Repellent function of male pheromones in the red-spotted newt

Pheromones act as attractants and sexual stimulants in most vertebrates. For example, in red-spotted newts, Notophthalmus viridescens, female pheromones attract males, and male pheromones increase female receptivity. However, no studies have determined whether male vertebrates produce a pheromone that repels competing males. Through a series of olfactory mate selection tests, we found that sexually motivated male red-spotted newts produce a pheromone that functions to repel other approaching males. Our finding is the first report of a repelling function for pheromones in male vertebrates. The pheromones may act to increase both the sender's and receiver's mating success when the operational sex ratio (OSR) is male biased.     

Identification and field evaluation of the sex pheromone components of a Korean population of Glossosphecia romanovi

Glossosphecia romanovi (Leech) (Lepidoptera: Sesiidae) is a pest of grape in northeast Asia. We analyzed pheromone gland extracts of female moths and compared attractiveness of various pheromone blends to male moths in the field. Two major components from pheromone gland extracts were identified as (Z,Z)‐3,13‐octadecadien‐1‐ol (Z3,Z13‐18:OH) and (Z,Z)‐3,13‐octadecadienyl acetate (Z3,Z13‐18:OAc) in a ratio of approximately 9:1. Field tests showed that male G. romanovi were attracted to Z3,Z13‐18:OH alone, but the maximum number of males was attracted to the binary blend of Z3,Z13‐18:OH and Z3,Z13‐18:OAc mimicking the blend found in female extracts. In addition to these components, small amounts of (E,Z)‐3,13‐octadecadien‐1‐ol (E3,Z13‐18:OH) were detected in the pheromone gland of females, but addition of this component inhibited attraction to the primary binary blend. The blend of Z3,Z13‐18:OH and Z3,Z13‐18:OAc at the natural ratio should provide a sensitive and effective lure for monitoring populations of this pest.     

Balancing sexual selection through opposing mate choice and male competition

Male–male competition and female mate choice act contemporaneously in the cockroach Nauphoeta cinerea and the social pheromone of males influences the outcome of both forms of sexual selection. We therefore examined the joint and separate effects of male–male competition and female mate choice to determine if the selective optima for the pheromone were the same or different. Dominant males in a newly established hierarchy mated more frequently, but not exclusively. Manipulations of the multi-component social pheromone produced by males of N. cinerea showed that both long- and close-range attraction of females by males were influenced by the quantity and composition of the pheromone. The most attractive composition, however, differed from that which was most likely to confer high status to males. Since the outcome of male–male competition can conflict with mating preferences exhibited by females, there is balancing sexual selection on the social pheromone of N. cinerea. Such balancing selection might act to maintain genetic variation in sexually selected traits. We suggest that the different forms of sexual selection conflict in N. cinerea because females prefer a blend different to that which is most effective in male–male competition in order to avoid mating with overly aggressive males.     

Female sex pheromone of a nettle caterpillar,Monema flavescens,in China

Monema flavescens Walker (Lepidoptera: Limacodidae) is a multivoltine, generalist moth whose larvae cause serious damage to many types of trees. Pheromone lures prepared according to a study of a Japanese population were found to be ineffective at attracting M. flavescens nettle caterpillars in China, and some studies have shown intraspecific geographical differences in the composition of sex pheromones. We therefore reexamined the sex pheromone composition of M. flavescens in a Chinese population. In this study, the electroantennographically (EAG) active compounds in an extract from Chinese virgin females of M. flavescens were identified as (E)‐8‐decen‐1‐ol (E8‐10:OH), (Z)‐7,9‐decadien‐1‐ol (Z7,9‐10:OH), (Z)‐9,11‐dodecadien‐1‐ol (Z9,11‐12:OH), and (Z)‐9,11‐dodecadienal (Z9,11‐12:Ald) via coupled gas chromatographic‐electroantennographic detection (GC‐EAD) and coupled GC‐mass spectrometry (MS). Pheromone dimorphism might occur in this species, as this mixture of compounds in Chinese females was different from that of E8‐10:OH and E7,9‐10:OH extracted from Japanese females in previous research. In wind tunnel and field tests, the males were significantly attracted to a blend of the pheromone components E8‐10:OH, Z7,9‐10:OH, and Z9,11‐12:OH in a 100:5:4 ratio. The addition of Z9,11‐12:Ald did not change the male response. The optimized three‐component lure blend may provide a useful tool for monitoring and controlling Chinese populations of M. flavescens.     

