Showing papers on "Sex pheromone published in 2003"

Molecular detection of pheromone signals in mammals: from genes to behaviour.

Abstract: The instinctive and species-specific behavioural response of animals to pheromones has intrigued biologists for a long time. Recent molecular and electrophysiological approaches have provided new insights into the mechanisms of pheromone detection in rodents and into the sensory coding of pheromone signals that lead to gender discrimination and aggressive behaviour.

“Pheromones and Animal Behaviour” - Communication by Smell and Taste”

Abstract: Summary.((no summary.))

Evolutionary deterioration of the vomeronasal pheromone transduction pathway in catarrhine primates.

Abstract: Pheromones are water-soluble chemicals released and sensed by individuals of the same species to elicit social and reproductive behaviors or physiological changes; they are perceived primarily by the vomeronasal organ (VNO) in terrestrial vertebrates Humans and some related primates possess only vestigial VNOs and have no or significantly reduced ability to detect pheromones, a phenomenon not well understood at the molecular level Here we show that genes encoding the TRP2 ion channel and V1R pheromone receptors, two components of the vomeronasal pheromone signal transduction pathway, have been impaired and removed from functional constraints since shortly before the separation of hominoids and Old World monkeys ≈23 million years ago, and that the random inactivation of pheromone receptor genes is an ongoing process even in present-day humans The phylogenetic distribution of vomeronasal pheromone insensitivity is concordant with those of conspicuous female sexual swelling and male trichromatic color vision, suggesting that a vision-based signaling-sensory mechanism may have in part replaced the VNO-mediated chemical-based system in the social/reproductive activities of hominoids and Old World monkeys (catarrhines)

The role of juvenile hormone in immune function and pheromone production trade-offs: a test of the immunocompetence handicap principle

Abstract: The immunocompetence handicap hypothesis postulates that secondary sexual traits are honest signals of mate quality because the hormones (e.g. testosterone) needed to develop secondary sexual traits have immunosuppressive effects. The best support for predictions arising from the immunocompetence handicap hypothesis so far comes from studies of insects, although they lack male-specific hormones such as testosterone. In our previous studies, we found that female mealworm beetles prefer pheromones of immunocompetent males. Here, we tested how juvenile hormone (JH) affects male investment in secondary sexual characteristics and immune functions in the mealworm beetle, Tenebrio molitor. We injected male mealworm beetles with JH (type III) and found that injection increased the attractiveness of male pheromones but simultaneously suppressed immune functions (phenoloxidase activity and encapsulation). Our results suggest that JH, which is involved in the control of reproduction and morphogenesis, also plays a central role in the regulation of a trade-off between the immune system and sexual advertisement in insects. Thus, the results reflect a general mechanism by which the immunocompetence handicap hypothesis may work in insects.

Condition dependence of pheromones and immune function in the grain beetle Tenebrio molitor

Abstract: Summary 1. Pheromones are chemical signals that function not only as mate attractors, but may also relay important information to prospective mates. In order for the information to be reliable, the signal must be costly to produce and this is likely to result in condition dependent expression of the signal. 2. We present results from two experiments on the grain beetle Tenebrio molitor examining phenotypic condition dependence of pheromones and patterns of female preference for pheromones. We also analysed condition dependence of two measures of immunocompetence: encapsulation response and phenoloxidase activity. 3. By manipulating the nutritional condition of the males we found that the attractiveness of the male pheromones to virgin females was condition-dependent, indicating that the production of the pheromones is affected by the condition of the male. We also found that the phenoloxidase activity of the males was affected by the nutritional condition of the male but that encapsulation rate was not. 4. Our results show that pheromones are condition-dependent signals, the quantity of which females use in their mate choice.

