The synergistic attractiveness effect of plant volatiles to sex pheromones in a moth

The effects of plant-derived chemicals (volatiles) on the attraction of the Spodoptera litura moth to sex pheromones were evaluated using an electroantennogram (EAG). Neuronal responses of male moths to sex pheromone mixtures (SPs) (a 9:1 mixture of synthetic (9Z,11E)-9,11-tetraddecadienyl acetate (Z9E11-14:OAc) and (9Z,12E)-9,12-tetradecadienyl acetate (Z9E12-14:OAc)) and to SPs mixtures with eight plant volatiles (benzaldehyde, (E)-β-caryophyllene, phenylacetaldehyde, 2,6-nonadienal, benzyl alcohol, racemic linalool, longifolene, and (E)-β-ocimene) were also measured. Then, wind tunnels and field trapping bioassays were conducted to determine the influence of plant volatiles on S. litura moth behavioral responses to SPs. The results indicated that benzaldehyde, phenylacetaldehyde, and benzyl alcohol significantly enhanced, and longifolene, (E)-β-caryophyllene, and (E)-β-ocimene had no significant effect on the attractions to SPs, whereas racemic linalool significantly decreased the attraction of male S. litura moths to SPs throughout the olfactory pathway. 2,6-Nonadienal significantly enhanced olfactory responses, but had no significant effect on output behavior. These findings provide foundations in utilization of plant volatiles and sex pheromones to manage the pest and other agricultural pests.     

Notes on New Zealand mammals 10. Effect of observer position on group size and level of aggression of mating brown hares

Abstract

The sex pheromones of two endemic New Zealand tortricid species were investigated. Females of the first species, Cnephasia jactatana, a pest of kiwifruit, were found to produce (Z)-11-tetradecenyl acetate (Z11-14:OAc) in their sex pheromone gland. When tested in the field, this compound on its own elicited significant catches of male C. jactatana. However, the addition of even very small amounts (0.3%) of the geometric isomer, (E)-11-tetradecenyl acetate (E11-14:OAc), to Z 11-14:OAc virtually suppressed trap catches. The sex pheromone of the second species, Merophyas leucaniana, was found to consist of a mixture of Z11-14:OAc, E11-14:OAc, tetradecyl acetate, and (Z)-11-tetradecenol. This species is morphologically very similar to the congeneric species, M. divulsana, the Australian lucerne leafroller. The sex pheromone of M. leucaniana is also very similar to that of the so-called “Z-type” of M. divulsana, which is now found in New Zealand. The pheromone components of C. jactatana and M. leucaniana are discussed in relation to those found in other tortricids.     

Sex pheromone analysis and effective attraction of males of the cabbage webworm,Hellula undalis,inhabiting the Mekong Delta of Vietnam

Hellula undalis is a harmful insect pest of green mustard in the Mekong Delta of Vietnam. In order to establish a tool for a sustainable pest control program, the sex pheromone of H. undalis inhabiting the Mekong Delta was examined. GC-EAD and GC–MS analyses of pheromone gland extracts from the virgin females elucidated three new components, (Z)-11-tetradecenyl acetate (Z11-14:OAc), (Z)-11-hexadecenal (Z11-16:Ald), and (11E,13E)-11,13-hexadecadien-1-ol, in addition to the known pheromone component (11E,13E)-11,13-hexadecadienal (E11,E13-16:Ald). Double bond positions of the two monoenyl components were determined by GC–MS analysis of the pheromone extract treated with dimethyl disulfide. On the other hand, GC–MS analysis of the female body extract detected the unsaturated hydrocarbon (3Z,6Z,9Z)-3,6,9-tricosatriene (Z3,Z6,Z9-23:H). Field examinations of their synthetic compounds indicated the significant role of E11,E13-16:Ald as a major component and a clear synergistic effect of the two monoenyl compounds as a minor component. Although the 3:3:7 mixture of Z11-14:OAc, E11-16:Ald, and E11,E13-16:Ald captured the largest number of males among the tested mixtures, the activity was still quite a bit lower than that of virgin females. However, the 3:3:7:1 mixture, which was prepared by adding a small amount of Z3,Z6,Z9-23:H to the 3:3:7 ternary lure, succeeded in attracting males more powerfully than the females did. This strong synergistic effect was not observed when the triene was added to unmixed E11,E13-16:Ald, indicating important roles of not only the triene but also the two monoenyl compounds as natural pheromone components.     

