself, as well as a pipecolic acid derived diketopiperazine with two expanded aliphatic ring systems, showed the highest attractivity. Hydroxylatoin of the aliphatic rings abolished any bioactivity. Diketopiperazines derived from acyclic amino acids were not attrative as well. All stereoisomers of boththe diproline and the pipecolic acid derived diketopiperazine were purified by enantioselective high-performance liquid chromatography, and application in bioactivity tests confirmed that attraction pheromone perception in this diatom is indeed not stereospecific. However, the lack of activity of diketopiperazines derived from acyclic amino acids suggests a specificitythat preventsmisguidance to sources of other naturally occurring diketopiperazines.

The directed evolution of ligand specificity in a GPCR and the unequal contributions of efficacy and affinity

G protein-coupled receptors (GPCRs) must discriminate between hundreds of related signal molecules. In order to better understand how GPCR specificity can arise from a common promiscuous ancestor, we used laboratory evolution to invert the specificity of the Saccharomyces cerevisiae mating receptor Ste2. This GPCR normally responds weakly to the pheromone of the related species Kluyveromyces lactis, though we previously showed that mutation N216S is sufficient to make this receptor promiscuous. Here, we found that three additional substitutions, A265T, Y266F and P290Q, can act together to confer a novel specificity for K. lactis pheromone. Unlike wild-type Ste2, this new variant does not rely on differences in binding affinity to discriminate against its non-preferred ligand. Instead, the mutation P290Q is critical for suppressing the efficacy of the native pheromone. These two alternative methods of ligand discrimination were mapped to specific amino acid positions on the peptide pheromones. Our work demonstrates that changes in ligand efficacy can drive changes in GPCR specificity, thus obviating the need for extensive binding pocket re-modeling.

Pheromone synthesis. Part 262: Determination of the absolute configuration of the female sex pheromone [(1S,2S)-(−)-(1,2-dimethyl-3-methylenecyclopentyl) acetaldehyde] of the pineapple mealybug (Dysmicoccus brevipes) by synthesis coupled with X-ray analysis

The enantiomers of (anti-1,2-dimethyl-3-methylenecyclopentyl)acetaldehyde, one of which is the female sex pheromone of the pineapple mealybug (Dysmicoccus brevipes), were synthesized. Chirality was introduced by means of lipase-catalyzed asymmetric acetylation of (±)-2,3-dimethyl-2-cyclopenten-l-ol. X-ray analysis of (−)-camphanate ester of (1S,2S)-(−)-2-(1,2-dimethyl-3-methylenecyclopentyl)ethanol confirmed its (1S,2S)-absolute configuration. The natural pheromone was identified with the (1S,2S)-aldehyde by comparing the specific rotation, enantioselective GC retention time and pheromone activity.

Evaluation of clinicopathological features in cats with chronic gastrointestinal signs.

Food-responsive enteropathy (FRE), idiopathic inflammatory bowel disease (IBD), and alimentary tract lymphoma (AL) are often the remaining differentials for cats presenting with chronic gastrointestinal (GI) signs. Differential diagnosis is further complicated by overlapping clinicopathological features and histopathological changes, however. In this study we describe the clinical presentation of cats with chronic GI signs secondary to FRE, IBD, and AL, and evaluate possible associations between clinical, clinicopathological, ultrasonographic findings and diagnosis. The medical records of client-owned cats with chronic GI signs secondary to FRE, IBD, and AL were reviewed. Univariate and multivariate logistic regression models and receiver-operating characteristic curve (ROC) analysis were used for testing the data. Of the 56 cats included in the study, 22 were diagnosed with FRE (mean age, 70 months ± 49), 17 with IBD (mean age, 101 months ± 40), and 17 with AL (mean age, 122 months ± 45). Cats with FRE were younger and presented more often with diarrhea and less frequently with muscle wasting than cats with IBD or AL. In cats with AL, serum cobalamin levels were lower than in those with FRE or IBD (239 ± 190 ng/L vs. 762 ± 408 ng/L and 625 ± 443 ng/L, respectively) and folate levels were higher than in cats with IBD (18.2 ± 4.2 μg/L vs. 9.1 ± 4.7 μg/L, respectively). Multivariate/ROC curve analysis showed increased values of BUN (sensitivity 100, specificity 29.4, criterion >37 mg/dl) and serum folate (sensitivity 80, specificity 100, criterion >15.6 μg/L) and reduced values of cobalamin (sensitivity 100, specificity 62.5, criterion ≤540 ng/L), which suggested a diagnosis of AL versus IBD. Some clinicopathological features evaluated at diagnosis might suggest AL; however, because differentiating AL from IBD is often difficult, definitive diagnosis should be based on invasive diagnostic workup.

