Production and perception of pheromones by the beetle Tribolium confusum

Adults of Tribolium confusum secrete two pheromones. The first, produced by the male, is attractive to both sexes and the second, produced by the female, is attractive to the male only. Pheromone production and perception was studied in relation to habituation, beetle age, time of day and previous mating. A living source of each pheromone habituates the responding beetles, the male pheromone habituating more strongly; female pheromone habituates only in the absence of the male pheromone. Habituation to one pheromone was always accompanied by an enhanced response to the other.Five days after emergence, production of male pheromone reaches a peak that is maintained. Production of female pheromone peaks after 3 days. Both sexes are responsive to male pheromone immediately upon eclosion, males reaching maximum response at 14 days, females at 8 days. Males are also responsive to female pheromone upon eclosion reaching maximum response at 8 days; female response to female pheromone is imperceptible. Males but not females display a 24 hr rhythm in pheromone production. Mated beetles did not differ significantly from unmated beetles in their ability to perceive pheromones. Alteration in male pheromone production after mating was detected by females but not males; this pheromone may, therefore, act as both a sex and aggregation pheromone.     

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.     

The Anna's hummingbird chirps with its tail: a new mechanism of sonation in birds

A diverse array of birds apparently make mechanical sounds (called sonations) with their feathers. Few studies have established that these sounds are non-vocal, and the mechanics of how these sounds are produced remains poorly studied. The loud, high-frequency chirp emitted by a male Anna's hummingbird (Calypte anna) during his display dive is a debated example. Production of the sound was originally attributed to the tail, but a more recent study argued that the sound is vocal. Here, we use high-speed video of diving birds, experimental manipulations on wild birds and laboratory experiments on individual feathers to show that the dive sound is made by tail feathers. High-speed video shows that fluttering of the trailing vane of the outermost tail feathers produces the sound. The mechanism is not a whistle, and we propose a flag model to explain the feather's fluttering and accompanying sound. The flag hypothesis predicts that subtle changes in feather shape will tune the frequency of sound produced by feathers. Many kinds of birds are reported to create aerodynamic sounds with their wings or tail, and this model may explain a wide diversity of non-vocal sounds produced by birds.     

A new mechanism of sound production by courting male jumping spiders (Araneae: Salticidae, Saitis michaelseni Simon)

Male Saitis michaelseni Simon (Araneae: Salticidae) produce sounds during courtship which can be heard several metres away. Courting males stridulate on dead leaves and are positioned on the opposite side of the leaf from the female. The courtship display contains both visual and acoustic elements. Courtship consists of three phases. In the first two phases, the male stridulates, and in the third phase, in which he makes tactile contact with the female, he alternates bursts of stridulatory sound with bouts of percussive sound in which the first pair of legs strikes the substratum. Stridulation apparently results from the thickened bases of short hairs on the anterior part of the abdomen moving over two files on the posterior part of the carapace. This stridulatory mechanism has not been previously reported for salticid spiders. The frequency spectra and amplitude modulation patterns of sounds produced by stridulation and percussion are presented.     

Spider sex pheromones: emission, reception, structures, and functions

Spiders and their mating systems are useful study subjects with which to investigate questions of widespread interest about sexual selection, pre- and post-copulatory mate choice, sperm competition, mating strategies, and sexual conflict. Conclusions drawn from such studies are broadly applicable to a range of taxa, but rely on accurate understanding of spider sexual interactions. Extensive behavioural experimentation demonstrates the presence of sex pheromones in many spider species, and recent major advances in the identification of spider sex pheromones merit review. Synthesised here are the emission, transmission, structures, and functions of spider sex pheromones, with emphasis on the crucial and dynamic role of sex pheromones in female and male mating strategies generally. Techniques for behavioural, chemical and electrophysiological study are summarised, and I aim to provide guidelines for incorporating sex pheromones into future studies of spider mating. In the spiders, pheromones are generally emitted by females and received by males, but this pattern is not universal. Female spiders emit cuticular and/or silk-based sex pheromones, which can be airborne or received via contact with chemoreceptors on male pedipalps. Airborne pheromones primarily attract males or elicit male searching behaviour. Contact pheromones stimulate male courtship behaviour and provide specific information about the emitter's identity. Male spiders are generally choosy and are often most attracted to adult virgin females and juvenile females prior to their final moult. This suggests the first male to mate with a female has significant advantages, perhaps due to sperm priority patterns, or mated female disinterest. Both sexes may attempt to control female pheromone emission, and thus dictate the frequency and timing of female mating, reflecting the potentially different costs of female signalling and/or polyandry to both sexes. Spider sex pheromones are likely to be lipids or lipid soluble, may be closely related to primary metabolites, and are not necessarily species specific, although they can still assist with species recognition. Newer electrophysiological techniques coupled with chemical analyses assist with the identification of sex pheromone compounds. This provides opportunities for more targeted behavioural experimentation, perhaps with synthetic pheromones, and for theorising about the biosynthesis and evolution of chemical signals generally. Given the intriguing biology of spiders, and the critical role of chemical signals for spiders and many other animal taxa, a deeper understanding of spider sex pheromones should prove productive.     

