福建省烟粉虱自然种群Wolbachia感染特点

Wolbachia是专性的细胞内细菌,广泛存在于节肢动物生殖组织。已有的研究结果表明,节肢动物中存在A组和B组Wolbachia,而烟粉虱Bemisia tabaci中主要检测到了B组Wolbachia。本研究从福建省采集到17个不同烟粉虱地理种群,首先通过rDNA-ITS1克隆测序鉴定了不同烟粉虱地理种群的生物型,然后采用Wolbachia 16S rDNA的特异引物,并通过PCR-RFLP技术分析了不同烟粉虱地理种群中Wolbachia的感染特点。结果表明：从福建省闽侯、平潭、南平、来舟、漳平和沙县采集到的烟粉虱自然种群属于非B型,而非B型烟粉虱种群中存在广泛的超感染现象,即单个非B型烟粉虱个体中同时感染了不同型Wolbachia。相反,B型烟粉虱自然种群的个体中只感染A组Wolbachia。该研究依据密集采样的数据进一步证实了Wolbachia在烟粉虱自然种群中的分布确实与宿主的生物型密切相关,提示Wolbachia可能在烟粉虱的种群分化中发挥作用。     

Biotype-dependent secondary symbiont communities in sympatric populations of Bemisia tabaci

The sweet potato whitefly, Bemisia tabaci, harbors Portiera aleyrodidarum, an obligatory symbiotic bacterium, as well as several secondary symbionts including Rickettsia, Hamiltonella, Wolbachia, Arsenophonus, Cardinium and Fritschea, the function of which is unknown. Bemisia tabaci is a species complex composed of numerous biotypes, which may differ from each other both genetically and biologically. Only the B and Q biotypes have been reported from Israel. Secondary symbiont infection frequencies of Israeli laboratory and field populations of B. tabaci from various host plants were determined by PCR, in order to test for correlation between bacterial composition to biotype and host plant. Hamiltonella was detected only in populations of the B biotype, while Wolbachia and Arsenophonus were found only in the Q biotype (33% and 87% infection, respectively). Rickettsia was abundant in both biotypes. Cardinium and Fritschea were not found in any of the populations. No differences in secondary symbionts were found among host plants within the B biotype; but within the Q biotype, all whiteflies collected from sage harboured both Rickettsia and Arsenophonus, an infection frequency which was significantly higher than those found in association with all other host plants. The association found between whitefly biotypes and secondary symbionts suggests a possible contribution of these bacteria to host characteristics such as insecticide resistance, host range, virus transmission and speciation.     

Symbiont diversity and non-random hybridization among indigenous (Ms) and invasive (B) biotypes of Bemisia tabaci

The whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) is a worldwide pest and a vector of numerous plant viruses. B. tabaci is composed of dozens of morphologically indistinguishable biotypes and its taxonomic status is still controversial. This phloem-feeder harbours the primary symbiont Portiera aleyrodidarum and potentially six secondary symbionts: Cardinium, Arsenophonus, Hamiltonella, Rickettsia, Wolbachia and Fritschea. In the southwest Indian Ocean, La Réunion hosts two biotypes of this species: B (invasive) and Ms (indigenous). A multiplex PCR was developed to study the symbiont community of B. tabaci on La Réunion. Symbiont community prevalence and composition, host mitochondrial and nuclear genetic diversity, as well as host plant and localization, were described on field populations of La Réunion for B and Ms B. tabaci biotypes and their hybrids. A clear association between symbiotypes and biotypes was shown. Cardinium, Arsenophonus and Rickettsia were found in the Ms biotype (73.6%, 64.2% and 3.3%, respectively). Hamiltonella (exclusively) and Rickettsia were found in the B biotype (78% and 91.2%, respectively). Hybrids harboured all symbiotypes found in Ms and B populations, but with a higher prevalence of Ms symbiotypes than expected under random hybridization. An unexpected majority was Cardinium mono-infected (65.6%), and a striking minority (9%) harboured Cardinium/Arsenophonus. In the hybrids only, genetic diversity was linked to symbiotype. Among the hybrids, significant links were found between symbiotypes and: (i) mitochondrial COI sequences, i.e. maternal origin; and (ii) alleles of nuclear microsatellite loci, specific to either Ms or B parental biotype. Taken together, our results suggest that Cardinium and/or Arsenophonus may manipulate the reproduction of indigenous (Ms) with invasive (B) biotypes of Bemisia tabaci.     

