Identification of a four-component sex pheromone blend in Bonagota cranaodes (Lepidoptera: Tortricidae)

Analysis of sex pheromone glands of the apple leafroller Bonagota cranaodes Meyrick by gas chromatography coupled with mass spectrometry or electroantennographic detection showed the presence of 14 structurally related acetates and alcohols of the chain length 10-18, including the main pheromone component (E,Z)-3,5-dodecadienyl acetate (E3,Z5-12Ac). Male antennae responded to the main compound, its Z,Z isomer, (E,Z) -3,5-tetradecadienyl acetate (E3,Z5-14Ac), and the monoenes (Z)-5-dodecenyl acetate (Z5-12Ac) and (Z)-9-hexadecenyl acetate (Z9-16Ac). Traps baited with a four-component blend of E3,Z5-12Ac, Z5-12Ac, E3,Z5-14Ac, and Z9-16Ac in a 100:5:5:100 ratio were significantly more attractive than the main compound alone. This improved trap lure is more suitable for monitoring population densities of B. cranaodes, and for detection of the onset of the seasonal flight period. A more complete pheromone blend is of importance also with respect to current attempts to develop mating disruption for control of this major pest of apple in Brazil.     

笋秀夜蛾雄蛾对性信息素化合物的电生理和行为反应

利用气质联用仪对笋秀夜蛾雌蛾性腺体粗提物成分进行了分析比对,通过触角电位(EAG)试验研究了笋秀夜蛾雄成虫对性信息素组分的电生理反应,以Y形嗅觉仪进行了室内和林间的行为生测.结果表明： 雌蛾性腺体粗提物中顺11-十六碳乙酸酯(Z11-16:Ac)和顺11-十六碳烯醇(Z11-16:OH)为笋秀夜蛾性信息素活性组分,性腺粗提物、两种化合物及其混合物均能激发雄蛾明显的EAG反应,且EAG反应值随性信息素组分浓度增加而增加.Z11-16:Ac和Z11-16:OH按57∶43配置成的二元混合物所激发的EAG反应强于同等剂量下的单一组分.室内的行为生测和林间诱捕试验结果与EAG反应基本一致,Z11-16:Ac+Z11-16:OH(57∶43)混合物对雄蛾引诱力最强,在林间单诱捕器(诱芯浓度为10⁴ng·μL^-1)的平均诱捕量达到(48.5±6.7)头.     

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.     

Female sex pheromone of Athetis lepigone (Lepidoptera: Noctuidae): Identification and field evaluation

Athetis lepigone has been recorded in many countries in Europe and Asia, but it had never been documented as an agricultural pest until 2005. For the purpose of using the sex pheromone to control this pest, we conducted a study to identify the sex pheromone of A. lepigone by gas chromatography with an electroantennographic detector (GC‐EAD) and GC coupled with mass spectrometry (GC/MS) analyses. Three pheromone candidates were detected by GC‐EAD analysis in the extracts of the female sex pheromone gland, and two candidates were identified as (Z)‐7‐dodecenyl acetate (Z7‐12:OAc) and (Z)‐9‐tetradecenyl acetate (Z9‐14:OAc) in a ratio of 1:5 by mass spectral analysis of natural pheromone components and dimethyl disulphide adducts. In the field male trapping test, the traps baited with the binary blend captured high number of males, while traps with single component hardly caught males, indicating that the two components are essential for the male attractiveness. In addition, the optimum ratios of Z7‐12:OAc and Z9‐14:OAc were determined as 3:7–7:3, and the best doses for the binary blend (at ratio of 3:7 between Z7‐12:OAc and Z9‐14:OAc) were 0.25–0.5 mg/trap, based on the number of male catches. The identification of a highly attractive sex pheromone will help in developing efficient strategies for monitoring and control of A. lepigone.     

