Z9-tetradecenyl Acetate Research Articles

Two Odorant-Binding Proteins Involved in the Recognition of Sex Pheromones in Spodoptera litura Larvae.

Usually, the recognition of sex pheromone signals is restricted to adult moths. Here, our behavioral assay showed that fourth-instar Spodoptera litura larvae are attracted to cabbage laced with minor sex pheromones Z9,E12-tetradecadienyl acetate (Z9,E12-14:Ac) or Z9-tetradecenyl acetate (Z9-14:Ac). Seven odorant-binding proteins (OBPs) were upregulated after exposure to Z9,E12-14:Ac, and one OBP was upregulated after exposure to Z9-14:Ac. Fluorescence competitive binding assays showed that GOBP2 and OBP7 bound to sex pheromones. RNAi treatment significantly downregulated GOBP2 and OBP7 mRNA expression by 70.37 and 63.27%, respectively. The siOBP-treated larvae were not attracted to Z9,E12-14:Ac or Z9-14:Ac, and the corresponding preference indices were significantly lower than those in siGFP-treated larvae. Therefore, we concluded that GOBP2 and OBP7 are involved in the attraction of S. litura larvae to food containing Z9,E12-14:Ac and Z9-14:Ac. These results provide an important basis for exploring the olfactory mechanisms underlying sex pheromone attraction in moth larvae.

A plant volatile alters the perception of sex pheromone blend ratios in a moth.

Mate finding in most moths is based on male perception of a female-emitted pheromone whose species specificity resides in component chemistry and proportions. Components are individually detected by specialized olfactory receptor neurons (ORNs) projecting into the macroglomerular complex (MGC) of the male brain. We asked how robust ratio recognition is when challenged by a plant volatile background. To test this, we investigated the perception of the pheromone blend in Agrotis ipsilon, a moth species whose females produce a blend of Z7-dodecenyl acetate (Z7-12:Ac), Z9-tetradecenyl acetate (Z9-14:Ac), and Z11-hexadecenyl acetate in a 4:1:4 ratio optimally attractive for males. First, we recorded the responses of specialist ORNs for Z7 and Z9 and showed that heptanal, a flower volatile, activated Z7 but not Z9 neurons. Then, we recorded intracellularly the responses of MGC neurons to various ratios and showed that heptanal altered ratio responses of pheromone-sensitive neurons. Finally, we analyzed the behavior of males in a wind tunnel and showed that their innate preference for the 4:1:4 blend was shifted in the presence of heptanal. Pheromone ratio recognition may thus be altered by background odorants. Therefore, the olfactory environment might be a selective force for the evolution of pheromone communication systems.

Molecular characterization and functional analysis of a novel candidate of cuticle carboxylesterase in Spodoptera exigua degradating sex pheromones and plant volatile esters

Odorant-degrading enzymes (ODEs) are considered to play key roles in odorant inactivation to maintain the odorant receptor sensitivity of insects. Some members of carboxylesterase (CXE) is a major sub-family of ODEs. However, only a few CXEs have been functionally characterized so far. In the present study, we cloned the antennal esterase SexiCXE11 cDNA full-length sequences from the male antennae of a notorious crop pest, Spodoptera exigua, and its encoded 538 amino acids. It was similar to other insect esterases and had the characteristics of a carboxylesterase. We expressed recombinant enzyme in High-Five insect cells and obtained the high level purified recombinant protein by affinity column. Furthermore we test enzyme activity toward its two acetate sex pheromone components (Z9,E12-Tetradecadienyl acetate, Z9E12-14:Ac and Z9-Tetradecenyl acetate, Z9-14:Ac) and other 18 ester plant volatiles. Our results demonstrated that SexiCXE11 degraded acetate sex pheromone components with similar degradation activities (about 15.75% with Z9E12-14:Ac and 19.28% with Z9-14:Ac) and plant volatiles with a relatively high activity such as pentyl acetate and (Z)-3-hexenyl caproate. SexiCXE11 had high hydrolytic activity with these two ester odorants (>50% degradation), which is characterized that although a ubiquitous expression esterase SexiCXE11 may be partly involved with olfaction. This study may facilitate a better understanding of moth ODE differentiation and suggest strategies for the development of new pest behavior inhibitors.

