Q型烟粉虱成虫传播番茄褪绿病毒的能力

为明确Q型烟粉虱Bemisia tabaci成虫对番茄褪绿病毒(Tomato chlorosis virus,ToCV)的传毒特征,应用RT-PCR技术检测了ToCV在Q型烟粉虱成虫体内的存留时间、Q型烟粉虱成虫对ToCV的获毒效率及传毒效率。结果表明,Q型烟粉虱成虫离开带毒番茄植株后,其带毒率随时间的延长逐渐降低,最初为85.73%,96 h后仅为17.14%。在相同温度下,Q型烟粉虱成虫的获毒率先随着取食时间的延长而提高,而后处于相对稳定状态,当温度为21、26、31℃时,Q型烟粉虱成虫获毒率达到峰值的时间分别为72、48、6 h,最高获毒率分别为56.52%、54.17%和61.64%。当温度为26℃时,Q型烟粉虱成虫的传毒效率随着取食时间的延长而提高,取食时间为0.5 h时,番茄植株带毒率为25.00%,取食时间为48 h时,番茄植株带毒率达91.67%;温度对Q型烟粉虱成虫的传毒效率有极显著影响,取食48 h后,在21~31℃条件下番茄植株带毒率为83.33%~91.67%,在16℃条件下仅为16.67%。表明Q型烟粉虱成虫对ToCV具有较强的获毒和传毒能力,对其进行有效控制可以防止ToCV的扩散和蔓延。     

棉盲蝽的发生规律及防治技术

近几年，棉盲蝽在郓城县发生呈逐年加重趋势，逐渐成为抗虫棉的常发性害虫。本县棉盲蝽主要包括绿盲蝽、苜蓿盲蝽、三点盲蝽和中黑盲蝽 4种。其中绿盲蝽占比例较大，约占调查虫量的 70％左右。 2000年盲蝽大发生，全县发生面积 1 600 hm2，占棉花播种面积的 60％，平均百株虫 20～ 35头，最高达 60头，平均植株受害率 40％～ 60％，最高达 90％以上，叶片平均受害率 25％～ 30％，最高 60％以上，造成叶片大量破碎，严重影响叶片的功能，对抗虫棉的产量和品质造成很大的影响。 1为害特点 　　以成虫、若虫刺吸为害，使子叶期棉苗顶芽焦枯变…     

三营养级体系烟盲蝽对温室内不同作物种类的选择性

在温室内采用笼罩观察,通过选择性和非选择性试验,在两营养级(作物-天敌)的基础上进一步研究了三营养级(作物-天敌-害虫)体系中烟盲蝽对5种不同植物种类的选择性。以落虫量为选择指标,烟盲蝽成虫选择性结果表明:黄瓜+粉虱成虫、番茄+粉虱成虫、茄子+粉虱成虫、菜豆+粉虱成虫之间不存在差异显著性,但对油菜+蚜虫的选择性较好。烟盲蝽成虫非选择性试验,以其产卵后初孵若蝽量和死亡率为衡量指标,结果表明,烟盲蝽初孵若虫量之间存在显著差异,排序为:黄瓜>番茄>油菜>菜豆>茄子;烟盲蝽死亡率之间存在显著差异,排序为:菜豆+粉虱成虫>茄子+粉虱成虫>番茄+粉虱成虫>黄瓜+粉虱成虫>油菜+蚜虫。烟盲蝽若虫选择性试验,以羽化率为选择指标,结果为:油菜+蚜虫>番茄+粉虱若虫>黄瓜+粉虱若虫>菜豆+粉虱若虫>茄子+粉虱若虫。另外,在茄子+粉虱若虫上的死亡率最高为90.5%,其次为菜豆+粉虱若虫90%,黄瓜+粉虱若虫71.4%,番茄+粉虱若虫42.9%,油菜+蚜虫40%。     

水稻南方黑条矮缩病发生规律及防控对策初探

我国新发生水稻病毒病水稻南方黑条矮缩病由斐济病毒属建议新种南方水稻黑条矮缩病毒(Southern rice black-streaked dwarf virus,SRBSDV,Genus Fijivirus)引起。迁飞性害虫白背飞虱为其传播介体。依据近年田间调查和试验结果分析,白背飞虱不能经卵将病毒传给下一代,后代须在病株上取食才能获毒。若虫最短获毒饲育时间为5～10min,体内循徊期为3～5d。若虫获毒后可终生传毒,最短传毒取食时间为5～10min,且若虫传毒效率高于成虫。白背飞虱带毒率与虫源性质密切相关,采自病株的虫源明显高于采于健株的虫源。因此,对灯下白背飞虱的检测能够反映自然种群的带毒状况,对早期监测和预警具有重要意义。田间发病表现为轻病田病株呈零星分布,重病田病株呈集团分布。水稻各生育期均可感病,感病生育期越早,症状越严重。针对大田的应急防控,应着重做好秧田避害、治虫防病和本田初期病株清除及介体防治,加强病情监测和灯下介体带毒检测。该病害的长期治理,除培育抗性品种、提高预警能力外,降低介体昆虫的种群数量,是控制病毒病流行的根本措施。     