Current research in canine and feline pheromones

Abstract: Pheromonotherapy seems to be a new therapeutic approach allowing practitioners to tackle the treatment of behavioral disorders in a natural, specific, and safe way. Although the efficacy of pheromones has been assessed in some specific behavioral problems, it seems that their range of action could cover the wide field of reduction of stress. Therefore, the use of pheromones should not be reduced to treatment of behavioral disorders (potentially associated with psychotropes or a behavioral modification program) but should be included in a strategy of improving the welfare of pets in veterinary structures (during examination and hospitalization) and in breeding networks (separation from the mother and transport). Moreover, further studies may allow the veterinary practitioner to use pheromone analogues in the field of diagnostics to determine the behavioral status of a pet (e.g., anxious or not, dominant or not). Pheromonotherapy is at its beginning, and the use of pheromones in various fields of medicine is heartening.

Insect pheromone biochemistry and molecular biology : the biosynthesis and detection of pheromones and plant volatiles

Abstract: Part 1: PHEROMONE PRODUCTION Biosynthesis and detection of pheromones and plant volatiles - Introduction and Overview. Biology and ultrastructure of sex pheromone producing tissue . Biochemistry of female moth sex pheromones. Molecular Biological Investigations of Pheromone Desaturases, PBAN regulation of pheromone biosynthesis in female moths. Biosynthesis and endocrine regulation of pheromone production in Coleoptera. Molecular Biology of Pheromone Production in Bark Beetles. Biosynthesis and ecdysteroid regulation of housefly sex pheromone production. Genetic studies on pheromone production in Drosophila. Regulation of pheromone biosynthesis, transport and emission in cockroaches. Pheromone biosynthesis in social insects. Alkaloid-derived pheromones and sexual selection in Lepidoptera. Part 2: PHEROMONE DETECTION The biochemical design of pheromone and odor detection The biochemistry of odor detection and its future prospects Biochemical Diversity in Odor Detection: OBPs, ODE, and SNMPs. Proteins that make sense. The peripheral pheromone olfactory system in insects: targets for species-selective control agents Biochemistry and diversity of insect odorant-binding proteins. Biochemistry and evolution of OBP and CSP proteins. Diversity and Expression of Odorant Receptors in Drosophila Transduction Mechanisms of Olfactory Sensory Neurons The external and internal environmental factors influencing the biochemical design of pheromone and odor detection The Biomechanical Design of an Insect Antenna as an Odor Capture Device Olfactory landscapes and deceptive pollination: signal noise and convergent evolution in floral Scent Physiology and genetics of odor perception in Drosophila Plasticity and coding mechanisms in the insect antennal lobe

Pheromone gland-specific fatty-acyl reductase of the silkmoth, Bombyx mori

Abstract: The C10-C18 unsaturated, acyclic, aliphatic compounds that contain an oxygenated functional group (alcohol, aldehyde, or acetate ester) are a major class of sex pheromones produced by female moths. In the biosynthesis of these pheromone components, the key enzyme required to produce the oxygenated functional groups is fatty-acyl reductase (FAR). This enzyme converts fatty-acyl pheromone precursors to their corresponding alcohols, which, depending on the moth species, can then be acetylated or oxidized to the corresponding aldehydes. Despite the significant role this enzyme has in generating the species-specific oxygenated constituents of lepidopteran sex pheromones, the enzyme has yet to be fully characterized and identified. In experiments designed to characterize a pheromone-gland-specific FAR in the silkmoth, Bombyx mori, we have isolated a cDNA clone encoding a protein homologous to a FAR from the desert shrub, Simmondsia chinensis, commonly known as jojoba. The deduced amino acid sequence of this clone predicts a 460-aa protein with a consensus NAD(P)H binding motif within the amino terminus. Northern blot analysis indicated that 2-kb transcripts of this gene were specifically expressed in the pheromone gland at 1 day before adult eclosion. Functional expression of this gene in the yeast Saccharomyces cerevisiae not only confirmed the long-chain FAR activity, but also indicated a distinct substrate specificity. Finally, the transformed yeast cells evoked typical mating behavior in male moths when cultured with the pheromone precursor fatty acid, (E,Z)-10,12-hexadecadienoic acid.