Applications and mechanisms of wax-based semiochemical dispenser technology for disruption of grape root borer mating

Grape root borer, Vitacea polistiformis (Harris) (Lepidoptera: Sesiidae), is an important pest of cultivated grapes (Vitis spp.) in the eastern United States from Michigan to Florida. There are few registered insecticides for control of this pest, and their efficacy is limited. Pheromone-based mating disruption is a potential alternative to insecticides for management of V. polistiformis. Wax-based Specialized Pheromone & Lure Application Technology (SPLAT) was tested as a mating disruption method. Deployment densities of 150 dispensers per ha dosed with 5 mg of V. polistiformis pheromone were sufficient to achieve 95% mating disruption during a 7-wk trapping period. The disruption mechanism was determined to be competitive attraction. The release rate of pheromone from these dispensers was quantified to be approximately linear, 77.4 microg/g SPLAT/d. At this release rate, a minimum initial load of 5.4 mg of pheromone per dispenser would be needed to maintain disruption over a 9-10-wk V. polistiformis flight season, approximately 19 August to 21 October in central Florida. It should be noted, however, that the main pheromone component alone, (E,Z)-2,13-octadecadienyl acetate (ODDA), was effective (presumably by a noncompetitive mechanism) at higher loads per area of crop. Due to the cost of synthesis of highly pure isomers of the V. polistiformis pheromone components, mating disruption of V. polistiformis may be more practical with higher doses of commercially produced Zeuzera pyrina L. blend [95% (E,Z)-2,13-ODDA:5% (E,Z)-3,13-octadecadien-1-ol] or with (E,Z)-2,13-ODDA alone than with the V. polistiformis blend at lower rates.     

Field trials of synthetic sex pheromone lures for the large cabbage-heart caterpillar moth, Crocidolomia pavonana (Lepidoptera: Crambidae) in Indonesia

The efficacy of synthetic female sex pheromone lures for Crocidolomia pavonana (Fabricius) (Lepidoptera: Crambidae) in the cabbage fields of Java and Bali, Indonesia, was investigated by varying the composition and dosage of the components. The lure containing a synthetic pheromone blend of (Z)-11-hexadecenyl acetate (Z11–16: Ac) and (Z)-9-tetradecenyl acetate (Z9–14: Ac) at a 10:1 ratio acquired significantly more male catches than single component lures and the control lure. Meanwhile, no attraction was observed when lures with 1:1 and 1:10 blends were tested. The composition of Z11–16: Ac and Z9–14: Ac at a ratio of 5, 10 and 20:1 attracted more males than the control lures. Dosage studies showed that 0.055 and 0.55 mg of a mixture of Z11–16: Ac and Z9–14: Ac (10:1 ratio) attracted more males than the control. These results are the first demonstration of the efficacy of synthetic pheromone for C. pavonana in field conditions. The present study suggests the feasibility of pheromone-based monitoring as a simple and low-cost technique for integrated pest management of this pest.     

Biosynthetic pathway for production of a conjugated dienyl sex pheromone of a Plusiinae moth,Thysanoplusia intermixta

Virgin females of Thysanoplusia intermixta (Lepidoptera; Noctuidae; Plusiinae) produce (5E,7Z)-5,7-dodecadienyl acetate as a main sex pheromone component. GC-MS analysis of the pheromone glands, which were treated with deuterated hexadecanoic, (Z)-11-hexadecenoic, and (Z)-7-dodecenoic acids, showed incorporation of the label into the dienyl component. Their incorporation rates confirmed that its biosynthesis proceeds in the following order: Delta11-desaturation of a C(16) acyl intermediate, chain shortening to a C(12) compound by beta-oxidation, Delta5-desaturation to produce a 5,7-dienyl system, reduction of the acyl group, and acetylation. These deuterated precursors also converted into a minor pheromone component, (Z)-7-docecenyl acetate, which might be prepared by the same pathway except for the step of Delta5-desaturation. While deuterium incorporation into the dienyl acetate was not observed in the extracts treated with other labeled dodecenoic acids with (E)-5-, (Z)-6-, and (E)-7-double bonds, the corresponding dodecenyl acetates were produced. This result showed low substrate specificity of the enzymes for reduction and acetylation. Labeled (Z)-10-hexadecenoic acid was not converted into a dodecenyl acetate, indicating the high substrate specificity of the enzyme for beta-oxidation.     

