Note: First report of the Q biotype of<Emphasis Type="Italic">Bemisia tabaci</Emphasis> in Southern Sonora,Mexico

Bemisia tabaci (Gennadius) adults were collected from poinsettia plants (Euphorbia pulcherrima) in retail nurseries in Cd. Obregon and Navojoa, Sonora, Mexico. A single field sample was collected from broccoli plants in Obregon, Sonora. Both adult whitefly and immature instars were observed on infested leaves. Whiteflies were identified asB. tabaci using morphological characters of the pupae to distinguish them from the greenhouse whitefly; and to specific biotype, by molecular analysis using the mitochondrial cytochrome oxidase I (mtCOI) sequence. Phylogenetic analysis of mtCOI sequences indicated that poinsettias were colonized both by the Q and the B biotype. The Q biotype was found only on poinsettia plants, and one poinsettia sample was infested with both the Q and the B biotype. The B biotype alone was associated with the field-collected broccoli sample analyzed in the study. A more extensive survey is required to determine the extent of the distribution of the Q biotype in Mexico, particularly where ornamental plants are transported from central to northern Mexico. Such plants could serve as the source of the Q biotype, which has been reported to be highly resistant to insecticides including the neo-nicotinoids that are widely used to control the B biotype in much of Mexico. This is the first report of the Q biotype in Mexico. http://www.phytoparasitica.org posting May 2, 2007.     

Biotype Q of<Emphasis Type="Italic">Bemisia tabaci</Emphasis> identified in Israel

The biotype status of samples of the whiteflyBemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) collected from several field and greenhouse sites in Israel during 1999–2000 was determined by polyacrylamide gel electrophoresis (PAGE) for general esterases, and by RAPD-PCR using primers of arbitrary sequence. Results of this survey provide the first published evidence for the occurrence of theB. tabaci Q biotype, alongside the more widely distributed B biotype. Based on the collected samples, it appears that both the B and Q biotypes are present in Israel, and that field populations consist of a mixture of the two biotypes. A possible link betweenB. tabaci biotypes and insecticide resistance is discussed. Contribution no. 508/02 from the Inst. of Plant Protection, ARO, The Volcani Center, Bet Dagan, Israel. http://www.phytoparasitica.org posting Dec. 5, 2002.     

High-throughput allelic discrimination of B and Q biotypes of the whitefly, Bemisia tabaci, using TaqMan allele-selective PCR

BACKGROUND: B and Q biotypes of the whitefly, Bemisia tabaci (Gennadius), are generally regarded as the most significant given their global distribution and strong resistance to insecticides. Since these biotypes can coexist and differ markedly in their insecticide resistance profiles, a rapid but reliable means of discriminating between them would be a valuable complement to resistance monitoring and management programmes. Recently, PCR‐based methods have been developed to determine the biotype status of B. tabaci populations. However, these require post‐amplification procedures, which increase time and labour. RESULTS: The authors have developed an allelic discrimination real‐time PCR assay using fluorescent dye‐labelled probes to distinguish the B and Q biotypes. The assay targets a single nucleotide polymorphism (SNP) in the mitochondrial cytochrome oxidase I (mtCOI) gene. To evaluate the assay, DNA was extracted from individual whiteflies of six known biotype strains, and all scored correctly as either a B or Q biotype. As further validation, 72 individuals from field samples collected in different parts of the world were also tested by the assay. No failed reactions were observed, with all 72 samples scoring clearly as either the B or Q biotype. CONCLUSION: The development of this rapid and high‐throughput assay has important potential for routine monitoring of B and Q biotypes on ornamental plants and for the screening of B. tabaci populations in countries where these biotypes are not yet established. Copyright © 2007 Society of Chemical Industry     

First report of the Q biotype of <Emphasis Type="Italic">Bemisia tabaci</Emphasis> in Argentina and Uruguay

Bemisia tabaci adults were collected from pepper and melon at different commercial production greenhouses in Argentina and Uruguay. The biotype status of adults was then established using cytochrome oxidase I gene (mtCOI) as molecular marker. Only the Q biotype was found on all plants sampled. This is the first report of the Q biotype in Argentina and Uruguay.     

