Extraordinary resistance to insecticides reveals exotic Q biotype of Bemisia tabaci in the New World

A strain of the whitefly Bemisia tabaci (Gennadius) possessing unusually high levels of resistance to a wide range of insecticides was discovered in 2004 in the course of routine resistance monitoring in Arizona. The multiply resistant insects, collected from poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) plants purchased at a retail store in Tucson, were subjected to biotype analysis in three laboratories. Polyacrylamide gel electrophoresis of naphthyl esterases and sequencing of the mitochondrial cytochrome oxidase I gene (780 bp) confirmed the first detection of the Q biotype of B. tabaci in the New World. This U.S. Q biotype strain, referred to as Poinsettia'04, was highly resistant to two selective insect growth regulators, pyriproxyfen and buprofezin, and to mixtures of fenpropathrin and acephate. It was also unusually low in susceptibility to the neonicotinoid insecticides imidacloprid, acetamiprid, and thiamethoxam, relative to B biotype whiteflies. In 100 collections of whiteflies made in Arizona cotton (Gossypium spp.), vegetable, and melon (Cucumis melo L.) fields from 2001 to 2005, no Q biotypes were detected. Regions of the United States that were severely impacted by the introduction of the B biotype of B. tabaci in the 1980s would be well advised to promote measures that limit movement of the Q biotype from controlled environments into field systems and to formulate alternatives for managing this multiply-resistant biotype, in the event that it becomes more widely distributed.     

辽宁省冬季温室内越冬粉虱伪蛹的种类鉴定及烟粉虱体内番茄黄化曲叶病毒的检测

为了揭示辽宁省冬季温室内越冬粉虱伪蛹的种类及烟粉虱Bemisia tabaci （Gennadius）携带番茄黄化曲叶病毒（tomato yellow leaf curl virus, TYLCV）情况, 于2012年1月份在辽宁省不同县市区的温室作物上采集了17份粉虱伪蛹样品（每样品含30头粉虱伪蛹） , 镜检鉴别粉虱种类并利用mtCOI基因对烟粉虱生物型进行了鉴定; 检测了烟粉虱携带TYLCV情况并对其PCR扩增产物进行了测序分析。结 果表明： 辽宁省冬季温室内存在越冬温室白粉虱Trialeurodes vaporariorum （Westwood）与烟粉虱。17份粉虱样品中, 11份样品为烟 粉虱样品, 6份样品为温室白粉虱和烟粉虱混合样品。混合样品中, 温室白粉虱仅在锦州凌海（LH）样品中占优势。17份烟粉虱样品（包 括混合样品）中, 仅有4份样品为B型与Q型混合样品, 其他13份样品烟粉虱生物型均为Q型。17份烟粉虱样品中有3份Q型烟粉虱样品检测 到TYLCV, 系统树分析进一步证实该病毒是TYLCV。调查结果为辽宁省粉虱与TYLCV的早期测报和防控提供了科学依据。     

西藏发现Q型烟粉虱

【目的】调查西藏自治区烟粉虱Bemisia tabaci(Gennadius)的发生情况。【方法】从西藏拉萨采集到烟粉虱各个虫态,采用3D数码显微镜观察所采集烟粉虱的形态特征,利用mt COⅠ分子标记检测烟粉虱的生物型。【结果】明确并详细描述了烟粉虱各形态特征,mt COⅠ分子标记检测显示西藏采集到的烟粉虱为Q生物型。【结论】在形态学鉴定的基础上,分子生物学鉴定该粉虱为Q型烟粉虱,这是Q型烟粉虱在西藏自治区发生的首次报道。     

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.     

