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。     

Genetic diversity of Iberian populations of Bemisia tabaci (Hemiptera: Aleyrodidae) based on random amplified polymorphic DNA-polymerase chain reaction

The genetic structure of six Iberian populations of the whitefly Bemisia tabaci, two of them biotype Q, one biotype B, and the other three a mixture of both, has been studied using random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). A total of 336 individuals was completely discriminated by means of 234 scored bands. Separate analyses of molecular variance of haploid males and diploid females using the pairwise number of differences between haplotypes showed that biotypes contribute significantly more to the observed variability than populations within biotypes. On average, gene flow between two biotypes of the same population is lower than between populations of identical biotypes. On the basis of these results and the nondetection under natural conditions of a single hybrid, we consider that both biotypes are genetically isolated under the ecological conditions prevailing in the south Iberian Peninsula. All populations of biotype Q presented similar values of intrapopulational diversity, which were higher than the values shown by populations of biotype B.     

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。     

Genetic differentiation of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype Q based on mitochondrial DNA markers

In the present study, genetic differentiation of Bemisia tabaci (Gennadius) biotype Q was analyzed based on mitochondrial cytochrome oxidase I (mt COI) gene sequence. The results showed that B. tabaci biotype Q could be separated into two subclades, which were labeled as subclades Q1 and Q2. Subclade Q1 was probably indigenous to the regions around the Mediterranean area and subclade Q2 to Israel or Cyprus. It was because B. tabaci was composed of several genetically distinct groups with a strong geographical association between more closely related biotypes. Not all of the B. tabaci biotype Q in the non‐Mediterranean countries come from the same regions. Until now, all B. tabaci biotype Q in China were grouped into subclade Q1. The B. tabaci biotype Q introduced into the US included both subclades Q1 and Q2. The genetic structure analysis showed higher genetic variation of subclade Q1 than that of subclade Q2.     

Evidence from molecular markers and population genetic analyses suggests recent invasions of the Western North Pacific region by biotypes B and Q of Bemisia tabaci (Gennadius)

Invasive events by Bemisia tabaci (Gennadius) biotypes in various parts of the world are of continuing interest. The most famous is biotype B that has caused great economic losses globally. In addition, biotype Q has also recently been reported to be a new invasive pest. These two biotypes have been monitored for some time in the Western North Pacific region, but the invasive events and population genetic structures of these two biotypes are still not clear in this region. In this study, the mitochondrial cytochrome oxidase I (COI) gene was used to reconstruct a phylogenetic tree for identifying biotypes B and Q and to study the relationships between invasive events and ornamental plants. Population genetic analyses of mtCOI sequences were also used to study the genetic relationships within and between populations. A combination of a phylogenetic tree and haplotype analysis suggested the recent invasion of biotype Q in this region is related to the international ornamental trade from the Mediterranean region. Low levels of haplotype diversity and nucleotide diversity indicate that the presence of biotypes B and Q in the Western North Pacific region are caused by multiple invasions. Hierarchical analysis of molecular variance supports the hypothesis of multiple invasions. In addition, high sequence identities and low genetic distances within and between populations of the two biotypes revealed that these invasive events occurred recently. The low levels of genetic differentiation revealed by pairwise F (ST) values between populations also suggests the invasions were recent. Therefore, results of this study suggested that biotypes B and Q entered this region through multiple recent invasions. A quarantine of agricultural crops may be necessary to prevent further invasions.     

Distribution and molecular characterization of distinct Asian populations of Bemisia tabaci (Hemiptera: Aleyrodidae) in Japan

Bemisia tabaci (Gennadius) is considered to be the most economically important pest insect worldwide. The invasive variant, the Q biotype of B. tabaci was first identified in 2004, and has caused significant crop yield losses in Japan. The distribution and molecular characterization of the different biotypes of B. tabaci in Japan have been little investigated. In this study, B. tabaci populations were sampled from the Japanese Archipelago, the Amami Archipelago and the Ryukyu Islands between 2004 and 2008, and the nucleotide sequences of their mitochondrial cytochrome oxidase I genes were determined. Bayesian phylogenetic relationship analysis provided the first molecular evidence that the indigenous Japanese populations could be separated into four distinct genetic groups. One major native population from the Japanese Archipelago, given the genetic group name Lonicera japonica, was separated into an independent group, distinct from the other genetic groups. The second major population, the Nauru biotype in the Asia II genetic group, was identified in the Amami Archipelago and the Ryukyu Islands. Two distinct minor genetic groups, the Asia I and the China, were also identified. One invasive B‐related population belonging to the Mediterranean/Asia Minor/Africa genetic group has been identified in Honshu. All lineages generated by the phylogenetic analyses were supported by high posterior probabilities. These distinct indigenous B. tabaci populations developed in Japan under geographical and/or biological isolation, prior to recent invasions of the B and Q biotypes.     