Molecular genetics and evolution of pheromone biosynthesis in Lepidoptera

Abstract: A great diversity of pheromone structures are used by moth species (Insecta: Lepidoptera) for long-distance mating signals. The signal/response channel seems to be narrow for each species, and a major conundrum is how signal divergence has occurred in the face of strong selection pressures against small changes in the signal. Observations of various closely related and morphologically similar species that use pheromone components biosynthesized by different enzymes and biosynthetic routes underscore the question as to how major jumps in the biosynthetic routes could have evolved with a mate recognition system that is based on responses to a specific blend of chemicals. Research on the desaturases used in the pheromone biosynthetic pathway for various moth species has revealed that one way to make a major shift in the pheromone blend is by activation of a different desaturase from mRNA that already exists in the pheromone gland. Data will be presented to support the hypothesis that this process was used in the evolution of the Asian corn borer, Ostrinia furnacalis species. In that context, moth sex-pheromone desaturase genes seem to be evolving under a birth-and-death process. According to this model of multigene family evolution, some genes are maintained in the genome for long periods of time, whereas others become deleted or lose their functionality, and new genes are created through gene duplication. This mode of evolution seems to play a role in moth speciation, as exemplified by the case of the Asian corn borer and European corn borer, Ostrinia nubilalis species.

Male Axillary Extracts Contain Pheromones that Affect Pulsatile Secretion of Luteinizing Hormone and Mood in Women Recipients

Abstract: Human underarm secretions, when applied to women recipients, alter the length and timing of the menstrual cycle. These effects are thought to arise from exposure to primer pheromones that are produced in the underarm. Pheromones can affect endocrine (primer) or behavioral (releaser) responses, provide information (signaler), or perhaps even modify emotion or mood (modulator). In this study, we extracted underarm secretions from pads worn by men and placed the extract under the nose of women volunteers while monitoring serum LH and emotion/mood. Pulses of LH are excellent indicators of the release of GnRH from the brain's hypothalamus. In women, the positive influence of GnRH on LH affects the length and timing of the menstrual cycle, which, in turn, affects fertility. Here we show that extracts of male axillary secretions have a direct effect upon LH-pulsing and mood of women. In our subjects, the putative male pheromone(s) advanced the onset of the next peak of LH after its application, reduced tension, and increased relaxation. These results demonstrate that male axillary secretions contain one or more constituents that act as primer and modulator pheromones.

Hormones, pheromones and reproductive behavior

Abstract: Fish commonly use reproductive hormones (steroids and prostaglandins) both as endogenous signals between reproductive tract and brain and as exogenous signals (hormonal pheromones) that synchronize gamete maturation and/or spawning interactions between and among conspecifics This dual function for hormonal products not only extends traditional concepts that sex hormone actions are limited to reproductive synchrony within the individual, but also implies we are unlikely to achieve a comprehensive understanding of reproductive function in any fish without knowledge of both the endogenous and exogenous actions of its hormones and related released compounds Such knowledge is beginning to accumulate for several species (eg goldfish, Atlantic salmon), but even here is far from complete Moreover, because hormonal pheromone studies have focused on oviparous gonochorists with relatively simple reproductive strategies, we know nothing about the potential hormonal pheromone functions of the numerous species with sequential hermaphroditism or alternative male strategies, or the possible changes in pheromone function associated with the numerous transitions from oviparity to viviparity Given the insights we have gained from studies of traditional species, it seems certain that expanding hormonal pheromone research to non-traditional species exemplifying the diverse nature of fish mating systems will similarly enrich our understanding of fish reproductive function

Effect of varying monoterpene concentrations on the response of Ips pini (Coleoptera: Scolytidae) to its aggregation pheromone: implications for pest management and ecology of bark beetles.