中国部分地区烟粉虱生物型种类及系统发育关系分析

烟粉虱是一种危害严重的世界性害虫,是一个快速进化的复合种.本文利用mtCOI分子标记方法,对2010和2011年采自我国9个省(市)的33个烟粉虱种群进行了生物型鉴定和系统发育分析.结果表明： 我国目前存在着B型、Q型、ZHJ-1型、ZHJ-3型、An型以及Nauru型等6种生物型,且不同生物型的分布是不均匀的.遗传距离及系统发育树的分析结果显示,海南省的An型和台湾省的An型聚为一支,为同一来源;中国B型与来自法国和乌干达的B型的亲缘关系较近,同源性达到99%以上;中国的Q型与来自摩洛哥和法国的Q型聚为一个分支,而来自以色列和土耳其的Q型烟粉虱单独聚为一支,说明中国的Q型烟粉虱与来自地中海西部的Q型烟粉虱亲缘关系更近,可以推断中国的Q型烟粉虱的起源地为地中海西部地区.
     

江苏地区烟粉虱生物型演替研究初报

本文连续5年系统监测了江苏省13个地级市烟粉虱Bemisia tabaci(Gennadius)生物型的发生分布状况,探讨了它们的迁移扩散和演替规律。利用RAPD分子标记和mtDNA COI基因序列进行烟粉虱生物型鉴定,结果表明:江苏地区发生的烟粉虱生物型为B型和Q型。自2005年到2009年,B型烟粉虱在苏南和苏北地区的发生分布频率逐年下降,在苏北地区的发生分布频率由52.58%下降为22.22%,在苏南由56.52%下降为9.37%;而Q型烟粉虱在苏南和苏北的发生分布频率逐年升高,在苏北由47.42%上升至77.78%,在苏南由43.48%上升为90.63%。B型烟粉虱的发生分布范围由全省逐渐向苏北地区缩小,而Q型烟粉虱的发生分布范围逐渐扩大遍及全省;此外,Q型烟粉虱在江苏是由苏中和苏南地区向苏北地区扩散,并逐步取代B型烟粉虱成为江苏地区农作物的主要害虫。     

New insights into the mitochondrial phylogeny of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) in the Mediterranean Basin

The whitefly Bemisia tabaci is vector of plant infecting viruses and it is considered as one of the most important agricultural pests around the Mediterranean basin. At present, five biotypes of B. tabaci have been reported in the Mediterranean Basin: B, Q, S, T and M. To establish the phylogeographic relationship of these Mediterranean biotypes with others, 54 samples collected in Europe and Africa were analysed by sequencing the mitochondrial cytochrome oxidase I gene (mtCOI). The phylogeny showed that Spanish samples corresponding to the biotype S were related to the haplotype Uganda 2 of the African clade, associated with recent epidemic upsurges of cassava mosaic virus (CMD) in that country. This phylogeographic relationship gave support to a distinct subgroup revealed within the African clade. Bemisia tabaci collected from Euphorbia plants in Italy (biotype T) formed one of the three distinct subgroups existing within the Southeast/Far East Asian clade, while samples from Turkey (biotype M) clustered together with reference mitochondrial sequences from whiteflies from Pakistan and Thailand. Recent reports indicate that Bemisia populations corresponding to the biotypes S and T are distributed in areas larger than those initially delimited. Other results indicated that samples collected in Sudan grouped within the Mediterranean–North Africa clade together with reference sequences of the biotype Q corresponding to insects collected in Spain and Morocco. Mitochondrial haplotypes of B. tabaci samples collected on sweet potato in Ghana clustered with reference sequences of samples from Cameroon corresponding to one of the five Sub-Saharan subgroups already described in the African clade. These data extends the phylogenetic information of the B. tabaci species complex and present new questions to be investigated.     

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.     

微卫星位点BEM06与BEM23鉴别烟粉虱B型与Q型的有效性

烟粉虱Bemisia tabaci (Gennadius) B型与Q型是烟粉虱复合种中入侵性较强、分布较广的2种生物型, 当前在许多地区混合发生。这2种生物型的快速鉴别对其种群动态调查及入侵生态学研究具有重要价值。为了验证微卫星位点BEM06与BEM23鉴别B型与Q型烟粉虱的有效性, 本研究分析了这2个微卫星位点的等位基因在国内外17个B型、4个Q型、3个非B/Q型烟粉虱种群的分布特点。结果表明: 这2个微卫星位点的联合使用可鉴别B型与Q型烟粉虱, 但是无法有效地将B型、Q型与一些非B/Q型烟粉虱某些个体区分开来。结果提示: 利用微卫星位点BEM06与BEM23鉴别B型与Q型烟粉虱具有一定的局限性, 尤其是田间烟粉虱存在其他生物型时需要慎重使用这种鉴别方法。     