Control of the biosynthetic pathway of Sesamia nonagrioides sex pheromone by the pheromone biosynthesis activating neuropeptide

(Z)-11-Hexadecenyl acetate, the main pheromone component of Sesamia nonagrioides sex pheromone, is biosynthesized from palmitic acid by Delta(11)-desaturation followed by reduction and acetylation. Production of (Z)-11-hexadecenyl acetate is regulated by the Pheromone Biosynthesis Activating Neuropeptide (PBAN). Transformation of (Z)-11-hexadecen-1-ol into the corresponding acetate is a target step for PBAN in the regulation of this biosynthetic sequence, thus being the first example of a PBAN-activated acetylation. The production of the minor component (Z)-11-hexadecenal is also stimulated by PBAN. The usefulness of pentafluorobenzyloxime-derivatives for the analysis of aldehyde pheromone constituents by gas chromatography coupled to mass spectrometry is also reported.     

Behavioural and electrophysiological activity of unsaturated analogues of the pheromone tetradecyl acetate in the small ermine moth Yponomeuta rorellus

ABSTRACT In field-trapping experiments the unsaturated analogues ( E )-6-, ( E )-12-, and ( Z )-12-tetradecenyl acetate were as attractive to male Yponomeuta rorellus Latr. as the native pheromone component tetradecyl acetate. All four analogues attracted more males than virgin females did, whereas ( Z )-6-, ( E )-11-, ( Z )-10- and ( Z )-11-tetradecenyl acetate were essentially non-attractive. Addition of 1–30% of ( Z )-11-tetradecenyl acetate to the pheromone tetradecyl acetate reduced the attraction to less than 2%. Flight tunnel experiments with Y. rorellus confirmed the activity of the ( E )-6- and ( E )-12-tetradecenyl acetates and demonstrated the activity of ( E )-7-tetradecenyl acetate as well. These analogues elicited orientation behaviour, upwind flight and landing at the odour source as frequently as the native pheromone did. Single sensillum recordings from male Y. rorellus showed two types of cells in most sensilla. A large spike amplitude cell was stimulated by tetradecyl acetate and the unsaturated analogues ( E )-11-, ( E )-6- and ( E )-12-tetradecenyl acetate, and to a lower extent by the ( Z )-6-, ( Z )-11- and ( Z )-12-isomers. A cell with medium spike amplitude was stimulated by ( Z )-9-tetradecenyl and ( Z )-11-hexadecenyl acetate. Some sensilla contained a third cell firing with a small spike amplitude which was activated by ( Z )-11-tetradecenol. Thus the tetradecyl acetate receptor was stimulated not only by the behaviourally active analogues, but also by behavioural antagonists. The interaction of ( E )-11-tetra-decenyl acetate and tetradecyl acetate with the same antennal receptor cell was also demonstrated in Y.cagnagellus . Electrophysiological discrimination between behavioural attractants and antagonists and the role of behavioural antagonists in the interspecific relations between Y.rorellus and sympatric closely related species are discussed.     