利用四季豆饲养盲蝽的方法

四季豆是多种盲蝽的寄主植物,该研究旨在发展一个利用四季豆豆荚规模化饲养多种盲蝽的技术.研究结果表明:绿盲蝽与中黑盲蝽的若虫最佳饲养密度约为100头/盒(2L),成虫为60～80头/盒.绿盲蝽成虫喜好在切头豆荚的两端伤口处产卵,而中黑盲蝽喜欢在完整豆荚的两端产卵.养虫盒内添加一些弯曲的纸条有助于提高若虫存活率和成虫产卵量.产卵后的豆荚需晾干后放置在25～28℃、相对湿度60%～70%、光照16:8(L:D)的环境下,以减少豆荚腐烂和提高卵的孵化率.利用这一方法饲养盲蝽的若虫存活率、成虫产卵量和卵孵化率分别达60%、40粒和80%.     

2003年绿盲蝽在大城县枣树上发生严重

绿盲蝽(LyguslucorumMeyer-Dür)属半翅目,盲蝽科。在廊坊市以成虫在枣树树皮裂缝、杂草间及枯枝、落叶下越冬,或以卵在苜蓿、苕子、蒿类的茎组织内越冬。以成虫、若虫刺吸枣树嫩芽进行为害。除枣树外,还为害棉花、豆类、苜蓿、多种禾本科作物及桑、杨、柳树等。绿盲蝽在大城县3月下旬至4月初始见成虫,4月初平均单株有虫1.5头。据跟踪监测,到4月20日止,虫量明显上升,在本市大城县枣树上绿盲蝽发生面积10万亩,平均单株有虫3.5头。绿盲蝽为害嫩芽后,影响叶片生长,叶片表面成洞,长势弱,严重影响产量。由于该虫寄主广泛,活动性较强,难于防治,…     

蠋蝽对荔枝蝽一龄若虫的捕食功能反应

为了筛选在荔枝蝽若虫期对其具有良好防效的天敌昆虫，本试验探究蠋蝽对荔枝蝽1龄若虫的捕食潜力，在室内条件下评价了蠋蝽4龄若虫、5龄若虫、雌成虫和雄成虫对荔枝蝽1龄若虫的捕食能力，结合果园的观察总结了蠋蝽捕食行为特点。结果表明：蠋蝽4龄若虫、5龄若虫、雌成虫和雄成虫对荔枝蝽1龄若虫的捕食功能反应符合Holling Ⅱ模型，对荔枝蝽若虫的日最大捕食量分别为9.066、8.210、8.354和5.903头，瞬时攻击率分别为0.956、1.327、1.100和1.244，处理时间分别为0.10、0.162、0.132和0.149 d。不同龄期蠋蝽对荔枝蝽1龄若虫的搜寻效应均随猎物密度的增大而减小。室内外观察发现，蠋蝽捕食荔枝蝽若虫时的行为和捕食草地夜蛾等其他猎物时相似，经历搜索、跟随、攻击、取食、转移等行为反应。捕食功能试验证实蠋蝽对荔枝蝽1龄若虫具有较高的控害潜能，是实现荔枝蝽绿色防控的一种良好备选天敌产品。     

灰飞虱传播水稻条纹叶枯病毒的特性

灰飞虱是水稻条纹叶枯病的传毒介体,带毒的长短翅型成虫及各龄若虫均能在秧苗期和分蘖期传毒感病,秧苗感病以卷叶型为主,均相继枯死,分蘖期感病以展叶型为主,病株95％以上不能抽穗结实。主蘖传毒,主蘖及各分蘖均发病,分蘖传毒,仅分蘖发病。带毒雌雄配对繁衍3代,无毒分离率平均为31.38％。带毒虫传毒3min,发病率为2％,传毒2h,发病率达22.5％。带毒率50％以上的群体一生传毒频次为3～5次,10％以下仅1次。各龄若虫及不同成虫1天传毒致病株:秧苗期为0.97株及1.26株:分蘖期为0.45株及0.42株。秧田传毒后,80％以上的隐症病株到本田期才陆续显现病状,故秧田“治虫防病”甚为重要。     

