Investigation of a sex pheromone for the oriental cockroach,Blatta orientalis

A sex pheromone for adult male oriental cockroaches Blatta orientalis was isolated from the faeces of adult virgin female oriental cockroaches. It elicited a sexual response at 10 pg and 1 ng with B. orientalis and Periplaneta americana adult males, respectively. The site of production appers to be the crop, oesophagus, and proventriculus. Electroantennogram responses of male antennae toward the isolated pheromone were greater than those of the female antennae. The adult male oriental cockroach also responded to the American cockroach sex pheromone. The isolated pheromone with a mol. wt of 232 may be similar to one of the components of the American cockroach sex pheromone.     

CONTROL OF SEX PHEROMONE BIOSYNTHETIC PATHWAY BY PBAN IN ASIAN CORN BORER OSTRINIA FURNACALlS*

Abstract Sex pheromone titer in Ostrinia furnacalis was significantly decreased to a very low level by decapitation, but it could be restored by injection of head extract prepared from both male and female moths or synthetic pheromone biosynthesis activating neuropepide (PBAN). This fact indicates that pheromone production is under the control of a PBAN-like factor. The sex pheromone biosynthetic pathway of O. furnacalis originates with the biosynthesis of palmitic acid and followed by A14 desaturation, chain shortening, reduction and acetylation to form the pheromone components, (Z) and (E)-12-tetradecenyl acetate. In order to determine which step in the pathway is controlled by PBAN, the incorporation of different labeled precursors into the pheromone and its intermediate were studied. Our results suggest that PBAN controls pheromone biosynthesis in O. furnacalis by mainly regulating an early step from acetate to palmitic acid.     

Sex-linked control of sex pheromone behavioral responses in European corn-borer moths (Ostrinia nubilalis) confirmed with TPI marker gene

In two races of European corn-borer moths (ECB), the E-race females emit and males respond to 99:1 sex pheromone blend of (E)/(Z)-11-tetradecenyl acetates, whereas the Z-race females and males produce and respond to the opposite 3:97 pheromone blend of (E)/(Z)-11-tetradecenyl acetates, respectively. We previously have shown that female production of the final blend ratio is under control of a major autosomal locus but that the sequence of male upwind flight responses to the blend is controlled by a sex-linked (Z-linked) locus. This sex-linked control of behavioral responses in crosses of E and Z ECB now is confirmed by use of sex-linked TPI (triose phosphate isomerase) allozyme phenotypes to determine the origin of the sex chromosomes in F₂ populations. F₁ males from reciprocal E × Z crosses generate similar behavioral-response profiles in wind-tunnel studies, with moderate numbers responding to the Z pheromone and intermediate blends (35%–65% Z), but very few responding to the E pheromone. The F₂ behavioral-response profiles indicate that they are composed of 1:1 mixtures of hybrids and paternal profiles. Analysis of TPI allozyme differences allowed us to separate male F₂ populations into individuals whose Z chromosomes both originated from their grandfathers, and individuals who had one Z chromosome originating from each grandparent. With these partitioned F₂s, the TPI homozygotes exhibited behavioral-response profiles very much like their grandfathers, whereas the TPI hybrids produced response profiles similar to their heterozygous F₁ fathers. These results demonstrate incontrovertibly that the response to sex pheromone in male ECB is controlled by a sex-linked gene that is tightly linked to the TPI locus and therefore is independent of the locus controlling pheromone blend production in females.     

Effects of pheromone concentration and photoperiod on the behavioral response sequence to sex pheromone in the male brown-banded cockroach,Supella longipalpa

The effects of female sex pheromone concentration and time of day on behavioral responses of male brown-banded cockroaches were monitored with a two-choice olfactometer. The duration of each behavior or behavioral event in a deterministic response sequence and the probabilities of behavioral transitions were analyzed. Pheromone concentration had a significant effect on all behaviors in the response sequence. The time of testing, relative to the entrainment photoperiodic regime, significantly affected behavioral events early in the sequence but not later-occuring behaviors. Although the probability of males choosing the pheromone rather than the solvent control was a function of the pheromone concentration, it was independent of the time of testing. By affecting the probability of behavioral transitions, the pheromone concentration and time of testing determined the number of insects exhibiting specific behaviors in the response sequence. The behavioral response sequence can be characterized by probabilities of behavioral transitions along with latencies of early behavioral acts.     

