Release of male courtship display in Periplaneta americana: evidence for female contact sex pheromone

Male American cockroaches (Periplaneta americana) are attracted to virgin females by volatile sex pheromones. After antennal contact with the female they turn through 180° and spread their wings in courtship display. A chemical contact stimulus releasing male courtship is demonstrated in the female cuticle. Experiments with standardized olfactory stimulation by volatile sex pheromones revealed that the contact stimulus is sex-specific and species-specific. It can be washed off the cuticle with non-polar solvents and was successfully transferred to glass dummies. However, it is not effective in the absence of volatile sex pheromones. Thus volatile sex pheromones are responsible for male attraction and sexual motivation, while mate recognition is accomplished through the contact pheromone.     

Female-derived sex pheromone mediates courtship behaviour in the parasitoid Lariophagus distinguendus

Brassiceye^®traps baited with ethylisothiocyanate were modified and used to collect live adults of Delia radicum(L.) and Delia floralis(Fallén) (Diptera: Anthomyiidae) from the field to observe the prevalence of Entomophthora muscae(Cohn) Fresenius and Strongwellsea castransBatko & Weiser. The traps were highly effective and selective for D. radicumand D. floralis. Of the flies identified, 98.4% in 1996 and 93.7% in 1997 were either D. radicumor D. floralis. In 1997 the maximum mean catch was as high as 82 flies per trap per day, and more than 80% of these were females.During both seasons E. muscaecaused relatively high levels of mortality in adult populations of D. radicumand D. floralis. The fungus caused a total infection level of 17.9% in 1996 and 47.7% in 1997 with infection peaks of 82.4% in 1996 and 87.5% in 1997. Both years, a significant positive correlation was found between E. muscaeprevalence and temperature. One infection peak was observed for S. castransin 1996, and during that season the total S. castransinfection level was 18.0%. In 1997, the total S. castransinfection level was as low as 8.1%. There is no strong indication that the prevalence of E. muscaeor S. castransdiffers between either the fly species or sexes within species.     

Female sex pheromone of a wandering spider (Cupiennius salei): identification and sensory reception

Females of the wandering spider Cupiennius salei attach a sex pheromone to their dragline. Males encountering the female dragline examine the silk thread with their pedipalps and then typically initiate reciprocal vibratory courtship with the sexual partner. The female pheromone was identified as (S)-1,1'-dimethyl citrate. The male pheromone receptive sensory cells are located in tip pore sensilla and respond to touching the sensillum tip with female silk or pieces of filter paper containing the synthetic pheromone.     

棉铃虫二种性诱芯田间诱蛾效果比较

棉铃虫Helicoverpa armigera(Hübner)是我国最严重害虫之一。为了提高监测和诱捕效率,2009年在山西和新疆进行2种性诱芯诱捕棉铃虫的田间试验,2种性诱芯分别来自中国科学院动物研究所和北京中捷四方公司,2种诱芯处理分别重复2次和6次,诱捕器分别为水盆和笼罩。试验结果:在山西试点,动物所诱芯的诱蛾数是中捷四方公司的8.60倍;在新疆试点,则达到11.89倍。以上差异均达极显著水准(P<0.01)。同时,在山西试点,动物所诱芯的有效期长达62d,比中捷四方公司的长14d。据此认为动物所棉铃虫性诱芯值得应用推广。     

Bioassay evidence for a sex attractant pheromone in the large carpenter bee, Xylocopa varipuncta (Anthophoridae: Hymenoptera)

A field bioassay was conducted to test i˜hethercompoundsp roduced in the thoracic gland of male X. varipuncta are involved in long-range mate attraction. Filter paper impregnated with the two most abundant compounds of the male gland was placed in sites comparable to those used by territorial males during the time of day when mating activity occurs. Females visited these filter paper 'lures' as often as they visited unmanipulated males in the study area. Males with the chemical mixture added to their territories did not receive more matings than males at territories where we had not added the chemical mixture. These findings and other studies, summarized herein, support the hypothesis that the male gland produces a pheromone which functions as a long-range sex attractant.     