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.
     

基于微卫星标记对中国Q型烟粉虱早期入侵种群与B型烟粉虱种群的遗传结构分析（英文）

2003年首次在云南昆明发现Q型烟粉虱Bemisia tabaci (Gennadius)传入中国。随后几年时间内, 它在许多省份逐年取代了B型烟粉虱种群。2008年后,Q型烟粉虱基本上成为了中国多数省份农区的优势生物型。为了进一步揭示Q型烟粉虱在中国快速扩散以及取代B型烟粉虱的遗传学基础, 本研究利用11个微卫星位点分析并比较了2003年中国云南昆明Q型烟粉虱入侵种群及其他地点的11个B型入侵种群, 西班牙2个Q型土著种群, 以色列1个Q型入侵种群, 以色列1个B型土著种群, 以及西班牙、 美国与澳大利亚的5个B型入侵种群的遗传结构。结果表明, 中国Q型烟粉虱早期种群（云南昆明种群）可能来自于西部地中海地区。中国B型烟粉虱种群遗传多样性高于西班牙、 澳大利亚、 美国B型种群, 中国B型可能存在多次传入或某个混合种群的再次传入。相对于原产地种群, 中国Q型烟粉虱早期入侵种群与B型烟粉虱种群遗传多样性并没有明显降低, 表明Q型与B型烟粉虱种群可能经历了较小的瓶颈效应或奠基者效应。中国Q型烟粉虱早期入侵种群遗传多样性高于B型烟粉虱种群, Q型烟粉虱这种较高的遗传多样性可能为其较强的生态适应性提供了遗传基础, 有利于Q型烟粉虱在新的环境下快速扩散并取代B型烟粉虱。     

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.     

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.     

Q型烟粉虱东地中海种群遗传多样性的mtCOI与SSR分析

前期研究表明入侵我国山东的Q型烟粉虱Bemisia tabaci（Genn.）种群来源于西地中海地区而非来源于东地中海地区。为了揭示Q型烟粉虱的入侵遗传机制, 本研究进一步利用线粒体COI（mtCOI）基因与6个具有多态性的微卫星位点（SSR）分析了东地中海Q型烟粉虱（Q1支系与Q2支系）种群的遗传多样性, 并与西地中海种群遗传多样性的前期研究结果进行了比较分析。基于mtCOI基因与微卫星标记分析结果表明, 东地中海种群与西地中海种群一样也具有较高的遗传多样性, 然而两个地区种群存在着遗传异质性。不同入侵性种群遗传结构的比较研究将为进一步解析外来种群的入侵生理生态机制奠定基础。     

Identification of biotypes and secondary endosymbionts of Bemisia tabaci in Korea and relationships with the occurrence of TYLCV disease

Bemisia tabaci is a species complex that consists of at least 24 genetically diverse biotypes. Here, we determined the biotypes of 27 populations collected in 17 different regions of Korea. Nucleotide sequence comparisons of cytochrome oxidase showed that 26 populations were Q biotype and that one population, the Goyang population, was B biotype. Further subgroup analysis of the Q biotype showed that all populations belonged to the Q1 subgroup, which originates from Western Mediterranean countries. Five endosymbiotic bacteria from various B. tabaci populations were analyzed by comparing rDNA sequences. Hamiltonella was detected in all the populations tested regardless of biotype. Cardinium was detected in all Q biotype populations but not in the B biotype population, while Rickettsia was detected in the B biotype population but not in Q biotype populations. Arsenophonus and Wolbachia were detected in 35% and 58% of Q biotype populations, respectively, but not in the B biotype population. Our results show that the endosymbiont profile is strongly associated with each biotype and with subgroups of the Q biotype. Survey of TYLCV disease from 2008 to 2010 indicated that this disease is widely spread in Korea. This study suggests that the rapid spread of TYLCV may be associated with endosymbiont infection, particularly Hamiltonella infection of B. tabaci.     

