Nippostrongylus brasiliensis: Female incubation,release of pheromone,fractionation of incubates

The release of pheromone by female Nippostrongylus brasiliensis as a crude incubate was linear for the first 2 hr, but declined after this period. Pheromone release in solution increased with temperature elevations until a 37 C incubation temperature was reached. Higher temperatures of incubation apparently caused diminished pheromone release. Gel filtration of female pheromone that was prepared as a crude incubate revealed biologically active elutions at K_av, 0.64 and 1.0. The timed release of female pheromone activity at these two elution regions coincided additively with the production of activity as a crude incubate. Each individual Chromatographic fraction from females accounted for about 50% of the pheromone activity of the crude, nonfractionated incubate, based on the male's bioassay response. Recombination of the K_av 0.64 and 1.0 elutions enabled recovery of pheromone activity that was similar to crude incubate. The gel filtration elution of 260-nm absorbance from male- or female-produced incubate was qualitatively similar, but a range of quantitative differences were evident. The fractionation of incubate from several female densities revealed only quantitative differences.     

1-Iodo-2 methylundecane [1I2MU]: An estrogen-dependent urinary sex pheromone of female mice

In our previous investigations [1], urine of female mice contained specific compounds, namely isocroctylhydrazine, 4-methyl-2-heptanone, and azulene during proestrus, whereas during estrus it contained 1-H-cyclopop.e.azulene, caryophyllene, and copanene. Furthermore, 1-iodo-2 methyl undecane (1I2MU), present during both proestrus and estrus, was regarded as a putative estrus-specific chemo-signal [1]. The primary objective of the present study was to determine the estrogen-dependency of the above-mentioned compounds, including 1I2MU. Furthermore, the effect of these compounds on pre-mating behavior, e.g., sniffing, licking, and grooming, were recorded to determine their role as sex pheromones. Based on gas chromatography linked mass spectrometry (GC-MS) of urine samples, profiles in oophorectomized female mice had 14 major peaks. Furthermore, neither 1I2MU (nor other estrus-specific compounds) were detected in the urine of these mice, although they were detected in urine of proestrus and estrus mice. In addition, 1I2MU was not detected in urine of prepubertal mice. It was noteworthy that both 1I2MU and 4-methyl-2-heptanone reappeared in estrogen-treated females. Based on pre-mating behavioral analysis, 1I2MU was the compound most preferred by males. In conclusion, production of 1I2MU was estrogen-dependent in females, and it enhanced reproductive activities in males.     

Elevation of pheromone response threshold in almond moth males pre-exposed to pheromone spray

Abstract. High percentages of naive Cadra cautella (Walker) (Lepidoptera: Pyralidae) males not pre-exposed to pheromone flew upwind to sources containing 50 ng (83%) and 500 ng (97%) of pheromone, but not to sources containing 5 μg (23%) and 50 μg (4%).Of the naive males that flew upwind in response to 50 ng sources, 67% located and landed on the source, whereas fewer than 19% of the naive males that flew upwind in response to higher doses located and landed on the sources.A 2-minute pre-exposure of C.cautella males to a spray cloud containing 50 ng, 500 ng, 5 μg or 50 μg of pheromone, induced shifts in response levels such that in wind-tunnel bioassays performed 1 h later, there was an increase in the doses that optimally elicited upwind flight and landing on the source that was proportional to the pre-exposure dose.Few of the pre-exposed males flew upwind to (10–43%) and landed on (0–33%) 50 ng sources, whereas they now perferentially flew upwind to(58–81% and 52–73%) and landed on (33–68% and 55–60%) pheromone sources of doses of 500 ng and 5 μg, respectively.Therefore pre-exposure to pheromone promoted a shift of threshold for response, and not an overall reduction in responsiveness to pheromone.     

Responsiveness of Pseudaletia unipuncta males to the female sex pheromone

ABSTRACT. In wind tunnel experiments male response to different concentrations of synthetic pheromone varied with age. At 25°C responsiveness increased up to day 5 and then declined slightly on day 7. For any given age the level of response generally increased with an increase in pheromone concentration. Males held at 15°C (since emergence) showed a continual increase in responsiveness with age; however, overall response levels were less than at 25°C. At 25°C male response to low concentrations of pheromone (10 and 30 μg) varied markedly over a 24 h period but no differences were observed at higher concentrations (100 and 300 μg).     