草地贪夜蛾的性信息素通讯研究进展

草地贪夜蛾Spodoptera frugiperda原产于美洲,具有长距离迁飞特性。该虫于1988年入侵欧洲,2016年入侵非洲,并引起巨大的粮食损失,2018年入侵亚洲,2019年从缅甸传入中国,并在短时间扩散至全国10多个省。草地贪夜蛾依赖性信息素通讯,实现雌雄间识别、交配和繁衍,为了深入研究草地贪夜蛾的性信息素通讯及其机制并开发更高效的预测预报和防治技术,本文综述了草地贪夜蛾性信息素通讯的研究现状。1967年首次报道草地贪夜蛾性信息素为顺9-十四乙酸酯,随后发现有不同的鉴定结果,1986年确认其性信息素由顺9-十四乙酸酯和顺7-十二乙酸酯两个组分组成,其比例为96.6∶3.4时表现出最强的引诱活性。除此而外,对不同地理种群的研究发现,草地贪夜蛾雌蛾的信息素腺体提取物还存在顺9-十二乙酸酯、顺11-十六乙酸酯和反7-十二乙酸酯,田间实验表明这些物质在性信息素通讯中也可发挥作用。根据分子标记和喜食寄主,草地贪夜蛾可分为玉米品系和水稻品系。两个品系在外部形态上无法区分,性信息素组分也相同,但在组分比例上存在一定的差异。两个品系间存在一定程度的生殖隔离,但室内可以正交和反交并产生可育的F1代,F1代的性信息素比例与母本的比较相似。关于草地贪夜蛾雄性对性信息素的感受机制方面研究较少,仅见有感器形态的鉴定和对性信息素组分的触角电位反应研究的报道。根据目前草地贪夜蛾在我国的发生情况及其性信息素通讯机制的研究现状,我们建议尽快开展以下研究：(1)鉴定草地贪夜蛾我国入侵种群的雌性性信息素,尽快用于其种群动态监测及防治;(2)研究草地贪夜蛾雄性对性信息素的嗅觉编码机制;(3)研究草地贪夜蛾两个品系的行为隔离程度及其演化结局。     

Sex pheromone biosynthetic pathway in Spodoptera littoralis and its activation by a neurohormone

Deuterium-labeled fatty acids have been used to elucidate the sex pheromone biosynthetic pathway in Spodoptera littoralis. Label from palmitic acid was incorporated during the scotophase into all the pheromone acetates and their corresponding fatty acyl intermediates. (Z,E)-9,11-tetradecadienyl acetate, the major component of the pheromone blend, is synthesized from palmitic acid via tetradecanoic acid, which, by the action of a specific (E)-11 desaturase and subsequently a (Z)-9 desaturase, is converted into (Z,E)-9,11-tetradecadienoate. By further reduction and acetylation, this compound leads to the dienne acetate. Deuterated precursors applied to the pheromone gland during the photophase were also incorporated into the pheromone. The percentage of labeled (Z,E)-9,11-tetradecadienyl acetate relative to natural compound was significantly higher during the light period. Label incorporation from different intermediates into the pheromone was stimulated by injection of brain-subesophageal ganglion extract during the photophase. The influence of the pheromone biosynthesis-activating neuropeptide on the biosynthetic pathway is discussed.     

