Prevalence of Wolbachia in 10 Tenebrionidae stored-product insects and spatiotemporal infection dynamics in Tribolium confusum(Jaquelin Du Val)(Coleoptera:Tenebrionidae)

Insect symbionts Wolbachia used for pest population control has focused on vector pest species and agricultural insects while rare reports in Chinese stored-product insect samples.In this paper,we surveyed the prevalence of Wolbachia using a PCR detection method in ten Tenebrionidae stored-product insects.Subsequently,the spatiotemporal Wolbachia infection dynamics in Tribolium confusum and Wolbachia elimination patterns using tetracycline treatment were investigated in detail by TaqMan®probe real-time quantitative PCR,and host reproductive fitness parameters were compared.T.confusum was the only Wolbachia infected species in all the surveyed species.Wolbachia infection density consistently increased with the development of T.confusumand plateaued at 3.7×107 wsp copies per individual insect at the young adult stage.Wolbachia densities in females were higher than that in males with a significant difference at the pupae stage and varied among different tissues and organs.Uninfected female beetles were completely incapable of producing mature progenies when crossed with Wolbachia infected males.Embryogenesis and egg hatch rate were specifically inhibited after Wolbachia elimination,while other traits,including the number of eggs,pupation rate and sex ratio,remained unaffected by tetracycline treatment.Our results showthat the TaqMan®probe qPCR is a reliable detection method for quantifying the density of Wolbachia as compared to qualitative detection of wsp gene by PCR and relatively quantified by real-time qPCR.The fitness results indicated that Wolbachia infection was not an obligate symbiont and benefited the host confused flour beetle.

昆虫内共生菌研究概况

内共生菌与昆虫形成互惠共生关系,在宿主昆虫的生长、生殖、传播植物病害以及探讨生命起源与进化等等方面都有很重要的意义。从昆虫内共生菌的特点、内共生菌在昆虫体内的分布、对昆虫的影响、获得少或缺内共生菌的方法及其研究内共生菌的潜在意义等方面进行了综述。

刺吸式昆虫次生内共生菌的研究进展

蚜虫作为典型的刺吸式昆虫,需要以取食植物韧皮部汁液来补充营养,几乎所有蚜虫均带有一种能为其提供植物韧皮部缺失营养物质的初生共生菌Buchnera aphidicola。此外,蚜虫还可携带一种或多种次生内共生菌。在众多共生菌—寄主系统中,蚜虫与其所带内共生菌间的互作研究最为透彻。虽然次生内共生菌对寄主的存活和生殖影响并不显著,但其在寄主对环境耐受力、天敌防御能力等方面作用明显。本文在查阅大量蚜虫次生内共生菌相关文献的基础上,着重对蚜虫次生内共生菌的种类及传播规律、次生内共生菌对蚜虫表型的影响、蚜虫次生内共生菌基因组学等方面的研究现状进行综述,以求为刺吸式昆虫次生内共生菌的研究提供参考。

昆虫内共生菌及其传病毒相关GroEL蛋白

昆虫传播的植物病毒种类多、危害大,其传病毒的能力与昆虫体内共生菌产生的GroEL蛋白关系密切,该蛋白是分子伴侣hsp60家族的成员,对病毒进入昆虫血体腔免遭破坏起着保护作用,也与昆虫传病毒的专一性有关。本文对昆虫内共生菌及其产生的GroEL进行了综述,并分析了研究内共生菌及其产生的蛋白质的科学意义与发展趋势,为植物病毒病的防治研究提供了新的思路。

植物病毒病媒介昆虫的传毒特性和机制研究进展

植物病毒病是农作物的"癌症",至今缺少有效的防治方法。目前已知80%的植物病毒病依赖于媒介昆虫传播,而媒介昆虫对植物病毒的传播是一个昆虫、病毒、寄主植物互作的过程,历经获毒、持毒和传毒等多个阶段,昆虫体内一系列病毒受体或蛋白参与了这个过程。昆虫传播病毒的方式有口针携带式、前肠保留式和体内循环式3类,它们各自对应的持久性为非持久性、半持久性和持久性,不同昆虫获取这3类病毒的获毒时间、在体内存留位置和传毒时间也各不相同。这个过程受到媒介昆虫的性别及龄期、寄主植物、环境条件、昆虫体内共生菌等多种因素的影响。与之相关的蛋白主要有病毒衣壳蛋白(CP)、次要衣壳蛋白(CPm)、GroEL蛋白、辅助因子(HC)和下颚口针蛋白等。近年来对植物病毒基因组的研究也取得了很大的进展,对昆虫传毒机制的研究正受到越来越广泛的关注。本文综述了近年来该领域内的相关研究进展,包括昆虫传播植物病毒的传毒方式、影响传毒效率的因素、传毒机制特别是昆虫体内与病毒传播可能相关的受体等。