Genetic structure of the invasive pest Bemisia tabaci: evidence of limited but persistent genetic differentiation in glasshouse populations

The geographic range of plant pests can be modified by the use of glasshouses. Bemisia tabaci, originating from warm to hot climates, has been shown to be a complex of distinct genetic groups with very limited gene flow. The genetic structure of this pest was studied in glasshouses in southern France, a region beyond the northern limit of its open-field development area in Europe. Seven microsatellite loci were scored in 22 populations sampled from various regions over 3 years. Two genetic groups were distinguished using a Bayesian clustering method and were assigned to the so-called biotypes B and Q using the gene sequence of cytochrome oxidase 1 (CO1). All but one population corresponded to biotype Q, even though only biotype B was previously reported. Despite the enclosed environment of glasshouses and their expected isolation due to low outdoor survival during the winter, only limited differentiation among biotype Q glasshouses was observed. A single sample site was notable for a decrease in expected heterozygosity and the mean number of alleles over the years. The lack of spatial genetic structure among biotype Q populations was indicative of a recent colonization event combined with large dispersal at all spatial scales. This migration pattern of biotype Q populations was further supported by additional CO1 sequences, since individuals from France, Asia and America exhibited 100% nucleotide identity. The evolution of genetic diversity observed in glasshouses in France is part of the worldwide invasion of biotype Q, which is discussed in light of human activities.     

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。     

Population genetic structure of the newly invasive Q biotype of Bemisia tabaci in Taiwan

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is among the top 100 invasive pests in the world, and it causes serious agricultural damage and economic losses in many countries. More than 24 biotypes of the sweetpotato whitefly have been detected worldwide, of which the Q biotype has recently been reported to be a new invasive pest spreading throughout the world via trade in poinsettias, Euphorbia pulcherrima Willd. ex Klotzsch (Euphorbiaceae). In 2006, the Q biotype was first recorded in Taiwan in greenhouses, but not in the field, suggesting that the invasion of this biotype might be at an early stage in that country. The mitochondrial cytochrome oxidase I (COI) gene and 12 microsatellite loci were used to investigate the genetic structure of multiple B. tabaci Q biotype populations. The presence of only a few COI haplotypes and a low number of nucleotide differences suggest high genetic similarity among these populations. Microsatellite analyses also revealed low genetic differentiation and frequent gene flow among greenhouses. The molecular evidence supports the occurrence of a recent genetic bottleneck in the B. tabaci Q biotype. Bayesian cluster analyses indicated that at least two invasion events have occurred in Taiwan. Phylogenetic analyses of microsatellites support Q biotype migration among greenhouses, which was likely facilitated by the frequent movement of poinsettias between greenhouses. Future management strategies should focus on developing plantlet trade regulations to avoid further anthropogenic dispersal of the B. tabaci Q biotype among greenhouses in Taiwan.     

Allozyme variation among biotypes of the brown planthopperNilaparvata lugens in the Philippines

Allozyme variation was studied in threeNilaparvata lugens biotypes infesting specific rice varieties and a biotype infesting a weed grass,Leersia hexandra. Of the 20 enzymes inN. lugens for which activity was noted, 9 were polymorphic. Eleven enzyme loci were monomorphic for the same allele in all biotype populations; the rest were polymorphic for two or more alleles. The mean number of alleles per polymorphic locus was 2.3, while the mean number of alleles per locus was 1.5; heterozygosity ranged from 0.02 to 0.06 (biotype 1 > biotype 3 >Leersia-infesting biotype > biotype 2). Allelic frequency differences were observed in five loci among the four biotypes. However, the coefficient of genetic identity (I) of 0.99+ showed that the four biotype populations were genetically close relatives or merely populations ofN. lugens undergoing genetic differentiation. This work was partly supported by a financial grant received from the Directorate for Technical Cooperation and Humanitarian Aid, Switzerland.     