Temperature-mediated sex pheromone production and response of the American cockroach

Temperature affects the production of and response to sex pheromone by the American cockroach. Female sex-pheromone production is directly related to acclimation temperature and rapidly decreases 1 week after acclimation to lower temperatures. Production decreases slightly between weeks 1 and 2 and remains constant thereafter. Phermone-release rates are not affected by substrate temperature. Male response to a 1 ♀-equivalent hr pheromone dose is also temperature dependent. Maximal response was obtained at 26.7°C. Acclimated males were able to perceive pheromone (EAG technique) and capable of movement at lower temperatures (10°C), suggesting central nervous system inhibition.     

The effect of male sandfly pheromone and host factors as attractants for female Lutzomyia longipalpis (Diptera: Psychodidae)

Abstract Male Lutzomyia longipalpis (Lutz & Neiva) pheromone extracted from tergal glands combined with heat, carbon dioxide gas and hamster urine was found to be attractive to virgin female sandflies. The host factors if offered in the absence of pheromone or a heat source were, however, unattractive to female flies. Pheromone stored for 6 days and then combined with the same host components remained attractive to female flies but storage failed to enhance its attractiveness. The effects of carbon dioxide gas, hamster urine, chicken uropygial gland extract and octenol plus acetone on the responses of females were inconsistent. A ceramic battery powered heat source was tested with pheromone and host attractants and showed potential for field application in developing a pheromone trap.     

Effect of the fine-scale structure of pheromone plumes: pulse frequency modulates activation and upwind flight of almond moth males

Abstract. The effects of plume intermittency and volume on behavioural and flight responses to pheromone of male Cadra cautella (Walker) (Lepidoptera: Phycitinae) were investigated in a pulling wind tunnel. The fine-scale structure of turbulent pheromone plumes was mimicked and manipulated using a pulser device that generated continuous ribbon plumes or intermittent plumes with defined pulse frequency and volume. As pulse frequency increased from 0.6 to 5 Hz and injected volume increased from 0.5 to 5 mls^-1, males flew progressively higher air and ground speeds, turned less frequently, and steered smaller course angles, resulting in straighter flight tracks. The faster the frequency of pulses and the greater the volume of the plume, the higher the proportion of males responding, the shorter their latencies, and the less time spent in the behaviour. Flight tracks of male C.cautella to point sources of pheromone depend on the frequency of filaments encountered.     

Sex pheromone components of female Cornutiplusia circumflexa

Capillary gas chromatography indicated the presence of (Z)-7-dodecenyl alcohol and (Z)-7-dodecenyl acetate in the abdominal tip extracts of female Cornutiplusia circumflexa (L.) (Lepidoptera: Noctuidae: Plusiinae) moths. Gas chromatography combined with mass spectrometry and dimethyl disulfide derivatization confirmed the structure of these two principal pheromone components. In a flight-tunnel bioassay, a 5:1 blend of alcohol and acetate elicited the complete courtship sequence by males. The response was comparable to that evoked by a live virgin female, but males spent significantly longer time at calling females than at the synthetic source. The 5:1 blend was also attractive to male C. circumflexa in the field, as indicated by catches in traps baited with this mixture. (Z)-7-dodecenyl alcohol alone was slightly attractive whereas (Z)-7-dodecenyl acetate alone was completely inactive. C. circumflexa is the first reported Plusiinae species which utilizes (Z)-7-dodecenyl alcohol as the major pheromone component.     