Acoustic communication between the sexes of the bush cricket, Leptophyes punctatissima

ABSTRACT. Both sexes of the speckled bush cricket, Leptophyes punctatissima (Bosc) (Tettigoniidae) produce sound by stridulation. The sound is used in courtship. The male sings for periods throughout the day and night, and there is a peak of activity in the early afternoon. The female sings only in response to a male chirp. The male increases his rate of singing if he receives replies from a female. After 3 days isolation from male song, the female replies most readily to male song mimics of short duration (10 ms) whose carrier frequency is 30 or 45 kHz. Females that have been isolated from male song for 10 days respond less readily than those isolated for 3 days. The short duration of the songs of both sexes reduces their value as locating signals. This disadvantage may be outweighed by the fact that a short signal reduces the chance of a predator detecting the singer by acoustic or visual cues.     

Acoustic courtship communication inSyntomeida epilais Wlk. (Lepidoptera: Arctiidae,Ctenuchinae)

The polka-dot wasp moth,Syntomedia epilais Wlk. (Lepidoptera, Arctiidae, Ctenuchinae), engages in extensive acoustic signaling during courtship. The signals, which are produced by both sexes, consist of sexually dimorphic trains of ultrasonic clicks. Field and laboratory behavioral experiments demonstrated that (1) sound production from both the male and the female is required for mating success, (2) femaleS. epilais show a higher level of acoustic responsiveness to male acoustic signals than to female signals, and (3) males use the female acoustic signals to locate their potential mates. It is suggested that the existence of the system is made possible by a reduction in bat predation pressure, perhaps the result of extreme distastefulness combined with the distinctive acoustic image that flying ctenuchines present to foraging bats.     

Source of alate excitant pheromones in the red imported fire antSolenopsis invicta (Hymenoptera: Formicidae)

At the onset of mating flights inSolenopsis invicta, workers swarm excitedly over the mound as alates prepare to fly. Previous studies demonstrated that this excitement is stimulated by the male and female alates. We investigated the glandular source(s) of pheromones produced by the alates that cause excitement. The only common female and male alate body part that elicited excitement when crushed was the head. Within the head, excised mandibular glands were found to be responsible for worker excitement. Fire ant workers are very sensitive to external stimuli and some excitement was elicited by crushed female gasters and male thoraces, but the response was never as significant as with crushed heads. Tests with summer and winter alates revealed similar results, except that gasters of winter female alates had a greater excitant effect than did gasters of summer female alates. This may be due to the production of attractant pheromones by the poison glands of overwintering female alates. We conclude that the mandibular gland is the source of alate excitant pheromones.     

Does the scent of a potential mate prevent the resorption of oocytes by apoptosis in Nauphoeta cinerea?