Note:Bemisia tabaci biotype B associated with tomato yellow leaf curl disease epidemics on rhodes Island, Greece

In 2006 an outbreak of tomato yellow leaf curl disease occurred in tomato crops on Rhodes Island, Greece. Diseased plants were found to be infested with the B biotype of theBemisia tabaci (Gennadius) complex and greenhouse and open-field-grown tomato crops were infected withTomato yellow leaf curl virus (TYLCV) introduced from the Middle East. This is the first report of TYLCV and the B biotype ofB. tabaci on Rhodes Island in Greece. http://www.phytoparasitica.org posting Dec. 11, 2007.     

Note: Current status ofBemisia tabaci in Coastal Croatia

Bemisia tabaci was first noted in Croatia in 2000, when it was identified in Split County, Dalmatia. Thirty-one plant species were identified as hosts of this pest in the central Adriatic region during 2001–2002. Four adult populations were analyzed at CIDA (Spain) by comparing a fragment of the COI gene of the mitochondrial DNA, and by examining a single microsatellitelocus. The results indicated a predominance of the Q biotype. The population dynamics ofB. tabaci was examined in outdoor conditions by observing populations fromIpomoea purpurea in 2002. The pest population appeared at the beginning of June and increased in number until its decline at the beginning of October. http://www.phytoparasitica.org posting Dec. 20, 2004.     

Molecular phylogenetic analysis reveals at least five genetic races of<Emphasis Type="Italic">Bemisia tabaci</Emphasis> in China

Phylogenetic analysis using ITS1 and CO1 nucleotide sequences has revealed six major races ofBemisia tabaci in the world, including three major indigenous races in the Asia-Pacific region,viz., B. tabaci (Asia),B. tabaci (Bali) andB. tabaci (Australia), but the status of a large collection of genotypes in this region remains unresolved. The ITS1 sequences of representative whitefly samples collected from around China were determined in this study. These sequences and other homologous sequences retrieved from GenBank were then used to conduct a phylogenetic analysis. The results demonstrated that the whiteflies collected in China were split genetically into four groups, where at least five genetic races were revealed,i.e., B biotype (SDLe, XJEp, XJAt, HNNt, BJIb, GDEp, XJGh, GDHrs, XJSm and SHEp), Bali group (ZJGh), M biotype (Hainan1), G biotype (GXCm) and Asian H/K group (FJIb, GDCv), although the Asian H/K group with low bootstrap score remains unresolved. Of all genetic races, the B biotype is the most extensively distributed. In the dendogram, the J biotype, L biotype and Q biotype cluster together and form a sister clade to the B biotype. The data indicate that extensive migration ofB. tabaci has taken place in Asian countries. The populations ZJGh, FJIb, GDCv, GXCm and Hainanl collected in China might have originated there, but the possibility that they were introduced from elsewhere cannot be excluded at this point. Using PyR from Israel as a reference Q biotype, the random amplified polymorphic DNA banding patterns of SDLe, XJEp, XJAt and HNNt were shown to be consistent with that of the Q biotype, which indicated that the four local whitefly populations identified as the B biotype based on ITS1 sequences were closely related to the Q biotype. http//www.phytoparasitica.org posting Sept. 12, 2006.     

Comparative spatial dispersal ofTomato yellow leaf curl virus vectored by B and Q biotypes ofBemisia tabaci in Tomato glasshouses

The spatial dispersal patterns ofTomato yellow leaf curl virus (TYLCV) disease vectored by the B and Q biotypes of the whiteflyBemisia tabaci in tomato glasshouses were compared. Tomato plants were arranged in glasshouses and TYLCV-infected plants were placed in the center of each plot. Adult whiteflies of each biotype were released onto TYLCV-infected plants and the insects were then freely dispersed in the glasshouses under high or moderate temperature conditions. The abundance and spatial distribution of dispersed whiteflies did not differ between the B and Q biotypes in tomato glasshouses. The disease incidence and dispersion of TYLCV as a result of short-distance movement of the whiteflies were also similar between the two biotypes, although on several investigation dates there was a tendency for the disease incidence caused by the B biotype to be slightly greater than that caused by the Q biotype. These results demonstrated that the aspects of spatial spread of TYLCV vectored by the B and Q biotypes ofB. tabaci in tomato glasshouses are similar. http://www.phytoparasitica.org posting Dec. 11, 2007.     

