Natural Pheromone Research Articles

Spotted Lanternflies Respond to Natural Pheromone Lures for Mate-Finding and Oviposition.

Using semiochemicals collected from spotted lanternflies Lycorma delicatula (Hemiptera: Fulgoridae) (SLF) and deployed in the field with circle traps, we demonstrated that SLF responded to SLF pheromones: in particular, this was the case for males while seeking mates and for females while ovipositing. The attractants consisted of SLF body extract emitted from diffuser lures and SLF honeydew on burlap ribbons, collected from heavily infested locations. Traps with attractants were deployed in field sites with very light SLF infestations to avoid competing signals of pre-existing aggregations. The number of SLF equivalents emitted by each diffuser per trapping period was used in a dose-response analysis. Three trees per block received either (1) a control hexane lure and a clean ribbon, (2) a lure containing SLF extract and a clean ribbon, or (3) a lure containing SLF extract and a honeydew-laden ribbon. Ten blocks were sampled three times per week for twelve weeks. We found a significant positive dose-response by males to SLF body extract only in the presence of SLF honeydew, indicating a synergistic effect between honeydew volatiles and body volatiles. This dose-response occurred for five weeks after mating started, after which males no longer responded. Subsequently, females had a significant positive dose-response to SLF extract only in the presence of honeydew when oviposition was their primary activity, continuing for two weeks, suggesting that females may use pheromones to aggregate for oviposition. The extract in the absence of honeydew did not result in a positive dose-response, nor did the hexane control. These findings suggest that SLF respond synergistically to the combination of pheromones present in both SLF honeydew and SLF bodies. Thus, combining key components from both sources may aid the development of semiochemical lures for SLF.

Interaction between females and males grapevine moth Lobesia botrana modifies further mating preference

During reproduction, females may boost their fitness by being selective based on direct material benefits provided by the males, such as nuptial gifts. In Lepidoptera, male provides a spermatophore containing nutrients. However, virgin males produce a bigger spermatophore, containing spermatozoa and nutrients, allowing higher female fertility. Lepidoptera females that could detect the sexual status of males may thus prefer a male without previous mating experience (i.e. a virgin male). This mate selection could be achieved by the use of chemical indices, such as sexual pheromones and cuticular compounds, known to be possibly exchanged during reproduction, and which can be indicators of a previous mating experience and known to be possibly sources of information exchanged. In this study, we experimentally presented Lobesia botrana virgin males with females in order for them to be exposed to females’ natural sexual pheromones or cuticular compounds. 12 or 48 h after the exposure of males to either females’ sexual pheromones or cuticular compounds, these males were confronted to naïve females, which have a choice between them or a virgin non-exposed males. We highlighted that, despite producing a spermatophore of similar volume, all exposed virgin males were less likely to mate with females 12 h after exposure, while after 48 h of exposure this is only the case for virgin males exposed to sexual pheromones. L. botrana females may thus discriminate male sexual experience based on chemical cues (either from cues transferred directly from females to males, or from changes in the cuticular or pheromone males’ profile) indicating past mating experiences. Mating duration was longer for males exposed to sexual pheromones after 12 h only, and for males exposed to cuticular compounds after 48 h only. Pheromones signal might be more persistent over time and seems to more easily gather information for males. The physiological reasoning behind this result still needs to be investigated.

Genetic modules for α-factor pheromone controlled growth regulation of Saccharomyces cerevisiae.

Saccharomyces cerevisiae is a commonly used microorganism in the biotechnological industry. For the industrial heterologous production of compounds, it is of great advantage to work with growth-controllable yeast strains. In our work, we utilized the natural pheromone system of S. cerevisiae and generated a set of different strains possessing an α-pheromone controllable growth behavior. Naturally, the α-factor pheromone is involved in communication between haploid S. cerevisiae cells. Perception of the pheromone initiates several cellular changes, enabling the cells to prepare for an upcoming mating event. We exploited this natural pheromone response system and developed two different plasmid-based modules, in which the target genes, MET15 and FAR1, are under control of the α-factor sensitive FIG1 promoter for a controlled expression in S. cerevisiae. Whereas expression of MET15 led to a growth induction, FAR1 expression inhibited growth. The utilization of low copy number or high copy number plasmids for target gene expression and different concentrations of α-factor allow a finely adjustable control of yeast growth rate.