Abstract: Host plant terpenes can influence attraction of conifer bark beetles to their aggregation pheromones: both synergistic and inhibitory compounds have been reported. However, we know little about how varying concentrations of individual monoterpenes affect responses. 2 We tested a gradient of ratios of a-pinene, the predominant monoterpene in host pines in the Great Lakes region of North America, to Ips pini's phero- mone, racemic ipsdienol plus lanierone. 3 Ips pini demonstrated a parabolic response, in which low concentrations of a-pinene had no effect on attraction to its pheromone, intermediate concentra- tions were synergistic and high concentrations were inhibitory. These results suggest optimal release rates for population monitoring and suppression programmes. 4 Inhibition of bark beetle attraction to pheromones may be an important component of conifer defences. At terpene to pheromone ratios emulating emissions from trees actively responding to a first attack, arrival of flying beetles was low. This may constitute an additional defensive role of terpenes, which are also toxic to bark beetles at high concentrations. 5 Reduced attraction to a low ratio of a-pinene to pheromone, as occurs when colonization densities become high and the tree's resin is largely depleted, might reflect a mechanism for preventing excessive crowding. 6 Thanasimus dubius, the predominant predator of I. pini, was also attracted to ipsdienol plus lanierone, but its response differed from that of its prey. Attrac- tion increased across all concentrations of a-pinene. This indicates that separate lures are needed to sample both predators and bark beetles effectively. It also provides an opportunity for maximizing pest removal while reducing adverse effects on beneficial species. This disparity further illustrates the complexity confronting natural enemies that track chemical signals to locate herbivores.

Role of contact pheromones in mate recognition in Xylotrechus colonus.

Abstract: Adult male and female rustic borers, Xylotrechus colonus F. (Coleoptera: Cerambycidae), aggregate on cut logs and fallen trees that are the hosts of their larvae. Our studies show that male X. colonus actively search for females, and only respond to them after contacting them with their antennae. Stripping cuticular hydrocarbons from females with solvent rendered them unattractive to males, suggesting that males did not recognize females by mechanoreception alone. Reapplying solvent extract to washed females restored their attractiveness to males, confirming the role of cuticular hydrocarbons in mate recognition. Female cuticular hydrocarbon extracts contain n-pentacosane, 9-methylpentacosane, and 3-methylpentacosane, components that were either absent or present in very small amounts on males. We demonstrate that the contact pheromone is a blend of these three cuticular hydrocarbons.

Biochemistry and molecular biology of de novo isoprenoid pheromone production in the Scolytidae.

Abstract: Recent application of biochemical and molecular techniques to study the genesis of scolytid aggregation pheromones has revealed that bark beetles are primarily responsible for the endogenous synthesis of widely occurring pheromone components such as ipsenol, ipsdienol, and frontalin. Because many of the chemical signals are isoprenoids, the roles of the mevalonate biosynthetic pathway and the enzyme HMG-CoA reductase (HMG-R) have been investigated. This has led to the identification of endothelial cells in the anterior midgut as the site of synthesis and to the concept that de novo pheromone biosynthesis is regulated in part by the positive effect of juvenile hormone III (JHIII) on gene expression for HMG-R. Both the pronounced regulation by JHIII and the expression pattern of eukaryotic HMG-R argue against synthesis of these pheromones by prokaryotes. As the mevalonate pathway and its regulation have been studied in few other insects, broader issues addressed through the study of scolytid pheromone biosynthesis include major step versus coordinate regulation of the pathway and a genomics approach to elucidating the entire pathway and the mode of action of JHIII.

Responses of female lizards, Lacerta monticola, to males' chemical cues reflect their mating preference for older males

Abstract: Female mate choice based on visual traits appears to be rare in lizards. Field observations suggest that females of the lizard Lacerta monticola preferred to mate with larger/older males. Although older males are usually green and larger, and younger males brown and smaller, there is some overlap in size and coloration between age classes. Thus, visual cues may not always be reliable indicators of a male's age. We hypothesized that female mate-choice preferences may be based on males' pheromones, which might transmit information about characteristics such as age. In a laboratory experiment, we analyzed the effect of age of males on attractiveness of their scents to females. When we offered scents of two males of different age, females associated preferentially with scents of older males. This suggested that females were able to assess the age of males by chemical signals alone, and that females preferred to be in areas scent-marked by older males. Thus, females may increase their opportunities to mate with males of high quality, or may avoid harassment by sneaking young males. This result agreed with field observations on females mating with old males, and rejection of advances by young males. Our results also suggested that female preference for older males may depend on their own body size. Large females showed a strong preference for older males, whereas smaller females were not so selective. This, together with males' preference for large females, might lead to size-assortative matings. We suggest that the quality and/or quantity of male pheromones could communicate to the female heritable male genetic quality (i.e. age) and thereby serve as the basis of adaptive female choice in lizards.