昆虫内共生菌及其功能研究进展

昆虫内共生菌与宿主之间的互作关系已逐渐成为昆虫学的研究热点之一。昆虫内共生菌具有协助宿主营养代谢、逃避天敌攻击和增强抗药性等功能:通过协助宿主营养代谢,提供食物中缺乏的营养物质来弥补食物中营养物质的不足;分泌抗菌肽、毒素等物质以增强对外源寄生物等的防御能力,抑制对宿主的不利影响;同时,也可以增强宿主抗逆性,调控植物生理反应,抑制植物对宿主的不利影响;利用对抗逆性基因精确的表达调控来增强宿主抗药性等。因此,内共生菌介导的宿主生物学性状的改变,扩大了宿主昆虫的生态位,成为昆虫生长发育过程中的重要调控因子。目前,昆虫内共生菌的功能往往是通过研究宿主感染共生菌前后性状的变化而证实。近几年,转录组学、蛋白质组学、基因组学等技术的进步,促进了内共生菌与宿主昆虫共生机制研究的发展。通过研究内共生菌及其功能基因在昆虫种群动态中的作用,特别是内共生菌感染对宿主生殖、存活、适应环境能力的影响,将有利于揭示内共生菌与宿主的共生机制,并最终为开发新的防控技术提供理论依据。本文针对昆虫内共生菌的功能进行了综述,并对日后的研究方向进行了展望,提供了研究昆虫内共生菌与宿主互作关系的方法及建议。

Metamicrobiomics in herbivore beetles of the genus Cryptocephalus （Chrysomelidae）： toward the understanding of ecological determinants in insect symbiosis

The Cryptocephalus marginellus （Coleoptera： Chrysomelidae） complex is composed by six species that are supposed to have originated by events of allo- or parapatric speciation. In the present study we investigated the altemative hypotheses that the bacterial communities associated with six populations of this species complex are shaped by environmental factors, or reflect the proposed pattern of speciation. The microbiota associated with the six populations, from five species of the complex, have been characterized through 16S rRNA pyrotag sequencing. Based on a 97% sequence similarity threshold, data were clustered into 381 OTUs, which were analyzed using a variety of diversity indices. The microbiota of C. acquitanus and C. marginellus （Calanques） were the most diverse （over 100 OTUs）, while that from C. zoiai yielded less bacterial diversity （45 OTUs）. Taxonomic assignment revealed Proteobacteria, Tenericutes and Firmicutes as the dominant components of these beetles＇ microbiota. The most abtmdant genera were Ralstonia, Sphingomonas, Rickettsia, and Pseudomonas. Different strains of Rickettsia were detected in C. eridani and C. renatae. The analysis of β-diversity revealed high OTU turnover among the populations of C. marginellus complex, with only few shared species. Hierarchical clustering taking into account relative abundances of OTUs does not match the phylogeny of the beetles, therefore we hypothesize that factors other than phylogenetic constraints play a role in shaping the insects＇ microbiota. Environmental factors that could potentially affect the composition of bacterial communities were tested by fitting them on the results of a multi-dimensional scaling analysis. No significant correlations were observed towards the geographic distances or the host plants, while the composition of the microbiota appeared associated with altitude. The metabolic profiles of the microbiotas associated with each population were inferred from bacterial taxonomy, and interestingly, the obtained clustering pattern was consistent with the host phylogeny.

植物介导的昆虫内共生菌水平传播及其对宿主生物学特性的影响

内共生菌(Endosymbionts)与其昆虫宿主的生物学特性联系非常密切。近年来,昆虫内共生菌水平传播的途径及机制已经成为昆虫学研究的热点之一。越来越多的研究表明,亲缘关系相距甚远的昆虫可以感染有相同或相似的内共生菌,说明昆虫内共生菌的水平传播在自然界中普遍存在。植物介导的昆虫内共生菌水平传播便是其中的一条途径,即同种或不同种类的昆虫可以通过取食,获得供体昆虫传入植物组织中的内共生菌,形成内共生菌从供体昆虫-寄主植物-受体昆虫传播的路径。本文主要以植物介导的昆虫内共生菌水平传播途径为对象,介绍了昆虫内共生菌的水平传播途径,以及内共生菌传入后对新宿主生物学、生态学特性的影响,以期为昆虫内共生菌水平领域的研究提供更多有价值的参考。

烟粉虱内共生菌Rickettsia在植物体内的形态及动态变化

【目的】通过研究烟粉虱Bemisia tabaci取食传入植物体内的昆虫内共生菌种类,探明其在不同植物中的分布形态及时空动态。【方法】以B型烟粉虱、棉花、番茄、豇豆为实验材料,利用常规PCR检测烟粉虱取食后传入植物体内的共生菌种类;利用透射电镜(Transmission electron microscope,TEM)检测Rickettsia传入植物后的分布及形态;利用q-PCR技术检测豇豆叶片中Rickettsia含量的动态变化。【结果】B型烟粉虱体内含有原生共生菌Portiera、次生共生菌Rickettsia,Hamiltonella和Hemipteriphilus,但只检测到Rickettsia可经烟粉虱传入棉花、番茄、豇豆植物体内,并可在植物体内存活、转移。在3种植物体内Rickettsia均分布于叶片韧皮部的筛管细胞中。烟粉虱、棉花、番茄组织内的Rickettsia形态基本一致,但豇豆中Rickettsia在形态上较小而钝圆。相同数量的烟粉虱取食,在豇豆体内最先检测到Rickettsia。随着烟粉虱取食时间的增加,豇豆体内的Rickettsia含量先增加后下降;而当无烟粉虱持续取食时,一定时间段内豇豆体内的Rickettsia先下降再小幅度上升,并可以在一定时间内保持不变。基于16S rDNA序列的系统发育分析表明,传入棉花、番茄、豇豆叶片中的Rickettsia与B型烟粉虱体内的Rickettsia高度同源。【结论】Rickettsia可经烟粉虱取食传入植物体内,分布并存活于韧皮部的筛管细胞中,并可在植物不同叶片之间转移;在不同植物宿主中,Rickettsia的形态会发生轻微变化;烟粉虱对Rickettsia的传播效率受到植物种类的影响。