烟粉虱生物型对浅黄恩蚜小蜂寄主选择及个体发育的影响

为探讨寄生蜂在Q型烟粉虱Bemisia tabaci替代B型烟粉虱的过程中是否起作用, 我们在实验室条件(温度27±1℃, 光周期16L∶8D, 相对湿度RH 70%～80%)下, 观察了浅黄恩蚜小蜂Encarsia sophia寄生B型和Q型烟粉虱若虫的行为, 研究了浅黄恩蚜小蜂对B型和Q型烟粉虱若虫的选择性、 烟粉虱生物型对浅黄恩蚜小蜂取食数量及个体发育的影响。结果发现, 浅黄恩蚜小蜂体外检测时间在B型和Q型烟粉虱若虫间差异不显著, 而寄生Q型烟粉虱若虫时的体内检测和产卵时间(190.2±14.6 s）显著高于寄生B型时所用时间(140.0±7.5 s)。在非选择条件下, 浅黄恩蚜小蜂寄生B型烟粉虱若虫的数量(8.1±0.5头)及总产卵量（9.3±0.6粒）显著高于仅提供Q型烟粉虱的寄生数量(6.3±0.5头)及总产卵量(7.0±0.6粒); 而被寄生若虫单头着卵量在处理间差异不显著。在选择性条件下, 该蜂寄生B型烟粉虱若虫量(3.1±0.4头)、总产卵量(3.8±0.5粒)及被寄生若虫单头着卵量(1.2±0.1粒)都显著高于寄生Q型烟粉虱时的情况(1.8±0.3头、1.8±0.4粒、0.7±0.1粒)。被寄生蜂取食的B型与Q型烟粉虱数量间差异不显著, 但对于同一生物型而言, 交配过的雌蜂能够取食更多的烟粉虱若虫。以B型烟粉虱为寄主时, 浅黄恩蚜小蜂雌蜂卵-黑蛹(7.2±0.1 d)、黑蛹-羽化(5.2±0.1 d)的发育时间与以Q型烟粉虱若虫为寄主时的相应发育时间(7.3±0.1 d, 5.6±0.1 d)间无显著性差异。以B型烟粉虱为寄主时寄生蜂的羽化率（73.55%±1.42%）与以Q型烟粉虱为寄主时的羽化率（68.42%±13.01%）间差异不显著。这些结果表明, 虽然浅黄恩蚜小蜂发育时间、 羽化率在烟粉虱2种生物型间无显著差异, 但该小蜂倾向于B型烟粉虱若虫作为寄主, 而且, 以B型烟粉虱若虫为寄主时, 小蜂的产卵量和寄生若虫数量均增加。但田间浅黄恩蚜小蜂的存在是否有助于Q型烟粉虱成为B型和Q型混合种群的优势种群, 还需进一步研究。     

Analysis of genetic diversity among different geographical populations and determination of biotypes of Bemisia tabaci in China

