蛾类性信息素研究进展

蛾类是昆虫性信息素中研究较多的类群,已有565种的性信息素成份被鉴定,其相关研究在害虫监测和防治上得到实际应用的同时,已涉及到生态、生化、遗传等诸多方面,特别是在物种多样性的化学表达及物种的生殖隔离现象的分子水平的表达上,提供了研究的典范。本文将介绍蛾类性信息素的多样性、性信息素化学结构鉴定、微量成分的作用、合成性信息素的利用、性信息素生物合成酶、性信息素生产的调节机制及性信息素的感受机制等方面的研究现状和存在的问题。     

蛾类昆虫性信息素生物合成的研究进展

综述了各种不同化学结构类型的蛾类雌性信息素生物合成途径。此外还叙述了特定比例的性信息素成分在雌蛾体内产生的机理以及某些蛾类中信息素生物合成酶类与物种进化间的关系。     

实夜蛾属和铃夜蛾属昆虫性信息素通讯系统的研究进展

实夜蛾属Heliothis和铃夜蛾属Helicoverpa昆虫的性信息素通讯系统主要包括雌蛾的性信息素合成和雄蛾对性信息素接收两个方面,每方面都有分子、细胞、系统水平上进行协同作用的生物过程。性信息素生物合成激活肽（PBAN）与其受体作用,启动信号转导系统,从而激活合成性信息素的酶系统来合成性信息素,利用化学和生物测定的方法鉴定出具有诱蛾活性的性信息素腺体组分及行为功能;性信息素分子与性信息素结合蛋白（PBP）的复合体同受体相互作用,启动信号转导系统,诱导产生神经信号,从而引起一系列性行为反应。这些生物过程受到各种内部和外部因素的影响。     

蛾类性信息素生物合成途径及其调控

蛾类通过产生和识别物种特异性性信息素来引发后续交配行为,因此它在两性交配行为中至关重要.它们具有不同碳链长度、末端官能团、不同双键位置和构型等化学结构特征,本文详细讨论了不同蛾类性信息素的合成途径以及催化每一步反应的相关酶系,列举了15种夜蛾科不同亚科常见物种的性信息素组分及其比例,总结了产生特定比例性信息素的可能原因,查阅了夜蛾科不同物种已经鉴别的性信息素,并按照不同亚科、不同官能团和碳链长度对其进行分类,归纳了同一物种及其亲缘物种性信息素组分和比例的变异,总结了产生变异的分子机理,讨论了性信息素变异和物种进化的关系.最后以生物合成激活神经肽(PBAN)为主, 介绍了其调控途径和机制.本文旨在以不同的蛾类性信息素合成途径为线索,从共有合成途径出发深入了解其规律和共性,从特异合成途径出发探究物种间的进化和变异,展望未来的研究方向及其应用.     

鳞翅目昆虫信息素生物合成活化神经肽（PBAN）的研究进展

鳞翅目昆虫腺体产生和释放性信息素是由其信息素生物合成活化种经肽（ＰＢＡＮ）调控的。文章综述了ＰＢＡＮ的结构、结构与活性的关系以及ＰＢＡＮ的作用模式等方面的最新研究进展,可看出从３种昆虫中分离出的ＰＢＡＮ结构在很大程度上相似,ＰＢＡＮ的传递方式基本有两种,同时发现对于某些昆虫来说．除了ＰＢＡＮ对信息素合成的调控外,还有其它因子的参与,从而说明鳞翅目昆虫信息素合成调控所包含的机制是复杂和多样的。     

植食性金龟子信息化学物质的研究

金龟子信息化学物质包括性信息素、聚集信息素和植物源引诱剂。目前已鉴定出的性信息素大多集中于丽金龟科和鳃金龟科,犀金龟科只鉴定出了几种聚集信息素,有关植物源引诱剂方面的研究则集中于丽金龟科和花金龟科。本文总结了金龟子信息化学物质的化学结构特点,并评述了金龟子化学通讯中独特的手性性信息素相互拮抗作用及性信息素生物合成的研究。     

昆虫性信息素研究进展

一、什么是昆虫性信息素性信息素(sexpheromone)是由一种昆虫产生和释放出来,引诱或激起同种异性昆虫交配的化学物质。昆虫性信息素按其作用方式可分为两种:一种是挥发性性信息素,有远距离的引诱效果,它广泛存在于鳞翅目昆虫及其它种类的昆虫中;另一种是非挥发性性信息素,须由接受的一性与释放的一性接触才能起作用,称之为性识     