黄杨绢野螟雌蛾性信息素的鉴定及诱蛾活性

【目的】研究旨在深入探讨中国黄杨绢野Diaphania perspectalis 的雌蛾性信息素组成及诱蛾活性。【方法】利用气质联用仪（GC-MS）对黄杨绢野螟正常型性成熟雌蛾的性腺体提取物和合成标样比较分析,并用反-11-十六碳烯醛(E11-16:Ald) 、顺-11-十六碳烯醛（Z-11-16:Ald）、顺-9-十六碳烯醛（Z-9-16:Ald)、顺-11-十六碳烯醇（Z-11-16:OH)等物质进行触角的电生理测定,最后开展田间诱集比较试验以筛选出最佳性信息素混合物。【结果】Z-11-16:Ald为中国黄杨绢野螟正常型性信息素主要组分,E-11-16:Ald的含量极低,Z-11-16:OH未检测到。正常型雄性黄杨绢野螟触角对Z-11-16:Ald, E-11-16:Ald, Z-9-16:Ald和Z-11-16:OH产生强烈的EAG反应,并随着浓度的提高而显著增加;而对Z-11-16:Ac和E-11-16:Ac的嗅觉反应较弱,低于对植物绿叶气味顺3-己烯乙酸酯（Z-3-6:Ac）的反应。单一Z-1-16:Ald对正常型雄性黄杨绢野螟具有强烈的诱集效果,加入E-11-16:Ald有一定的增效作用,但在统计上则不显著。单一Z-11-16:Ald组分对黑化型雄性黄杨绢野螟无引诱活性,必需加入一定比例的E-11-16:Ald才显示诱蛾活性。Z-11-16:Ald:E-11-16:Ald的比例为250 μg:250 μg时诱集到的黑化型雄性黄杨绢野螟数量最多,而Z-11-16:Ald:E-11-16:Ald的比例为429 μg:71 μg时则诱集到的正常型雄性黄杨绢野螟数量最多。同时,单一Z-11-16:Ald也可引诱大量雄性粘虫Mythimna separata,但E-11-16:Ald抑制其活性。【结论】中国黄杨绢野螟的性信息素主成分是Z-11-16:Ald,单一组分即可在田间强烈引诱雄蛾,E-11-16:Ald的功能只起到微弱的增效作用,但也可能起种的专一性的作用。正常型与黑化型黄杨绢野螟对性信息素的嗅觉反应存在差异,黑化型黄杨绢野螟的性信息素接近日本种,即性信息素组成为Z-11-16:Ald和E-11-16:Ald 的混合物,其比例为1:1,且E-11-16:Ald为必需。     

Sex pheromone precursors in the processionary moth Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeae)

The fatty acid composition of Thaumetopoea pityocampa female sex pheromone gland was determined. In addition to the common C16 and C18 fatty acids, the glandular tissue contains large amounts of (Z)-11-hexadecenoate, (Z,Z)-11,13-hexadecadienoate, (Z)-13-hexadecen-11-ynoate and 11-hexadecynoate, as well as some unusual C18 fatty acids, such as (Z)-11 and (Z)-13-octadecenoic acids. From these results, different biosynthetic pathways are discussed for the formation of (Z)-13-hexadecen-11-ynyl acetate, the main component of the sex pheromone of the processionary moth.     

植物气味化合物与斜纹夜蛾性信息素的协同作用

为提高现有性信息素对雄蛾的引诱活性, 本研究通过大量的田间试验探索植物气味化合物与斜纹夜蛾Spodoptera litura性信息素（顺9, 反11-十四碳二烯乙酸酯∶顺9, 反12-十四碳二烯乙酸酯=10∶1）的协同作用机制。从斜纹夜蛾寄主植物和花的气味化合物中, 选择9种有代表性的化合物, 并以一定剂量分别加入到斜纹夜蛾性信息素诱芯中, 在田间测试对雄蛾的引诱活性。结果表明: 在测试的9种植源性化合物中, 发现一定剂量(每个诱芯加入0.4 mg)的苯乙醛(PAA), 具有显著提高斜纹夜蛾性信息素的引诱作用, 而高剂量的苯乙醛则强烈抑制性信息素的引诱活性; 此外, 其他各种浓度的测试化合物或混合物对性信息素则没有统计上显著的增效作用。不同剂量的苯乙醛单个化合物及各种植物气味化合物组成的混合物对斜纹夜蛾也有微弱的引诱作用。苯乙醛必须要与性信息素的完整组分(以10∶1比例混合的顺9, 反11-十四碳二烯乙酸酯和顺9反, 12-十四碳二烯乙酸酯)混合才能起作用, 缺少顺9, 反12-十四碳二烯乙酸酯则没有引诱活性。本研究证明, 苯乙醛作为理想的性信息素诱芯增效剂, 可应用于建立更理想的斜纹夜蛾性信息素诱杀技术, 对性诱害虫防治和测报具有应用价值。     