Studies on the response of normal and irradiated pink bollworm males towards pheromone source

Sterile Insect Technique (SIT) is the right eco-friendly method to overcome the pink bollworm Pectinophora gossypiella (Saunder) menace. In SIT attractiveness of released moths to their natural counterpart is most important as such this ability was examined in our study. For this, newly emerged five virgin female gamma irradiated with 0–250 Gy were used. These females were placed inside small plastic vial provided with aeration and suspended inside the delta traps by providing 10% honey solution. Traps were placed in the field during evening. Moth catches in each trap were counted and removed daily and these observations continued up to 5 days. In a same manner irradiated males were released separately inside the field cage to know its attractiveness to virgin female. The results indicated that attraction of male moths to irradiated virgin females decreased significantly with increasing doses of radiation i.e., at 200 and 250 Gy. The number of males captured per female was greatest on day 2nd due to its peak sexual activity, i.e., 25.60, 23.05, 19.45, 14, 9.4 and 5.9 moths at 0, 50, 100, 150, 150, 200, and 250 Gy, respectively. Gamma radiation also affected the irradiated males to find their natural mates at a higher dose; however, the maximum number of 5.30, 5.95 and 5.10 irradiated male moths were attracted to the natural pheromone secreted by female moths at 50, 100 and 150 Gy respectively, compared to the 6.80 moths at 0 Gy. The results on attractiveness of irradiated male moths towards virgin female-baited traps were considered a good measure of male competitiveness.

Sex Pheromone of the Azalea Mealybug: Absolute Configuration and Kairomonal Activity.

The sex pheromone of the azalea mealybug, Crisicoccus azaleae (Tinsley, 1898) (Hemiptera: Pseudococcidae), includes esters of a methyl-branched medium-chain fatty acid, ethyl and isopropyl (E)-7-methyl-4-nonenoate. These compounds are exceptional among mealybug pheromones, which are commonly monoterpenes. Determination of the absolute configuration is challenging, because both chromatographic and spectrometric separations of stereoisomers of fatty acids with a methyl group distant from the carboxyl group are difficult. To solve this problem, we synthesized the enantiomers via the Johnson-Claisen rearrangement to build (E)-4-alkenoic acid by using (R)- and (S)-3-methylpentanal as chiral blocks, which were readily available from the amino acids L-(+)-alloisoleucine and L-(+)-isoleucine, respectively. Each pure enantiomer, as well as the natural pheromone, was subsequently derivatized with a highly potent chiral labeling reagent used in the Ohrui-Akasaka method. Through NMR spectral comparisons of these derivatives, the absolute configuration of the natural pheromone was determined to be S. Field-trap bioassays showed that male mealybugs were attracted more to (S)-enantiomers and preferred the natural stereochemistry. Moreover, the synthetic pheromones attracted Anagyrus wasps, indicating that the azalea mealybug pheromone has kairomonal activity.

The application of pheromones extracted from Shami goats' male hair and Awassi sheep male wool during the breeding season on LH and Progesterone concentrations in Awassi ewes in Syria.

The efficiency and profitability of animal farming systems are closely linked to the reproductive success of livestock, which requires effective management through biological, hormonal, and nutritional strategies. The "male effect," referring to the influence of male pheromones on female reproductive hormones, offers several benefits. This leads to improved reproductive management, better timing of breeding, and increased fertility rates. Additionally, using natural pheromones provides a non-invasive and sustainable method for managing reproduction, and it can be a cost-effective strategy, reducing the need for expensive hormonal treatments. Incorporating male pheromones into reproductive management practices can thus boost the efficiency and profitability of animal farming systems. The study's objective is to examine the influence of pheromones, extracted from Awassi ram's wool and Shami goat buck's hair, on the secretion of luteinizing hormone (LH) and Progesterone (P4) in Awassi ewes during the breeding season. The pheromones were extracted using a soaking method with dichloromethane as the solvent. The resulting organic extract was then analyzed using a Chromatec-Crystal 5,000 gas chromatography-mass spectrometry device, equipped with a quadrupole mass spectrometer. The experiment was carried out on three equal groups, each consisting of 17 subjects, during the breeding season. In Group I, 15 ml of the ram's wool extract was applied to a piece of gauze and placed in a specially designed mask that was attached directly to the nose. In the second group, a similar procedure was followed using 15 ml of the buck's hair extract. The third group consisted of Awassi rams. The LH assay was conducted immediately before the treatment and again at 1, 10, and 20 hours post-treatment, and after 5 and 30 days of treatment to assess P4 levels. The study found that pheromones from Awassi rams and Shami goat bucks significantly increased the levels of LH and P4 in female Awassi sheep. The study concludes that the pheromones extracted from the wool of rams and Shami goat bucks can stimulate the response of female Awassi sheep. This finding opens up the possibility of using these pheromones in the reproductive management of female Awassi sheep.