Relationships of Reproductive Traits With the Phylogeny of the African Noctuid Stem Borers.

The display of the reproductive behavior in most noctuid Lepidoptera follows a diel periodicity and is limited to a precise period of either the day or the night. These behavioral traits and the sex pheromone chemistry can be species specific and thus might be linked to the phylogeny. The objective of this study was to test the relationship of these reproductive traits with phylogeny. The study was undertaken using eight closely related species of noctuid stem borers, which are easy to rear under artificial conditions, namely, Busseola fusca, B. nairobica, B. sp. nr. segeta, Manga melanodonta, M. sp. nr. nubifera, Pirateolea piscator, Sesamia calamistis, and S. nonagrioides. For each species, the adult emergence period, the mating time, and the oviposition period were estimated, referred as biological traits. The components of the sex pheromones emitted by the females of each species were also analyzed by gas chromatography–mass spectrometry. Among the biological traits measured, only those linked to the oviposition pattern (timing and egg loads per night) were significantly correlated with the phylogeny of these species. For the sex pheromone components, among the 13 components identified in all species, only four, namely, Z9-tetradecenyl acetate (Z9-TDA), Z11-TDA, E11-TDA, and Z11-hexadecenyl acetate (Z11-HDA), showed the highest significant correlations with the phylogeny. These results suggest that among the different reproductive traits evaluated, only few are phylogenetically constrained. Their involvement in the reinforcement of ecological speciation in noctuid stem borers is discussed.

Identification of the sex pheromone of the tree infesting Cossid Moth Coryphodema tristis (Lepidoptera: Cossidae).

The cossid moth (Coryphodema tristis) has a broad range of native tree hosts in South Africa. The moth recently moved into non-native Eucalyptus plantations in South Africa, on which it now causes significant damage. Here we investigate the chemicals involved in pheromone communication between the sexes of this moth in order to better understand its ecology, and with a view to potentially develop management tools for it. In particular, we characterize female gland extracts and headspace samples through coupled gas chromatography electro-antennographic detection (GC-EAD) and two dimensional gas chromatography mass spectrometry (GCxGC-MS). Tentative identities of the potential pheromone compounds were confirmed by comparing both retention time and mass spectra with authentic standards. Two electrophysiologically active pheromone compounds, tetradecyl acetate (14:OAc) and Z9-tetradecenyl acetate (Z9-14:OAc) were identified from pheromone gland extracts, and an additional compound (Z9-14:OH) from headspace samples. We further determined dose response curves for the identified compounds and six other structurally similar compounds that are common to the order Cossidae. Male antennae showed superior sensitivity toward Z9-14:OAc, Z7-tetradecenyl acetate (Z7-14:OAc), E9-tetradecenyl acetate (E9-14:OAc), Z9-tetradecenol (Z9-14:OH) and Z9-tetradecenal (Z9-14:Ald) when compared to female antennae. While we could show electrophysiological responses to single pheromone compounds, behavioral attraction of males was dependent on the synergistic effect of at least two of these compounds. Signal specificity is shown to be gained through pheromone blends. A field trial showed that a significant number of males were caught only in traps baited with a combination of Z9-14:OAc (circa 95% of the ratio) and Z9-14:OH. Addition of 14:OAc to this mixture also improved the number of males caught, although not significantly. This study represents a major step towards developing a useful attractant to be used in management tools for C. tristis and contributes to the understanding of chemical communication and biology of this group of insects.

Sex pheromone receptor specificity in the European corn borer moth, Ostrinia nubilalis.

