Responses Of Male Antennae Research Articles

Identification of sex pheromone in Macdunnoughia crassisigna Warren (Lepidoptera: Noctuidae) and field optimization of the sex attractant.

Sex pheromones have proven to be a viable tool for monitoring and controlling pests and is an important part of integrated pest management (IPM). The noctuid moth Macdunnoughia crassisigna Warren poses a significant threat as a defoliator pest, impacting soybean and cruciferous vegetable production and quality in East Asia. However, a lack of comprehensive knowledge about its sexual chemical signaling hampers the development of semiochemical-based IPM approaches for M. crassisigna. We first determined the mating rhythms of M. crassisigna. We then collected pheromones from the sex glands of virgin females at the mating peak and analyzed their components using gas chromatography-electroantennogram detection analysis. The results showed that three components elicited significant electrophysiological responses in male antennae. Gas chromatography-mass spectrometry analysis characterized these components as (Z)-7-dodecene acetate (Z7-12:OAc), (Z)-9-tetradecene acetate (Z9-14:OAc), and (Z)-11-hexadecen-1-ol (Z11-16:OH). Further field experiments indicated that the mixture of Z7-12:OAc and Z9-14:OAc at a ratio of 3:1 displayed significant attractivity to males, confirming its role as a putative sex pheromone of M. crassisigna. Long-term monitoring tests showed that traps baited with these pheromone lures effectively mirrored the population dynamics of M. crassisigna. This study successfully identified and validated the sex pheromone released by female M. crassisigna and formulated potent sex lures for field-based pest monitoring. These findings enriched our understanding of chemical communication in Noctuidae and laid a foundation for developing practical monitoring and control methods against M. crassisigna. © 2023 Society of Chemical Industry.

Components of the Female Sex Pheromone of the Newly-Described Canola Flower Midge, Contarinia brassicola

The canola flower midge, Contarinia brassicola Sinclair (Diptera: Cecidomyiidae), is a newly-described species that induces galls on canola, Brassica napus Linnaeus and Brassica rapa Linnaeus (Brassicaceae). Identification of the sex pheromone of C. brassicola is essential to developing monitoring tools to elucidate the geographic range and hosts of this new pest, and the extent to which it threatens the $30 billion Canadian canola industry. The aim of this study was to identify and synthesize the female-produced sex pheromone of C. brassicola and demonstrate its effectiveness in attracting males to traps in the field. Two peaks were identified through GC-EAG analysis of female-produced volatiles which elicited electrophysiological responses in male antennae. These peaks were initially characterized through GC–MS and synthesis as 2,7-diacetoxynonane (major component) and 2-acetoxynonane (minor component), and the racemic compounds elicited EAG responses in male antennae. All four stereoisomers of 2,7-diacetoxynonane were synthesized and the naturally-produced compound was shown to be primarily the (2R,7S)-isomer by analysis on an enantioselective GC column, with a small amount of (2R,7R)-2,7-diacetoxynonane also present. The configuration of the minor component could not be determined because of the small amount present, but this was assumed to be (2R)-2-acetoxynonane by comparison with the configuration of the other two components. In field trials, none of the four stereoisomers of 2,7-diacetoxynonane, presented individually or as a racemic mixture, was attractive to male C. brassicola. However, dispensers loaded with a 10 µg:1 µg blend of (2R,7S)- and (2R,7R)-2,7-diacetoxynonane caught large numbers of male C. brassicola and significantly more than other blends tested. The addition of 0.5 µg of (2R)-2-acetoxynonane to this blend further increased the number of males caught. In future work, we will seek to identify the optimum trapping protocol for the application of the pheromone in monitoring and surveillance.