Biotype and insecticide resistance status of the whitefly Bemisia tabaci from China

BACKGROUND: Resistance to numerous insecticide classes in Bemisia tabaci Gennadius has impaired field control efficacy in south‐eastern China. The biotype and resistance status of B. tabaci collected from these areas was investigated. RESULTS: Two different biotypes of B. tabaci (B‐biotype and Q‐biotype) were detected in south‐eastern China, and the samples collected from geographical regions showed a prevalence of the Q‐biotype and the coexistence of B‐ and Q‐biotypes in some regions. Moderate to high levels of resistance to two neonicotinoids were established in both biotypes (28–1900‐fold to imidacloprid, 29–1200‐fold to thiamethoxam). Medium to high levels of resistance to alpha‐cypermethrin (22–610‐fold) were also detected in both biotypes. Four out of 12 populations had low to medium levels of resistance to fipronil (10–25‐fold). Four out of 12 populations showed low levels of resistance to spinosad (5.7–6.4‐fold). All populations tested were susceptible to abamectin. CONCLUSION: The Q‐biotype B. tabaci is supplanting the B‐biotype which used to be ubiquitous in China. Field populations of both B‐ and Q‐biotypes of B. tabaci have developed high levels of resistance to imidacloprid and thiamethoxam. Abamectin is the most effective insecticide against adult B. tabaci from all populations. Copyright © 2010 Society of Chemical Industry     

日光温室番茄褪绿病毒病的发生规律及其与Q型烟粉虱种群动态关系

为有效控制日光温室番茄褪绿病毒病,于2014—2015年通过RT-PCR检测方法研究了济南市日光温室番茄褪绿病毒(Tomato chlorosis virus,ToCV)的发生规律、其与Q型烟粉虱Bemisia tabaci种群动态的关系及防虫网对该病毒病的防控效果。结果表明,春季日光温室番茄植株上Q型烟粉虱成虫数量呈增长趋势,5月下旬最高达到0.10头/叶,秋季日光温室番茄植株上Q型烟粉虱成虫数量9月上旬达最高7.42头/叶,后逐渐下降;日光温室Q型烟粉虱带毒率随着定植时间的延长而逐渐上升,之后维持相对稳定状态,即春季为20.00%~24.14%,秋季为30.00%~40.00%。日光温室ToCV发生与Q型烟粉虱成虫数量和带毒率密切相关,春季番茄最高发病率为12.00%;秋季番茄植株最高发病率为93.02%。番茄育苗和生长期用100目防虫网隔离可显著降低番茄植株带毒率。因此,秋季是日光温室ToCV防控关键期,覆盖防虫网阻隔烟粉虱可有效防治ToCV,推荐在日光温室使用。     

Susceptibility to insecticides in the Q biotype of Bemisia tabaci is correlated with bacterial symbiont densities

BACKGROUND: The presence of symbiotic microorganisms may influence an insect's ability to tolerate natural and artificial stress agents such as insecticides. The authors have previously shown that Rickettsia in the B biotype of the whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) increases this insect's susceptibility to several insecticidal compounds. This communication reports a comparison of the susceptibilities of three isofemale strains of the Q biotype of B. tabaci harbouring different bacterial complements to major insecticides from different chemical groups: one strain harboured only Arsenophonus, one harboured Rickettsia and Arsenophonus and one harboured Arsenophonus and Wolbachia. RESULTS: The presence of different symbiont combinations in the three strains had a significant influence on their susceptibility to most of the insecticides tested. Thiamethoxam, imidacloprid, pyriproxyfen and spiromesifen had a significant influence on strains that had the double infections Rickettsia–Arsenophonus and Wolbachia–Arsenophonus, which also carried higher amounts of symbionts as assessed by quantitative real‐time PCR. No significant differences in mortality rates were observed when the tested strains were treated with diafenthiuron. CONCLUSION: The results suggest a correlation between the presence of high bacterial densities in B. tabaci and the insect's ability to detoxify toxic compounds such as insecticides. Copyright © 2009 Society of Chemical Industry     