Natural pesticides and pheromones for natural pest control in sustainable agriculture

The use of synthetic pheromones and natural pesticides has proven to be a viable alternative to the use of pesticides. The pest control technique using pheromones consists of interfering with the reproduction of insects through sexual confusion or attracting them to a trap through mass collection.

'Speed-ageing' of human skin in serum-free organ culture exvivo: An instructive novel assay for preclinical human skin ageing research demonstrates senolytic effects of caffeine and 2,5-dimethylpyrazine.

Preclinical human skin ageing research has been limited by the paucity of instructive and clinically relevant models. In this pilot study, we report that healthy human skin of different age groups undergoes extremely accelerated ageing within only 3 days, if organ-cultured in a defined serum-free medium. Quantitative (immuno-)histomorphometry documented this unexpected exvivo phenotype on the basis of ageing-associated biomarkers: the epidermis showed significantly reduced rete ridges and keratinocyte proliferation, sirtuin-1, MTCO1 and collagen 17a1 protein levels; this contrasted with significantly increased expression of the DNA-damage marker, γH2A.X. In the dermis, collagen 1 and 3 and hyaluronic acid content were significantly reduced compared to Day 0 skin. qRT-PCR of whole skin RNA extracts also showed up-regulated mRNA levels of several (inflamm-) ageing biomarkers (MMP-1, -2, -3, -9; IL6, IL8, CXCL10 and CDKN1). Caffeine, a methylxanthine with recognized anti-ageing properties, counteracted the dermal collagen 1 and 3 reduction, the epidermal accumulation of γH2A.X, and the up-regulation of CXCL10, IL6, IL8, MMP2 and CDKN1. Finally, we present novel anti-ageing effects of topical 2,5-dimethylpyrazine, a natural pheromone TRPM5 ion channel activator. Thus, this instructive, clinically relevant "speed-ageing" assay provides a simple, but powerful new research tool for dissecting skin ageing and rejuvenation, and is well-suited to identify novel anti-ageing actives directly in the human target organ.

Vittatalactone is the Male-Produced Aggregation Pheromone of the Western Striped Cucumber Beetle, Acalymma trivittatum.

We found that vittatalactone, specifically (3R,4R)-3-methyl-4-[(1S,3S,5S)-1,3,5,7-tetramethyloctyl]oxetan-2-one, is the male-produced aggregation pheromone of the western striped cucumber beetle, Acalymma trivittatum (Mannerheim), as was previously shown for the striped cucumber beetle, Acalymma vittatum (F.) (Coleoptera: Chrysomelidae). A synthetic mixture containing 9% of the authentic natural pheromone, is attractive to both sexes of both species in the field, as demonstrated by trapping using baited and unbaited sticky panels in California and earlier in Maryland. Females of both species do not produce detectable vittatalactone. This finding expands the usefulness of the synthetic vittatalactone mixture for pest management throughout the range of both A. vittatum and A. trivittatum. Development of vittatalactone time-release formulations combined with cucurbitacin feeding stimulants offer the potential for selective and environmentally-friendly cucurbit pest management tactics.

Behavioural and Electrophysiological Response of Anastrepha fraterculus (Diptera: Tephritidae) to a γ-Lactone Synthetic Semiochemical.