Identification of Queen Sex Pheromone Components of the Bumblebee Bombus terrestris

We investigated the origin and chemical composition of the queen sex pheromone of the primitively eusocial bumblebee, Bombus terrestris (Apidae). Physiologically and behaviorally active compounds were identified by coupled gas chromatography electro-antennography (GC-EAD), gas chromatography-mass spectrometry (GC-MS), and laboratory behavioral tests. In the behavioral assays, virgin queens frozen previously at -20 degrees C were highly attractive to males. Dummies impregnated with surface and cephalic extracts obtained from virgin queens that had been frozen at -50 degrees C were more attractive to males than odorless dummies. Male mating behavior was stimulated by components of cephalic secretions that are smeared onto the cuticle surface by the queen. Overall, 21 compounds present in surface and cephalic extracts evoked electroantennographic responses in male antennae. These included saturated and unsaturated fatty acids, ethyl- and methyl esters of the fatty acids, heptacosene, 2-nonanone, and geranyl geraniol. A blend of synthetic versions of these compounds elicited typical male mating behavior. Since solvent-impregnated dummies were approached by the males, but did not release copulatory behavior, visual cues may be important in the initial step of stimulating male mating behavior. Close-range olfactory signals are more important for releasing male mating behavior as well as for species recognition. In further behavioral assays, the attractiveness of a frozen virgin queen decreased as the storage time at -20 degrees C increased from 2 hr to 1 d. Therefore, the chemical composition of the sex pheromone may change during freezing as behaviorally active compounds may decompose.

Sex pheromone mimicry in the early spider orchid ( Ophrys sphegodes ): patterns of hydrocarbons as the key mechanism for pollination by sexual deception

We investigated the female-produced sex pheromone of the solitary bee Andrena nigroaenea and compared it with floral scent of the sexually deceptive orchid Ophrys sphegodes which is pollinated by Andrena nigroaenea males. We identified physiologically and behaviorally active compounds by gas chromatography with electroantennographic detection, gas chromatography-mass spectrometry, and behavioral tests in the field. Dummies scented with cuticle extracts of virgin females or of O. sphegodes labellum extracts elicited significantly more male reactions than odorless dummies. Therefore, copulation behavior eliciting semiochemicals are located on the surface of the females' cuticle and the surface of the flowers. Within bee and orchid samples, n-alkanes and n-alkenes, aldehydes, esters, all-trans-farnesol and all-trans-farnesyl hexanoate triggered electroantennographic responses in male antennae. Most of the alkanes and alkenes occurred in similar patterns both in the bees and orchids. O. sphegodes leaf extracts contained mostly the same compounds but in different proportions. In behavioral tests with synthetic compounds, blends of alkenes triggered significantly more approaches and pounces of the males whereas alkanes were not more attractive than odorless dummies. Since alkanes and alkenes together were most attractive, we conclude they constitute the bees' sex pheromone as well as the pseudocopulation-behavior releasing orchid-odor bouquet.

Electroantennogram Responses of Both Sexes of Grape Root Borer (Lepidoptera: Sesiidae) to Synthetic Female Sex Pheromone

The effect of mating status and sex on antennal response to sex pheromone components was tested in the grape root borer, Vitacea polistiformis (Harris). The grape root borer pheromone is a 99:1 blend of (E,Z)-2,13-octadecadien-1-ol acetate (EZ) and (Z,Z)-3,13- octadecadien-1-ol acetate (ZZ). Antennae of both virgin male and female moths exhibited similar dose—response patterns, with a threshold dosage of 1 mg of the EZ:ZZ blend on filter paper. Four treatments were tested at a dose of 5 mg on filter paper: EZ, ZZ, a blend of 99:1 EZ:ZZ, and the alcohol (E,Z)-2,13-octadecadien-1-ol (EZ-OH). Male antennae responded significantly to all compounds, regardless of mating status. Virgin female antennae responded significantly to all compounds, although their responses were significantly lower than the responses of male antennae. However, female antennae were relatively more responsive to EZ-OH than male antennae. Mated female antennae responded significantly to EZ and 99:1 EZ:ZZ. Pheromone detection by females has considerable implications to mating disruption strategies.