Identification and field testing of sex pheromone components of a Korean population of the allium leafminer,Acrolepiopsis sapporensis

The allium leafminer, Acrolepiopsis sapporensis Matsumura (Lepidoptera: Acrolepiidae), is a pest of Allium species (Liliaceae) in Asia and Hawaii, USA. We identified candidate sex pheromone components in pheromone gland extracts of female moths and field tested the response of male moths to blends with different components and ratios. Gas chromatographic comparison of abdominal tip extracts from both sexes showed three female‐specific components: (Z)‐11‐hexadecenal (Z11‐16:Ald), (Z)‐11‐hexadecenyl acetate (Z11‐16:OAc), and (Z)‐11‐hexadecen‐1‐ol (Z11‐16:OH). These compounds were identified by mass spectral analysis of natural pheromone components and dimethyldisulfide adducts, and retention index comparisons with synthetic standards. The average ratio of three components, Z11‐16:Ald, Z11‐16:OAc, and Z11‐16:OH, in female extract was 33:100:14. Field trapping experiments indicated that all three components were essential for maximal attraction of male moths. Traps baited with a ternary blend mimicking the blend found in the pheromone gland extracts caught significantly more males than traps baited with caged live females. Increasing doses of the pheromone blend in the lures from 0.01 to 1.0 mg increased catches of male A. sapporensis.     

烟青虫(Helicoverpa assulta Guenée)信息素的结构鉴定及田间试验(英语)

北京地区的烟青虫(Helicover Pa asslta Cucn(?)e)的性信息素腺体提取物经毛细管柱气相色谱分析及GC MS分析,鉴定了6种组分.这6种组分为:十六醛(16:Ald)、顺 9—十六烯醛(Z9—16:Ald)、顺11—十六烯醛(Zll 16:Ald)、顺9—十六烯醇(Z9-16:OH)、顺11—十六烯醇(Zll-16:OH)、顺9—十六烯基乙酸酯(Z9 16:OAc),比例为10.9:58.7:3.9:14.7:1.1:10.7.田间试验表明,只有16:Ald、Z9 16:Ald和Zll 16:Ald(比例为15.3:79.2:5.5)组成的三组分诱芯和Z9—16:Ald和Zll—16:Ald(比例为93.4:6.6)组成的两组分诱芯对于雄蛾有强烈的引诱活性.在3种醛为组分的诱芯中加入Z9 16:OH明显地降低引诱活性.     

Illiberis (Primilliberis) rotundata Jordan (Lepidoptera: Zygaenidae: Procridinae) male sex attractant: Optimization and use for seasonal monitoring

Illiberis (Primilliberis) rotundata Jordan, 1907 (Lepidoptera: Zygaenidae) is an orchard pest distributed in Honshu, Shikoku and Kyushu in Japan and also in China, Korea, Mongolia and Russia (south‐eastern Siberia and Far East). For optimizing a known sex attractant lure containing sex pheromone components of the species (2R)‐butyl (7Z)‐dodecenoate and (2R)‐butyl (9Z)‐tetradecenoate, field work was organized in three cherry tree plots in Naruto, Tokushima in 2009 and 2010. As a result, the mixture of (2R)‐butyl (7Z)‐dodecenoate and (2R)‐butyl (9Z)‐tetradecenoate in a ratio of 30:100–50:100 (130–150 µg, respectively) was found to be the most attractive for the males of this pest. The seasonal flight of I. rotundata in Naruto, Japan as estimated by pheromone traps started at the end of May and lasted up to the end of June with a mass flight at the very end of May to first week of June.     

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

Athetis 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.     