Sex pheromone of Ostrinia sp. newly found on the leopard plant Farfugium japonicum

Recently, larvae of Ostrinia were found feeding on the leopard plant Farfugium japonicum (Asteraceae), previously unrecorded as a host plant of this genus. The adult moths that developed from these borers were morphologically similar to, but distinct from, Ostrinia zaguliaevi, a monophagous species specialized for feeding on another Asteraceae plant, the butterbur Petasites japonicus. Although the taxonomical status of the moth feeding on F. japonicum is to be determined, distinct morphological differences in the adults strongly suggest this to be a new species (hereafter referred to as O. sp.). To gain an insight into the reproductive isolation between O. sp. and other members of the genus Ostrinia, the female sex pheromone and the males’ response to it were investigated using samples collected from F. japonicum. (Z)‐9‐tetradecenyl acetate (Z9‐14:OAc), (Z)‐11‐tetradecenyl acetate (Z11‐14:OAc), (E)‐11‐tetradecenyl acetate (E11‐14:OAc), tetradecyl acetate, and (Z)‐11‐hexadecenyl acetate were identified as candidates for sex pheromone components by analyses using gas chromatographs coupled to a mass spectrometer (GC‐MS) and electroantennographic detector (GC‐EAD). A series of bioassays of male responses in a wind‐tunnel and a field cage indicated that the former three compounds are essential for attracting males, and the latter two have no synergistic effect on the attraction. We therefore concluded that Z9‐14:OAc, Z11‐14:OAc and E11‐14:OAc are the sex pheromone components of O. sp. Although the same three compounds are used as the sex pheromone components of O. zaguliaevi and another congener, Ostrinia zealis, the blend proportions differed greatly among the three (Z9‐14:OAc/Z11‐14:OAc/E11‐14:OAc = 18/76/6 in O. sp., 45/50/5 in O. zaguliaevi and 70/6/24 in O. zealis). Differences in sex pheromones could contribute to the reproductive isolation between O. sp. and the other two Ostrinia species if males of each species exhibit a narrow window of response to their own blend ratio.     

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.     

Behavioral and electrophysiological responses of Helicoverpa assulta, H. armigera (Lepidoptera: Noctuidae), their F1 hybrids and backcross progenies to sex pheromone component blends

Two sibling species, Helicoverpa assulta and Helicoverpa armigera both use (Z)-9-hexadecenal and (Z)-11-hexadecenal as their sex pheromone components but in almost reversed ratios, 93:7 and 3:97, respectively. H. assulta and H. armigera males performed upwind flight in response to the H. assulta sex pheromone blend (93:7). H. armigera responded strongly to the H. armigera blend (3:97), whereas H. assulta males remained inactive upon exposure to this blend. Both species gave clear dose-dependent electrophysiological responses to (Z)-11-hexadecenal. However, (Z)-9-hexadecenal evoked strong dose-dependent electrophysiological responses in H. assulta males but not in H. armigera. The two male F₁ hybrids exhibited similar behavioral responses to two sex pheromone blends and electrophysiological responses to two pheromone components as H. armigera males. This indicated that H. armigera genes appear dominant in determining the behavioral response and electrophysiological responses. Behavioral and electrophysiological responses of backcrosses of male F₁ hybrids (H. armigera female × H. assulta male) with female H. assulta and H. armigera were close to that of H. assulta and H. armigera, respectively. However, backcrosses of female F₁ hybrids (H. assulta female × H. armigera male) with male H. assulta and H. armigera showed reduced behavioral responses but normal electrophysiological responses compared to males of the respective parental line.     