Manipulation of parasitoids for aphid pest management: progress and prospects†

Abstract: This paper describes research at IACR-Rothamsted on aphid parasitoid responses to semiochemical foraging stimuli, aimed at developing novel ways of manipulating these behaviours to overcome ecological constraints to biological and integrated pest control. Female parasitoids respond both to aphid sex pheromones acting as kairomones, and to aphid-induced plant volatiles, acting as synomones. A range of economically important parasitoid species respond to aphid sex pheromones, and their potential for enhancing parasitization of aphid populations has been demonstrated in the field. Commercial production of the pheromone from the plant Nepeta cataria L has been developed and strategies for its use in arable crops are being investigated. Aphid-induced plant volatiles are released systemically throughout the plant and are aphid species specific, probably induced by elicitors in aphid saliva. Aphid-infested plants can induce uninfested neighbours to release damage-related volatiles, plant-to-plant communication occurring via the rhizosphere. The plant compound cis-jasmone has been identified as a plant signal with potential for aphid control, inducing plant defence mechanisms that both deter colonising aphids and attract parasitoids and predators. Such compounds may represent a new generation of crop protectants and their further investigation and development will be aided by the tools generated by genomic and post-genomic biology.

Alkaloid-Derived Pheromones and Sexual Selection in Lepidoptera

Abstract: Publisher Summary This chapter discusses alkaloid-derived pheromones and sexual selection in Lepidoptera In certain insects, foreplay is basically a sexually selective process, involving assessment by the female of certain male traits that are a measure of an eventual benefit to the offspring The foreplay is in the nature of a pheromone-mediated dialogue, and the insects are certain butterflies and moths What kindled the interest in this area of research was the seminal paper by Brower et al on the courtship of the queen butterfly, Danaus gilippus, and the motion picture that these investigators made of this behavior Their data showed clearly that the two brushlike structures, or hairpencils, that the males ordinarily keep tucked away in their abdomen are in fact everted and splayed during courtship, and are brushed against the female prior to copulation The hairpencils of Danaus gilippus turned out to be chemically similar to those of Lycorea While they lacked the esters, and had instead the viscous terpenoid alcohol, they too were laden with danaidone It became clear that danaidone and closely related pyrrolizidines are very generally present in the hairpencils of these insects, having been found in a number of genera beside Danaus and Lycorea Accompanying compounds are also present, but these are variable and have been identified in only a few species

Biochemistry of female moth sex pheromones

Abstract: Publisher Summary This chapter discusses a research conducted on sex pheromone biosynthesis in female moths Female moth pheromones are relatively simple structures consisting of a hydrocarbon chain that contains an oxygenated functional group The functional group can include an ester linkage, alcohols, aldehydes, and epoxides There are also groups of moths that utilize hydrocarbons as sex pheromones The structure of the sex pheromones led to speculatations that they were fatty acid derived This provided the key to defining pheromone biosynthetic pathways These pathways utilize fatty acid enzymes found in normal fatty acid metabolism For moths that utilize aldehydes, alcohols, or esters, biosynthesis occurs in the pheromone gland The exceptions are those that utilize linoleic or linolenic acids, which must be obtained from the diet However, modifications of these fatty acids occur in the gland For moths that utilize hydrocarbons or epoxides of hydrocarbons, the hydrocarbon is produced in oenocyte cells and then transported to the pheromone gland, where the epoxidation step takes place

Characteristic odor of Osmoderma eremita identified as a male-released pheromone.