Phenotypic plasticity in sexual communication signal of a noctuid moth

Variability within sex pheromone signalling systems is generally believed to be low because of strong stabilizing selection; yet the noctuid moth Heliothis subflexa (Hs) shows significant intraspecific variation. One possible explanation is that females may alter their sex pheromone blend depending on prevailing olfactory cues in the habitat, which we termed the 'experience hypothesis'. This could be adaptive if Hs females experiencing the pheromone of another species, Heliothis virescens (Hv), responded to reduce the frequency of heterospecific matings. We exposed Hs females to no pheromone, Hs pheromone or Hv pheromone in the first 3 days of their adult lives. Hs females in the latter treatment produced significantly more of the acetate Z11-16:OAc, which inhibits the attraction of Hv males. To our knowledge, this is the first study showing adaptive phenotypic plasticity in a moth sex pheromone and suggests that behavioural differentiation may precede genetic divergence in the sexual signals of moths.     

THE EVOLUTION OF SOCIAL SIGNALS: MORPHOLOGICAL,FUNCTIONAL, AND GENETIC INTEGRATION OF THE SEX PHEROMONE IN NAUPHOETA CINEREA

Social signals that mediate intraspecific interactions can be complex, conveying considerable information concerning the probable behavior of individuals and minimizing overt aggression and wasted energy. In the cockroach Nauphoeta cinerea, male-male competition and female mate choice are mediated by a multicomponent male-produced sex pheromone. In this study, I examine variation in this pheromone. First I measure differences among males in both individual pheromone compounds and the overall composition of the pheromone. Principal component analysis is used to quantify and describe pheromone composition. Next, I explore some of the causes and consequences of this variation by examining the pheromone of males with different social experiences. Compared to subordinate males, dominant males have significantly less variable quantities of the individual pheromone compounds and are significantly less variable in the composition of their pheromone. Because of an association between status and mating success, male-male competition can result in stabilizing sexual selection on the sex pheromone. Finally, I test the hypothesis that the pheromone compounds evolve in a manner consistent with their function. As predicted for morphologically integrated characters, the patterns of phenotypic, genetic, and environmental correlations among my measures of pheromone compounds and composition match functional patterns suggested by this study and the developmental patterns demonstrated in my previous studies. Based on these studies of the N. cinerea sex pheromone, I argue that stabilizing sexual selection shapes the evolution of pheromonal communication involved in social interactions among male N. cinerea. Further, I argue that coordinated evolution of social signals may be possible due to the morphological integration of their multiple compounds.     

A Selective Method of Estimation of Bacitracin in the Presence of Other Antibiotics and Growth Factors

The plum cankerworm moth, Cystidia couaggaria couaggaria (Geometridae: Ennominae), is a defoliator of Chinese plum trees (Prunus mume). The pheromone components of the female were analyzed by gas chromatography (GC) with an electro-antennographic (EAG) detector and GC coupled with mass spectrometry. The crude pheromone extract included several EAG-active components, i.e., trienyl, dienyl, and saturated hydrocarbons, with a C₂₁–C₂₅ straight chain. The characteristic mass spectra indicated the unsaturated hydrocarbons to be (3Z,6Z,9Z)-3,6,9-trienes and (6Z,9Z)-6,9-dienes. In the fields, mixtures of the synthetic C₂₁ and C₂₃ trienes in a ratio of 2:3 and 1:4 successfully attracted males of this diurnal species during daytime. While the male antennae responded to the C₂₅ triene and saturated hydrocarbons, their synergistic effects were not observed on the male attraction in the fields. Addition of the C₂₁ diene interestingly inhibited the activity of the triene mixture. Males of Cystidia truncangulata, a sympatric diurnal congener of C. c. couaggaria, showed similar EAG responses to the unsaturated hydrocarbons, but no C. truncangulata males were attracted by the lures tested for C. c. couaggaria males, indicating that the identified hydrocarbons comprised the species-specific pheromone of C. c. couaggaria females.     