Wolbachia infections of the whitefly Bemisia tabaci

We report the first systematic survey for the presence of Wolbachia endosymbionts in aphids and whiteflies, particularly different populations and biotypes of Bemisia tabaci. Additional agriculturally important species included were predator species, leafhoppers, and lepidopterans. We used a polymerase chain reaction (PCR)-based detection assay with ribosomal 16S rDNA and Wolbachia cell surface protein (wsp) gene primers. Wolbachia were detected in a number of whitefly populations and species, whitefly predators, and one leafhopper species; however, none of the aphid species tested were found infected. Single, double, and triple infections were detected in some of the B. tabaci populations. PCR and phylogenetic analysis of wsp gene sequences indicated that all Wolbachia strains found belong to group B. Topologies of the optimal tree derived by maximum likelihood (ML) and a ML tree in which Wolbachia sequences from B. tabaci are constrained to be monophyletic are significantly different. Our results indicate that there have been at least four independent Wolbachia infection events in B. tabaci. The importance of the presence of Wolbachia infections in B. tabaci is discussed.     

不同生物型烟粉虱体内Wolbachia共生菌的检测及其系统树分析

Wolbachia是广泛分布于节肢动物体内一类共生细菌,它能够通过多种机制调控宿主的生殖方式。近年来的研究表明,Wolbachia与许多外来生物的成功入侵相关。本文利用长PCR的方法特异扩增了不同生物型烟粉虱（共24个种群）体内Wolbachia的wsp基因,结果发现B型和Q型烟粉虱入侵种群体内均未检测到Wolbachia,而在非B/Q型的浙江种群和肯尼亚种群体内检测到了Wolbachia。对该wsp基因进行测序并和已知序列进行同源性分析发现,浙江烟粉虱种群的Wolbachia属于B组Con/Rug亚种群,而肯尼亚种群属于B组Btab1亚种群。Wolbachia的存在与否可能与烟粉虱的成功入侵有一定的关系。图2表2参23     

Identification and localization of a Rickettsia sp. in Bemisia tabaci (Homoptera: Aleyrodidae)

Whiteflies (Homoptera: Aleyrodidae) are sap-sucking insects that harbor "Candidatus Portiera aleyrodidarum," an obligatory symbiotic bacterium which is housed in a special organ called the bacteriome. These insects are also home for a diverse facultative microbial community which may include Hamiltonella, Arsenophonus, Fritchea, Wolbachia, and Cardinium spp. In this study, the bacteria associated with a B biotype of the sweet potato whitefly Bemisia tabaci were characterized using molecular fingerprinting techniques, and a Rickettsia sp. was detected for the first time in this insect family. Rickettsia sp. distribution, transmission and localization were studied using PCR and fluorescence in situ hybridizations (FISH). Rickettsia was found in all 20 Israeli B. tabaci populations screened but not in all individuals within each population. A FISH analysis of B. tabaci eggs, nymphs, and adults revealed a unique concentration of Rickettsia around the gut and follicle cells, as well as a random distribution in the hemolymph. We postulate that the Rickettsia enters the oocyte together with the bacteriocytes, leaves these symbiont-housing cells when the egg is laid, multiplies and spreads throughout the egg during embryogenesis and, subsequently, disperses throughout the body of the hatching nymph, excluding the bacteriomes. Although the role Rickettsia plays in the biology of the whitefly is currently unknown, the vertical transmission on the one hand and the partial within-population infection on the other suggest a phenotype that is advantageous under certain conditions but may be deleterious enough to prevent fixation under others.     