Abstract: Osmoderma eremita (Scopoli) is an endangered scarab beetle living in hollow trees. It has mainly been known for its characteristic odor, typically described as a fruity, peachlike or plumlike aroma. The odor emanating from a single beetle can sometimes be perceived from a distance of several meters. In this paper, we show that the characteristic odor from O. eremita is caused by the compound (R)-(+)-γ-decalactone, released in large quantities mainly or exclusively by male beetles. Antennae from male and female beetles responded in a similar way to (R)-(+)-γ-decalactone in electroantennographic recordings. Field trapping experiments showed that (R)-(+)-γ-decalactone is a pheromone attracting female beetles. Lactones similar to (R)-(+)-γ-decalactone are frequently used as female-released sex pheromones by phytophagous scarabs. This is, however, the first evidence of a lactone used as a male-produced pheromone in scarab beetles. We propose that the strong signal from males is a sexually selected trait used to compete for females and matings. The signal could work within trees but also act as a guide to tree hollows, which are an essential resource for O. eremita. Males may, thus, attract females dispersing from their natal tree by advertising a suitable habitat. This signal could also be exploited by other males searching for tree hollows or for females, which would explain the catch of several males in our traps.

Contact Pheromones as Mate Recognition Cues of Four Species of Longhorned Beetles (Coleoptera: Cerambycidae)

Abstract: We tested the hypothesis that contact phermones mediate mate recognition for four species of longhorned beetles, Neoclytus mucronatus mucronatus (F.), Megacyllene caryae (Gahan), Megacyllene robiniae (Forster), and Plectrodera scalator (F.). All tested males of all four species attempted to mate with females only after contacting them with their antennae. From 66.7 to 80% of tested males attempted to mate with hexane-extracted dead females treated with 0.1–1.0 female equivalents of conspecific female extracts, confirming that nonpolar compounds on the cuticle of females are essential for mate recognition in all four species. These findings are further evidence of the critical role of contact pheromones in mating systems of longhorned beetles.

(Z)-9-pentacosene - Contact sex pheromone of the locust borer, Megacyllene robiniae

Abstract: Male locust borers, Megacyllene robiniae (Forster), responded to females only after contacting them with their antennae, indicating that mate recognition was mediated by a contact sex pheromone. GC-MS analyses of whole-body extracts of males and females determined that the profiles of compounds in the extracts were qualitatively similar, but differed considerably in the ratios of compounds between sexes. Biological activities of reconstructed blends of the most abundant straight-chain (nC23, nC24, nC25, nC26), methyl-branched (3me-C23, 3me-C25), and unsaturated (Z9:C23, Z9:C25, Z9:C27 compounds in extracts from females were assessed in arena bioassays, assessing four distinct steps in the mating behavior sequence of males (orientation, arrestment, body alignment, mounting and attempting to couple the genitalia). Males were unresponsive to freeze-killed, solventwashed females treated with blends of straight-chain and methyl-branched alkanes, but responded strongly to females treated with the blend of alkenes. Further trials determined that the complete sequence of mating behaviors, up to and including coupling the genitalia, was elicited by Z9:C25 alone. Z9:C25 comprised 16.4 ± 1.3% of the total hydrocarbons in whole-body hexane extracts of females and was co-dominant with two other hydrocarbons that were not active. In contrast, in solid phase microextraction (SPME) wipe samples from several areas of the cuticle, Z9:C25 appeared as the single dominant peak, comprising 34.6 − 37.8% of the sampled hydrocarbons. Our data indicate that Z9:C25 is a contact sex pheromone of M. robiniae, being the most abundant hydrocarbon on the surface of the cuticular wax layer of females where it is readily accessible to the antennae of males.

Human pheromones: have they been demonstrated?

Abstract: Efforts to collect evidence of human pheromones have focused on three partly overlapping classes of possible human pheromones: (1) axillary steroids, (2) vaginal aliphatic acids, and (3) stimulators of the vomeronasal organ. Examples of each of these classes have been patented for commercial use, and in some cases aggressively marketed, but there is only incomplete evidence supporting any particular claim that a substance acts as a human pheromone. The large axillary scent glands found in humans appear to be well adapted for the production of pheromones, but may actually be used for non-pheromonal odor communication, such as the sharing of information about the immune system. Putative menstrual synchronization within social groups of women and putative acceleration of the menstrual cycle caused by men's odors may suggest the existence of human pheromone systems, but evidence in both cases is still inconclusive.