Cuticular hydrocarbons as contact sex pheromone in the parasitoid Dibrachys cavus

Cuticular hydrocarbons (CHCs) cover the cuticle of virtually any insect and do not only protect them from desiccation, but also possess various communicative functions. Previous studies suggested a function as contact sex pheromones in the parasitic wasp family Pteromalidae, but further species need to be studied before more general conclusions are possible. Here, we demonstrate a contact sex pheromone in females of Dibrachys cavus (Walker) (Hymenoptera: Pteromalidae). Males of this parasitoid were arrested on cadavers of 1‐ to 2‐day‐old females, but neither on newly emerged females nor on males. Extracts from 1‐ to 2‐day‐old females and non‐polar fractions were also behaviorally active suggesting a non‐polar contact sex pheromone. Chemical analyses of bioactive and non‐active CHC profiles by gas chromatography–mass spectrometry and subsequent principal component analysis (PCA) revealed that the bioactive profiles from 1‐ to 2‐day‐old females were clearly distinguishable from all other profiles. Among the chemicals showing the strongest impact in the PCA were the two 3‐methylalkanes 3‐methylnonacosane and 3‐methylhentriacontane, which were absent or trace components in the inactive profiles and whose relative amounts increased in females when they became sexually attractive. The putative function of 3‐methylalkanes as key components of the contact sex pheromones in Pteromalidae is discussed.     

Lineage-specific differences in evolutionary mode in a salamander courtship pheromone

Functionally equivalent genes may evolve heterogeneously across closely related taxa as a consequence of lineage-specific selective pressures. Such disparate evolutionary modes are especially prevalent in genes that encode postcopulatory reproductive proteins, presumably as a result of sexual selection. We might therefore expect genes that mediate reproduction prior to insemination to evolve in a similar manner. Plethodontid receptivity factor (PRF), a proteinaceous salamander pheromone produced by the male, increases female receptivity during courtship interactions. To test for lineage-specific differences in PRF's evolution, we intensively sampled PRF genes across the eastern Plethodon phylogeny (27 spp.; 34 populations) to compare gene diversification, rates of evolution, modes of selection, and types of amino acid substitution. Our analyses indicate that PRF evolutionary dynamics vary considerably from lineage to lineage. Underlying this heterogeneity, however, are two well-defined transitions in evolutionary mode. The first mode is representative of a typical protein profile, wherein neutral divergence and purifying selection are the dominant features. The second mode is characterized by incessant, cyclical evolution driven by positive selection. In this mode, the positively selected sites are bound by a limited assortment of acceptable amino acids that appear to evolve independently of other sites, resulting in a tremendous number of unique PRF alleles. Several of these selected sites are implicated in receptor binding. These sites are apparently involved in a molecular tango in which the male signal and female receptors coevolve within a confined molecular space. PRF's lineage-specific evolutionary dynamics, in combination with evidence of a molecular tango, highlight the molecular action of sexual selection on a chemical signal that is used during courtship.     

Pecan weevil sex attractant: Bioassay and chemical studies

When the distillable oil from adult pecan weevils, Curculio caryae, of both sexes was investigated separately with an integrated gas chromatographymass spectrometry system, evidence was obtained for a number of di- and trisubstituted aromatic hydrocarbons, seven phenolic and carbonyl aromatic compounds, and at least three alcohols. The major compounds were a series of alkanes and alkenes, four esters and four heterocyclic compounds. Among these, eleven compounds were unique to males and four were unique to females. The volatiles were also bioassayed in the field and each attracted the opposite sex. This investigation was part of a study made to identify the possible rôle of these compounds as a pheromone produced by the pecan weevil.     