浙江B型与非B型（China-ZHJ-1）烟粉虱种群共生细菌的检测及系统发育分析

烟粉虱体内存在共生细菌,包括初生共生细菌（primary endosymbiont）和次生共生细菌（secondary endosymbiont）。本项研究应用PCR技术检测了烟粉虱浙江B型和非B型China-ZHJ-1种群中共生细菌的分布。结果表明,烟粉虱B型和非B型体内均存在初生共生细菌,而两者次生共生细菌的组成存在差异。一种肠杆菌科次生共生细菌仅在B型烟粉虱中发现,而另两种次生共生细菌Wolbachia和杀雄菌Arsenophonus仅在非B型中发现。初生共生细菌的系统发育分析表明,B型是入侵生物型,而浙江非B型是本地生物型。     

不同作物田烟粉虱发生的时空动态

2008～2009年连续2年系统调查了番茄、茄子、棉花、大豆、玉米等寄主植物上烟粉虱种群发生的时间与空间动态。结果表明：不同寄主植物上的烟粉虱成虫及其伪蛹数量有显著性差异,其密度大小依次为：茄子>棉花>番茄>大豆>玉米。其中,在玉米上除了发现极少量的成虫逗留外,没有发现烟粉虱的卵及若虫。在发生的时间序列上,烟粉虱成虫及伪蛹的数量呈现为先逐渐上升后又下降的变化过程,发生高峰期集中在8月5日到8月31日,9月初以后烟粉虱数量慢慢减少。在空间分布上,表现为烟粉虱成虫喜食寄主的上部叶片。统计分析显示,寄主对烟粉虱成虫和伪蛹的数量的影响极显著,而年份对其数量的影响没有显著差异。由此得出的烟粉虱发生和达到高峰的时间,可为烟粉虱预测预报和区域性综合治理提供重要理论依据。     

Records of Natural Enemies of Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) Biotype B in Brazil

Collections of natural enemies of Bemisia tabaci biotype B (Genn.) (Hemiptera: Aleyrodidae) were made in Lavras, state of Minas Gerais, Brazil. In the greenhouse, 6,495 predators and 16,628 parasitoids belonging to three families were collected. In the field, 267 predators and 344 parasitoids belonging to five families were found. For the first time in Brazil, five species of predators associated with this whitefly were reported. Because of the diversity of natural enemies of B. tabaci biotype B recorded, this study points out the importance of these data for studies on integrated pest management.     

广东省烟粉虱蚜小蜂种类及种群动态调查初报

通过调查采集和鉴定 ,初步获得了广东省内烟粉虱蚜小蜂 6种 ,其中隶属于恩蚜小蜂属EncarsiaFoerster的有 4种 ,隶属于桨角蚜小蜂属ErtmocerusHaldeman有 2种。调查发现 ,蚜小蜂在蔬菜和园林植物上的寄生动态有一定的规律 ,4月中旬至 6月下旬和 9月下旬至 1 1月下旬寄生率较高 ,6月下旬至 8月上旬和 1 1月下旬至翌年 2月下旬寄生率较低。初步确定双斑恩蚜小蜂Encarsiabimaculata和桨角蚜小蜂Eretmocerussp .为广东省内烟粉虱的寄生蜂优势种类。     

Arsenophonus GroEL Interacts with CLCuV and Is Localized in Midgut and Salivary Gland of Whitefly B. tabaci

Cotton leaf curl virus (CLCuV) (Gemininiviridae: Begomovirus) is the causative agent of leaf curl disease in cotton plants (Gossypium hirsutum). CLCuV is exclusively transmitted by the whitefly species B. tabaci (Gennadius) (Hemiptera: Alerodidae). B. tabaci contains several biotypes which harbor dissimilar bacterial endo-symbiotic community. It is reported that these bacterial endosymbionts produce a 63 kDa chaperon GroEL protein which binds to geminivirus particles and protects them from rapid degradation in gut and haemolymph. In biotype B, GroEL protein of Hamiltonella has been shown to interact with Tomato yellow leaf curl virus (TYLCV). The present study was initiated to find out whether endosymbionts of B. tabaci are similarly involved in CLCuV transmission in Sriganganagar (Rajasthan), an area endemic with cotton leaf curl disease. Biotype and endosymbiont diversity of B. tabaci were identified using MtCO1 and 16S rDNA genes respectively. Analysis of our results indicated that the collected B. tabaci population belong to AsiaII genetic group and harbor the primary endosymbiont Portiera and the secondary endosymbiont Arsenophonus. The GroEL proteins of Portiera and Arsenophonus were purified and in-vitro interaction studies were carried out using pull down and co-immunoprecipitation assays. In-vivo interaction was confirmed using yeast two hybrid system. In both in-vitro and in-vivo studies, the GroEL protein of Arsenophonus was found to be interacting with the CLCuV coat protein. Further, we also localized the presence of Arsenophonus in the salivary glands and the midgut of B. tabaci besides the already reported bacteriocytes. These results suggest the involvement of Arsenophonus in the transmission of CLCuV in AsiaII genetic group of B. tabaci.     