Nippostrongylus brasiliensis: local humoral responses in the lungs and intestines of rats following vaccination with irradiated larvae

Groups of rats were infected with 2000 normal larvae of Nippostrongylus brasiliensis or larvae irradiated with 10 to 120 kR. On Day 10 after infection half the animals from each group were autopsied. The remainder were challenged with 5000 unirradiated larvae on Day 15 and killed ten days later. During the experiment enteric antibody levels were estimated by coproantibody measurement. At autopsy the worm burdens were determined and worm-specific antibodies evaluated in lung extracts and serum. It was found that the levels of coproantibody detected with adult worm metabolites were positively correlated with the number of adult nematodes recovered from the intestine after primary infection. The challenge induced a similar increase of these antibodies in all immunised rats which reflected a high immunity to reinfection of vaccinated animals. Preliminary immunochemical studies suggested that the coproantibodies had SIgA properties. In lung extracts of rats immunised with larvae irradiated at 40, 80, or 120 kR and in all animals after challenge, antibodies reacting with infective larval antigens were found. Their titres were negatively correlated with serum antibody levels. The significance of bronchial and enteric antibodies in conferring protection against challenge remains to be elucidated.     

A comparative study of sex pheromone reception in the Hadeninae (Lepidoptera: Noctuidae)

Abstract A comparative study of the olfactory responses to pheromone compounds was performed in twenty-four species of Hadeninae. Electroantennograms (EAG) were recorded on male moths in response to thirty compounds and the response profiles of each species were analysed by factorial correspondence analysis. A limited number of molecules were found active and the most effective stimuli were Z9 tetradecenes and Z11 hexadecenes. The species of the Mythimna genus were most sensitive to aldehydes. Tholera decimalis did not respond to any of the molecules tested. The species belonging to the Mamestra and the Orthosia genera responded to a variety of molecules and no simple correlation was found between the genus and the EAG sensibility. Pheromone reception is discussed in relation to the taxonomy and the evolution of olfactory communication in Hadeninae.     

Mechanisms of communication disruption by pheromone in the control of Lepidoptera: a review

ABSTRACT. Five possible mechanisms involved in the disruption of phero-mone-mediated behaviour in the control of lepidopterous pests are discussed. The various techniques used in the field, laboratory investigations of such mechanisms, and possible limitations in the application of such studies, are reviewed.     

A female sex pheromone in Bruchidius atrolineatus (Pic) (Coleoptera, Bruchidae): analysis of the factors affecting production or emission of this pheromone

ABSTRACT. . The females of the tropical Bruchid Bruchidius atrolineatus (Pic) (Coleoptera) produce a sex pheromone that influences male behaviour. This pheromone, tested on males in an olfactometer, triggers characteristic antennal movements followed by a distinct chemo-anemotaxis. Sex pheromone production depends on the age of the females and is partly correlated with their ovarian activity. Females 0–24 h old are not attractive, but they begin to attract males on the second day of adult life. Vitellogenesis seems to correlate with the emission or the production of the pheromone but there is no precise synchrony between the two phenomena which are probably induced by the same endocrine factors. Within 1 h after mating there is a decrease in the females' attractiveness, which lasts at least 48 h. Under our experimental conditions no particular rhythm of production or emission of the sex pheromone in B. atrolineatus could be observed.     

Response specificity of male olfactory receptor neurones for the major and minor components of a female pheromone blend

Abstract The sex attractant of the female redbanded leafroller moth, Argyrotaenia velutinana (Walker), is a blend of seven compounds. Specialized olfactory receptor neurones had been found for only two of the compounds, (Z)-11-tetradecenyl acetate (Z11-14:Ac) and (E)-11-tetradecenyl acetate (E11–14:Ac). These receptor neurones were always found in pairs within the long trichoid sensilla, which are the most abundant multi-pored sensilla on the male antenna. A systematic survey of all regions of the male antenna with standard extracellular recording techniques was undertaken to find receptor neurones responsive to the remaining five minor components of the female pheromone. Of the 113 long trichoid sensilla sampled, all contained two receptor neurones, one specialized for Z11–14:Ac and a second specialized for Ell –14:Ac. A comparable number of recordings were then obtained from the less abundant classes of multi-pored sensilla. Two new receptor neurone types were found, responsive to the minor pheromone components (E)-9-dodecenyl acetate (E9-12:Ac) and (Z)-9-dodecenyl acetate (Z9-12:Ac). Scanning electron micrographs indicated that these recordings were obtained from shorter, narrower trichoid sensilla. The majority of these sensilla appeared to contain three neurones capable of spontaneous action potential production. In each sensillum, only one receptor neurone appeared to respond to stimulation with a minor component of the female blend. The remaining two neurones did not respond to the chemical stimuli evaluated.     