利用捕食功能模型评价波氏烟盲蝽对烟蚜、烟粉虱和西花蓟马的捕食能力

为评价波氏烟盲蝽Nesidiocoris poppiusi Carvalho对害虫的捕食能力和控害潜能,在室内条件下研究了波氏烟盲蝽对烟蚜、烟粉虱和西花蓟马三种常见农田小型害虫的捕食功能反应和搜寻效应。结果表明波氏烟盲蝽雌、雄成虫对所试三种害虫的捕食功能反应均拟合HollingⅡ型。雌虫对烟蚜、烟粉虱和西花蓟马有较高的捕食能力,理论日最大捕食量分别为123.5、133.35和192.3头。雄虫对三种害虫的捕食能力弱于雌虫,理论日最大捕食量分别为43.3、19.6和22.1头。雌虫对烟蚜、烟粉虱和西花蓟马的瞬时攻击率分别为1.065、1.037和0.810,雄虫分别为1.184、1.129和0.853。雌虫对烟蚜、烟粉虱和西花蓟马的处理时间分别为0.0081 d、0.0075 d和0.0052 d,均短于雄虫。波氏烟盲蝽对三种猎物的搜寻效应均随猎物密度增加而降低,对烟蚜和烟粉虱的搜寻效应高于西花蓟马,雄虫搜寻效应的下降趋势高于雌虫。本研究为波氏烟盲蝽对以上三种常见农业害虫的防控提供了理论基础和数据支撑。     

东亚小花蝽对茶棍蓟马成虫的捕食功能

为明确东亚小花蝽Orius sauteri对茶棍蓟马Dendrothrips minowai的捕食作用和生物防治潜能,于室内系统研究东亚小花蝽3～5龄若虫和成虫对茶棍蓟马雌成虫的捕食行为、捕食功能反应、搜寻效应、自身干扰反应及两者之间的相互干扰效应。结果表明,东亚小花蝽取食单头茶棍蓟马雌成虫的时间随着自身发育阶段的增大而变短,成虫取食时间最短,为7.40 min。在一定的猎物密度范围内,东亚小花蝽3～5龄若虫与成虫对茶棍蓟马的捕食作用均符合HollingⅡ功能反应模型,东亚小花蝽3～5龄若虫与雌成虫的捕食量均随猎物密度的增加而升高。东亚小花蝽雌成虫对茶棍蓟马雌成虫的瞬时攻击率、捕食能力和日最大捕食量均最高,分别为0.459、124.05和250.00头。东亚小花蝽对茶棍蓟马的捕食量与猎物密度呈正相关,但搜寻效应与猎物密度呈负相关,且东亚小花蝽雌成虫的搜寻效应最高。东亚小花蝽对茶棍蓟马的捕食作用同时受自身密度的影响,随着自身密度的增大其平均捕食率降低。东亚小花蝽成虫的捕食作用率随着自身密度和猎物密度的增大而降低。表明东亚小花蝽对茶棍蓟马有较好的生物防治潜能。     

The virus-vector relationship of the tomato leafcurl virus (TLCV) and its vector,Bemisia tabaci gennadius (Hemiptera: aleyrodidae)

Basic studies carried out in India showed that the incubation period of TLCV in plants varied from 8 days in August to 90 days in winter. The acquisition threshold for the whitefly,Bemisia tabaci Gen., was 31 min; it resulted in 3% transmission. An acquisition access of 24 h for a female whitefly on a TLCV source resulted in 30% transmission. A minimum feeding period of 32 min was required by a viruliferous whitefly to cause infection on tomato test plants; this gave 4% transmission. With inoculation access of 24 h on tomato test plants, the transmission rose to 24%. Starving the vector for 1 h pre-acquisition or 1 h pre-inoculation resulted in higher levels of transmission of TLCV: 36 and 40%, respectively, compared with 20% for non-starved whiteflies. Extending the fasting period beyond 1 h resulted in a reduced transmission level. The whiteflies could acquire the virus from the cotyledonary leaves of an infected tomato plant, with a resultant 28% transmission; but infection did not occur when the whiteflies had an inoculation access to such leaves. Higher transmission rates were obtained when the younger leaves on tomato plants were used for acquisition and inoculation. Transmission was 8 and 38% when five whiteflies per plant were allowed 24 h of acquisition access to 11- and 2-month-old virus sources, respectively. After an acquisition access of 24 h to a TLCV source, male and female whiteflies retained their infectivity for 5 and 53 days, respectively. Nymphs can acquire and transmit the virus. When ten whiteflies of each sex were given 24 h of acquisition and of inoculation access, the subsequent transmission rate of males and females was 56 and 86%, respectively. This virus is not transovarially transmitted. Whitefly colonies raised on brinjal were more efficient (70 and 84% transmission in two experiments) than those raised on chilli, cotton, cowpea, tobacco or tomato.     