温度对二化螟性信息素通讯的影响

环境因素影响昆虫两性间的化学通讯,也影响性信息素技术的田间防治效果.本文探讨了温度对二化螟雌蛾性信息素产生以及雄蛾对性信息素触角电位反应的影响,以期为田间二化螟的性信息素防治提供指导.在二化螟蛹期和成虫期进行不同温度处理(15、20、25、30和35 ℃),然后利用气相色谱仪(GC)分析雌蛾性腺内各性信息素组分的含量及比例,同时利用触角电位仪(EAG)测定雄蛾对性信息素组分的电生理反应.结果表明: 25 ℃处理中雌蛾性腺内3个性信息素组分(Z9-16:Ald、Z11-16:Ald和Z13-18:Ald)的含量均显著高于其他温度处理(15、20和30 ℃),且25 ℃处理中Z13-18:Ald的相对比例也显著低于其他温度处理.就雄蛾对性信息素的敏感性而言,对3种性信息素单一组分及特定比例混合物的EAG反应在15～25 ℃间没有显著差异,但在25～35 ℃间(Z13-18:Ald在30～35 ℃间)随温度升高呈下降趋势,且30 ℃较25 ℃显著降低,35 ℃较30 ℃又显著降低.综合分析认为,二化螟性信息素通讯的适宜温度为20～25 ℃,温度过高或过低均不利于二化螟两性间的正常化学通讯.研究结果为二化螟性信息素防治技术的合理应用及极端温度条件下害虫种群发生的预测预报,提供了重要参考.     

Reidentification of the female sex pheromone of the Indian meal moth, Plodia interpunctella: evidence for a four-component pheromone blend

Pheromone gland extracts from calling female Plodia interpunctella contained at least seven compounds that consistently elicited electroantennographic responses from male antennae upon gas chromatographic analysis. Three of these compounds were found to be the previously identified gland constituents, i.e., (Z,E)-9,12-tetradecadienyl acetate (Z9,E12-14:OAc), (Z,E)-9,12-tetradecadienal (Z9,E12-14:Ald) and (Z,E)-9,12-tetradecadienol (Z9,E12-14:OH). A fourth EAD-active compound was identified as (Z)-9-tetradecenyl acetate (Z9-14:OAc). The homologue (Z)-11-hexadecenyl acetate (Z11-16:OAc) was also identified in the extracts, but showed no EAD activity. The identity of all five compounds was confirmed by comparison of GC retention times and mass spectra with those of synthetic standards. In flight tunnel tests there were no significant differences in response of male P. interpunctella to the bait containing all four EAD-active compounds and the responses to female gland extacts. A behavioural assay of different two-compound blends in the flight tunnel showed that only addition of the corresponding aldehyde to the major pheromone component Z9,E12-14:OAc raised the male response. A subtractive assay, however, revealed that the exclusion of any of the compounds from the complete four-compound blend reduced its activity significantly. We thus conclude that the female-produced sex pheromone of P. interpunctella consists of at least four components, i.e., Z9,E12-14:OAc, Z9,E12-14:Ald, Z9,E12-14:OH and Z9-14:OAc.In a field trapping test performed in a storage facility, the four-component blend attracted significantly more males of P. interpunctella than traps baited with Z9,E12-14:OAc alone. In contrast, the highest number of Ephestia kuehniella males was found in the traps baited with this major component, suggesting that the secondary pheromone components contribute to the species specificity of the blend.     

Suppression of leopard moth (Lepidoptera: Cossidae) populations in olive trees in Egypt through mating disruption