Abstract  We expect organisms to have evolved mechanisms to gather and use the information available within their environments, to steer resource investment decisions toward the traits that will give the greatest fitness returns. Pheromones are social signals, a common purpose of which is to act as indicators of mate presence. Consequently, pheromones have the potential to act as signals to increase or maintain reproductive investment over that of competing life-history traits. In the cockroach, Nauphoeta cinerea (Oliver), females pay costs of maintaining investment in reproduction when there are no males, and males produce pheromones that are known to effect female reproductive outcomes. Whether the pheromones have an influence on resource physiology is unknown. We subjected newly eclosed females to either a synthetic blend of male pheromones or control. We dissected females at 7, 12, 17 or 22 days. We measured apoptosis levels and size of all oocytes within the vitellerium, and measured dry fat body mass. Synthetic male pheromone blend did not have an effect on any measure of female reproductive or somatic resource physiology. Although negative results are always problematic, the success of the synthetic pheromone method in the past suggests that females may be insensitive to male pheromones in the pre-oviposition period, and may rely on mating stimulus rather than pheromone as the cue for oocyte maintenance and growth. Previous studies reporting effects of male pheromones on female reproduction suggest that the period of pheromone sensitivity may be between mating and birth.     

Interaction of dopamine, female pheromones, locomotion and sex behavior in Drosophila melanogaster

The regulation of female hydrocarbons and courtship behavior by dopamine and their relationship with locomotion, were investigated in Drosophila melanogaster. Ddc mutants and wild-type female flies treated with tyrosine hydroxylase inhibitors (alpha-methyltyrosine or 3-iodotyrosine) had fewer diene hydrocarbons (female pheromones) and there was a total (Ddc), partial (alpha-methyltyrosine) or no (3-iodotyrosine) rescue of hydrocarbon pattern after dopamine ingestion. There was a correlation between female pheromone level and male courtship intensity for these dopamine-depleted or rescued flies. Female locomotion was decreased in flies treated with tyrosine hydroxylase inhibitors and restored by dopamine, showing that decreased mobility of the female has little importance on male courtship. However, male courtship was inhibited by an increased mobility of dopamine-supplemented females. Tanning, which is altered in dopamine-deficient flies and in tan and ebony mutants, seemed to have no significant influence on female pheromones. Females with increased quantities of dopamine (by ingestion) exhibited larger quantities of pheromones. However, Catsup mutants did not, probably as a result of defects in the epidermis. The Dat mutation, which resulted in more dopamine being produced in the brain, showed no pheromone modification. Together, these data show a complex interaction between dopamine, female hydrocarbons, locomotion and male courtship behavior.     

Courtship Sounds Advertise Species Identity and Male Quality in Sympatric Pomatoschistus spp. Gobies

Acoustic signals can encode crucial information about species identity and individual quality. We recorded and compared male courtship drum sounds of the sand goby Pomatoschistus minutus and the painted goby P. pictus and examined if they can function in species recognition within sympatric populations. We also examined which acoustic features are related to male quality and the factors that affect female courtship in the sand goby, to determine whether vocalisations potentially play a role in mate assessment. Drums produced by the painted goby showed significantly higher dominant frequencies, higher sound pulse repetition rates and longer intervals between sounds than those of the sand goby. In the sand goby, male quality was predicted by visual and acoustic courtship signals. Regression analyses showed that sound amplitude was a good predictor of male length, whereas the duration of nest behaviour and active calling rate (i.e. excluding silent periods) were good predictors of male condition factor and fat reserves respectively. In addition, the level of female courtship was predicted by male nest behaviour. The results suggest that the frequency and temporal patterns of sounds can encode species identity, whereas sound amplitude and calling activity reflects male size and fat reserves. Visual courtship duration (nest-related behaviour) also seems relevant to mate choice, since it reflects male condition and is related to female courtship. Our work suggests that acoustic communication can contribute to mate choice in the sand goby group, and invites further study.     

Sound production in Scolytidae: Rivalry and premating stridulation of male Douglas-fir beetle

The previously reported attractant chirp of male Dendroctonus pseudotsugae changed to a distinctive long interrupted chirp after several minutes in the female gallery, and the same chirp occurred during fighting with another male. It was experimentally evoked by synthetic 3-methylcyclohex-2-en-1-one and frontalin, both known pheromone components of the male. A different, short, uninterrupted male chirp emitted shortly before copulation, was not evoked by these pheromones. It is suggested that chemostimulus allows or maintains dual contexts for the interrupted chirp. Observation of premating and mating behaviour showed some initial male aggressiveness with the female that subsided as gallery cooperation was established before mating and as the uninterrupted chirp replaced the interrupted chirp.     