Aphid stylet activities during potyvirus acquisition from plants and anin vitro system that correlate with subsequent transmission

The behavioural events associated with acquisition of tobacco etch potyvirus by starvedMyzus persicae during single, electrically-recorded penetrations of plants or a Parafilm membrane were compared. Twenty nine percent of aphids acquired virus from plants and subsequently transmitted to test plants. Stylet puncture of the plasmalemma, indicated by a potential drop (pd) to the intracellular signal voltage level, occurred during 84% of penetrations, and virus transmission was always associated with this behavioural event during acquisition. Periods of intracellular stylet tip location, known as pd phase II, ranged from 3.6–12.2s, and always comprised three consecutive sub-phases, designated II1, II2 and II3. Ninety six percent of pds included distinct pulses during phase II3. A waveform which closely resembled these pulses was produced by 59% of aphids that probed a virus suspension through a Parafilm membrane; nineteen percent of the aphids subsequently transmitted membrane-acquired virus and transmission was significantly associated with the occurrence of the phase II3-like pulses during acquisition. The duration of occurrence of recorded phase II3 pulses, either on plants or thein vitro system, did not influence the virus transmission efficiency of aphids. The association of virus uptake from aqueous suspension with a particular behavioural activity is discussed as evidence for the ingestion-egestion hypothesis for nonpersistent transmission. Starved aphids acquiring virus from infected leaf tissue or thein vitro system had significantly higher transmission efficiencies than non-starved aphids. Starved and non-starved insects were electrically-recorded penetrating the artificial membrane, and again there was a clear difference in transmission efficiency (starved aphids, 26%; non-starved aphids, 2%). The higher transmission efficiency of starved insects could not be explained by behavioural differences, and the results lend support to the hypothesis that non-behavioural factors determine the enhancement of potyvirus transmission by preacquisition starvation.Abbreviations BMV Beet mosaic virus - EMF Electromotive force - HAT Highly aphid-transmissible - HC Helper component - pd Potential drop - PVY Potato virus Y - TEV Tobacco etch virus     

嗜线虫致病杆菌HB310菌株对东亚飞蝗的生物活性

通过生物测定比较了9种昆虫病原线虫共生菌对东亚飞蝗Locusta migratoria manilensis 4龄蝗蝻的杀虫活性,其中嗜线虫致病杆菌Xenorhabdus nematophila HB310菌株(以下简称Xn HB310)对4龄蝗蝻的活性最高;采用浸叶法进一步测定了Xn HB310菌液对不同虫态的东亚飞蝗的毒力。结果表明:在饲喂96 h 后,Xn HB310菌液对2龄蝗蝻、4龄蝗蝻和成虫的致死中浓度(LC50)分别为2.97×105、4.90×105和6.24×105 CFU/mL,致死中时间(LT50)分别为51.48、52.59和64.34 h。研究还发现该菌株对东亚飞蝗具有明显的拒食活性,处理48 h 后Xn HB310菌液对2龄蝗蝻、4龄蝗蝻和成虫的拒食中浓度(AFC50)分别为1.15×105、2.36×105和3.16×105 CFU/mL。通过点滴或剪除东亚飞蝗成虫感觉器官的方法,证实了Xn HB310菌液对东亚飞蝗产生拒食作用的器官是下颚须和下唇须,剪除下颚须和下唇须及两者均剪除的拒食率分别为37.36%、51.28%和100%。研究结果表明,嗜线虫致病杆菌Xn HB310菌液对东亚飞蝗的杀虫速度快且活性高,具有开发为防治东亚飞蝗杀虫剂的潜力。     

Transmission of Tomato Yellow Leaf Curl Virus by two invasive biotypes and a Chinese indigenous biotype of the whitefly Bemisia tabaci