烟粉虱的分类地位及在中国的分布

烟粉虱广泛分布于全球热带和亚热带地区。近20多年,烟粉虱的一些遗传群入侵世界各地,严重危害作物生产。烟粉虱遗传结构的多样性和复杂性早已被关注,但其分类地位,尤其是烟粉虱到底是一个包含多个生物型的种还是一个包含许多隐种的物种复合体,一直颇受争议。近几年,有关烟粉虱种系发生和系统学的研究取得长足进展,有证据推论其是一个包含至少31个隐种的物种复合体,但生殖隔离证据仍显不足,种系发生分析结果也因仅依据COI一个基因而受到质疑。因此,在大多数从事烟粉虱研究的同行接受其为一个物种复合体的概念的同时,仍有同行沿用生物型的概念。在我国境内已先后报道了包括13个本地种和2个全球入侵种在内的15个烟粉虱隐种。本地种主要分布在我国南部及包括海南岛和台湾岛的东南沿海地区,隐种的多样性由南向北逐渐降低。入侵种“中东一小亚细亚1”隐种（MEAMl）（即“B型”）和“地中海”隐种（MED）（即“Q型”）分别于20世纪90年代中后期和2003年前后入侵我国,并在许多地区迅速取代了本地种而占据优势地位。全国范围内的调查数据显示,这2个入侵种可在大部分区域共同存在,但自2005年以来,MED在许多地区陆续取代MEAMl,这很可能与MED对大量使用的新烟碱类杀虫剂有较强抗性有关。本文还讨论了烟粉虱隐种复合体分类所面临的命名等难题以及大范围抽样调查的数据偏差问题。     

F supergroup <Emphasis Type="Italic">Wolbachia</Emphasis> in bush crickets: what do patterns of sequence variation reveal about this supergroup and horizontal transfer between nematodes and arthropods?

Wolbachia pipientis, an intracellular, α-proteobacterium, is commonly found in arthropods and filarial nematodes. Most infected insects are known to harbor strains of Wolbachia from supergroups A or B, whereas supergroups C and D occur only in filarial nematodes. Here, we present molecular evidence from two genes (ftsZ and 16S rDNA) that 2 Orthopterans (the bush cricket species Orocharis saltator and Hapithus agitator; Gryllidae: Eneopterinae) are infected with Wolbachia from the F supergroup. Additionally, a series of PCR tests revealed that these bush cricket specimens did not harbor nematodes, thus indicating that our positive results were not a by-product of nematodes being present in these cricket samples. Patterns of molecular variation suggest that (1) strains of F supergroup Wolbachia exhibit less genetic variation than the nematode-specific C and D supergroups but more than the A and B supergroups found in arthropods and (2) that there is no evidence of recombination within F supergroup strains. The above data support previous findings that F supergroup Wolbachia is not only harbored in both nematodes and arthropods, but that horizontal transfer has likely occurred recently between these diverse taxonomic groups (although the exact details of such horizontal transmissions remain unclear). Moreover, the limited genetic variation and lack of recombination in the F supergroup suggest that this clade of Wolbachia has radiated relatively rapidly with either (1) little time for recombination to occur or (2) selection against recombination as occurs in the mutualistic C and D strains of Wolbachia – both of which remain to be explored further.     