Sex pheromone components of the cabbage armyworm, Mamestra brassicae: Isolation, identification and field experiments

Glass capillary gaschromatography coupled to a mass spectrometer has shown that in addition to Z-11-hexadecenyl acetate, hexadecyl acetate and Z-11-heptadecenyl acetate are present in pheromone glands of calling virgin females of Mamestra brassicae L. (Lepidoptera: Noctuidae, Hadeninae). Electroantennography revealed positive responses for Z 11–17: Ac and 16: Ac, while behavioural tests were only positive for Z 11–17: Ac.

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Résumé Il a été procédé à l'identification des phéromones par chromatographie en phase gazeuse et par spectrographie de masse. Outre l'acétoxy-1 hexadécène-11Z, on identifié l'acétoxy-heptadécène-11Z et l'acétoxy-1-hexadécane dans les glandes des femelles vierges de M. brassicae. L'antennographie a montré des réactions positives à l'acétoxy-hepta-décène-11Z et à l'acétoxy-1-hexadécane, tandis que seul l'acétoxyhepta-décène-11Z provoque un comportement sexuel des mâles.

     

Age-dependent plasticity of sex pheromone response in the moth, Agrotis ipsilon: Combined effects of octopamine and juvenile hormone

Male moths use sex pheromones to find their mating partners. In the moth, Agrotis ipsilon, the behavioral response and the neuron sensitivity within the primary olfactory centre, the antennal lobe (AL), to sex pheromone increase with age and juvenile hormone (JH) biosynthesis. By manipulating the JH level, we previously showed that JH controls this age-dependent neuronal plasticity, and that its effects are slow (within 2 days). We hypothesized that the hormonal effect might be indirect, and one neuromodulator candidate, which might serve as a mediator, is octopamine (OA). Here, we studied the effects of OA and an OA receptor antagonist, mianserin, on behavioral and AL neuron responses of mature and immature males during stimulation with sex pheromone. Our results indicate that, although OA injections enhanced the behavioral pheromone response in mature males, OA had no significant effect on behavior in immature males. However, mianserin injections decreased the behavioral response in mature males. AL neuron sensitivity increased after OA treatment in immature males, and decreased after mianserin treatment in mature males. Determination of OA levels in ALs of immature and mature males did not reveal any difference. To study the possible interactive effects of JH and OA, the behavioral pheromone response was analyzed in JH-deprived mature males injected with OA, and in immature males injected with fenoxycarb, a JH agonist, and mianserin. Results show that both JH and OA are necessary to elicit a behavioral response of A. ipsilon males to sex pheromone.     

A novel mechanism regulating a sexual signal: The testosterone-based inhibition of female sex pheromone expression in garter snakes

Vertebrates communicate their sex to conspecifics through the use of sexually dimorphic signals, such as ornaments, behaviors and scents. Furthermore, the physiological connection between hormones and secondary sexual signal expression is key to understanding their dimorphism, seasonality and evolution. The red-sided garter snake (Thamnophis sirtalis parietalis) is the only reptile for which a described pheromone currently exists, and because garter snakes rely completely on the sexual attractiveness pheromone for species identification and mate choice, they constitute a unique model species for exploring the relationship between pheromones and the endocrine system. We recently demonstrated that estrogen can activate female pheromone production in male garter snakes. The purpose of this study was to determine the mechanism(s) acting to prevent female pheromone production in males. We found that castrated males (GX) are courted by wild males in the field and produce appreciable amounts of female sex pheromone. Furthermore, pheromone production is inhibited in castrates given testosterone implants (GX + T), suggesting that pheromone production is actively inhibited by the presence of testosterone. Lastly, testosterone supplementation alone (T) increased the production of several saturated methyl ketones in the pheromone but not the unsaturated ketones; this may indicate that saturated ketones are testosterone-activated components of the garter snake's skin lipid milieu. Collectively, our research has shown that pheromone expression in snakes results from two processes: activation by the feminizing steroid estradiol and inhibition by testosterone. We suggest that basal birds and garter snakes share common pathways of activation that modulate crucial intraspecific signals that originate from skin.     