白蚁踪迹信息素研究进展

近年来, 固相微萃取技术的使用显著促进了白蚁踪迹信息素研究的开展。目前, 已有77种白蚁的踪迹信息素得到研究, 常见化学成分为十二碳单烯醇、 十二碳二烯醇和十二碳三烯醇, 其次为新松柏烯。已经鉴定的踪迹信息素主要为单组分或双组分系统。白蚁踪迹信息素由腹板腺分泌, 除澳白蚁科的达氏澳白蚁Mastotermes darwiniensis具有3个腹板腺外, 现存的白蚁均具有1个腹板腺, 位于第4或第5腹节。所有腹板腺都具有类型Ⅰ和Ⅱ两类细胞, 原白蚁亚科（Termopsinae）、 齿白蚁科（Serritermitidae）、 鼻白蚁科（Rhinotermitidae）种类的腹板腺还具有类型Ⅲ细胞。踪迹信息素的生物合成还缺乏研究, 推测有甲羟戊酸、 脂肪醇和饱和表皮烃3种途径。白蚁踪迹信息素的简约性十分显著, 不同地理分布、 生物生态习性以及一些系统距离较远的种类具有相同和密切相关的踪迹信息素。对于许多种类, 相同的信息化合物具有踪迹信息素和配对性信息素双重功能。白蚁踪迹信息素种特异性和简约性的适应意义和进化机制需要进一步研究。     

交配和温度对小地老虎雌蛾性信息素产生的影响

研究了交配和温度对小地老虎雌蛾性信息素产生的影响,结果表明,交配对性信息素各组分的滴度无显著影响,因此不影响小地老虎在下一暗期的再次求偶和交配.但环境温度对小地老虎性信息素的含量则有显著的影响,20～25℃最有利于小地老虎性信息素的生物合成,而低温和高温则均不利于小地老虎性信息素的正常产生与释放.     

蚜虫性信息素

蚜虫属同翅目蚜总科,是重要的农作物害虫。蚜虫长年行孤雌生殖,在中、高纬度深秋时,产生性蚜,以卵越冬。雌性蚜分泌性信息素荆芥内酯(nepetalactone)和荆芥醇(nepetalactol)。该文综述了蚜虫性信息素的结构与组分、性腺的形态结构、性信息素释放及影响因素;性信息素对雌性母和天敌的引诱作用;性信息素在蚜虫种间隔离中的地位和作用以及蚜虫性信息素在蚜虫防治中的应用前景。     

Molecular mechanisms underlying sex pheromone production in the silkmoth, Bombyx mori: characterization of the molecular components involved in bombykol biosynthesis

Many species of female moths produce sex pheromones to attract conspecific males. To date, sex pheromones from more than 570 moth species have been chemically identified. Most moth species utilize Type I pheromones that consist of straight-chain compounds 10-18 carbons in length with a functional group of a primary alcohol, aldehyde, or acetate ester and usually with several double bonds. In contrast, some moth species use unsaturated hydrocarbons or hydrocarbon epoxides, classified as Type II lepidopteran pheromones, as sex pheromones. Studies over the past three decades have demonstrated that female moths usually produce sex pheromones as multi-component blends where the ratio of the individual components is precisely controlled, thus making it possible to generate species-specific pheromone blends. As for the biosynthesis of Type I pheromones, it is well established that they are de novo synthesized in the pheromone gland (PG) through modifications of fatty acid biosynthetic pathways. However, as many of the molecular components within the PG cells (i.e., enzymes, proteins, and small regulatory molecules) have not been functionally characterized, the molecular mechanisms underlying sex pheromone production in PG cells remain poorly understood. To address this, we have recently characterized some of the molecules involved in the biosynthesis of the sex pheromone bombykol in the silkmoth, Bombyx mori. Characterization of these, and other, key molecules will facilitate our understanding of the precise mechanisms underlying lepidopteran sex pheromone production.     

Change in reductase activity is responsible for senescent decline in sex pheromone titre in the lightbrown apple moth,Epiphyas postvittana (Walker)