BackgroundThe European corn borer (ECB), Ostrinia nubilalis (Hubner), exists as two separate sex pheromone races. ECB(Z) females produce a 97∶3 blend of Z11- and E11-tetradecenyl acetate whereas ECB(E) females produce an opposite 1∶99 ratio of the Z and E isomers. Males of each race respond specifically to their conspecific female's blend. A closely related species, the Asian corn borer (ACB), O. furnacalis, uses a 3∶2 blend of Z12- and E12-tetradecenyl acetate, and is believed to have evolved from an ECB-like ancestor. To further knowledge of the molecular mechanisms of pheromone detection and its evolution among closely related species we identified and characterized sex pheromone receptors from ECB(Z).MethodologyHomology-dependent (degenerate PCR primers designed to conserved amino acid motifs) and homology-independent (pyrophosphate sequencing of antennal cDNA) approaches were used to identify candidate sex pheromone transcripts. Expression in male and female antennae was assayed by quantitative real-time PCR. Two-electrode voltage clamp electrophysiology was used to functionally characterize candidate receptors expressed in Xenopus oocytes.ConclusionWe characterized five sex pheromone receptors, OnOrs1 and 3–6. Their transcripts were 14–100 times more abundant in male compared to female antennae. OnOr6 was highly selective for Z11-tetradecenyl acetate (EC50 = 0.86±0.27 µM) and was at least three orders of magnitude less responsive to E11-tetradecenyl acetate. Surprisingly, OnOr1, 3 and 5 responded to all four pheromones tested (Z11- and E11-tetradecenyl acetate, and Z12- and E12-tetradecenyl acetate) and to Z9-tetradecenyl acetate, a behavioral antagonist. OnOr1 was selective for E12-tetradecenyl acetate based on an efficacy that was at least 5-fold greater compared to the other four components. This combination of specifically- and broadly-responsive pheromone receptors corresponds to published results of sensory neuron activity in vivo. Receptors broadly-responsive to a class of pheromone components may provide a mechanism for variation in the male moth response that enables population level shifts in pheromone blend use.

Optimal Sex Pheromone Composition for Monitoring Spodoptera exigua (Lepidoptera: Noctuidae) in Korea

The sex pheromone composition for the Korean population of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) was determined from the abdominal tip extract of virgin females during her calling period. Gas chromatography of the extracts revealed 3 components; Z,E-9, 12-tetradecadienyl acetate ( Z,E-9,12–14: Ac), Z9-tetradecen-1-ol ( Z9–14: OH), and Z9-tetradecenyl acetate ( Z9–14: Ac). In electroantennogram analyses to males, a main component, Z,E-9,12–14: Ac, evoked significantly higher response than did the other two components. Although male moths were broadly attracted to lures, composed of Z,E-9,12–14: Ac and Z9–14: OH with ratios from 9:1 to 1:9, in Andong and Seosan field areas, the 7:3 blend was found to be the most effective. The optimal height of trap location was 1.5 m above ground. Three minor sex pheromone components including Z9-hexadecenyl acetate ( Z9–16: Ac), Z11- tetradecenyl acetate ( Z11–14: Ac), and Z9-tetradecenyl acetate ( Z9–14: Ac) were reported before from local populations. But, in this study, only Z11–16: Ac showed significant synergistic effect on enhancing the attractiveness of the major component blends at ratios of 7:3:1 and 7:3:5 of Z,E-9,12–14: Ac, Z9–14: OH, and Z11–16: Ac.