Attractants are a powerful tool for pest management. The lack of specific attractants for the South American fruit fly, Anastrepha fraterculus, a complex of cryptic species of great economic importance in South America, makes it difficult to monitor the pest in the field. The γ-lactone male sex and aggregation pheromones of several Anastrepha species, naturally released in a 7:3 epianastrephin to anastrephin ratio, and a structurally related naturally occurring γ-lactone ((±)-trans-tetrahydroactinidiolide) with gem-dimethyl groups (dimethyl) at C(4), were evaluated as potential attractants of this species. Different age and mating conditions of A. fraterculus males and females were evaluated during electroantennography (EAG) and field cage experiments in which polymeric lures were deployed to contain 100 mg of attractant. Epianastrephin and dimethyl were EAG+ for all fly conditions, with epianastrephin eliciting the highest response for both sexes and immature flies showing greater responsiveness than mature flies. In the field cage experiments, immature flies were only attracted to leks; virgin females were attracted to leks, dimethyl, and both epianastrephin-anastrephin formulations (95 and 70 wt.% epianastrephin); mature-mated males were attracted to leks, dimethyl and 70 wt.% epianastrephin; and mature-mated females were only attracted to leks. Our bioassays showed a promising performance of the analog dimethyl since it elicited the same response as epianastrephin, requires fewer steps to synthesize, and contains one less chiral center than the natural pheromones. The attraction to leks was recorded for all mating conditions and ages of flies and suggests that air-borne volatiles of calling males contain cues that could act as sensory traps. The addition of any of these compounds in the synthetic attractants may result in a greater attraction and thus deserves further evaluation. Dose-response experiments will provide additional information to move a step forward and validate the results obtained in open-field conditions.

Male sex pheromone in the parasitoid wasp Nasonia longicornis: Chemical and behavioral analyses

The use of sex pheromones for the attraction of potential mating partners is widespread in insects. Species-specificity of these chemical signals is essential, particularly in closely related species with overlapping habitats. In parasitoid wasps of the genus Nasonia, it is the males that produce sex pheromones in their rectal vesicles. The genus consists of four species: N. vitripennis (Nv), N. giraulti (Ng), N. oneida (No), and N. longicornis (Nl). The cosmopolitan species Nv is sympatric with Ng and No in eastern North America and with Nl in the west. Interspecific courtship is common in Nasonia although hybridization is prevented in most combinations by Wolbachia-mediated cytoplasmic incompatibility. The pheromone of Nv males differs from all Nasonia congeners by an additional component that is believed to ensure precopulatory isolation from the sympatric congeners. Detailed investigations on these interactions, however, exist only for the species combination Nv/Ng. Here, we report the results of chemical and behavioral investigations on the sex pheromone of Nl males. The pheromone consists of (4R,5S)-5-hydroxy-4-decanolide (RS) and 4-methylquinazoline (MQ) as a minor component which are produced only after eclosion. Pheromone titers peaked 2 days after eclosion and remained constant on day three. The pheromone is deposited by abdomen dipping which males increasingly exhibited after mating or brief contact with a female. The presence of hosts containing females about to emerge did not increase marking behavior. Site fidelity of males at their own pheromone markings is mediated by MQ. Both natural and synthetic pheromone attracted virgin but not mated females and both RS and MQ are required for female attraction. Females collected during emergence from the host responded likewise to the pheromone and 84% of them produced mixed-sex offspring showing that most of them emerge unmated. Nl females preferred pheromone extract from conspecific males to extract from Nv males, and the addition of the Nv-specific component (4R,5R)-5-hydroxy-4-decanolide (RR) to the Nl pheromone made them unresponsive. The present study demonstrates that Nl uses the male sex pheromone in a similar way as previously shown for Nv and Ng. Furthermore, it shows that Nl females use the Nv-specific pheromone component RR to avoid costly sexual interactions with Nv males in regions of sympatry.

The effectiveness of tomato leaf miner control by disorientation in greenhouses

The article presents the results of a study of the effectiveness of the biological control method of the tomato leaf miner Tuta absoluta by the disorientation method using synthetic sexual pheromones of the pest in greenhouses with tomato grown. The effectiveness of two preparative forms of lures: rubber rings and rubber stoppers which contain the similar compositions of the synthetic sex pheromone of the tomato leaf miner – acetate E3, Z8, Z11-tetradecatriene-1-ola, at a dosage of 15 mg/ lure, was evaluated. It was managed to disrupt the orientation of males in an enclosed space and reduce the influence of the natural pheromone of females on their attraction by using synthetic sexual pheromones of Tuta absoluta. During the study, the effectiveness of the method ranged from 50 to 95%. In greenhouses, the disorientation method allowed to reduce the number of tomato fruits damaged by tomato leaf miner caterpillars by up to 12%, as well as to improve the quality of the crop by up to 30%.