中国印度谷螟性信息素次级组份的研究

印度谷螟是我国危害性较严重的仓储害虫之一,食性很广,几乎危害每一种植物性仓储物.印度谷螟雌虫性信息素主要成份顺9,反12-十四碳二烯醇醋酸酯(TDA)早已被鉴定,并利用TDA单一组份诱捕印度谷螟雄蛾也较为有效,但该虫的完整信息素系统尚不清楚.本研究采用单个雌蛾性信息素腺体抽提技术,利用毛细管气相色谱GC保留时间定性方法和气质联用GC-MS分析鉴定技术,从印度谷螟雌虫腺体提取物中鉴定了顺9,反12-十四碳二烯醇醋酸酯(A),顺9,反12-十四碳二烯醇(B),顺9,反12-十四碳二烯醛(C)和顺9-十四碳醋酸醋(D)4种主要信息素成份,其比例为A∶B∶C∶D=100∶22∶12∶9.风洞试验结果表明,以该4种主要成分按A∶B∶C∶D=8∶2∶1∶0.8比例配制成的诱芯,其引诱雄蛾的活性接近于雌蛾腺体提取物.     

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 biosynthesis in the tortricid moth Planotortrix excessana (Walker) involves chain-shortening of palmitoleate and oleate

Biosynthesis of the sex pheromone components, (Z)-5-tetradecenyl acetate (Z5-14:OAc) and (Z)-7-tetradecenyl acetate (Z7-14:OAc), was investigated in the New Zealand tortricid moth Planotortrix excessana (Walker) by fatty acid methyl ester (FAME) analysis of base-methanolyzed extracts of lipids in the sex pheromone gland and through application of various labelled fatty acids. Analysis of the base-methanolyzed gland extracts revealed common FAMEs, including methyl oleate and methyl palmitoleate, as well as the FAMEs of the putative precursors, methyl (Z)-5-tetradecenoate and methyl (Z)-7-tetradecenoate. Application of labelled, saturated fatty acids, myristic, palmitic, and stearic did not result in any significant incorporation of label into either of the unsaturated pheromone components, although label was incorporated into tetradecyl acetate (14:OAc). In contrast, application of labelled oleic acid resulted in incorporation of label into Z5-14:OAc but not into Z7-14:OAc or into 14:OAc, whereas application of labelled palmitoleic acid resulted in incorporation of label into Z7-14:OAc but not into Z5-14:OAc or 14:OAc. These data support a route for biosynthesis of Z5-14:OAc and Z7-14:OAc in this species by limited β-oxidation of the common fatty acyl moieties, respectively, oleate (involving two cycles of 2-carbon chain-shortening) and palmitoleate (involving only one cycle of 2-carbon chain-shortening), and apparently involving no desaturase (other than the common Δ9) specific to sex pheromone biosynthesis. Interestingly, P. excessana females biosynthesize the same component (Z5-14:OAc) from an entirely different route from that of the related species Ctenopseustis obliquana (which biosynthesizes Z5-14:OAc by Δ5-desaturation of myristate). Additionally, the pheromone biosynthesis activating neuropeptide (PBAN) stimulates pheromone biosynthesis in this species. Arch. Insect Biochem. Physiol. 37:158–167, 1998. © 1998 Wiley-Liss, Inc.     

Sex pheromone of the butterbur borer, Ostrinia zaguliaevi

The sex pheromone blend of the butterbur borer, Ostrinia zaguliaevi (Lepidoptera: Pyralidae) was analyzed by means of gas chromatography-electroantennographic detection (GC-EAD), GC-mass spectrometry and a series of wind-tunnel bioassays. Four EAD-active compounds were detected in the female sex pheromone gland extract, and these were identified as tetradecyl acetate (14:OAc), (Z)-9-tetradecenyl acetate (Z9-14:OAc), (E)-11-tetradecenyl acetate (E11-14:OAc) and (Z)-11-tetradecenyl acetate (Z11-14:OAc). The average amounts ± s.d. of the four compounds in a single sex pheromone gland were 7.9±3.7 ng, 10.1±3.2 ng, 1.1±0.5 ng and 11.6±5.1 ng, respectively. In a wind-tunnel bioassay, the ternary blend of Z9-, E11- and Z11-14:OAc at a ratio found in the sex pheromone gland (45:5:50) elicited the same behavioral responses from the males as did virgin females and pheromone gland extract. Removal of any single compound from the ternary blend significantly diminished the pheromonal activity, whereas addition of 14:OAc to the ternary blend had no effect on the males' behavioral responses. Therefore, it was concluded that the sex pheromone blend of O. zaguliaevi is composed of Z9-14:OAc, E11-14:OAc and Z11-14:OAc at a ratio of 45:5:50.     