Opsin expression predicts male nuptial color in threespine stickleback

Theoretical models of sexual selection suggest that male courtship signals can evolve through the build‐up of genetic correlations between the male signal and female preference. When preference is mediated via increased sensitivity of the signal characteristics, correlations between male signal and perception/sensitivity are expected. When signal expression is limited to males, we would expect to find signal‐sensitivity correlations in males. Here, we document such a correlation within a breeding population of threespine stickleback mediated by differences in opsin expression. Males with redder nuptial coloration express more long‐wavelength‐sensitive (LWS) opsin, making them more sensitive to orange and red. This correlation is not an artifact of shared tuning to the optical microhabitat. Such correlations are an essential feature of many models of sexual selection, and our results highlight the potential importance of opsin expression variation as a substrate for signal‐preference evolution. Finally, these results suggest a potential sensory mechanism that could drive negative frequency‐dependent selection via male–male competition and thus maintain variation in male nuptial color.     

Identification and functional characterization of sex pheromone receptors in beet armyworm Spodoptera exigua (Hübner)

In moths, males can detect a distinct blend of several pheromone components by specialized olfactory receptor neurons (ORNs) on the antennae. Four candidate pheromone receptors (PR) with seven transmembrane domains were identified by homology cloning from the antennae of Spodoptera exigua (Sexi). Phylogenetic analyses reveal that all four odorant receptors (OR) belong to pheromone receptor subtypes. Expression patterns revealed that PRs were male-specific in the antenna except for SexiOR11, which was female antenna-biased. Functional analyses of these PRs were conducted using heterologous expression in Xenopus oocytes. SexiOR13 and SexiOR16 were all broadly activated by multiple pheromone components. SexiOR13 responded robustly to the critical pheromone component, Z9, E12-14:OAc and the minor pheromone component, Z9-14:OAc at a concentration of 10^?4 M. Dose-response studies indicate that SexiOR13 was approximately 4 times more sensitive to Z9,E12-14:OAc (EC50 = 3.158 × 10^?6 M) compared to Z9-14:OAc (EC50 = 1.203 × 10^?5 M). While, SexiOR16 responded robustly to the secondary pheromone component Z9-14:OH with high sensitivity (EC50 = 9.690 × 10^?7 M). However, similar tests of the five pheromones with SexiOR6 and SexiOR11 failed to elicit any response. These results provide basic knowledge to further advance research on the molecular mechanisms of pheromone reception.     

SEX PHEROMONE COMPONENTS OF THE OREIENTAL TOBACCO BUDWORM, HELICOVERPA ASSULTA GUENÉE: IDENTIFICATION AND FIELD TRIALS

Abstract  The sex pheromone gland extracts of the Oriental tobacco budworm, Helicover assulta Guenée, collected from North China in Beijing area, were analyzed by capillary gas chromatograph(GC) and 6 components from the extracts were identified by capillary GC—MS as hexadecanal (16:Ald), (Z)9-hexadecenal (Z9–16:Ald), (Z)-11-hexadecenal (Z11–16:Ald), (Z)-9-hexadecen-1-ol (Z9–16:OH), Z11-hexadecen-1-ol (Z11–16:OH), Z-9-hexadecenylacetate (Z9–16:OAc) at a ratio of 10. 9: 58. 7: 3. 9: 14. 7: 1.1: 10. 7. Field studies indicated that an optimum blend of Z9–16:Ald and Z11–16:Ald was 100: 7. Addition of 16: Ald or Z9–16:Ac to the two aldehyde blend showed no significant effect on attractiveness. However presence of Z9–16:OH in the blends significantly reduced male captures.     

Male-specific (Z)-9-tricosene stimulates female mating behaviour in the spider Pholcus beijingensis

Chemical signals play an important role in spider sexual communication, yet the chemistry of spider sex pheromones remains poorly understood. Chemical identification of male-produced pheromone-mediating sexual behaviour in spiders has also, to our knowledge, not been reported before. This study aimed to examine whether chemically mediated strategies are used by males of the spider Pholcus beijingensis for increasing the probability of copulation. Based on data from gas chromatography–mass spectrometry analysis, electroantennography assay and a series of behavioural tests, we verified that (Z)-9-tricosene is a male-specific compound in the spider P. beijingensis. This compound acts as an aphrodisiac: it increases the likelihood that a female will mate. Mate-searching males release (Z)-9-tricosene to stimulate sexual behaviour of conspecific females. In the two-choice assay, however, sexually receptive females show no preference to the chambers containing (Z)-9-tricosene. This indicates that the male pheromone of P. beijingensis is not an attractant per se to the conspecific females. This is, to our knowledge, the first identification of a male-produced aphrodisiac pheromone in spiders.     