Differential Bio-Activity of Ips and Dendroctonus (Coleoptera: Scolytidae) Pheromone Components for Monochamus clamator and M. scutellatus (Coleoptera: Cerambycidae)

Abstract: Male and female Monochamus clamator (LeConte) and M. scutellatus (Say) are able to detect bark beetle pheromone components electrophysiologically and are attracted to traps baited with blends of pheromone components of scolytid bark beetles. We investigated the effect of individual pheromone components (ipsenol, ipsdienol, 3-methyl-2-cyclohexen-1-one (MCH), frontalin, verbenone, cis- and trans-verbenol, and endo- and exo-brevicomin) on Monochamus Dejean trap catches. Only traps baited with ipsenol and/or ipsdienol together with the host volatiles ethanol and α-pinene caught significantly more male and female M. scutellatus and M. clamator than traps baited with host volatiles alone. Ipsenol and ipsdienol are aggregation pheromones of secondary bark beetles in the genus Ips DeGeer while the other components are pheromones of primary bark beetles in the genus Dendroctonus Erichson. The former should be the most reliable indicators of suitable host material because most Ips spp. attack weakened or moribund trees or trees already successfully under attack by primary bark beetles, and their pheromones may be more persistent in space and time than those of Dendroctonus spp. In two successive years in an operational (commercial) mass-trapping program, traps baited with ethanol, α-pinene, and ipsenol captured twice as many beetles as traps baited with host volatiles alone. These results suggest that operational monitoring or mass-trapping programs could be improved significantly by the inclusion of ipsenol in baits at a minimal cost.

Mating behaviour and evidence for a female released courtship pheromone in the signal crayfish Pacifastacus leniusculus.

Abstract: The mating behaviour of the signal crayfish, Pacifastacus leniusculus (Dana), has been categorised into seven distinct stages: orientation; contact; seizure; turning; mounting; spermatophore deposition; and dismounting. These categories were used in the development of a bioassay to test whether mature females release a sex pheromone during the breeding season to which males respond. Water conditioned by 1) mature females (MF water), 2) immature females (IF water) and 3) freshwater (C water), were injected through standard aquarium air-stones into tanks containing mature males. The behaviour of the male was recorded on video for 15 minutes before and after injection of each test water. The time that the males spent exhibiting the three behavioural categories of 'quiescent,' 'motile' and 'handling' of the air-stone, were recorded. 'Handling' of the air-stone included the mating behaviours of seizure, mounting, and spermatophore deposition onto the surface of the air-stone. Males exposed to MF water exhibited significantly increased levels of motile activity and handling behaviour, than males exposed to C water or IF water. These results demonstrate for the first time the presence of a sex pheromone, released during the breeding season by mature females, that stimulates courtship and mating behaviour in male P. leniusculus.

Genetic identification of two sibling species of Lutzomyia longipalpis (Diptera: Psychodidae) that produce distinct male sex pheromones in Sobral, Ceará State, Brazil.