The leopard moth, Zeuzera pyrina (L.) (Lepidoptera: Cossidae), is a damaging pest for many fruit trees (e.g., apple [Malus spp.], pear [Pyrus spp.] peach [Prunus spp.], and olive [Olea]). Recently, it caused serious yield losses in newly established olive orchards in Egypt, including the death of young trees. Chemical and biological control have shown limited efficiency against this pest. Field tests were conducted in 2005 and 2006 to evaluate mating disruption (MD) for the control of the leopard moth, on heavily infested, densely planted olive plots (336 trees per ha). The binary blend of the pheromone components (E,Z)-2,13-octadecenyl acetate and (E,Z)-3,13-octadecenyl acetate (95:5) was dispensed from polyethylene vials. Efficacy was measured considering reduction of catches in pheromone traps, reduction of active galleries of leopard moth per tree and fruit yield in the pheromone-treated plots (MD) compared with control plots (CO). Male captures in MD plots were reduced by 89.3% in 2005 and 82.9% in 2006, during a trapping period of 14 and 13 wk, respectively. Application of MD over two consecutive years progressively reduced the number of active galleries per tree in the third year where no sex pheromone was applied. In all years, larval galleries outnumbered moth captures. Fruit yield from trees where sex pheromone had been applied in 2005 and 2006 increased significantly in 2006 (98.8 +/- 2.9 kg per tree) and 2007 (23 +/- 1.3 kg per tree) compared with control ones (61.0 +/- 3.9 and 10.0 +/- 0.6 kg per tree, respectively). Mating disruption shows promising for suppressing leopard moth infestation in olives.     

Sex pheromone biosynthesis in Ostrinia zaguliaevi, a congener of the European corn borer moth O. nubilalis

In order to clarify the biochemical basis to the divergence of sex pheromones in the genus Ostrinia (Lepidoptera: Crambidae), the pheromone biosynthetic pathway in O. zaguliaevi, a close relative of the European corn borer O. nubilalis, was investigated. Deuterium-labeled hexadecanoic or tetradecanoic acids were topically applied to the surface of the pheromone gland, and the incorporation of the label into pheromone components and their putative precursors was determined. It was suggested that the two components shared by O. zaguliaevi and O. nubilalis, (E)-11- and (Z)-11-tetradecenyl acetates, are biosynthesized from hexadecanoic acid through one round of chain shortening, Delta11 desaturation, reduction, and acetylation. An additional component specifically found in O. zaguliaevi, (Z)-9-tetradecenyl acetate, is likely to be produced by delta11 desaturation of hexadecanoic acid, one round of chain shortening, reduction, and acetylation. Non-production of (Z)-9-tetradecenyl acetate in O. nubilalis was suggested to be due to the blockage of chain shortening from (Z)-11-hexadecenoate to (Z)-9-tetradecenoate.     

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.     

Correlation between dendrite diameter and action potential amplitude in sex pheromone specific receptor neurons in male Ostrinia nubilalis (Lepidoptera: Pyralidae)

Outer dendritic segments of olfactory receptor neurons tuned to sex pheromone components were measured morphometrically on the antenna of male European corn borers. Ostrinia nubilalis, to determine if a correlation exists between the diameter of the outer dendritic segment and the spike amplitude. The olfactory sensilla investigated each contained three receptor cells. Two cells were each specific for one of the two pheromone components, (Z)-11-tetradecenyl acetate (Z11-14:OAc) and (E)-11-tetradecenyl acetate (E11-14:OAc). Two strains of cornborers (Z and E) differ as to which of the two pheromone components is the main one. In both strains a large difference could be observed between the spike amplitudes elicited in the receptor cells by the two pheromone components, the main component always eliciting the large spike. In F1-hybrids (EZ) of these two strains, producing both pheromone components in similar quantities, the spike amplitudes were equal in the two pheromone-specific receptor cells. The third cell responded specifically to a behavioural antagonist. (Z)-9-tetradecenyl acetate (Z9-14:OAc) in both the parental and hybrid strains, and always showed the smallest spike amplitude. In a morphometric study, the outer dendritic segments were shown to differ more in diameter between the largest and second largest cell in the two parental strains than in the hybrid strain, while the smallest diameter cell did not differ between the different strains. These results imply that receptor cells with larger diameter produce spikes with greater amplitude. The data also show that all three types of receptor neurons display outer dendritic segments with strong variation in the diameter along the length of the segment, and with a pronounced taper towards the tip.