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

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.     

Does divergence in female mate choice affect male size distributions in two cave fish populations?

Sexual selection by female choice can maintain male traits that are counter selected by natural selection. Alteration of the potential for sexual selection can thus lead to shifts in the expression of male traits. We investigated female mate choice for large male body size in a fish (Poecilia mexicana) that, besides surface streams, also inhabits two caves. All four populations investigated, exhibited an ancestral visual preference for large males. However, only one of the cave populations also expressed this female preference in darkness. Hence, the lack of expression of female preference in darkness in the other cave population leads to relaxation of sexual selection for large male body size. While P. mexicana populations with size-specific female mate choice are characterized by a pronounced male size variation, the absence of female choice in one cave coincides with the absence of large bodied males in that population. Our results suggest that population differences in the potential for sexual selection may affect male trait variation.     

Modification of Male Courtship Motivation by Olfactory Habituation via the GABAA Receptor in Drosophila melanogaster

A male-specific component, 11-cis-vaccenyl acetate (cVA) works as an anti-aphrodisiac pheromone in Drosophila melanogaster. The presence of cVA on a male suppresses the courtship motivation of other males and contributes to suppression of male-male homosexual courtship, while the absence of cVA on a female stimulates the sexual motivation of nearby males and enhances the male-female interaction. However, little is known how a male distinguishes the presence or absence of cVA on a target fly from either self-produced cVA or secondhand cVA from other males in the vicinity. In this study, we demonstrate that male flies have keen sensitivity to cVA; therefore, the presence of another male in the area reduces courtship toward a female. This reduced level of sexual motivation, however, could be overcome by pretest odor exposure via olfactory habituation to cVA. Real-time imaging of cVA-responsive sensory neurons using the neural activity sensor revealed that prolonged exposure to cVA decreased the levels of cVA responses in the primary olfactory center. Pharmacological and genetic screening revealed that signal transduction via GABA_A receptors contributed to this olfactory habituation. We also found that the habituation experience increased the copulation success of wild-type males in a group. In contrast, transgenic males, in which GABA input in a small subset of local neurons was blocked by RNAi, failed to acquire the sexual advantage conferred by habituation. Thus, we illustrate a novel phenomenon in which olfactory habituation positively affects sexual capability in a competitive environment.     

Sexual conflict and the evolution of female mate choice and male social dominance

Conflicts between the sexes over control of reproduction are thought to lead to a cost of sexual selection through the evolution of male traits that manipulate female reproductive physiology and behaviour, and female traits that resist this manipulation. Although studies have begun to document negative fitness effects of sexual conflict, studies showing the expected association between sexual conflict and the specific behavioural mechanisms of sexual selection are lacking. Here we experimentally manipulated the opportunity for sexual conflict in the cockroach. Nauphoeta cinerea and showed that, for this species, odour cues in the social environment influence the behavioural strategies and fitness of males and females during sexual selection. Females provided with the opportunity for discriminating between males but not necessarily mating with preferred males produced fewer male offspring than females mated at random. The number of female offspring produced was not affected, nor was the viability of the offspring. Experimental modification of the composition of the males' pheromone showed that the fecundity effects were caused by exposure to the pheromone component that makes males attractive to females but also makes males less likely to be dominant. Female mate choice therefore carries a demographic cost but functions to avoid male manipulation and aggression. Male-male competition appears to function to circumvent mate choice rather than directly manipulating females, as the mate choice can be cryptic. The dynamic struggle between the sexes for control of mating opportunities and outcomes in N. cinerea therefore reveals a unique role for sexual conflict in the evolution of the behavioural components of sexual selection.