基于16S rDNA序列的Wolbachia的检测及分型

Wolbachia是广泛分布于节肢动物体内的一类共生细菌。采用16S rDNA特异片段的PCR-RFLP方法对烟粉虱Bemisia tabaci （Gennadius）不同生物型及米蛾Corcyra cephalonica （Stainton）共生菌Wolbachia进行了检测与分型分析。基于wsp基因对烟粉虱共生菌B组Wolbachia以及米蛾共生菌Wolbachia进行了系统树分析,并对相应的Wolbachia16S rDNA特异片段进行了克隆、测序以及序列比对。结果表明:16S rDNA的特异片段经NheⅠ酶切后RFLP图谱可有效检测与鉴别Wolbachia。烟粉虱共生菌Wolbachia的16S rDNA特异片段经VspⅠ酶切后可得到预期RFLP图谱,而米蛾共生菌B组Wolbachia （基于wsp序列分析为B组）则产生不同的RFLP图谱。序列分析表明,Nauru型烟粉虱体内B组Wolbachia的16S rDNA片段序列与已知B组Wolbachia对应序列（DQ278884）同源性为100%;米蛾体内B组Wolbachia 16S rDNA特异片段有碱基变异,并存在于VspⅠ识别位点内,这是导致VspⅠ酶切后RFLP图谱不同的原因。结果提示,B组Wolbachia 16S rDNA特异片段经VspⅠ酶切的RFLP图谱存在多态性。本研究结果可为今后Wolbachia的检测与分型提供借鉴。     

烟粉虱和温室粉虱在甘蓝上的刺探取食行为比较

利用刺吸电波图技术研究B型、ZHJ_1型烟粉虱Bemisia tabaci(Gennadius)和温室粉虱Trialeurodes vaporariorum(Westwood)在甘蓝上的取食行为,将3种粉虱的电波图进行比较,其中,B型和ZHJ_1型烟粉虱记录到np,C,pd,E1,E2,F和G波7种波形,温室粉虱只记录到刺探波形,少有取食波形。B型的20个记录中只有1个没有持续吸食波形;ZHJ_1型的25个记录中有10个记录没有持续吸食波形;温室粉虱没有持续吸食记录。甘蓝叶片韧皮部的结构或汁液的化学成分与温室粉虱的抗性密切相关。     

Biotype status and genetic polymorphism of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) in Greece: mitochondrial DNA and microsatellites

The genetic polymorphism and the biotype identity of the tobacco whitefly Bemisia tabaci (Gennadius) have been studied in population samples taken from different localities within Greece from cultivated plants growing in greenhouses or in open environments and from non-cultivated plants. Two different approaches were used: sequencing of the mitochondrial cytochrome oxidase I (mtCOI) gene and genotyping using microsatellite markers. Analyses of the mtCOI sequences revealed a high homogeneity between the Greek samples which clustered together with Q biotype samples that had been collected from other countries. When genetic polymorphism was examined using six microsatellite markers, the Greek samples, which were all characterized as Q biotype were significantly differentiated from each other and clustered into at least two distinct genetic populations. Moreover, based on the fixed differences revealed by the mtCOI comparison of known B. tabaci biotype sequences, two diagnostic tests for discriminating between Q and B and non-Q/non-B biotypes were developed. Implementation of these diagnostic tools allowed an absence of the B biotype and presence of the Q biotype in the Greek samples to be determined.     

Differential indirect effects of two plant viruses on an invasive and an indigenous whitefly vector: implications for competitive displacement

The role of vector–begomovirus–plant interactions in the widespread invasion by some members of the whitefly species complex Bemisia tabaci is poorly understood. The invasive B biotype of B. tabaci entered China in the late 1990s and had become the predominant or only biotype of the whitefly in many regions of the country by 2005–2006. Meanwhile epidemics of begomoviruses have been observed in many crops including tomato for which Tomato yellow leaf curl China virus (TYLCCNV) and Tomato yellow leaf curl virus (TYLCV) have been identified as two major disease-causing agents. Here, we conducted laboratory experiments to compare the performance of the invasive B and indigenous ZHJ1 whitefly biotypes on uninfected, TYLCCNV-infected and TYLCV-infected plants of tomato cv. Hezuo903, a cultivar that has been widely cultivated in many regions of China. The infection of tomato plants by either of the viruses had no or only marginal effects on the development, survival and fecundity of the B biotype. In contrast, survival and fecundity of the ZHJ1 biotype were significantly reduced on virus-infected plants compared to those on uninfected plants. Populations of the B biotype on uninfected and TYLCCNV-infected plants increased at similar rates, whereas population increase of the ZHJ1 biotype on TYLCCNV-infected plants was affected adversely. These asymmetric responses to virus infection of tomato plants between the B and ZHJ1 biotypes are likely to offer advantages to the B biotype in its invasion and displacement of the indigenous biotype.     