A recombinant courtship pheromone affects sexual receptivity in a plethodontid salamander

Pheromones are important chemical signals for many vertebrates, particularly during reproductive interactions. In the terrestrial salamander Plethodon shermani, a male delivers proteinaceous pheromones to the female as part of their ritualistic courtship behavior. These pheromones increase the female's receptivity to mating, as shown by a reduction in courtship duration. One pheromone component in particular is plethodontid receptivity factor (PRF), a 22-kDa protein with multiple isoforms. This protein alone can act as a courtship pheromone that causes the female to be more receptive. We used a bacterial expression system to synthesize a single recombinant isoform of PRF. The recombinant protein was identical to the native PRF, based on mass spectrometry, circular dichroism spectra, and a behavioral bioassay that tested the effects of recombinant PRF (rPRF) on female receptivity (21% reduction in courtship duration). The rPRF appears to mimic the activity of a mixture of PRF isoforms, as well as a mixture of multiple different proteins that comprise the male courtship gland extract. Pheromones that are peptides have been characterized for some vertebrates; to date, however, rPRF is one of only 2 synthesized vertebrate proteins to retain full biological activity.     

Effect of specific and generic sex attractant blends on pheromone trap captures of four leafroller species in mid-Atlantic apple orchards

The responses of tufted apple bud moth, Platynota idaeusalis (Walker), the leafroller P. flavedana Clemens, redbanded leafroller, Argyrotaenia velutinana (Walker), and obliquebanded leafroller, Choristoneura rosaceana (Harris), to the pheromone blends of each, as well as to 3 putative generic blends (two- and three-component blends containing pheromone elements of each of the 4 species) were evaluated in small orchard plots. P. idaeusalis and P. flavedana, and A. velutinana and C. rosaceana comprise 2 pairs of species, each pair with broad overlap in pheromone blend, and quite different from one another. Each generic blend suppressed trap captures of all 4 species. The blends for P. idaeusalis and P. flavedana each reduced captures for these species. Furthermore, the blend for P. idaeusalis also suppressed captures of A. velutinana. The P. flavedana blend did not reduce captures of A. velutinana; in fact, at times captures increased. This study determines relative abilities of several sex attractant blends to reduce captures of 4 leafroller species in pheromone traps, presumably reflecting the ability of a blend to reduce orientation of males to females in a large block situation. This is a requisite 1st step in the development of a multispecies mating disruption blend.     

Unconventional sex: fresh approaches to courtship learning

Understanding the complex array of genes, proteins and cells involved in learning and memory is a major challenge for neuroscientists. Using the genetically powerful model system, Drosophila melanogaster, and its well-studied courtship behavior, investigators have begun to delineate essential elements of associative and nonassociative behavioral plasticity. Advances in transgenic tools and developments in behavioral assays have increased the power of studying courtship learning in the fruit fly.     

Flexibility in the multi-modal courtship of a wolf spider, Schizocosa ocreata

Male Schizocosa ocreata wolf spiders court females with synchronous visual and seismic displays. We tested whether male S. ocreata modify their courtship in relation to light environment, and associated utility of the visual components. Males were generally more active and more likely to perform the major courtship element (jerky tapping) when in the light. One courtship element (arching) was only observed in the light while another (vertical leg-extend) was only observed in the dark. Courtship in the dark retained visual components, suggesting spiders cannot disengage these components of multi-modal display even when superfluous. Once initiated, there was no evidence that performance rate or time spent in each courtship element differed in the light and in the dark.     

Temperature and sex allocation in a spider mite

Although temperature is the most important environmental factor regulating arthropod development and reproduction, its influence on sex allocation in haplodiploid arthropods remains largely unexplored. We investigated under laboratory conditions how maternal age and temperature mediate offspring sex ratio of the spider mite Tetranychus mcdanieli (Acari: Tetranychidae). Over nine temperature regimes, female-biased sex ratios were consistently observed, varying from 57 to 87% among progeny produced over lifetime. Spider mite sex ratio was affected by maternal age: more male progeny were produced at both the beginning and the end of the female lifespan, yielding a dome shaped curvilinear relationship. This pattern of variation with age probably results from constraints on using sperm at young ages and sperm depletion or viability at older ages. We found a significant curvilinear relationship between temperature and sex ratio. The proportion of female offspring was lowest at intermediate temperatures and highest at extreme temperatures. We suggest that increased female-biased sex ratio at extreme temperatures is an evolutionary response of spider mites to deteriorating habitats as, in the Tetranychidae, females have better capacities than males to disperse and survive under harsh conditions.     