Geographic Variation in Sex Pheromone Blend of Hemileuca electra from Southern California

Differences were found in the pheromonally mediated mate location systems of two subspecies of Hemileuca electra, H. electra electra (Hee) and H. e. mojavensis (Hem), from southern California. Hem female pheromone gland extracts contained eight times as much (10E,12Z)-hexadeca-10,12-dienal (E10,Z12–16:Ald) and half as much hexadecyl acetate (16:Ac) as Hee extracts. Relative amounts of the other major component of the pheromone blends, (10E,12Z)-hexadeca-10,12-dien-1-ol (E10,Z12–16:OH) did not differ between the two subspecies. In coupled gas chromatography–electroantennogram studies, responses of male antennae to 1:1:1 mixtures of the three principal components (E10,Z12–16:Ac, E10,Z12–16:OH, E10,Z12–16:Ald) also differed, with Hem antennae producing significantly larger responses to E10,Z12–16:Ald and significantly smaller responses to 10E,12Z–16:Ac than Hee. In field trials, male Hem were attracted to Hem females in preference to Hee females. Males of a second species, H. burnsi, which is sympatric with Hem but not Hee, also were attracted to females of Hee transported to their range. Field tests of blends of synthesized pheromone components confirmed that male Hem preferred E10,Z12–16:Ald ratios of 10–100% of the major component, E10,Z12–16:Ac, whereas males of Hee and H. burnsi responded optimally to ratios of 0.3–1% E10,Z12–16:Ald to E10,Z12–16:Ac. 16:Ac added to lures increased attraction of Hee but not Hem males. The data presented are consistent with reproductive character displacement, whereby the Hem subspecies has modified its pheromone-based mating system to reduce interference from sympatric H. burnsi.

Evidence for the Site of Female Sex Pheromone Production in Periplaneta americana

We used bioassays to determine the sex pheromone production site in the female American cockroach (Periplaneta americana). Bioassayed extracts from various body parts aroused sexual responses from unmated males. However, the extract of hindgut (including both colon and rectum) induced strong responses. Colon extract stimulated the strongest sexual response. To compare the sex pheromone contents of atrial glands, pygidium, rectum, and colon, we recorded the EAG responses of male antennae to these extracts. Among the four tissues, colon extract caused the strongest EAG response. From gas chromatographic (GC) analysis, the quantities of periplanone-A (PA) and periplanone-B (PB) (the main sex pheromone components in female American cockroach) were 0.34 and 8.31 ng, respectively, in the colon of a virgin female. The ratio of PA to PB was ca. 1:24. The present results are different from those reported in a previous study, in which it was concluded that atrial glands are the sites of sex pheromone production in P. americana, and from GC analysis the quantity of PB was estimated to be 60 ng/female. There was no difference in sexual behaviors induced by colon and atrial glands of calling virgin females. It is unclear whether the colon is the sole sex pheromone source in the female American cockroach.

MINOR SEX-PHEROMONE COMPONENTS OF MAMESTRA CONFIGURATA (LEPIDOPTERA: NOCTUIDAE) AND IMPROVED BLENDS FOR ATTRACTION OF MALE MOTHS

The sex pheromone of bertha armyworm, Mamestra configurata (Walker), was reported to be (Z)-11-hexadecenyl acetate (Z11-16:Ac) and an unidentified tetradecenyl acetate. Electroantennogram responses of male antennae to synthetic isomeric tetradecenyl acetates and attractancy tests under field conditions showed that the highest number of males were captured with a blend of Z9-14:Ac: Z11-16:Ac in a ratio of 1:19 (Underhill et al. 1977). This blend has been useful for monitoring the relative abundances of bertha armyworm; however, in 162 monitor traps in southern Alberta from 1979 to 1982, the catches consisted of 18.4% Agroperina cogitata (Sm)