Potential for the evolution of resistance to pheromone‐based mating disruption tested using two pheromone strains of the cabbage looper, Trichoplusia ni

The reliance of most moth species on female-produced sex pheromones for mate attraction makes their communication system an ideal target for pest management. Mating disruption, by release of synthetic sex pheromone into the atmosphere, has been developed to control many lepidopteran pests and is available commercially for several species (Carde & Minks, 1995). Selection pressure provided by continuous application of mating disruptants could result in the evolution of resistance to this tactic, and this possibility should be evaluated before it occurs. The potential for resistance to mating disruption will depend on genetically-based variation in production of and response to pheromone within and amongst populations (Lofstedt, 1990, 1993; Phelan, 1992). The diverse phylogenetic pattern of lepidopteran pheromones suggests that natural selection has shaped the evolution of species-specific pheromones. Long-term use of mating disruptants that effectively control pest populations, could provide the necessary selection pressure for an alteration in the communication system and the evolution of resistance to mating disruption (Carde & Minks, 1995). In the cabbage looper, Trichoplusia ni (Hubner), the sex pheromone consists of a main component, Z7-dodecenyl acetate (Z7-12:Ac), and five minor components (Bjostad et al., 1984). Haynes & Hunt (1990) discovered an abnormal pheromone phenotype in a laboratory colony of T. ni that was the result of a single, recessive autosomal gene mutation. Mutant females release a pheromone that contains a twenty-fold increase of one minor component, Z9-tetradecenyl acetate (Z9-14:Ac) and a thirty-fold decrease of another minor component, Z5-dodecenyl acetate (Z512:Ac). Initially, male T. ni that carried the mutant gene responded like normal males, demonstrating a preference for the normal pheromone. However, after 49 generations within a pure mutant colony, males responded equally well to both mutant and normal pheromones (Liu & Haynes, 1994). Thus, there are genetically-based differences in both female pheromone and male response (Liu & Haynes, 1994). The potential for mating disruption to result in evolutionary changes in the pheromone was tested on laboratory-derived populations of T. ni using a replicated selection experiment in large field cages. We manipulated the environment (pheromone-treated vs. clean-air control) that moths were exposed to and followed the evolution of the pheromone phenotype in five closed (no gene flow) populations across four offspring generations. The normal pheromone blend applied as a mating disruptant provided selection pressure that influenced the frequency of the mutant allele in the population.

A synomone imparting distinct sex pheromone communication channels for Choristoneura rosaceana (Harris) and Pandemis limitata (Robinson) (Lepidoptera: Tortricidae)

Male obliquebanded leafrollers, Choristoneura rosaceana (Harris), were induced to respond to a pheromone source tainted with a behavioural antagonist, Z9-tetradecenyl acetate, when a source releasing the antagonist was placed 10 cm upwind of the tainted source in a wind tunnel. However, placement of the antagonist upwind of an attractive pheromone source did not interrupt pheromone-mediated responses. Placement of a source releasing Z9-tetradecenyl acetate, a minor pheromone component of the sympatric species, the threelined leafroller, Pandemis limitata (Robinson), upwind of a calling P. limitata female, reduced conspecific male pheromone-mediated response but resulted in upwind flight by male C. rosaceana and contact with heterospecific females. Male P. limitata locked on and flew upwind to but did not contact heterospecific females when a source releasing Z9-tetradecenyl acetate was positioned upwind of a calling C. rosaceana female. In the field, adaptation or habituation to Z9-tetradecenyl acetate caused by atmospheric treatment with this compound apparently resulted in reciprocal heterospecific pheromone responses. More C. rosaceana males were captured in traps baited with their pheromone and the behavioural antagonist in small field plots treated atmospherically with Z9-tetradecenyl acetate than in nontreated control plots. Fewer male P. limitata were captured in traps baited with their own pheromone, or with C. rosaceana pheromone tainted with Z9-tetradecenyl acetate in plots treated atmospherically with Z9-tetradecenyl acetate than in nontreated control plots. We argue that Z9-tetradecenyl acetate is an important synomone which assists in partitioning the sexual chemical communication channels of C. rosaceana and P. limitata.

Sex pheromone of the female large cabbage-heart caterpillar, Crocidolomia binotalis Zeller (Lepidoptera:Pyralidae).