Insecticide resistance status of Bemisia tabaci Q‐biotype in south‐eastern Spain

BACKGROUND: Bemisia tabaci Gennadius Q‐biotype has readily developed resistance to numerous insecticide classes. Studies in the Mediterranean area are needed to clarify the resistance status and cross‐resistance patterns in this invasive whitefly biotype. The levels of resistance in nymphs of seven strains of B. tabaci Q‐biotype from south‐eastern Spain to representative insecticides were determined. RESULTS: Six populations had low to moderate levels of resistance to azadirachtin (0.2‐ to 7‐fold), buprofezin (11‐ to 59‐fold), imidacloprid (1‐ to 15‐fold), methomyl (3‐ to 55‐fold), pyridaben (0.9‐ to 9‐fold), pyriproxyfen (0.7‐ to 15‐fold) and spiromesifen (1‐ to 7‐fold), when compared with a contemporary Spanish Q‐biotype reference population (LC₅₀ = 2.7, 8.7, 15.2, 19.9, 0.34, 20.9 and 1.1 mg L^?1 respectively). A single population collected from a greenhouse subject to intensive insecticide use exhibited generally higher resistance levels to the same array of compounds (31‐, 1164‐, 3‐, 52‐, 9‐, 19‐ and 3‐fold respectively). Pyridaben and spiromesifen were extremely effective against nymphs of all strains, with LC₅₀ values significantly below recommended application rates. CONCLUSION: In contrast to previous reports, high rates of efficacy exist for numerous insecticide classes against B. tabaci Q‐biotype populations in these intensive agricultural regions of south‐eastern Spain. This probably reflects the recent and significant reductions in exposure that have resulted from a wider uptake of IPM technologies and strategies. However, the continued presence of resistance genes also suggests that a reversion to levels of high insecticide exposure could result in a rapid selection for resistance. Copyright © 2009 Society of Chemical Industry     

Q型烟粉虱芳香基硫酸酯酶B基因的克隆及表达分析

为明确烟粉虱Bemisia tabaci取食感染番茄黄化曲叶病毒(Tomato yellow leaf curl virus,TYLCV)的番茄植株后,其体内的芳香基硫酸酯酶B基因(arylsulfatase B,ARSB)是否能够做出应答反应,基于Q型烟粉虱基因组数据克隆得到ARSB基因cDNA全长,采用生物信息学方法分析其序列特征,并通过实时荧光定量PCR技术测定ARSB基因在Q型烟粉虱不同发育阶段、不同组织及携带TYLCV前后的表达量变化情况。结果显示:Q型烟粉虱ARSB基因的cDNA全长为1 731 bp,编码576个氨基酸,分子量为64.89 kD,具有ARSB的保守结构域。ARSB基因在Q型烟粉虱不同发育阶段均有表达,在卵期表达量最高,成虫期表达量最低;该基因在Q型烟粉虱头胸部的表达量显著高于腹部;Q型烟粉虱获取TYLCV 72 h后其体内ARSB基因表达量显著提高。表明ARSB基因在Q型烟粉虱不同龄期、不同组织内存在差异表达,并可能参与Q型烟粉虱对TYLCV的响应和传毒过程。     

Note: Biotype status ofBemisia tabaci from various crops in Cyprus

An extensive survey ofBemisia tabaci populations covering the southern half of the island of Cyprus was conducted in 2006 and 2007 in order to define the biotype status of the pest. Sampling was done both on protected and outdoor cultivations of vegetables and ornamental plants. Biotype identification was performed using molecular diagnostics based on the mitochondrial cytochrome oxydase I gene. Our results indicated the presence of only the biotype B in all 25 collections. http://www.phytoparasitica.org posting August 8, 2008.     

L-阿拉伯糖对B型和Q型烟粉虱毒性及取食行为的影响

为明确L-阿拉伯糖对B型和Q型烟粉虱毒性及其取食行为的影响,调查了饲喂含有L-阿拉伯糖人工饲料后烟粉虱的死亡率,利用刺吸电位技术(EPG)记录其取食行为,并观察了饲喂后其在人工饲料膜上的刺孔数量及直径。结果表明,B型和Q型烟粉虱的校正死亡率均随L-阿拉伯糖浓度及饲喂时间的增加而升高;在3种浓度下,B型烟粉虱校正死亡率均显著高于Q型烟粉虱;在5%、10%浓度下,Q型烟粉虱校正死亡率分别在第5天和第3天达100%,B型烟粉虱分别在第3天和第2天达到100%;5%L-阿拉伯糖对B型烟粉虱取食行为影响比Q型大;在5%浓度下,B型和Q型烟粉虱在膜上的刺孔数量总体少于对照组。研究表明,L-阿拉伯糖对烟粉虱具有杀虫活性,且对B型和Q型烟粉虱的毒性效果不同。     