Peripheral, central and behavioral responses to the cuticular pheromone bouquet in Drosophila melanogaster males

Pheromonal communication is crucial with regard to mate choice in many animals including insects. Drosophila melanogaster flies produce a pheromonal bouquet with many cuticular hydrocarbons some of which diverge between the sexes and differently affect male courtship behavior. Cuticular pheromones have a relatively high weight and are thought to be -- mostly but not only -- detected by gustatory contact. However, the response of the peripheral and central gustatory systems to these substances remains poorly explored. We measured the effect induced by pheromonal cuticular mixtures on (i) the electrophysiological response of peripheral gustatory receptor neurons, (ii) the calcium variation in brain centers receiving these gustatory inputs and (iii) the behavioral reaction induced in control males and in mutant desat1 males, which show abnormal pheromone production and perception. While male and female pheromones induced inhibitory-like effects on taste receptor neurons, the contact of male pheromones on male fore-tarsi elicits a long-lasting response of higher intensity in the dedicated gustatory brain center. We found that the behavior of control males was more strongly inhibited by male pheromones than by female pheromones, but this difference disappeared in anosmic males. Mutant desat1 males showed an increased sensitivity of their peripheral gustatory neurons to contact pheromones and a behavioral incapacity to discriminate sex pheromones. Together our data indicate that cuticular hydrocarbons induce long-lasting inhibitory effects on the relevant taste pathway which may interact with the olfactory pathway to modulate pheromonal perception.     

Pheromonal and behavioral cues trigger male-to-female aggression in Drosophila

Appropriate displays of aggression rely on the ability to recognize potential competitors. As in most species, Drosophila males fight with other males and do not attack females. In insects, sex recognition is strongly dependent on chemosensory communication, mediated by cuticular hydrocarbons acting as pheromones. While the roles of chemical and other sensory cues in stimulating male to female courtship have been well characterized in Drosophila, the signals that elicit aggression remain unclear. Here we show that when female pheromones or behavior are masculinized, males recognize females as competitors and switch from courtship to aggression. To masculinize female pheromones, a transgene carrying dsRNA for the sex determination factor transformer (traIR) was targeted to the pheromone producing cells, the oenocytes. Shortly after copulation males attacked these females, indicating that pheromonal cues can override other sensory cues. Surprisingly, masculinization of female behavior by targeting traIR to the nervous system in an otherwise normal female also was sufficient to trigger male aggression. Simultaneous masculinization of both pheromones and behavior induced a complete switch in the normal male response to a female. Control males now fought rather than copulated with these females. In a reciprocal experiment, feminization of the oenocytes and nervous system in males by expression of transformer (traF) elicited high levels of courtship and little or no aggression from control males. Finally, when confronted with flies devoid of pheromones, control males attacked male but not female opponents, suggesting that aggression is not a default behavior in the absence of pheromonal cues. Thus, our results show that masculinization of either pheromones or behavior in females is sufficient to trigger male-to-female aggression. Moreover, by manipulating both the pheromonal profile and the fighting patterns displayed by the opponent, male behavioral responses towards males and females can be completely reversed. Therefore, both pheromonal and behavioral cues are used by Drosophila males in recognizing a conspecific as a competitor.     

天牛性信息素、引诱植物和植物性引诱剂的研究与应用

由于目前所拥有的各种天牛防治方法都难以获得理想的防治效果,研发新型天牛控制技术势在必行。其中利用引诱剂是最具潜力的研究领域之一。对天牛的性信息素、引诱植物和植物性引诱剂3个方面的研究及应用作了综述。天牛雌、雄成虫均可释放性信息素进行两性间的通讯联系。天牛性信息素的分泌部位因天牛种类不同而存在着差异。雄、雌成虫触角上均有感受性信息素的感受器,但报道较多的是雄虫感受器。迄今已鉴定出13种天牛性信息素的化学结构。一般而言,天牛成虫的嗜食树种,对天牛具有较强的引诱作用,可作为诱饵树种使用。寄主植物的某些挥发性物质对天牛成虫也有独特的引诱效果。除此之外,对天牛性信息素、引诱植物和植物性引诱剂研究与应用中存在的困难也进行了讨论,并对它们的应用前景做了展望。     