The circadian rhythm of flight activity of Spodoptera exigua males in response to sex pheromone

In many moths, male attraction to the blend of synthetic sex pheromone releasing continuously in the field shows an apparent circadian rhythm similar to that of locomotion activity. In this study, the daily rhythms of electroantennography (EAG) and behavioral responses to sex pheromone, and the daily rhythms of locomotion activity were measured in male beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae). The peaks of males trapped by light and sex pheromone were all during the latter part of the night in the field. However, there was no significant variation among time intervals in the EAG responses of male antennae to sex pheromone stimuli. The principal period of locomotion activity under L15:D9 (LD) continued to occur during the scotophase and the subjective scotophase in the day of constant darkness (DD1) and the second of two consecutive days of constant darkness (DD2). The majority of males contacted the sex pheromone source in a wind tunnel during the latter part of the scotophase under LD and the subjective scotophase for DD1 and DD2. There were significant associations between the rhythm of the behavioral response to sex pheromone and locomotion activity. These results suggested that the male's behavioral response to sex pheromone in the beet armyworm could be observed only until locomotion activity of the male occurred at the end of the dark period, despite sex pheromone being released continuously from synthetic pheromone‐baited traps in the field.     

OLFACTORY RESPONSES OF COTTON BOLLWORM,HELICOVERPA ARMIGERA TO SEX PHEROMONE AND PLANT VOLATILE COMPONENTS*

Abstract Electroantennograms (EAGs) were recorded from unmated, laboratory-reared male and female Helicover pa armigera (Lepidoptera:Noctuidae) adults to two sex pheromone components and a range of plant volatile components, some of which are known volatiles from leaves and fruits. The female-produced sex pheromone was not detected by other female moths. The sex pheromone components to which male moths responded previously show to possess biological activity. As for plant volatile components, a large degree of EAG response uniformity between male and female moth was observed. The greatest EAG responses of all plant volatiles tested were elicited by monoenic C-6 alcohol and aldehyde. They are constituents of the “general green-leaf odor” that emanates from most plants. The potential adaptive benefit of selective perception to sex pheromone and green-leaf volatile components is discussed.     

The roles of juvenile hormone and biogenic amines on pheromone response plasticity and diapause termination in male Caloptilia fraxinella

In insects that exhibit a period of delayed reproduction, the timing of mating and reproduction is controlled by environmental conditions that regulate endogenous factors such as hormones and biogenic amines (BAs). Caloptilia fraxinella (Ely) (Lepidoptera: Gracillariidae) undergoes a 9‐month reproductive diapause from adult eclosion in the summer until diapause termination the following spring when adults mate. Male response to female sex pheromone is plastic, and is most acute when moths are reproductively active. The aim of this study is to further elucidate the mechanisms involved in the regulation of male response to pheromone in C. fraxinella, and to test whether the application of BAs with and without a juvenile hormone analogue (JHA) to males in different physiological states impacts pheromone responsiveness, as measured by electroantennogram and wind tunnel bioassays. Treatment of male C. fraxinella in reproductive diapause with one application of a JHA induces the highest subsequent pheromone response in the fall, but does not alter pheromone response earlier in reproductive diapause in the summer. The JHAs methoprene and pyriproxyfen similarly enhance pheromone response in the fall. Treatment with methoprene alone or in combination with one of the BAs octopamine, dopamine or serotonin increases male pheromone responsiveness in the fall. The increase in pheromone response can be attributed to methoprene only, as treatment with any of the BAs alone does not enhance male response to pheromone. Biogenic amine treatment lowers male responsiveness to pheromone in some experiments, indicating that there may be a role for BAs in maintaining low pheromone response during reproductive diapause in this species.     