Morphofunctional features of ovaries in repair pigs after stimulation with a preparation of natural sexual pheromones of a boar

Purpose: development of a new way to obtain a drug of natural genital pheromones of boar, and its approbation in production conditions.Materials and methods. A method of manufacturing a drug of natural genital phargs, including grinding of testicles, obtained from half-arms, incubated homogenizates at a temperature of 37-39 ° C for 50-60 min, adding inkubat urine of semi-cream boars and distillation of the mixture in the rotary evaporator R-213B to the urine incubate. The finished preparation was a transparent liquid of a yellowish shade with a specific smell. Checking the drug on pigs showed its harmlessness, clinical parameters and general hematological indicators in animals after treatment with the drug were within physiological boundaries.Results. In the scientific and production experiment, it was established that after stimulation of 5-month-old impaired repair pigs with a preparation in a dose of 0.5 ml / goal twice a day, sexual ripening has occurred at a 178-day age, which was 6 days before compared to Pilts stimulated by a synthetic analogue of the Formon Sidor (Germany's production) and 14 days earlier than in the pigs of the control group. It was found that pigs treated with the preparation made for 20 days of experiment in the blood contained more estradiol-17β (81.3 ± 4.0 pmol / l) and progesterone (37.7 ± 2.5 nmol / l) than Sidor stimulated pigs (75.7 ± 3.5 pmol / l; 31.1 ± 2.0 nmol / l) and in control animals (64.4 ±, 1 pmol / l; 28.1 ± 2.0 mol / l). The drug has a positive impact on the development of ovaries. In the pigs after stimulation in the 8-month-old age, the mass indicators, volume, linear parameters of the ovaries, as well as the number of follicles and the yellow bodies of the past sex cycle exceeded those in the control animals and pigs undergoing stimulation by Sidor.Conclusion. Research suggests that the method developed by us allows us to obtain a natural genital cartridge pheromone preparation with high biological activity. As a natural stimulator, sex pheromones through olfactory analyzers have a stimulating effect on the relevant cerebral centers and through them to the hypothalamic-pituitary complex, which activates the growth and hormonal activity of ovaries.

A Highly Selective and Sensitive Chiral Derivatization Method for High- Performance Liquid Chromatographic Determination of the Stereoisomer Composition of Natural Products With Chiral Branched Alkyl Chains.

In the study of chiral biologically active compounds such as pheromones, the analysis of the stereoisomer composition is essential to gain more insight into their stereochemical diversity, which affects the pheromone communication channels and therefore the diversification of species. This mini-review summarizes the development of fluorescence derivatization reagents for high-performance liquid chromatographic (HPLC) determination of the absolute configuration and stereoisomer composition of natural products with a chiral branched alkyl chain. The diastereomeric separation of anteiso fatty acids bearing a branched methyl group up to the C-26 position was achieved by reversed-phase HPLC under very low column temperature conditions using (1S,2S)-2-(2,3-anthracenedicarboximido)cyclohexanol as a derivatization reagent, enabling fluorescent detection of these compounds at femtomole levels. This method was also applicable to chiral alcohols and amines with chiral branched methyl groups using similar reagents containing a carboxyl group. These reagents were successfully applied to determine the absolute configurations and stereoisomer composition of the chiral alkyl chain of natural compounds including some insect pheromones, miyakosyne A, and plakoside A. The combination of these reagents and two-dimensional HPLC constitutes a very powerful tool for the analysis of the stereoisomers of natural crude samples. Furthermore, the analysis of some natural bioactive substances using this method demonstrated that natural substances are not always optically pure, consisting instead of stereoisomer mixtures exhibiting stronger activity than optically pure enantiomers. These results cast doubts on the concept of biological homochirality and demonstrate that natural pheromones do not always show the highest activity among all stereoisomers.

Circadian rhythms of insect pheromone titer, calling, emission, and response: a review.