Sex pheromone components of the female Crocidolomia binotalis, an insect pest of cabbages in Indonesia, were identified from the ovipositor tip extract of virgin females by analyzing with chromatographic fractionation and capillary GC/MS. In an EAG response and attractivity test with a wind tunnel system, a mixture of synthetic compounds, (Z)-9-tetradecenyl acetate (Z-9-TDA) and (Z)-11-hexadecenyl acetate (Z-11-HDA), in the ratio of 1:7-1:60 and an amount of 1-50 ng on a filter paper, showed strong activities comparable to the activity of the ovipositor tip extract, which contained the two compounds at a ratio of c. 1:10 (Z-9-TDA:Z-11-HDA). The mixture of these two compounds might be the sex pheromone of C. binotalis.

Wind Tunnel Tests on the Disruption of Pheromonal Orientation of the Male Smaller Tea Tortrix Moth, Adoxophyes sp : Lepidoptera : Tortricidae : I. Disruptive Effect of Sex Pheromone Components

A wind tunnel was used to evaluate controlled-release dispensers containing (Z)-9-tetradecenyl acetate (Z-9-TDA), (Z)-11-tetradecenyl acetate (Z-11-TDA), (E)-11-tetradecenyl acetate (E-11-TDA), 10-methyldodecyl acetate (10-Me-DA), a 4-component mixuture (Z-9-TDA : Z-11-TDA : E-11-TDA : 10-Me-DA=70 : 30 : 5 : 20) and a 3-component mixture [Z-9-TDA : Z-11-TDA : (Z)-9-dodecenyl acetate (Z-9-DDA)=1 : 1 : 1] as disruptants for the smaller tea tortrix moth, Adoxophyes sp. Among the 6 candidate dispensers, Z-11-TDA, the 4-component mixture and the 3-component mixture effectively suppressed the male moth catch in a trap baited with 4-component pheromone dispenser in the wind tunnel. The mechanisms of orientation disruption were discussed based on the behavior of male moths in the tunnel.

Notizen: Supplementary Data on the Sex Attractant System of Panolis flammea

Pheromonal synergism and inhibition in P. flammea was further studied through electrophysiological and field trapping tests. Z11-tetradecenyl acetate and Z11-hexa - decenyl acetate, each acting upon a separate type of male sensory cell, were equally effective in synergizing attraction responses to the major pheromone component, Z9-tetradecenyl acetate. Addition of Z7-dodecenyl acetate to these lures reduced captures. Male attraction specificity markedly varied with local moth density.

Communication Disruption of the Cotton Leafworm, Spodoptera littoralis1 , by Using Its Sex Pheromone or Other Related Compounds Emitted at Different Distances from the Attractant

(Z)-9-tetradecenyl formate (Z-9-TDF) had no disruptive effect in Spodoptera littoralis when released at high rates from 4 evaporators located at 3.5 m radius from the attractant. At this distance, (Z)-9-tetradecenyl acetate (Z-9-TDA) was an effective disruptant, somewhat less effective at 7 m radius and totally ineffective at 32 m. At 32 m, (Z,E)-9,12-tetradecadienyl acetate (Z,E-9,12-TDDA) was also ineffective. However, (Z,E)-9,11-tetradecadienyl acetate (Z,E-9,11-TDDA), the synthetic sex pheromone of S. littoralis , was an effective disruptant even when released 44.5 m away from the attractant: 80–90% disruption was achieved at release rates of 2 to 4 mg/h/ha.

Sex Attractant for Male Alfalfa Looper Moths, Autographa californica12

Male alfalfa looper moths were attracted to lures comprising Z7-dodecenyl acetate and Z7-dodecenol. Optimum field captures occurred with acetate:alcohol ratios of ca. 10:1 and dose rates of 10 μg. The species was excluded from traps when small proportions of Z5-dodecenyl acetate, Z9-dodecenyl acetate or Z9-tetradecenyl acetate were incorporated in the lures. Analysis of female extracts and electroantennogram measurements suggested that the major attractant found is a natural pheromone component in this species.