Abstract:  Analysis of the genetic diversity among 27 different geographical populations of Bemisia tabaci and determination of biotypes of B. tabaci in China based on amplified fragment-length polymorphism (AFLP) and the mitochondrial cytochrome oxidase I (mtDNA COI) gene sequences were conducted. In AFLP assay, the use of five primer combinations selected from 64 primer combinations allowed the identification of 229 polymorphic bands (97.03%) from 60 to 500 bp, suggesting abundant genetic diversity among different geographical populations of B. tabaci. To further identify biotypes of B. tabaci in China, the mtDNA COI gene sequences of nine representative populations from China, Israel and Spain were obtained. Molecular phylogenetic tree based on AFLP and mtDNA COI gene analyses revealed the presence, in China, of at least four different genetic groups of B. tabaci. B biotype, Q biotype and two non-B/Q biotype. B biotype was distributed nationwide. Q biotype was present only in the local region of China including the YunNan province and BeiJing city. This was also the first report about the invasion of Q biotype into China. Of the other two non-B/Q biotype groups, one was found in ShanDong and HeBei provinces, and another in ZheJiang province. The non-B/Q biotype ZheJiang population showed very high similarity with another Asian population India-IW ( AF110704 ) in mtDNA COI sequences and was possibly a Chinese indigenous population. The close monitoring of the Q biotype in locales of China where commercial plants were exported or imported, is now essential to avoid the further accidental distribution of the Q biotype.     

Molecular characterization of Bemisia tabaci populations in Tunisia: genetic structure and evidence for multiple acquisition of secondary symbionts

A survey was conducted during 2009-2010 seasons to identify the distribution of Bemisia tabaci (Gennadius) biotypes in Tunisia. The genetic affiliation of collected populations was determined by polymerase chain reaction (PCR)-restriction fragment-length polymorphism (TaqI) of the mitochondrial cytochrom oxidase I (mtCOI) gene. Results, validated by sequencing and phylogenetic analysis, allowed the clustering of sampled sweetpotato whiteflies into B and Q biotypes. As B. tabaci harbors the obligatory bacterium Portiera aleyrodidarum, and a diverse array of secondary symbionts including Rickettsia, Hamiltonella, Wolbachia, Cardinium, Arsenophonus, and Fritschea, we report here the infectious status of Tunisian populations by secondary symbionts to find out a correlation between bacterial composition to biotype. The genetic variability and structure of B. tabaci populations in Tunisia was driven by analysis of molecular variance (AMOVA) and the hypothesis of isolation by distance was explored. Selective neutrality and genetic haplotype network tests suggested that Tunisian sweetpotato whiteflies have been undergoing a potential expansion followed by gene flow restriction.     

烟粉虱生物型的监测及其遗传结构研究

烟粉虱Bemisia tabaci(Gennadius)是一种重要的农业害虫并包括许多生物型,其中B型和Q型是入侵性较强的2种生物型。文章着重介绍近年来在烟粉虱生物型的监测及其遗传结构方面的研究进展。B型烟粉虱和Q型烟粉虱这2个生物型均已入侵我国,其中多数地区烟粉虱是B型烟粉虱,局部地区有Q型烟粉虱并呈现不断蔓延趋势。微卫星(SSR)分子标记分析结果表明我国B型烟粉虱的入侵来源具有多元化,而云南地区Q型烟粉虱来源比较单一。化学农药的使用能够影响室内种群的遗传结构,降低种群的遗传多样性。基于RAPD、ISSR分子标记的分析结果表明,Q型烟粉虱种群各项遗传多样性指数均比B型烟粉虱的高。今后加强烟粉虱入侵生物型的遗传结构及其种群动态关系等方面的研究,对于揭示烟粉虱的灾变机制及其控制具有重要的意义。     

Further insights into the strange role of bacterial endosymbionts in whitefly, Bemisia tabaci: comparison of secondary symbionts from biotypes B and Q in China

The percentage infection of secondary symbionts (SS) (Wolbachia, Arsenophonus, Rickettsia, Hamiltonella, Fritschea and Cardinium) in the exotic Bemisia tabaci (Genn.) invaders, commonly known as biotypes B and Q from China, were determined by PCR. In total, 373 biotype B and 1830 biotype Q individuals were screened for the presence of SS. Biotype B was more abundant than biotype Q from 2005 to 2006, and biotype Q was more abundant from 2007 to 2009. Each of the SS, with the exception of Fritschea, was detected in both biotypes B and Q; Fritschea was found in none of the samples examined. For biotype B, the percentage infection of Hamiltonella was the highest (92.0%) followed by Rickettsia (70.2%). For biotype Q, the percentage infection of Hamiltonella was again the highest (73.3%). Arsenophonus was the least common of the SS observed in both biotypes B and Q. The percentage infection of Wolbachia, Rickettsia and Hamiltonella in biotype B was each significantly higher than in biotype Q, whereas the percentage infection of Cardinium in biotype B was significantly lower than in biotype Q. The percentage infection of SS in biotypes B and Q varied from year to year over the period 2005-2009. Furthermore, within biotype Q, two distinct subgroups were identified which differ from each other in terms of their SS complement. We discuss these results in the light of the potentially influential factors and roles of the SS.     