Many insect species have circadian rhythms of pheromone production/titer, calling, emission, and response that are involved in intraspecific communication and impact pest management practices. Rhythms of pheromone biosynthesis, most studied in moths affecting forestry and agriculture, contribute to a periodicity of pheromone concentration or titer within glands or hemolymph. Calling rhythms by the pheromone-emitting sex are physical movements (pumping, vibrating wings) that aid in release and dispersion of the volatile pheromone components attractive to the opposite conspecific sex or both sexes. Circadian rhythms of emission of pheromone also occur as a result of an interaction between calling and the titer of pheromone available for release. Responding individuals usually show a coincidental rhythm of dispersal flight while seeking pheromone plumes in which, by orienting upwind, the insects find mates or food resources. However, some species begin searching an hour or more before the emitting sex initiates calling and emission, which benefits mass trapping control programs because the baited traps do not compete initially with natural pheromone sources. In our review, data of daily rhythms of moths and other insects were extracted from the literature by screen capture software to calculate mean time of activity and standard deviation and fit to normal curves. These methods are illustrated for various insects and as a basis for discussion of interactions of pheromonal circadian rhythms of the well-studied gypsy moth Lymantria dispar, spruce budworm moth Choristoneura fumiferana, turnip moth Agrotis segetum, and cabbage looper moth Trichoplusia ni. The various circadian rhythms are discussed in relation to application of species-specific sex and aggregation pheromones for benign biological control and management of pest insects.

Small-molecule mimicry hunting strategy in the imperial cone snail, Conus imperialis.

Venomous animals hunt using bioactive peptides, but relatively little is known about venom small molecules and the resulting complex hunting behaviors. Here, we explored the specialized metabolites from the venom of the worm-hunting cone snail, Conus imperialis Using the model polychaete worm Platynereis dumerilii, we demonstrate that C. imperialis venom contains small molecules that mimic natural polychaete mating pheromones, evoking the mating phenotype in worms. The specialized metabolites from different cone snails are species-specific and structurally diverse, suggesting that the cones may adopt many different prey-hunting strategies enabled by small molecules. Predators sometimes attract prey using the prey's own pheromones, in a strategy known as aggressive mimicry. Instead, C. imperialis uses metabolically stable mimics of those pheromones, indicating that, in biological mimicry, even the molecules themselves may be disguised, providing a twist on fake news in chemical ecology.

Altering the Sex Pheromone Cyclo(l-Pro-l-Pro) of the Diatom Seminavis robusta towards a Chemical Probe.

As a major group of algae, diatoms are responsible for a substantial part of the primary production on the planet. Pennate diatoms have a predominantly benthic lifestyle and are the most species-rich diatom group, with members of the raphid clades being motile and generally having heterothallic sexual reproduction. It was recently shown that the model species Seminavis robusta uses multiple sexual cues during mating, including cyclo(l-Pro-l-Pro) as an attraction pheromone. Elaboration of the pheromone-detection system is a key aspect in elucidating pennate diatom life-cycle regulation that could yield novel fundamental insights into diatom speciation. This study reports the synthesis and bio-evaluation of seven novel pheromone analogs containing small structural alterations to the cyclo(l-Pro-l-Pro) pheromone. Toxicity, attraction, and interference assays were applied to assess their potential activity as a pheromone. Most of our analogs show a moderate-to-good bioactivity and low-to-no phytotoxicity. The pheromone activity of azide- and diazirine-containing analogs was unaffected and induced a similar mating behavior as the natural pheromone. These results demonstrate that the introduction of confined structural modifications can be used to develop a chemical probe based on the diazirine- and/or azide-containing analogs to study the pheromone-detection system of S. robusta.

Sex pheromone analysis and effective attraction of males of the cabbage webworm, Hellula undalis, inhabiting the Mekong Delta of Vietnam

Abstract Hellula undalis is a harmful insect pest of green mustard in the Mekong Delta of Vietnam. In order to establish a tool for a sustainable pest control program, the sex pheromone of H. undalis inhabiting the Mekong Delta was examined. GC-EAD and GC–MS analyses of pheromone gland extracts from the virgin females elucidated three new components, (Z)-11-tetradecenyl acetate (Z11-14:OAc), (Z)-11-hexadecenal (Z11-16:Ald), and (11E,13E)-11,13-hexadecadien-1-ol, in addition to the known pheromone component (11E,13E)-11,13-hexadecadienal (E11,E13-16:Ald). Double bond positions of the two monoenyl components were determined by GC–MS analysis of the pheromone extract treated with dimethyl disulfide. On the other hand, GC–MS analysis of the female body extract detected the unsaturated hydrocarbon (3Z,6Z,9Z)-3,6,9-tricosatriene (Z3,Z6,Z9-23:H). Field examinations of their synthetic compounds indicated the significant role of E11,E13-16:Ald as a major component and a clear synergistic effect of the two monoenyl compounds as a minor component. Although the 3:3:7 mixture of Z11-14:OAc, E11-16:Ald, and E11,E13-16:Ald captured the largest number of males among the tested mixtures, the activity was still quite a bit lower than that of virgin females. However, the 3:3:7:1 mixture, which was prepared by adding a small amount of Z3,Z6,Z9-23:H to the 3:3:7 ternary lure, succeeded in attracting males more powerfully than the females did. This strong synergistic effect was not observed when the triene was added to unmixed E11,E13-16:Ald, indicating important roles of not only the triene but also the two monoenyl compounds as natural pheromone components.