Abstract: Lutzomyia longipalpis, the main sandfly vector for New World visceral leishmaniasis is a complex of an as yet undefined number of sibling species. At present, there is no consensus on the status (single species vs. species complex) of Brazilian populations. We applied five microsatellite loci to test the hypothesis that L. longipalpis occurs as two sympatric cryptic species in Sobral, Ceara State, Brazil as predicted by male sex pheromone chemotypes described previously for field specimens from this site [S-9-methyl-germacrene-B (9MGB) and a cembrene compound]. Abdominal spot morphology corresponds with pheromone type at this locality (9MGB in '1 spot' males and cembrene in '2 spot' males). Genotype data from 190 wild-caught L. longipalpis specimens collected in October 1999 and April 2001 were used to estimate genetic differentiation between the two sex pheromone populations and sampling dates. No significant (P > 0.05) genetic differences were found between the 1999 and 2001 9MGB samples (theta = 0.018; RST = -0.005), and genetic differentiation was low between the cembrene collections (theta = 0.037, P 0.05). By contrast, highly divergent allelic frequencies (largely at two microsatellite loci) corresponded to significant (P > 0.05) genetic differentiation (theta = 0.221; RST = 0.215) for all comparisons between samples with different pheromones. When pheromone samples were pooled across sample date, genetic differentiation was high (theta = 0.229; P < 0.001; Nem = 0.84). The allele frequency distribution at each of the five microsatellite loci was similar for males and females from the two collection years. Two of these loci showed highly divergent allele frequencies in the two sex pheromone populations. This was reflected in the highly significant genetic differentiation obtained from the male genotypes, between populations producing different pheromones (theta = 0.229-0.268; P < 0.0001 for the 2001 and theta = 0.254-0.558; P < 0.0001 for the 1999 collections, respectively). Similar results were obtained when the females, assigned to a pheromone type, were included in the analysis. Both a Bayesian analysis of the data set and a population assignment test provided strong evidence for two distinct populations corresponding to pheromone type. Given its genotype, the probability of assigning a 9MGB male to the original 9MGB population was 100% once the two years' collections were pooled. For cembrene-producing '2 spot' males this probability although still high, was lower than for 9MGB males, at 86%. This microsatellite data together with previously reported reproductive isolation between the two Sobral populations confirm that premating barriers are important in speciation of L. longipalpis.

Increased risk of parasitism as ecological costs of using aggregation pheromones: laboratory and field study of Drosophila‐Leptopilina interaction

Abstract: Information conveyance plays an important role in parasitoid-host interactions. Several sources of information are available for searching parasitoids and exploitation of that information during the different phases of host location depends on its reliability, detectability and accuracy. One source of information especially suitable for exploitation by parasitoids is a host aggregation pheromone, because this often combines all three aspects. In laboratory and field experiments we studied the behavioural responses of the parasitoid Leptopilina heterotoma to the aggregation pheromone of the fruit fly Drosophila melanogaster, both for substrate selection and the behaviour on host substrates. Our results show that substrates with increasing dose of the host's aggregation pheromone attract increasingly more parasitoids, whereas we found no significant effects of pheromone on parasitoid searching behaviour on the substrates. Parasitoid searching behaviour on substrates was influenced by other host cues (e.g. larval excrements, traces of adults other than aggregation pheromone), which is discussed in relation to the expectations from reliability-detectability theory. The responses of the parasitoids were further influenced by substrate quality (i.e. yeast concentration) and the microscale distribution of pheromone. In several field experiments, the fraction of fruit fly larvae that was parasitised was significantly higher in substrates with aggregation pheromone than in control substrates, indicating an ecological cost to the use of aggregation pheromones in adult D. melanogaster.

Floral evolution and pollinator mate choice in a sexually deceptive orchid.

Abstract: Sexually deceptive orchids mimic sex pheromones and appearance of female insects to attract males, which pollinate the flowers in an attempted mating. This study examines the effects of pollinator mate choice on orchid floral evolution using the Thynnine wasp Neozeleboria cryptoides (Smith) (Hymenoptera: Tiphiidae), which pollinates the sexually deceptive orchid Chiloglottis trapeziformis Fitzg. (i) When male wasps were given the choice between two female dummies of different sizes and identical amount of synthetic pheromone, they preferentially attempted to copulate with medium-sized dummies over small dummies. (ii) When given the choice between two dummies of identical size but different amounts of pheromone, males preferred the larger amount of pheromone. Larger amounts of pheromone generally attracted more males than smaller amounts. (iii) Orchid flower labella, which mimic a female body, were significantly longer and broader than female wasp bodies, and the flowers also produced on average 10 times more 'pheromone' than females. The evolution and maintenance of these exaggerated mating signals is likely to be mediated by the male pollinator behaviour demonstrated here. (iv) When five dummies were offered simultaneously in a 10 cm circular array, males rarely attempted copulation on more than one dummy during a single visit. This behaviour may foster the evolution or maintenance of clonality in C. trapeziformis, as it will minimize pollen exchange within clones.