Identification and field attraction of the female sex pheromone of a kiwifruit pest,Nokona feralis (Lepidoptera: Sesiidae)

Female sex pheromone of a clearwing moth Nokona feralis (Leech) (Lepidoptera: Sesiidae), a pest of kiwifruit, was identified to be a 7:3 mixture of (3E,13Z)-3,13-octadecadienyl acetate (E3,Z13-18:OAc) and (3E,13Z)-3,13-octadecadien-1-ol (E3,Z13-18:OH) by GC-EAD and GC/MS analyses. Males were attracted to wide-range mixtures of E3,Z13-18:OAc and E3,Z13-18:OH, and a 7:3 mixture of those two compounds strongly attracted the males in the field.     

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.     

Functional characterization of SlitPBP3 in Spodoptera litura by CRISPR/Cas9 mediated genome editing

Functional gene analysis by using genome editing techniques is limited only in few model insects. Here, we reported an efficient and heritable gene mutagenesis analysis in an important lepidopteran pest, Spodoptera litura, using the CRISPR/Cas9 system. By using this system, we successfully obtained the homozygous S. litura strain by targeting the pheromone binding protein 3 gene (SlitPBP3), which allowed us to elucidate the role of this gene in the olfaction of the female sex pheromones. By co-injection of Cas9 mRNA and sgRNA into S. litura eggs, highly efficient chimera mutation in SlitPBP3 loci was detected both in injected eggs (39.1%) and in the resulting individual moths (87.5%). We used the mutant moths as parents to obtain the G1 offspring and the homozygous mutant strain in G2. The function of SlitPBP3 was explored by Electroantennogram (EAG) recordings with a homozygous mutant strain. The result showed that the EAG responses were significantly decreased in mutant males than in control males when treated with the major sex pheromone component (Z9,E11-14:Ac) and a minor component (Z9-14:Ac) at higher dosages. The results demonstrate that s SlitPBP3 gene plays a minor role in the perception of the female sex pheromones. Furthermore, our study provides a useful methodology with the CRISPR/Cas9 system for gene in vivo functional study, particular for lepidopteran species in which the RNAi approach is not efficient.     

斜纹夜蛾性信息素通讯系统

采用单雌腺体微量分析技术,对斜纹夜蛾(中国种群)雌蛾腺体的组份进行鉴定,并研究了各组份的个体差异及释放规律,测试了雄蛾对各组份及其混合物的触角电位反应。雌蛾腺体内含有4个组份：Z9, E11-14∶Ac(A)、Z9, E12-14∶Ac(B)、Z9-14∶Ac© 和E11-14∶Ac(D),其比例为100∶27∶20∶27。     

Electrophysiological and behavioural evidence for a fourth sex pheromone component in the turnip moth, Agrotis segetum

Abstract. In addition to the pheromone components (Z)-5-decenyl, (Z)-7-dodecenyl and (Z)-9-tetradecenyl acetate (Z5-10:OAc, Z7-12:OAc and Z9-14:OAc), it has previously been shown that the sex pheromone gland of the turnip moth, Agrotis segetum (Lepidoptera: Noctuidae Schiff) contains 10:OAc, 12:OAc, Z5-12:OAc, Z9-12:OAc, 11–12:OAc, Z5-14:OAc, Z7-14:OAc and Z11-16:OAc. To find out whether any of these additional compounds is involved in the sex pheromone communication in A. segetum, a comprehensive electro-physiological and behavioural investigation was conducted. Single-sensillum recordings on male antennae revealed three subtypes of sensilla among the previously so-called Z5-10:OAc sensilla. One subtype was identified having one receptor neurone (A) that responded to Z5-10:OAc with a large spike amplitude and another neurone (B) that responded to (Z)-5-decenol (Z5-10:OH) with a small spike amplitude. In another subtype the B neurone responded to Z5-12:OAc and sometimes also to 27-12:OAc and 10:OAc, in addition to responding to Z5-10:OH. In a third subtype the A neurone responded to all acetates identified from the female pheromone gland, whereas the small spike amplitude neurone was tuned to Z5-10:OH. A flight tunnel assay showed that blends composed of nine, eight or seven compounds were equivalent to the previously identified three-component pheromone blend in eliciting male behavioural responses. In field trapping tests, blends of eleven, nine or seven compounds did, however, catch significantly more moths than the three-component blend. Further assays showed that only 25- 12:OAc could significantly increase the catch numbers when added to the three-component blend, and thus qualified as a fourth pheromone component in A. segerum. The behavioural significance of additional female-produced acetates — for which males possess antennal receptors — is suggested, but may be impossible to confirm because of ‘diminishing returns’ when trying to refine a multicomponent pheromone further.     