Variación en la captura de machos de Neoleucinodes elegantalis Guenée (Lepidoptera: Crambidae) usando feromonas sexuales comerciales en tres hospederos solanáceos

Neoleucinodes elegantalis Guenée (Lepidoptera: Crambidae) represents the most damaging pest of the Solanaceae family. Current studies have demonstrated that the species has differentiated into four races according to variations in female genitalia, wing morphometrics and sequencing of the cytochrome Oxydase (CO1) mitochondrial gene. The number of males captured in Colombia and Ecuador were registered using traps baited with two sex pheromone: Neolegantol ® and P228. These pheromones were synthesized using natural female pheromones collected in Solanum lycopersicum L. plantations in Venezuela. In Colombia, the number of male catches was significantly higher for Neolegantol ® than for P228 and this number was significantly higher on S. lycopersicum followed by S. quitoense and S. betaceum. The haplotype net obtained with the CO1 gene produced two main clusters: one cluster was comprised by specimens from S. lycopersicum and S. quitoense plants (both with medium sized female genitalia) and the other cluster by specimens from S. betaceum (large sized genitalia). The Neolegantol® pheromone was also tested in Ecuador, however, insignificant number of males were attracted. Results suggest that pheromone composition or concentration, host biotypes and geographic location are relevant to monitor populations of N. elegantalis. Further studies of the species should concentrate on establishing the pheromone composition and concentration among the four biotypes.

Olfactometer Responses of Plum Curculio Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae) to Host Plant Volatiles, Synthetic Grandisoic Acid, and Live Conspecifics

The plum curculio Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae) is a major pest of pome and stone fruit, but will also attack other fruits. Males produce the aggregation pheromone grandisoic acid; emitting only the (+)-enantiomer which is attractive to both sexes of the univoltine and multivoltine strains, while the synthetic racemic mixture contains optical isomers with equal amounts of (+)- and (−)-enantiomers. Synergy between odours can increase trap captures and improve monitoring techniques, therefore tests were performed in a dual-choice olfactometer with odours attractive to plum curculios according to literature to determine 1) under what physiological conditions (mating status, age, starvation period) these odours are attractive or repulsive, 2) if the (+)-enantiomer or the odour of live males synergizes with host plant volatiles, and 3) if there is a difference in response between plum curculio strains. Females were exposed to: benzaldehyde; trans-2-hexenal; apples; extracts of: plums, apples, blueberries; grandisoic acid; and live males. Plum essence was found to be the most attractive host-plant odour for both immature and mature virgin females, and immature whole apples were attractive to starved females, while trans-2-hexenal, McIntosh apple essence, benzaldehyde along with the combination of benzaldehyde and plume essence was found to be repulsive. Starvation, age, and mated status all influence response to odours. No synergistic or additive affects were observed between any of the odour combinations tested, including the combination of both the natural and synthetic pheromone and plum essence or apples.

Synthetic Co-Attractants of the Aggregation Pheromone of the Date Palm Root Borer Oryctes agamemnon.

Laboratory and field investigations to identify and evaluate plant co-attractants of the aggregation pheromone of the date palm pest Oryctes agamemnon are reported. Volatiles emitted by freshly cut palm core and palm core with feeding males, were collected, analyzed by gas chromatography coupled to mass spectrometry and evaluated in olfactometers alone or combined with synthetic pheromone. A collection of palm odor without male effluvia was attractive alone and enhanced attraction to synthetic pheromone in an olfactometer similar to that to a collection of palm odor emitted with feeding males and containing natural pheromone. Behavioral responses to collections of palm volatiles were correlated to the amount of volatiles material in them. Enhancement of the attractiveness of the pheromone was not correlated to chemicals specific to beetle feeding. The chemicals common to the active collections extracts were benzoate esters, mostly ethyl benzoate, anisole derivatives and sesquiterpenes. Blends of the most abundant components of the extracts were evaluated for enhancement of the attractiveness of pheromone (1μg) in olfactometers at 1 or 10μg doses. The mixtures were further evaluated by field trapping in Tunisia at 3-10mg/day using reference (6mg/day) or experimental pheromone formulations. A mixture of ethyl benzoate, 4-methylanisole and farnesol (1:1:1 w/w at 6.5mg/day) enhanced captures in pheromone baited traps in 2014 and 2015 and this mixture was as active as the natural palm bait. The practical prospect of the result for the management for O. agamemnon, and other palm beetles is discussed.

Sex pheromone in the moth Heliothis virescens is produced as a mixture of two pools: de novo and via precursor storage in glycerolipids