Sex pheromone titre in the tortricid moth Epiphyas postvittana follows a pattern commonly observed in other species of moths: an increase to a peak some time after eclosion (2-3days), and then a slow decline as the female ages. Previous work has shown that this decline is not regulated by the pheromone biosynthesis activating neuropeptide PBAN. Using in vivo and in vitro enzyme assays, and fatty acid methyl ester (FAME) analyses of pheromone precursors in the gland, we have investigated this senescent decline in pheromone titre. The enzyme assays have shown that in older females the fatty acid reductase and fatty acid synthesis enzyme systems decrease in activity (relative to younger females), whereas other enzyme systems involved in pheromone biosynthesis, including limited beta-oxidation (2-carbon chain-shortening), (E)-11-desaturation, and acetylation (by an acetyl transferase) remain unchanged in their activity. Of the two enzymatic processes involved, the more important one contributing to the decline appears to be the fatty acid reductase. This is consistent with FAME analyses of pheromone glands in old and young females, which show little difference in levels of saturated FAME, but a significant increase in the level of the putative precursor, (E)-11-tetradecenoate, of the sex pheromone component (E)-11-tetradecenyl acetate. Thus, this decline in fatty acid reductase activity results in a buildup of the precursor as the female ages. The near ubiquity of fatty acid reductases in moth sex pheromone systems suggests that this may be a common mechanism for the senescent decline of sex pheromone titre in moths.     

Does PBAN play an alternative role of controlling pheromone emission in the cabbage looper moth,Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae)?

There is an active process by which sex pheromone reserves of female cabbage looper moths, Trichoplusia ni, are transported to the gland's surface during the nocturnal period of calling. We hypothesized that this mobilization was controlled by a head factor, possibly related to the pheromone biosynthesis activating neuropeptides (PBAN) that in other species stimulate pheromone synthesis. We evaluated the impact of head extracts of T. ni on pheromone emission and glandular content of pheromone. During the photophase injected head extracts stimulated an increased pheromone emission rate in females, but glandular content of pheromone was not affected. Head extracts of H. virescens, a species with known PBAN activity, and synthetic PBAN stimulated an increased pheromone emission rate in T. ni. There was some specificity of the response of female T. ni to PBAN, in that several other unrelated polypeptides did not stimulate this type of response. Previously it had been determined that brain factors do not play a role in stimulating pheromone biosynthesis in T. ni. Our results indicate that there may be additional avenues by which PBAN or related neuropeptides control pheromone emission, including transport of pheromone reserves to the surface of the sex pheromone gland.     

Mating Effect on Sex Pheromone Production of the Oriental tobacco budworm,Helicoverpa assulta

This study was undertaken to clarify the suppression phenomenon of sex pheromone production after mating and its relationship to the physiological mechanism in adult females of Helicoverpa assulta, and determine the mating factor from males causing depletion of sex pheromonc production. Sex pheromone production of H. assulta females was mostly terminated in 3 hours after mating. Mated females maintained with a low titer of sex pheromone until 3 days when it started to increase again, which showed a characteristic of species mating more than once. The mated female again produced pheromone upon injection of pheromone biosynthesis activating neuropeptide (PBAN) or extracts of brain-suboesophageal ganglion complexes (Br-Sg) of mated female, which were shown similar pheromonotropic activities as compared with virgin females. These results indicated that the mating did not inhibit the receptivity of pheromone gland itself and PBAN biosynthesis in suboesophageal ganglion of the mated females. And it seems to support that the depletion of sex pheromone production is responsible for blocking of PBAN release from head. To investigate the mating factor from adult males, when extracts of reproductive organs of male were injected into hemocoel of virgin females evoking depletion of sex pheromone production as shown in mated female. The results suggest that a chemical substance(s) from the male reproductive organs could be responsible for the loss of sex pheromone biosynthesis in H. assulta.     

Sex pheromone evolution is associated with differential regulation of the same desaturase gene in two genera of leafroller moths

Chemical signals are prevalent in sexual communication systems. Mate recognition has been extensively studied within the Lepidoptera, where the production and recognition of species-specific sex pheromone signals are typically the defining character. While the specific blend of compounds that makes up the sex pheromones of many species has been characterized, the molecular mechanisms underpinning the evolution of pheromone-based mate recognition systems remain largely unknown. We have focused on two sets of sibling species within the leafroller moth genera Ctenopseustis and Planotortrix that have rapidly evolved the use of distinct sex pheromone blends. The compounds within these blends differ almost exclusively in the relative position of double bonds that are introduced by desaturase enzymes. Of the six desaturase orthologs isolated from all four species, functional analyses in yeast and gene expression in pheromone glands implicate three in pheromone biosynthesis, two Δ9-desaturases, and a Δ10-desaturase, while the remaining three desaturases include a Δ6-desaturase, a terminal desaturase, and a non-functional desaturase. Comparative quantitative real-time PCR reveals that the Δ10-desaturase is differentially expressed in the pheromone glands of the two sets of sibling species, consistent with differences in the pheromone blend in both species pairs. In the pheromone glands of species that utilize (Z)-8-tetradecenyl acetate as sex pheromone component (Ctenopseustis obliquana and Planotortrix octo), the expression levels of the Δ10-desaturase are significantly higher than in the pheromone glands of their respective sibling species (C. herana and P. excessana). Our results demonstrate that interspecific sex pheromone differences are associated with differential regulation of the same desaturase gene in two genera of moths. We suggest that differential gene regulation among members of a multigene family may be an important mechanism of molecular innovation in sex pheromone evolution and speciation.     