Aggression and courtship in Drosophila: pheromonal communication and sex recognition

Upon encountering a conspecific in the wild, males have to rapidly detect, integrate and process the most relevant signals to evoke an appropriate behavioral response. Courtship and aggression are the most important social behaviors in nature for procreation and survival: for males, making the right choice between the two depends on the ability to identify the sex of the other individual. In flies as in most species, males court females and attack other males. Although many sensory modalities are involved in sex recognition, chemosensory communication mediated by specific molecules that serve as pheromones plays a key role in helping males distinguish between courtship and aggression targets. The chemosensory signals used by flies include volatile and non-volatile compounds, detected by the olfactory and gustatory systems. Recently, several putative olfactory and gustatory receptors have been identified that play key roles in sex recognition, allowing investigators to begin to map the neuronal circuits that convey this sensory information to higher processing centers in the brain. Here, we describe how Drosophila melanogaster males use taste and smell to make correct behavioral choices.     

PrgU: a suppressor of sex pheromone toxicity in Enterococcus faecalis

Upon sensing of the peptide pheromone cCF10, Enterococcus faecalis cells carrying pCF10 produce three surface adhesins (PrgA, PrgB or Aggregation Substance, PrgC) and the Prg/Pcf type IV secretion system and, in turn, conjugatively transfer the plasmid at high frequencies to recipient cells. Here, we report that cCF10 induction is highly toxic to cells sustaining a deletion of prgU, a small orf located immediately downstream of prgB on pCF10. Upon pheromone exposure, these cells overproduce the Prg adhesins and display impaired envelope integrity, as evidenced by antibiotic susceptibility, misplaced division septa and cell lysis. Compensatory mutations in regulatory loci controlling expression of pCF10‐encoded prg/pcf genes, or constitutive PrgU overproduction, block production of the Prg adhesins and render cells insensitive to pheromone. Cells engineered to overproduce PrgB, even independently of other pCF10‐encoded proteins, have severely compromised cell envelopes and strong growth defects. PrgU has an RNA‐binding fold, and prgB‐prgU gene pairs are widely distributed among E. faecalis isolates and other enterococcal and staphylococcal species. Together, our findings support a model in which PrgU proteins represent a novel class of RNA‐binding regulators that act to mitigate toxicity accompanying overproduction of PrgB‐like adhesins in E. faecalis and other clinically‐important Gram‐positive species.     

Behavioral evidence for a female-produced sex attractant in Diaphorina citri

Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is an important worldwide pest of citrus. It vectors three phloem-restricted bacteria in the genus Candidatus Liberibacter that cause huanglongbing (citrus greening disease). Studies were conducted to examine the behavioral responses of male and female D. citri to conspecifics of the same and opposite sex, with and without associated citrus host plants, in both open-air arena choice assays and Y-tube olfactometer assays. Virgin and mated male D. citri colonized citrus plants that were currently or had been previously colonized by virgin or mated female D. citri in greater numbers than control plants without females. However, males or females did not accumulate more on plants colonized by conspecifics of the same sex compared to uninfested plants, and females showed no preference for plants pre-infested with males compared with uninfested controls. In complementary Y-tube olfactometer assays, virgin and mated males chose arms with odor sources from mated females compared with blank controls in the absence of associated citrus host plant volatiles. In both behavioral assays, mated female D. citri appeared more attractive than virgin females. The vibrational calling behavior of male D. citri was reduced when males were challenged by the odors of conspecific mated females relative to when males were challenged by the odor of other males. Collectively, our results provide behavioral evidence for a female-produced volatile sex attractant pheromone in D. citri . Future identification and synthesis of a sex attractant pheromone will be an important contribution to current monitoring and management practices for D. citri .