Biotype and insecticide resistance status of Bemisia tabaci populations from Peninsular Malaysia

Bemisia tabaci, a resistance‐prone insect pest, is a cryptic species complex with important invasive biotypes such as B and Q. The biotype and resistance statuses of this pest in Malaysia remain unclear. This study assessed the biotype and resistance status of a number of contemporary populations of B. tabaci based on the mtCO1 marker and the dose‐response method, respectively. The Pahang (PHG) population was labelled as the Q biotype, while the remainder of the populations belonged to the Asia 1 biotype. A very low level of resistance for profenofos, cypermethrin, and imidacloprid was detected for all populations [resistance factor (RF) < 10]. Resistance to diafenthiuron ranged from very low to very high (RF > 100). All populations showed a very low level of resistance against pymetrozine except Q‐type PHG population, which exhibited a very high level of resistance. For most insecticides, the highest level of resistance was detected in the PHG population. The implications of these findings for better management of this noxious pest are discussed.     

Effects of host,temperature and relative humidity on competitive displacement of two invasive Bemisia tabaci biotypes [Q and B]

Abstract Bemisia tabaci shifted unexpectedly in China from a predominance of B biotype to Q biotype during 2005–2008. This observation stimulated an interest in investigating whether environmental factors, including host, temperature and relative humidity (RH) could possibly explain the observed shift in biotypes distribution. Results indicated that all three parameters examined influenced biotype survivability. The percentage of B biotype, when reared together on pepper plants with the Q biotype, decreased significantly from 66.7% in the founder population, to 13.6% and 3.7% in the first and second generations, respectively. When the B (founder at 66.7%) and Q (founder at 33.3%) biotypes were reared together on eggplant alone, or on pepper‐plus‐eggplant combination, the population size of the B biotype either remained constant, or increased somewhat in the first and second generations. On eggplant, the effects of RH and temperature on the competitiveness between the Q and B biotypes (3 pairs of Q and 6 pairs of B) were not significant.     

Insights into the neutral and adaptive processes shaping the spatial distribution of genomic variation in the economically important Moroccan locust (Dociostaurus maroccanus)

Understanding the processes that shape neutral and adaptive genomic variation is a fundamental step to determine the demographic and evolutionary dynamics of pest species. Here, we use genomic data obtained via restriction site‐associated DNA sequencing to investigate the genetic structure of Moroccan locust (Dociostaurus maroccanus) populations from the westernmost portion of the species distribution (Iberian Peninsula and Canary Islands), infer demographic trends, and determine the role of neutral versus selective processes in shaping spatial patterns of genomic variation in this pest species of great economic importance. Our analyses showed that Iberian populations are characterized by high gene flow, whereas the highly isolated Canarian populations have experienced strong genetic drift and loss of genetic diversity. Historical demographic reconstructions revealed that all populations have passed through a substantial genetic bottleneck around the last glacial maximum (~21 ka BP) followed by a sharp demographic expansion at the onset of the Holocene, indicating increased effective population sizes during warm periods as expected from the thermophilic nature of the species. Genome scans and environmental association analyses identified several loci putatively under selection, suggesting that local adaptation processes in certain populations might not be impeded by widespread gene flow. Finally, all analyses showed few differences between outbreak and nonoutbreak populations. Integrated pest management practices should consider high population connectivity and the potential importance of local adaptation processes on population persistence.     

DISEQUILIBRIUM BETWEEN DISEASE-RESISTANCE VARIANTS AND ALLOZYME LOCI IN AN ANNUAL LEGUME

Polymorphism existed at 58% of the enzyme loci examined (11/19) in one population of the highly self-pollinated annual legume Amphicarpaea bracteata. Due to extreme gametic disequilibrium among loci, genetic variation in this population was structured into a small number of multilocus genotypes. Over 97% of the plants sampled could be grouped into two classes (biotypes “A” and “B”), each consisting of a few highly similar genotypes. The two classes had mutually exclusive sets of alleles at nine loci. These classes differed sharply in their disease resistance toward one isolate of the specialist fungal pathogen Synchytrium decipiens from their native habitat. All biotype A plants were strongly susceptible, and all biotype B plants were resistant. When plants of both biotypes were exposed to this pathogen in a greenhouse, the resistant biotype (B) exhibited a significantly higher growth rate. The strong association between plant disease-resistance phenotypes and allozyme variants implies that pathogen attack could be a major selective agent influencing the evolution of neutral or near-neutral alleles at enzyme loci in this plant.