Identification of a hyperactive pheromone analog in field tests of pheromone mimics for two click beetle species in the genus Cardiophorus (Coleoptera: Elateridae)

Females of two click beetle species, Cardiophorus tenebrosus and C. edwardsi (Coleoptera: Elateridae), produce methyl (3R,6E)-2,3-dihydrofarnesoate as their sex pheromone. We had serendipitously discovered that males of both species were also strongly attracted to (R)-fuscumol acetate ((E)-6,10-dimethylundeca-5,9-dien-2-yl acetate), a known longhorned beetle (Coleoptera: Cerambycidae) pheromone, due to its structural similarities to the click beetle pheromone. To further investigate the specificity of the responses of Cardiophorus males, additional analogs with different chain lengths and structural relationships compared to the natural pheromone were synthesized and tested. In field and electroantennogram bioassays, only fuscumol propionate ((E)-6,10-dimethylundeca-5,9-dien-2-yl propionate) elicited strong responses from Cardiophorus males, indicating that they were able to distinguish chain length and spatial relationships between the structural elements. In field trials, C. tenebrosus males were attracted equally to the analog and their natural pheromone, but the pheromone elicited stronger antennal responses from males. In contrast, traps baited with fuscumol propionate caught approximately 26 times as many C. edwardsi males compared to traps baited with the natural pheromone, although the analog elicited significantly smaller antennal responses from C. edwardsi males. Thus, in terms of behavioral responses, fuscumol propionate appears to be acting as a hyperactive pheromone mimic, a phenomenon which has rarely been observed in insect semiochemistry.

Pheromone Odorant Receptor Responses Reveal the Presence of a Cryptic, Redundant Sex Pheromone Component in the European Corn Borer, Ostrinia nubilalis.

Two odorant receptors (ORs), OnubOR3 and OnubOR6, in the sex pheromone communication systems of E- and Z-strain European corn borers, Ostrinia nubilalis, were broadly receptive to analogs of their pheromone components. In addition to responding to their natural 14-carbon pheromone components, (Z)-11- and (E)-11-tetradecenyl acetates (Z11- and E11-14:OAc), these pheromone ORs responded to the longer-chain compounds, (Z)-11- and (E)-11-hexadecenyl acetate (Z11- and E11-16:OAc). Z11-16:OAc is a pheromone gland constituent of E-strain O. nubilalis females in Europe but has not previously been shown to have behavioral activity to males. Here, we demonstrate that Z11-16:OAc evokes high levels of upwind flight and source location in E-strain males when substituted for Z11-14:OAc (minor component) in the E-strain blend. Since Z11-16:OAc is found in the gland and has behavioral activity when Z11-14:OAc is missing, then it should be classified as a cryptic, redundant minor pheromone component in E-strain O. nubilalis. The opposite geometric isomer, E11-16:OAc, also functions in Z-strain O. nubilalis, substituting behaviorally for the E11-14:OAc minor component, but has not been found in Z-strain female glands. Single-sensillum recordings showed that sensory neurons of E- and Z-strain male antennae expressing OnubOR3 and OnubOR6 produced responses to these hexadecenyl acetates similar to those evoked by the natural (tetradecenyl acetate) pheromone components. We postulate that the wide responsiveness of these two ORs to the 16-carbon acetates could be a preadaptation for O. nubilalis to use these compounds as minor components in lieu of the respective 14-carbon acetates. Alternatively, the responsiveness of OnubOR3 to E11-16:OAc and OnubOR6 to Z11-16:OAc could represent a vestigial state of these receptors, with the 16-carbon acetates having previously acted as functional minor components in an ancestral blend.