Wolbachia infection and an all-female trait in Ostrinia orientalis and Ostrinia zaguliaevi

Sex ratio distortion toward females (SR trait), induced by a Wolbachia bacterium, has been reported in two species of the Ostrinia furnacalis group, viz., O. furnacalis, and O. scapulalis (Lepidoptera: Crambidae). In addition, an SR trait caused by abacterial, unidentified agent(s) is known in O. scapulalis. Here we examined the SR trait in four other species of the furnacalis group, viz., O. orientalis, O. zaguliaevi, and O. zealis from Japan, and O. nubilalis from central and eastern Europe. Wolbachia infection was detected in three O. orientalis females and in one O. zaguliaevi female, and the infection was always associated with the SR trait. In terms of wsp and ftsZ gene sequences, Wolbachia strains in O. orientalis and O. zaguliaevi were indistinguishable from each other, or from those in O. furnacalis and O. scapulalis. These findings suggest that Wolbachia strains in the four Ostrinia species are probably identical. In addition, one O. zealis female, which was negative in diagnostic PCRs for Wolbachia and general bacteria, produced an all‐female brood. This trait was very similar to the SR trait caused by abacterial agent(s) in O. scapulalis.     

EFFECTS OF SUBLETHAL ESERINE ON THE CHEMICAL COMMUNICATION SYSTEM OF ASIAN CORN BORER,OSTRINIA FURNACALIS (GUENEE)*

Abstract Topically applied sublethal doses of eserine may interrupt chemical communication between the two sexes of Asian corn borer, Ostrinia furnacalis (Guenee), by affecting calling and sex pheromone titre released by the females. (1) Studies on the effects of sublethal eserine on the chemical communication system of O. furnacalis indicated that there was a decreasing probability of females calling and sex pheromone titre as the eserine dosage increased from 0.27 to 2 700 ng, with no effect on the periodicity. However, at 2 700 ng, the E/Z ratio of the sex pheromone components was affected. The sexual chemical communication system could not control within narrow level. (2) The recovery test of 27ng‐treated female indicated that the calling percentages of the 1st, 2nd and 4th day post‐treatment were 50%, 78% and 84% respectively. Sex pheromone titre was 40%, 40% and 80% of control female repectively. There was a trend toward recovery. The sexual chemical communication system could control within narrow level from the 2nd day post‐treatment.     

Electrophysiological and Behavioral Responses of Female Beet Armyworm Spodoptera exigua (Hübner) to the Conspecific Female Sex Pheromone

Electroantennogram (EAG) recordings showed that female Spodoptera exigua can detect their own sex pheromones (two single components and their mixture), displaying a similar dose–response pattern to that of males, although intensities of female responses were much less at all doses compared with males. Furthermore, the female calling behavior was inhibited and late-shifted by the presence of the female sex pheromone. When the pheromone components were presented, the calling female proportion in the peak calling period was significantly reduced and the calling peak time and calling termination time postponed, compared with controls. Although the calling behavior was inhibited, the pheromone titer of treated females was not different to the control, implying a reduced pheromone biosynthesis in the pheromone glands of treated moths. However, observations during the olfactometer experiments revealed that there were no obvious behavioral responses of females exposed to sex pheromone stimuli including whole gland extracts, 0.1, 1 or 10 μg binary pheromone mixtures.     

<Emphasis Type="Italic">S</Emphasis>-isorobinal as the female sex pheromone from an alarm pheromone emitting mite, <Emphasis Type="Italic">Rhizoglyphus setosus</Emphasis>

The female sex pheromone of Rhizoglyphus setosus Manson (Astigmata: Acaridae) was identified as S-isorobinal (4S-4-isopropenyl-3-oxo-1-cyclohexene-1-carboxyaldehyde), which stimulated males sexually and enhanced the frequency of the male’s tapping and mounting behavior. Although the female hexane extract indicated no sign of sex pheromone activity against tested males, possibly due to the presence of the alarm pheromone neryl formate, an SiO₂ column fraction containing isorobinal elicited sex pheromone activity at a dose of one female equivalent. The stereochemistry of natural isorobinal was identified as S by an HPLC using a chiral column. Both S- and R-isorobinals exhibited maximum activity at the same dose of 1 and 10 ng with a convex dose–response relationship. Amounts of S-isorobinal were determined to be 11.7 ± 1.0 ng per female and 6.4 ± 1.3 ng per male by GLC. This is the second example of two pheromones (the alarm pheromone neryl formate, and the sex pheromone S-isorobinal) demonstrated to be components of the same opisthonotal gland secretion.Chemical ecology of astigmatid mites. LXXVIII     