Effects of putative male pheromones on female ratings of male attractiveness: influence of oral contraceptives and the menstrual cycle

Previous research has revealed that natural and synthetic pheromones can enhance ratings of opposite sex attractiveness. The present study investigated the effects of exposure to male axillary secretions on female ratings of the sexual attractiveness of male stimuli. Thirty-two female undergraduates, half of whom were contraceptive pill users, rated male vignette characters and photographs of male faces on aspects of attractiveness. On two separate study days, corresponding to different phases of their menstrual cycle, stimuli were presented while exposed to male axillary pheromones and under a control condition (no pheromone). The order of testing was balanced with respect to pheromone/control condition and menstrual cycle phase. Pheromone exposure resulted in significantly higher attractiveness ratings of vignette characters and faces. Use of the contraceptive pill or menstrual cycle phase had equivocal effects on some vignette items and neither had any influence on female ratings of male facial attractiveness. The results of this study suggest that exposure to natural male axillary pheromones can significantly enhance female perceptions of various aspects of male attractiveness.     

The attraction of virgin female hide beetles (Dermestes maculatus) to cadavers by a combination of decomposition odour and male sex pheromones

ABSTRACT: INTRODUCTION: The hide beetle Dermestes maculatus (Coleoptera: Dermestidae) feeds as an adult and larva on decomposing animal remains and can also be found on human corpses. Therefore, forensic entomological questions with regard to when and how the first receptive females appear on carcasses are important, as the developmental stages of their larvae can be used to calculate the post-mortem interval. To date, we know that freshly emerged males respond to the cadaver odour of post-bloated carcasses (approximately 9 days after death at Tmean = 27degrees), being attracted by benzyl butyrate. This component occurs at its highest concentration at this stage of decay. The aim of our study was to determine the principle of attraction of virgin females to the feeding and breeding substrate. For this purpose, we tested the response of these females to headspace samples of piglet cadavers and male sex pheromones [(Z9)-unsaturated fatty acid isopropyl esters] in a Y-olfactometer. Because we expected that such an odour combination is of importance for virgin female attraction, we tested the following two questions: 1) Are virgin female hide beetles attracted by a combination of cadaver odour and male sex pheromones? 2) During which decomposition stage do the first virgin females respond to cadaver odour when combined with male sex pheromones? RESULTS: We found that young virgin females were attracted to the cadaver by a combination of cadaver odour and male sex pheromones. Neither cadaver odour alone nor male sex pheromones alone was significantly more attractive than a solvent control. Our results also gave a weak indication that the first young virgin females respond as early as the post-bloating stage to its associated decomposition odour when combined with male sex pheromones. CONCLUSIONS: Our results indicate that freshly emerged males possibly respond to cadaver odour and visit carcasses before virgin females. Being attracted to cadavers when male sex pheromone is perceived as well, virgin females can optimise their reproductive possibilities.     

The male sex pheromone of the butterfly Bicyclus anynana: towards an evolutionary analysis

Background

Female sex pheromones attracting mating partners over long distances are a major determinant of reproductive isolation and speciation in Lepidoptera. Males can also produce sex pheromones but their study, particularly in butterflies, has received little attention. A detailed comparison of sex pheromones in male butterflies with those of female moths would reveal patterns of conservation versus novelty in the associated behaviours, biosynthetic pathways, compounds, scent-releasing structures and receiving systems. Here we assess whether the African butterfly Bicyclus anynana, for which genetic, genomic, phylogenetic, ecological and ethological tools are available, represents a relevant model to contribute to such comparative studies.

Methodology/Principal Findings

Using a multidisciplinary approach, we determined the chemical composition of the male sex pheromone (MSP) in the African butterfly B. anynana, and demonstrated its behavioural activity. First, we identified three compounds forming the presumptive MSP, namely (Z)-9-tetradecenol (Z9-14:OH), hexadecanal (16:Ald ) and 6,10,14-trimethylpentadecan-2-ol (6,10,14-trime-15-2-ol), and produced by the male secondary sexual structures, the androconia. Second, we described the male courtship sequence and found that males with artificially reduced amounts of MSP have a reduced mating success in semi-field conditions. Finally, we could restore the mating success of these males by perfuming them with the synthetic MSP.