江苏地区Q型烟粉虱的单倍型分析

为明确江苏地区Q型烟粉虱的遗传多样性及其入侵来源,基于mt DNA COI基因序列,对2010、2011年采自江苏13个市的Q型烟粉虱种群进行了单倍型分析。结果显示,江苏地区Q型烟粉虱有4个单倍型,分别为单倍型Q1、Q2、Q3、Q4,不同单倍型的分布和发生频率不同,其中单倍型Q2是13个地理种群的共享单倍型,2010、2011年的发生频率均超过50%;单倍型Q1和Q3分别是部分地理种群的共享单倍型,发生频率较低;单倍型Q4仅在扬州种群中出现,发生频率最低;单倍型Q1和Q3亲缘关系较近,单倍型Q2和Q4亲缘关系较近,表明各地理种群间既有一定的基因交流,也存在一定程度的遗传分化;系统发育分析表明,江苏地区的Q型烟粉虱可能来源于西部地中海地区,与日本的Q型烟粉虱具有相同的入侵来源。     

山东寿光地区Q型烟粉虱对番茄褪绿病毒的传播

为明确山东寿光地区Q型烟粉虱对番茄褪绿病毒(Tomato chlorosis virus,To CV)感病流行的影响及其传毒特性,于2014年调查了该地区设施番茄上烟粉虱种群动态与To CV发病情况,利用特异引物对烟粉虱体内To CV进行了RT-PCR检测;并在室内测定了带毒Q型烟粉虱取食时间和种群数量对To CV感病株率的影响。结果表明,在番茄发病植株上采集的烟粉虱种群体内可检测到To CV;春茬番茄To CV发病株率随烟粉虱种群数量增加而逐渐升高,4—6月是To CV发生高峰期,6月22日发病株率达100%;秋茬番茄烟粉虱种群数量从10月下旬明显下降,而To CV发病株率升高,11月12日发病株率达100%;室内试验表明,To CV感病株率随着带毒Q型烟粉虱数量与取食时间的增加而明显升高。研究表明,Q型烟粉虱能有效传播To CV,且其种群数量对To CV发病株率存在显著影响,可通过防控烟粉虱以控制To CV的危害。     

PCR-RFLP identification ofBemisia tabaci biotypes in the Mediterranean Basin

At least 20 genetic biotypes, with varying degrees of biological characterization, are currently recognized within theBemisia tabaci (Hemiptera: Aleyrodidae) species complex. Their identification relies on a set of different molecular techniques. However, none of the available markers is completely adequate, due to technical difficulties or lack of reproducibility. We therefore developed a method for rapid biotyping ofB. tabaci populations. The five biotypes (B, Q, M, S and T) reported until now in the Mediterranean Basin have been tested by PCR amplification of the cytochrome oxidase I mitochondrial gene followed by restriction with the enzymeTru9I. The digestion patterns produced by this enzyme were able to identify the five biotypes clearly. Digestion with another enzyme,TaqI, discriminated only between biotypes B and Q. The newly developed method enables rapid biotyping and can be applied in studies aimed at assessing biotype distribution and competition at least in the Mediterranean area. http://www.phytoparasitica.org May 14, 2006.     

The use of isozyme patterns to distinguish sweetpotato whitefly (Bemisia tabaci) biotypes

Recent collections ofBemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) from California desert regions represent a mixture of biotypes. One biotype was identical to a culture originally obtained in 1981 and since maintained in the laboratory. The other and most prevalent biotype could not be distinguished morphologically but could be distinguished by esterase isozyme banding patterns. The banding patterns of the biotypes were not affected by culturing the whiteflies on different plant species. Different developmental stages, and adults of both sexes, had the same isozyme patterns.     

First record of the Q biotype of the sweetpotato whitefly, <Emphasis Type="Italic">Bemisia tabaci</Emphasis>, in Guatemala

Bemisia tabaci (Gennadius) adults and immatures were collected from poinsettia plants at two commercial production greenhouses in Guatemala during an invited tour to observe IPM practices within the facilities. Despite extensive scouting, only low numbers of insects were collected from vegetable, weed and wild ornamentals species located close to these facilities. Prior to molecular and biochemical analyses, whitefly immatures were initially identified as B. tabaci using morphological characters of the pupae to distinguish them from the greenhouse whitefly. The biotype status of adults and immatures was then established using esterase isozyme patterns and MTCO1 sequencing. The Q biotype was the only biotype found on commercially grown poinsettia plants. The previously recorded B biotype was observed outside the greenhouse facilities on Lactuca spp., Hibiscus spp. and Euphorbia spp. (wild poinsettia). The New World biotype was observed on wild poinsettia and field-grown beans (Phaseolus spp.). This is the first report of the Q biotype in Guatemala, and serves notice of the need for greater vigilance in the management of whiteflies on poinsettia mother stock used as a source of cuttings for export to the USA.