Sex pheromone titre in the glands of Spodoptera litura females: circadian rhythm and the effects of age and mating

The present study investigates the effects of age and mating status on the circadian variations of gland sex pheromone titre in female Spodoptera litura Fabricius. Similar to other nocturnal moths, S. litura females exhibit circadian variations of gland sex pheromone contents, with higher levels during scotophase and lower levels during photophase. The sex pheromone titre in the glands peaks during the first scotophase after eclosion and sharply declines afterwards. Higher pheromone contents during scotophase may facilitate female reproductive activities, and the negative relationship between pheromone titre and female calling is likely the result of pheromone release during female calling. Interestingly, the present study demonstrates that mated S. litura females have significantly higher sex pheromone titre in their pheromone glands (PGs) than virgin females. This finding contrasts with all previous studies of other insect species, in which mating generally reduces the sex pheromone titre in female PGs. In S. litura, mating and male accessory gland fluids can suppress female calling behaviours and re‐matings. These results suggest that the suppression of female calling behaviours by mating and male accessory gland fluids may significantly reduce the release of sex pheromones and thus result in higher sex pheromone titre in the PGs of mated females.     

S-isorobinal as the female sex pheromone from an alarm pheromone emitting mite, Rhizoglyphus setosus

The female sex pheromone of Rhizoglyphus setosus Manson (Astigmata: Acaridae) was identified as S-isorobinal (4S-4-isopropenyl-3-oxo-1-cyclohexene-1-carboxyaldehyde), which stimulated males sexually and enhanced the frequency of the male’s tapping and mounting behavior. Although the female hexane extract indicated no sign of sex pheromone activity against tested males, possibly due to the presence of the alarm pheromone neryl formate, an SiO₂ column fraction containing isorobinal elicited sex pheromone activity at a dose of one female equivalent. The stereochemistry of natural isorobinal was identified as S by an HPLC using a chiral column. Both S- and R-isorobinals exhibited maximum activity at the same dose of 1 and 10 ng with a convex dose–response relationship. Amounts of S-isorobinal were determined to be 11.7 ± 1.0 ng per female and 6.4 ± 1.3 ng per male by GLC. This is the second example of two pheromones (the alarm pheromone neryl formate, and the sex pheromone S-isorobinal) demonstrated to be components of the same opisthonotal gland secretion.     

<Emphasis Type="Italic">Ostrinia</Emphasis> revisited: Evidence for sex linkage in European Corn Borer <Emphasis Type="Italic">Ostrinia nubilalis</Emphasis>(Hubner) pheromone reception

Background  

The European Corn Borer, Ostrinia nubilalis (Hubner), is a keystone model for studies on the evolution of sex pheromone diversity and its role in establishing reproductive isolation. This species consists of two sympatric races, each utilizing opposite isomers of the same compound as their major pheromone component. Female production and male response are congruent in each race, and males from each strain exhibit phenotypic differences in peripheral physiology. Both strains possess co-localized pheromone-sensitive olfactory sensory neurons characterized by a larger amplitude action potential (spike) responding to the major pheromone component, and a smaller spike amplitude cell responding to the minor component, i.e. the opposite isomer. These differences in amplitude correspond to differences in dendritic diameter between the two neurons. Previous studies showed that behavioral response to the pheromone blend was sex-linked, but spike amplitude response to pheromone components matched autosomal, not sex-linked inheritance.     