Conclusions/Significance

This study provides one of the first integrative analyses of a MSP in butterflies. The toolkit it has developed will enable the investigation of the type of information about male quality that is conveyed by the MSP in intraspecific communication. Interestingly, the chemical structure of B. anynana MSP is similar to some sex pheromones of female moths making a direct comparison of pheromone biosynthesis between male butterflies and female moths relevant to future research. Such a comparison will in turn contribute to understanding the evolution of sex pheromone production and reception in butterflies.     

Integrative Studies of Amphibians: From Molecules to Mating

SYNOPSIS. Studies of reproductive behavior in amphibians havebeen especially successful in synthesizing data produced frommolecular and physiological research with evolutionary parameters,such as measures of reproductive success. In particular, tworelatively new areas of amphibian research are highly amenableto synthetic studies. One area is the nature of chemical communicationby pheromone delivery in terrestrial salamanders. Male courtshippheromones, for example, are delivered to the female duringmating. These pheromones typically are received by the accessoryolfactory system and act (presumably via the hypothalamus) toincrease female receptivity. At an evolutionary level, pheromonedelivery can increase male courtship success and thus the likelihoodthat a given male will sire offspring. Variation in pheromonecomposition and effectiveness will permit us to trace the evolutionof the male pheromone on a phylogeny of related populationsand species. At a proximal level, salamander courtship pheromonesare being chemically analyzed in order to identify specificprotein components that affect female receptivity. It also willbe possible to determine whether chemical variation among malesis related to behavioral effectiveness. Thus, courtship pheromonedelivery is a behavior that has invited scrutiny from a combinationof evolutionary and mechanistic perspectives. The second researcharea that is gaining from a synthetic approach is the investigationof relationships between hormonal mechanisms and reproductivebehavior in field populations of anurans and salamanders. Amphibiansare an understudied group, and the area of hormone-behaviorrelationships is inspired by testable hypotheses based on studiesof other terrestrial vertebrates. The ability to correlate physiologicalmeasures with estimates of reproductive success identifies areasof amphibian research that will profit from continued attention.     

2‐(Undecyloxy)‐ethanol is a major component of the male‐produced aggregation pheromone of Monochamus sutor

The small white‐marmorated longicorn beetle, Monochamus sutor (L.) (Coleoptera: Cerambycidae), is widely distributed throughout Europe and Asia. It is a potential vector of the pine wood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle, the causal agent of the devastating pine wilt disease. Volatiles were collected from both male and female beetles after maturation feeding. In analyses of these collections using gas chromatography (GC) coupled to mass spectrometry, a single male‐specific compound was detected and identified as 2‐(undecyloxy)‐ethanol. In analyses by GC coupled to electroantennography the only consistent responses from both female and male antennae were to this compound. Trapping tests were carried out in Spain, Sweden, and China. 2‐(Undecyloxy)‐ethanol was attractive to both male and female M. sutor beetles. A blend of the bark beetle pheromones ipsenol, ipsdienol, and 2‐methyl‐3‐buten‐2‐ol was also attractive to both sexes in Spain and Sweden, and further increased the attractiveness of the 2‐(undecyloxy)‐ethanol. The host plant volatiles α‐pinene, 3‐carene, and ethanol were weakly attractive, if at all, in all three countries and did not significantly increase the attractiveness of the blend of 2‐(undecyloxy)‐ethanol and bark beetle pheromones. 2‐(Undecyloxy)‐ethanol is thus proposed to be the major, if not only, component of the male‐produced aggregation pheromone of M. sutor, and its role is discussed. This compound has been reported as a pheromone of several other Monochamus species and is another example of the parsimony that seems to exist among the pheromones of many of the Cerambycidae. Traps baited with 2‐(undecyloxy)‐ethanol and bark beetle pheromones should be useful for monitoring and control of pine wilt disease, should M. sutor be proven to be a vector of the nematode.