Most species of moths use a female-produced volatile sex pheromone, typically produced via de novo fatty acid synthesis in a specialized gland, for communication among mates. While de novo biosynthesis of pheromone (DNP) is rapid, suggesting transient precursor acids, substantial amounts of pheromone precursor (and other) acids are stored, predominantly in triacylglycerols in the pheromone gland. Whether these stored acids are converted to pheromone later or not has been the subject of some debate. Using a tracer/tracee approach, in which we fed female Heliothis virescens U-13C-glucose, we were able to distinguish two pools of pheromone, in which precursors were temporally separated (after and before feeding on labeled glucose): DNP synthesized from a mixed tracer/tracee acetyl CoA pool after feeding, and pheromone made from precursor acids primarily synthesized before feeding, which we call recycled precursor fat pheromone (RPP). DNP titer varied from high (during scotophase) to low (photophase) and with presence/absence of pheromone biosynthesis activating neuropeptide (PBAN), in accord with native pheromone titer previously observed. By contrast, RPP was constant throughout the photoperiod and did not change with PBAN presence/absence. The amount of RPP (6.3–10.3 ng/female) was typically much lower than that of DNP, especially during the scotophase (peak DNP, 105 ng/female). We propose an integral role for stored fats in pheromone biosynthesis, in which they are hydrolyzed and re-esterified throughout the photoperiod, with a small proportion of liberated precursor acyl CoAs being converted to pheromone. During the sexually active period, release of PBAN results in increased flux of glucose (from trehalose) and hydrolyzed acids entering the mitochondria, producing acetyl CoA precursor for de novo fat and pheromone biosynthesis.

Female sex pheromone of Athetis lepigone (Lepidoptera: Noctuidae): Identification and field evaluation

AbstractAthetis lepigone has been recorded in many countries in Europe and Asia, but it had never been documented as an agricultural pest until 2005. For the purpose of using the sex pheromone to control this pest, we conducted a study to identify the sex pheromone of A. lepigone by gas chromatography with an electroantennographic detector (GC‐EAD) and GC coupled with mass spectrometry (GC/MS) analyses. Three pheromone candidates were detected by GC‐EAD analysis in the extracts of the female sex pheromone gland, and two candidates were identified as (Z)‐7‐dodecenyl acetate (Z7‐12:OAc) and (Z)‐9‐tetradecenyl acetate (Z9‐14:OAc) in a ratio of 1:5 by mass spectral analysis of natural pheromone components and dimethyl disulphide adducts. In the field male trapping test, the traps baited with the binary blend captured high number of males, while traps with single component hardly caught males, indicating that the two components are essential for the male attractiveness. In addition, the optimum ratios of Z7‐12:OAc and Z9‐14:OAc were determined as 3:7–7:3, and the best doses for the binary blend (at ratio of 3:7 between Z7‐12:OAc and Z9‐14:OAc) were 0.25–0.5 mg/trap, based on the number of male catches. The identification of a highly attractive sex pheromone will help in developing efficient strategies for monitoring and control of A. lepigone.

Deletion of the Bombyx mori odorant receptor co-receptor (BmOrco) impairs olfactory sensitivity in silkworms

Olfaction plays an essential role in many important insect behaviors such as feeding and reproduction. To detect olfactory stimuli, an odorant receptor co-receptor (Orco) is required. In this study, we deleted the Orco gene in the Lepidopteran model insect, Bombyx mori, using a binary transgene-based clustered regulatory interspaced short palindromic repeats (CRISPR)/Cas9 system. We initially generated somatic mutations in two targeted sites, from which we obtained homozygous mutants with deletion of a 866 base pair sequence. Because of the flight inability of B. mori, we developed a novel method to examine the adult mating behavior. Considering the specialization in larval feeding, we examined food selection behavior in Orco somatic mutants by the walking trail analysis of silkworm position over time. Single sensillum recordings indicated that the antenna of the homozygous mutant was unable to respond to either of the two sex pheromones, bombykol or bombykal. An adult mating behavior assay revealed that the Orco mutant displayed a significantly impaired mating selection behavior in response to natural pheromone released by a wild-type female moth as well as an 11:1 mixture of bombykol/bombykal. The mutants also exhibited a decreased response to bombykol and, similar to wild-type moths, they displayed no response to bombykal. A larval feeding behavior assay revealed that the Orco mutant displayed defective selection for mulberry leaves and different concentrations of the volatile compound cis-jasmone found in mulberry leaves. Deletion of BmOrco severely disrupts the olfactory system, suggesting that BmOrco is indispensable in the olfactory pathway. The approach used for generating somatic and homozygous mutations also highlights a novel method for mutagenesis. This study on BmOrco function provides insights into the insect olfactory system and also provides a paradigm for agroforestry pest control.

Synthesis of the enantiomers of (3Z,9Z)-cis-6,7-epoxy-3,9-octadecadiene, one of the major components of the sex pheromone of Ectropis oblique Prout

Both enantiomers of (3Z,9Z)-cis-6,7-epoxy-3,9-octadecadiene, one of which is the major component of the sex pheromone of Ectropis oblique Prout, were synthesized in 23% overall yield for the (−)-(6S,7R)-enantiomer and 18% yield for the (+)-(6R,7S)-isomer. This protocol uses a sequential regioselective ring-opening strategy and provides a convenient and reliable access to other structurally related insect sex pheromones. Preliminary biological studies revealed that (−)-(6S,7R)-2a was roughly as active as the natural pheromone, while racemic (±)-2 was less bioactive and (+)-2b was much less bioactive.