Inhibition of PK/PBAN-mediated functions in insects: discovery of selective and non-selective inhibitors

The antagonistic properties of a few linear and backbone cyclic (BBC) conformationally constraint peptide libraries and their analogs, were tested for the ability to inhibit pyrokinin/pheromone biosynthesis activating neuropeptide (PK/PBAN) mediated functions: sex pheromone biosynthesis in Heliothis peltigera female moths, cuticular melanization in Spodoptera littoralis larvae, pupariation in the fleshfly Neobellieria bullata and hindgut contraction in Leucophaea maderae, elicited by exogenously injected PBAN, pheromonotropin (PT), leucopyrokinin (LPK), myotropin (MT) or by the endogenous peptides. The data revealed differential inhibitory patterns within the same assay with different elicitors (in both the pheromonotropic and melanotropic assays) and among the different functions and disclosed selective antagonists, hinting at the possibility that the receptors that mediate those functions may differ from one another structurally.     

Common functional elements of Drosophila melanogaster seminal peptides involved in reproduction of Drosophila melanogaster and Helicoverpa armigera females

Sex peptide (SP) and Ductus ejaculatorius peptide (Dup) 99B are synthesized in the retrogonadal complex of adult male Drosophila melanogaster, and are transferred in the male seminal fluid to the female genital tract during mating. They have been sequenced and shown to exhibit a high degree of homology in the C-terminal region. Both affect subsequent mating and oviposition by female D. melanogaster. SP also increases in vitro juvenile hormone (JH) biosynthesis in excised corpora allata (CA) of D. melanogaster and Helicoverpa armigera. We herein report that the partial C-terminal peptides SP(8-36) and SP(21-36) of D. melanogaster, and the truncated N-terminal SP(6-20) do not stimulate JH biosynthesis in vitro in CA of both species. Both of these C-terminal peptides reduce JH-III biosynthesis significantly. Dup99B, with no appreciable homology to SP in the N-terminal region, similarly lacks an effect on JH production by H. armigera CA. In contrast, the N-terminal peptides - SP(1-11) and SP(1-22) - do significantly activate JH biosynthesis of both species in vitro. We conclude that the first five N-terminal amino acid residues at the least, are essential for allatal stimulation in these disparate insect species. We have previously shown that the full-length SP(1-36) depresses pheromone biosynthesis in H. armigera in vivo and in vitro. We now show that full-length Dup99B and the C-terminal partial sequence SP(8-36) at low concentrations strongly depress (in the range of 90% inhibition) PBAN-stimulated pheromone biosynthesis of H. armigera. In addition, the N-terminal peptide SP(1-22), the shorter N-terminal peptide SP(1-11) and the truncated N-terminal SP(6-20) strongly inhibit pheromone biosynthesis at higher concentrations.     

Drosophila melanogaster sex peptide stimulates juvenile hormone synthesis and depresses sex pheromone production in Helicoverpa armigera

Previous studies demonstrate that virgin female adult Helicoverpa armigera (Lepidoptera: Noctuidae) moths exhibit calling behaviour and produce sex pheromone in scotophase from the day after emergence, and that mating turns off both of these pre-mating activities. In the fruit fly Drosophila melanogaster, a product of the male accessory glands, termed sex peptide (SP), has been identified as being responsible for suppressing female receptivity after transfer to the female genital tract during mating. Juvenile hormone (JH) production is activated in the D. melanogaster corpus allatum (CA) by SP in vitro. We herein demonstrate cross-reactivity of D. melanogaster SP in the H. armigera moth: JH production in photophase virgin female moth CA in vitro is directly activated in a dose-dependent manner by synthetic D. melanogaster SP, and concurrently inhibits pheromone biosynthesis activating neuropeptide (PBAN)-activated pheromone production by isolated pheromone glands of virgin females. Control peptides (locust adipokinetic hormone, AKH-I, and human corticotropin, ACTH) do not inhibit in vitro pheromone biosynthesis. Moreover, SP injected into virgin H. armigera females, decapitated 24 h after eclosion, or into scotophase virgin females, suppresses pheromone production. In the light of these results, we hypothesize the presumptive existence of a SP-like factor among the peptides transmitted to female H. armigera during copulation, inducing an increased level of JH production and depressing the levels of pheromone produced thereafter.