Genetic analysis and population survey of sex pheromone variation in the adzuki bean borer moth, Ostrinia scapulalis

Sexual communication in many moths occurs between females emitting a sex pheromone and males responding to it. Females of Ostrinia scapulalis (Lepidoptera: Crambidae) show a large variation in blend ratios of the two sex pheromone components (E)‐ and (Z)‐11‐tetradecenyl acetates. E type females produce a pheromone with a high percentage of (E)‐11‐tetradecenyl acetate, whereas Z type females produce the opposite blend. We established laboratory cultures of E and Z types. Females of the F₁ generation produced an intermediate blend (I type) in both reciprocal crosses of the E and Z cultures. Results of further crossing experiments suggested that the three pheromone types are primarily controlled by a single autosomal locus with two alleles. Also, analyses of the variation in pheromone blend within F₁, backcross and F₂ families suggested that other genetic factors modify the pheromone blend of the I and Z types. Investigation of the pheromone variation in natural populations at 14 localities in Japan has shown that the E type was predominant in northern Japan, whereas the pheromone was highly polymorphic in central Japan. At a locality in central Japan, the pheromone was constantly polymorphic for several years, and the pheromone type frequencies did not deviate from Hardy–Weinberg expectations, providing no evidence of selection or assortative mating between the pheromone types. Analyses of pheromone variation within families derived from feral females indicated that matings between a pair with different genotypes for pheromone production was occurring in natural populations. Overall, this study showed that the genetic basis of the pheromone variation in O. scapulalis is very similar to that in its sibling species Ostrinia nubilalis although the state of pheromone polymorphisms in natural populations appears to differ between the two species. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 84 , 143–160.     

Cockroach mating behaviors,sex pheromones,and abdominal glands (Dictyoptera: Blaberidae)

Two chemical signals are essential in all cockroach sexual behavioral sequences: the sex pheromone released by one partner, generally the female (for long distance attraction), and an aphrodisiac sex pheromone produced exclusively by male tergal glands (for female mounting and tergal contact or feeding behavior). Unlike the other cockroach groups, the males of the Oxyhaloinae species produce both chemical signals: the pheromone and the aphrodisiac. The occurrence of three patterns of mating behavior (A, B, and C), the production of male sex pheromones, and the existence in the male of developed sternal and tergal glands in seven related Oxyhaloinae species, make these cockroaches a useful model for studying the evolution of mating behavior patterns. The various types of mating behavior were not classified in the previous studies by Roth and Barth. In this report, they have been named type A (female in upper position), B (male in upper position), and C (male and female end to end). In type A mating, the male tergal glands, which are licked by the females, are well developed, whereas in types B and C, there is no licking of the male's tergal secretion by the females and the tergal glands are much less developed; the aphrodisiacs secreted by the tergal glands may no longer act in this case through contact chemoreception, but through an olfactory process involving volatile components. One common sex pheromone component seems to be acetoin. I suggest that the mating behavior tends from A toward B and C during the evolutionary process with a concomitant regression of the tergal glands and changes in the aphrodisiac emission levels. The mating behavioral sequences of cockroaches (Dictyoptera) and crickets (Orthoptera) show a striking degree of similarity and are probably examples of convergent evolution.     

Mating Effect on Sex Pheromone Production of the Oriental tobacco budworm,Helicoverpa assulta

This study was undertaken to clarify the suppression phenomenon of sex pheromone production after mating and its relationship to the physiological mechanism in adult females of Helicoverpa assulta, and determine the mating factor from males causing depletion of sex pheromonc production. Sex pheromone production of H. assulta females was mostly terminated in 3 hours after mating. Mated females maintained with a low titer of sex pheromone until 3 days when it started to increase again, which showed a characteristic of species mating more than once. The mated female again produced pheromone upon injection of pheromone biosynthesis activating neuropeptide (PBAN) or extracts of brain-suboesophageal ganglion complexes (Br-Sg) of mated female, which were shown similar pheromonotropic activities as compared with virgin females. These results indicated that the mating did not inhibit the receptivity of pheromone gland itself and PBAN biosynthesis in suboesophageal ganglion of the mated females. And it seems to support that the depletion of sex pheromone production is responsible for blocking of PBAN release from head. To investigate the mating factor from adult males, when extracts of reproductive organs of male were injected into hemocoel of virgin females evoking depletion of sex pheromone production as shown in mated female. The results suggest that a chemical substance(s) from the male reproductive organs could be responsible for the loss of sex pheromone biosynthesis in H. assulta.