Rhythmicity of sex pheromone content in female Heliothis virescens: impact of mating

Abstract Pheromone production in virgin females of Heliothis virescens (F.) (Lepidoptera: Noctuidae) peaked between the fourth and seventh hours of scotophase on the second, third, fourth and fifth days following eclosion. The highest peak (186 ng) occurred on day 3 after eclosion. Z-11-Hexadecenal comprised the highest proportion of seven components in the pheromone glands. Disproportionately higher amounts of hexadecanal and Z-11-hexadecenol occurred during photo-phase and other periods when low quantities of total pheromone were recorded.
Mating suppressed pheromone production which remained low until 48 h after mating. Coupling females with males mated three times previously or with 6-day-old males was less effective in causing a drop in pheromone content which peaked again 24 h after mating. This suggests the transfer of a male factor, a pheromonostatic factor, that suppresses pheromone production in mated females and that the factor from older and previously mated males is less effective.     

Sex pheromone dosage and blend specificity of response by oriental fruit moth males

The sex pheromone-mediated responses of male oriental fruit moths, Grapholitha molesta (Busck), to an array of blends and dosages of Z8-12Ac and E8-12:Ac, were analyzed. Males exhibited sustained upwind flight resulting in source location only to intermediate blends and dosages. This optimal range of treatments appeared to be bounded by dosages too low or too high to result in significant attraction (net within-plume displacement toward the source), the higher concentrations causing arrestment (no net within-plume displacement) at some distance from the source. Similar results were obtained in field-trapping studies with the same treatments, except that the optimal dosages were moved up about 10-fold. Increased turning and decreased linear velocity could account for arrestment with increasing amounts of the (E) isomer in high dosages and high (E)/(Z) ratio blends.

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Zusammenfassung Das Sexualverhalten männlicher Falter des Pfirsichtriebwicklers, Grapholitha molesta (Busck), gegenüber verschiedenen Dosierungen und Mischungen von (Z)-8- und (E)-8-Dodecenylacetat wurde untersucht. Ein stetiger Aufwindflug, der zum Auffinden der Duftquelle führte, konnte nur im mittleren Dosierungs- und Mischungsbereich beobachtet werden. Ausserhalb dieses Optimums war die Dosierung offenbar entweder zu hoch oder zu niedrig, um eine deutliche Anlockung, d.h. einen gerichteten Flug innerhalb der Duftfahne zu bewirken; bei hoher Konzentration näherten sich die Tiere der Quelle nur auf bestimmte Distanz (arrestment). Freilandversuche mit Fallen führten zu ähnlichen Ergebnissen, nur dass dort das Dosierungsoptimum bei ca. zehnmal höheren Werten lag als in den Versuchen im Windkanal. Der bei hohen Mengen an E-Isomer (hohe Dosis oder hohes E/Z-verhältnis) beobachtete Arrestment-Effekt könnte auf Erhöhung der Drehbewegungen oder Verringerung der Fluggeschwindigkeit zurückzuführen sein.

     

The role of host generated free radicals in helminth infections: Nippostrongylus brasiliensis and Nematospiroides dubius compared

and 1986. The role of host generated free radicals in helminth infections: Nippostrongylus brasiliensis and Nematospiroides dubius compared. International Journal for Parasitology 16: 617–622. The possibility that free radicals are involved in the expulsion of Nippostrongylus brasiliensis from the small intestine of its mice host was explored by comparing the susceptibilities to free radicals, and levels of protective enzymes, of adult N. brasiliensis and Nematospiroides dubius, a closely related intestinal parasite of mice. Nippostrongylus brasiliensis was markedly more susceptible to in vitro free radical damage than N. dubius. The difference in susceptibility is probably related to differences in enzymatic protection against free oxygen radicals as N. dubius had roughly twice as much Superoxide dismutase, about 3 times as much catalase and about 4 times as much glutathione reductase as N. brasiliensis. This result may indicate that N. dubius persists in the rodent small intestine, whilst N. brasiliensis is spontaneously expelled, because of a more efficient enzymatic defence system against host-generated free oxygen radicals.