Further spread of and domination by Bemisia tabaci (Hemiptera: Aleyrodidae) biotype Q on field crops in China

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), causes severe crop losses to many crops. The worst of these losses are often associated with the invasion and establishment of biotypes B and Q of this pest. Previous research in 2007 showed that biotype Q occurred with other biotypes in most field populations in China. To determine the current status of the biotype composition in the field, an extensive survey covering mainly eastern parts of China was conducted in 2009. Using polymerase chain reaction primers specific for the mitochondrial cytochrome oxidase I of biotypes B and Q and gene sequencing, we determined the biotypes composition in 61 whitefly populations and their distribution across 19 provinces in China. Our research revealed that only biotypes B and Q have been found in the field in 2009 in China. Among them, biotype Q was dominant in 44 locations (100.0%) and biotype B was dominant in 17 locations (100.0%). The current survey indicates that biotype Q has rapidly displaced biotype B in most locations in China.     

华东、华南和西南地区烟粉虱的种群及寄主分化

烟粉虱Bemisia tabaci是一个复合种,它具有的生物型分化、较强的传播病毒的能力和抗药性、较快的繁殖速率等特征使其成为我国农业生产中重要害虫之一。本研究利用细胞色素线粒体氧化酶Ⅰ基因,对采集自江苏、广东和云南三省的烟粉虱样本进行了生物型鉴定,并对烟粉虱生物型与寄主植物之间的关联性开展了调查。结果表明,在广东和云南省,都存在未鉴定的土著种群与入侵的B型、Q型共存的现象;同时,在本研究中广东省尚未采集到Q型烟粉虱,而在江苏采集到的粉虱样本全部为入侵型。研究结果还表明,相对于入侵种而言,土著种群显示出更强的寄主植物趋同性;丰富的寄主植物以及本身具有的多食性特性有助于B型、Q型等生物型在世界各地的广泛入侵。     

Invasive mechanism and management strategy of Bemisia tabaci (Gennadius) biotype B: Progress report of 973 Program on invasive alien species in China

Bemisia tabaci (Gennadius) biotype B, called a “superbug”, is one of the most harmful biotypes of this species complex worldwide. In this report, the invasive mechanism and management of B. tabaci bio-type B, based on our 5-year studies, are presented. Six B. tabaci biotypes, B, Q, ZHJ1, ZHJ2, ZHJ3 and FJ1, have been identified in China. Biotype B dominates the other biotypes in many regions of the country. Genetic diversity in biotype B might be induced by host plant, geographical conditions, and/or insecticidal application. The activities of CarE (carboxylesterase) and GSTs (glutathione-S-transferase) in biotype B reared on cucumber and squash were greater than on other host plants, which might have increased its resistance to insecticides. The higher activities of detoxification enzymes in biotype B might be induced by the secondary metabolites in host plants. Higher adaptive ability of biotype B adults to adverse conditions might be linked to the expression of heat shock protein genes. The in-digenous B. tabaci biotypes were displaced by the biotype B within 225 d. The asymmetric mating in-teractions and mutualism between biotype B and begomoviruses via its host plants speed up wide-spread invasion and displacement of other biotypes. B. tabaci biotype B displaced Trialeurodes vapo-rariorum (Westwood) after 4－7 generations under glasshouse conditions. Greater adaptive ability of the biotype B to adverse conditions and its rapid population increase might be the reasons of its suc-cessful displacement of T. vaporariorum. Greater ability of the biotype B to switch to different host plants may enrich its host plants, which might enable it to better compete with T. vaporariorum. Native predatory natural enemies possess greater ability to suppress B. tabaci under field conditions. The kairomones in the 3rd and 4th instars of biotype B may provide an important stimulus in host searching and location by its parasitoids. The present results provide useful information in explaining the mechanisms of genetic diversity, evolution and molecular eco-adaptation of biotype B. Furthermore, it provides a base for sustainable management of B. tabaci using biological and ecological measures.     