Presence and distribution of the endosymbiont Wolbachia among Solenopsis spp. (Hymenoptera: Formicidae) from Brazil and its evolutionary history

Wolbachia are intracellular bacteria that commonly infect arthropods. Its prevalence among ants of the genus Solenopsis is high. In the present study, the presence and distribution of these endosymbionts was examined among populations of Solenopsis spp. from Brazil. A phylogenetic analysis based on the wsp gene was conducted to infer the evolutionary history of Wolbachia infections within the populations surveyed. A high frequency of Wolbachia bacteria was observed among the genus Solenopsis, 51% of the colonies examined were infected. Incidence was higher in populations from southern Brazil. However, little genetic variability was found among different Wolbachia strains within supergroups A and B. Our findings also suggest that horizontal transmission events can occur through the social parasite S. daguerrei.     

丽蚜小蜂两个品系寄生行为及对不同寄主植物上烟粉虱的选择性

对丽蚜小蜂两个品系(分别来自北京和美国)寄生烟粉虱的行为和在番茄、黄瓜、甘蓝、茄子及棉花烟粉虱上的发育历期和寄生率进行了研究。结果表明,丽蚜小蜂通过寄主定位、寄主检查、产卵、清扫和梳理等过程对烟粉虱进行寄生,北京品系平均产卵寄生时间为5.0 m in,美国品系为4.2 m in,品系间差异显著。北京品系在棉花烟粉虱上发育历期最短,为17.4 d,甘蓝烟粉虱上发育历期最长,为20.0 d;美国品系在棉花烟粉虱上发育历期最短,为16.3 d,在其余4种寄主植物烟粉虱上发育历期较长(17.3~17.9 d)。2个品系的寄生率均表现为番茄烟粉虱上最高,分别为37.3%和39.0%;棉花次之,分别为32.2%和35.5%;黄瓜上最低,分别为30.2%和29.6%。在寄主植物选择性试验中,2个品系亦表现为寄生番茄烟粉虱时寄生率最高,美国品系为62.7%,北京品系为56.3%,寄生黄瓜烟粉虱时寄生率最低,分别为30.8%和29.0%。     

Yellow sticky trap catches of parasitoids of Bemisia tabaci (Hemiptera: Aleyrodidae) in vegetable crops and their relationship to in-field populations

We examined the relationship of yellow sticky trap captures of Bemisia tabaci (Gennadius) biotype B parasitoids to the local population of parasitoids as measured by leaf samples of parasitized whiteflies and mass release of parasitoids. Traps were placed in experimental collard and cowpea field plots in Charleston, SC, and in commercial organic fields of spring cantaloupe and watermelon in the Imperial Valley, CA. The exotic parasitoid Eretmocerus emiratus Zolnerowich and Rose was released in Imperial Valley fields to ensure parasitoid populations would be present. Bemisia adults were trapped in the greatest numbers on the upper surface of horizontally oriented sticky traps in melon fields. In contrast, the lower trap surfaces consistently captured more Eretmocerus than upper surfaces. Female parasitoids were trapped in greater numbers than males, especially on the lower trap surfaces. Progeny of released exotic Eretmocerus greatly outnumbered native E. eremicus Rose and Zolnerowich and Encarsia spp. on traps. Throughout the season, the trend of increasing numbers of Eretmocerus on traps parallelled the increase in numbers of whiteflies. Over the season, 23-84% of all B. tabaci fourth instars were visibly parasitized by Eretmocerus. The numbers of Eretmocerus caught by traps in cantaloupe were similar in trend to numbers on leaf samples in melons, but not with those in watermelon, where whitefly populations were lower. Parasitoid numbers were low in collard and cowpea samples, and no trend was observed in numbers of parasitoids captured on traps and numbers on leaves for these two crops. Overall, there were no significant correlations between sticky trap catches of parasitoids and numbers of parasitized whiteflies on leaf samples in any test fields. Nevertheless, sticky traps placed within crops may be useful for observing trends in whitefly parasitoid populations at a particular site and for detecting parasitoids at specific locations.