Identification of the sex pheromone secreted by Synanthedon tenuis (Lepidoptera: Sesiidae)

The Japanese persimmon treeborer, Synanthedon tenuis (Butler) (Lepidoptera: Sesiidae), is a harmful pest of persimmon trees (Diospyros spp.). Because males of this species are known to be attracted by (3Z,13Z)-3,13-octadecadienyl acetate (Z3,Z13-18:OAc), a mating disruptant composed of a 1:1 mixture of Z3,Z13-18:OAc and the (3E,13Z)-isomer, the original target of which is an allied pest, S. hector (Butler), has been diverted to control S. tenuis. However, the sex pheromone secreted by S. tenuis females has not been characterized. Analyses of pheromone gland extracts using gas chromatography (GC) equipped with an electroantennographic detector (GC-EAD) and GC combined with mass spectrometry (GC–MS) detected only Z3,Z13-18:OAc, and no other known sesiid pheromone components were found. In a persimmon orchard, S. tenuis males were selectively attracted by a lure baited with Z3,Z13-18:OAc among four geometrical isomers of 3,13-octadecadienyl acetate, indicating that males strictly discriminated among the configurations of the two double bonds. Lures baited with single Z3,Z13-18:OAc attracted only S. tenuis. Further field experiments revealed that the attractiveness of Z3,Z13-18:OAc is significantly inhibited by the addition of the (3E,13Z) isomer or the parent alcohol.     

Terminal fatty-acyl-CoA desaturase involved in sex pheromone biosynthesis in the winter moth (Operophtera brumata)

The winter moth (Operophtera brumata L., Lepidoptera: Geometridae) utilizes a single hydrocarbon, 1,Z3,Z6,Z9-nonadecatetraene, as its sex pheromone. We tested the hypothesis that a fatty acid precursor, Z11,Z14,Z17,19-nonadecanoic acid, is biosynthesized from ??-linolenic acid, through chain elongation by one 2-carbon unit, and subsequent methyl-terminus desaturation. Our results show that labeled ??-linolenic acid is indeed incorporated into the pheromone component in vivo. A fatty-acyl-CoA desaturase gene that we found to be expressed in the abdominal epidermal tissue, the presumed site of biosynthesis for type II pheromones, was characterized and expressed heterologously in a yeast system. The transgenic yeast expressing this insect derived gene could convert Z11,Z14,Z17-eicosatrienoic acid into Z11,Z14,Z17,19-eicosatetraenoic acid. These results provide evidence that a terminal desaturation step is involved in the winter moth pheromone biosynthesis, prior to the decarboxylation.     

Functional Specificity of Sex Pheromone Receptors in the Cotton Bollworm Helicoverpa armigera

Male moths can accurately perceive the sex pheromone emitted from conspecific females by their highly accurate and specific olfactory sensory system. Pheromone receptors are of special importance in moth pheromone reception because of their central role in chemosensory signal transduction processes that occur in olfactory receptor neurons in the male antennae. There are a number of pheromone receptor genes have been cloned, however, only a few have been functionally characterized. Here we cloned six full-length pheromone receptor genes from Helicoverpa armigera male antennae. Real-time PCR showing all genes exhibited male-biased expression in adult antennae. Functional analyses of the six pheromone receptor genes were then conducted in the heterologous expression system of Xenopus oocytes. HarmOR13 was found to be a specific receptor for the major sex pheromone component Z11-16:Ald. HarmOR6 was equally tuned to both of Z9-16: Ald and Z9-14: Ald. HarmOR16 was sensitively tuned to Z11-16: OH. HarmOR11, HarmOR14 and HarmOR15 failed to respond to the tested candidate pheromone compounds. Our experiments elucidated the functions of some pheromone receptor genes of H. armigera. These advances may provide remarkable evidence for intraspecific mating choice and speciation extension in moths at molecular level.