Utility of MtCOI polymerase chain reaction-restriction fragment length polymorphism in differentiating between Q and B whitefly Bemisia tabaci biotypes

The invasive, insecticide-resistant, Q whitefly biotype, has gradually spread to other countries including the US via human-mediated movement of plant materials. We assessed the utility of the VspI -based mtCOI (mitochondrion cytochrome oxidase I) polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique as a rapid, cost-effective, and reliable alternative for differentiating the Q from the dominant B biotype in Arizona. Using the standard mtCOI gene sequencing and mtCOI PCR-RFLP techniques, we biotyped eight whitefly strains of five individuals each collected from poinsettia and cotton at different locations in Arizona. Complete concordance was observed between the two methods, with three strains being identified as the Q biotype and five samples as the B biotype. We also scanned the mtCOI gene sequences for VspI polymorphisms in the B and Q biotype whiteflies currently available in the GenBank database. This global screening revealed the existence of three and four VspI polymorphic types for the Q and B biotypes, respectively. Nevertheless, all three VspI polymorphic Q biotype whiteflies shared a common and unique VspI site that can be used to differentiate Q biotype from the four VspI polymorphic B biotype whiteflies identified. These results demonstrate that the VspI -based mtCOI gene PCR-RFLP provides a reliable diagnostic tool for differentiating the Q and B biotype whiteflies in the US and elsewhere.     

Distribution patterns of the Q and B biotypes of Bemisia tabaci in the Mediterranean Basin based on microsatellite variation

At least five of the biotypes described in the Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) complex are known to be present in the Mediterranean Basin area. Only two of them, however, are economically relevant, that is, biotypes B and Q. Biological and genetic differences between the two biotypes have been well studied, but less is known about their patterns of genetic variation and population structure. To address these issues, a study was undertaken based on variation at six microsatellite loci among a subset of nine B. tabaci populations (five belonging to the Q and four to the B biotype). The data obtained show that (i) these loci showed considerable polymorphism in the Q and B biotypes populations although the presence of null alleles can obscure the picture; (ii) the Iberian‐Q, Canarian‐Q, and Egyptian‐B populations exhibit heterozygosity excess as a result of bottleneck events; (iii) the low genetic differentiation between the Israeli, Iberian Peninsula, and Italian populations suggest that these populations share a common gene pool; (iv) the genetic distances between the Canarian‐Q population and the geographically close population from Morocco indicates spatial isolation and a limited gene flow; and finally (v) the microsatellite data for the B populations indicate that the whiteflies from Egypt and Israel have a close phylogenetic relationship, but the source of these biotype B invasions into the Mediterranean area remains unknown.     

烟粉虱B型和Q型群体遗传结构的RAPD分析

近20年来,烟粉虱B型传入世界各地并暴发成灾,成为一种重要的农业入侵害虫; 烟粉虱Q型则是近几年引起人们高度重视的一种新的入侵生物型,目前已传入许多国家并造成一定危害。本文利用RAPD分子标记对烟粉虱B型和Q型不同地理种群的遗传结构进行了分析。结果表明：（1）引物H16对烟粉虱B型不同种群扩增的特异带,能有效区分烟粉虱B型和Q型、浙江非B/Q型种群;（2）烟粉虱Q型种群各项遗传多样性指数均比烟粉虱B型的要高;（3）我国烟粉虱Q型来自伊比利亚半岛的可能性比来自中东地区的可能性要大。另外,聚类分析结果提示,RAPD分子标记能有效地区分烟粉虱不同生物型,但可能不适用于生物型之间亲缘关系分析。