The global invasion of certain Bemisia tabaci biotypes provides opportunities to compare the competency of virus transmission between invasive and indigenous biotypes. Here we report on the acquisition, retention and transmission of Tomato Yellow Leaf Curl Virus (TYLCV) by the invasive B, Q and indigenous ZHJ2 biotypes of B. tabaci from Zhejiang, China. For all whitefly biotypes, TYLCV DNA was detected within a 30-min acquisition access period (AAP) to infected leaves. The percentage of adults with viral DNA increased with the length of AAP and reached 100% after 10–12 h. Following acquisition, viruliferous B, Q and ZHJ2 adults retained TYLCV DNA for the rest of their lives. Transmission was achieved with one B/Q adult per plant at the frequency of 50–55%, which rose to 100% with 10 insects per plant. In contrast, transmission of the virus was not observed with one ZHJ2 adult per plant in the experiments, and the transmission frequency rose to only 30–45% when whitefly adults increased to 5–10 per plant. These new data will help in the determination of the pest status of the whitefly biotypes as virus vectors in the regions of invasion, and so help in the development of management strategies.     

The Efficiency by Which Thrips tabaci Populations Transmit Tomato spotted wilt virus Depends on Their Host Preference and Reproductive Strategy

ABSTRACT Arrhenotokous and thelytokous populations of Thrips tabaci from tobacco or leek plants were evaluated for their ability to transmit Tomato spotted wilt virus (TSWV) and for their host preference. Transmission efficiencies were comparatively studied using leaf disks of Petunia hybrida, Datura stramonium, and Nicotiana tabacum cv. Basmas. Adults of arrhenotokous populations collected on infected tobacco plants in the field were efficient transmitters (up to 48.5% transmission) and remained so when maintained on tobacco for several generations. Arrhenotokous T. tabacipopulations from leek plants were poor transmitters (up to 3.1% transmission), whereas no transmission was obtained with thelytokous populations from leek. All populations could infest leek, however none of the arrhenotokous and thelytokous populations from leek plants was able to infest tobacco. TSWV could be acquired by both first and second larval instars of a T. tabacipopulation from tobacco. However, the transmission by adults decreased with the age at which the virus was acquired by larvae. The highest efficiencies (61% of males and 51% of females transmitted) were obtained when newborn (0- to 24-h old) larvae acquired the virus. The majority of thrips started to transmit after becoming adult and rates were positively correlated with the temperature at which the thrips were kept. The median latent period values found for adults decreased with increasing temperature. The median acquisition access period (AAP50) of the population was 41 min, whereas the AAP(50) was 65 min for males and 35 min for females. The median inoculation access period of males was 246 and 365 min on tobacco and petunia, respectively, and 96 and 345 min for females. The results show that T. tabaci forms a complex in terms of host preference, reproductive strategy, and ability to transmit TSWV. The transmission parameters show that the thrips of arrhenotokous populations infesting tobacco are highly efficient vectors.     

B型烟粉虱携带传播烟草曲茎病毒的能力

B型烟粉虱近20年来入侵许多国家和地区,已成为重要的世界性作物害虫,其主要危害方式之一是传播双生病毒,造成作物病毒病大发生.应用PCR技术,研究了入侵我国的B型烟粉虱个体获取、存留及传播烟草曲茎病毒（Tobacco curly shoot virus,TbCSV）的能力.B型烟粉虱在感染TbCSV的普通烟毒株上饲毒30 min时,就可在40%的个体内检测到TbCSV DNA,个体带毒率随饲毒时间延长而增加,饲毒12 h后,带毒率达100%;TbCSV DNA在B型烟粉虱体内可存留10天左右,但不能终身存留;传毒处理植株的发病症状及PCR检测结果表明,B型烟粉虱是TbCSV的传播媒介.     

Acquisition of Tomato spotted wilt virus by Adults of Two Thrips Species

ABSTRACT Only larval thrips that acquire Tomato spotted wilt virus (TSWV), or adults derived from such larvae, transmit the virus. Nonviruliferous adults can ingest virus particles while feeding on TSWV-infected plants, but such adult thrips have not been shown to transmit TSWV. Immunofluorescence microscopy was used to show that thrips 1, 5, 10, and 20 days after adult emergence (DAE) fed on TSWV-infected plants acquired TSWV with virus replication and accumulation occurring in both epithelial and muscle cells of Frankliniella fusca (tobacco thrips [TT]) and F. occidentalis (western flower thrips [WFT]), as indicated by immunodetection of the nonstructural (NSs) protein encoded by the small RNA and the nucleocapsid (N) protein, respectively. Adult WFT acquired TSWV more efficiently than TT. There was no significant effect of insect age on TSWV acquisition by TT. In contrast, acquisition by adult WFT at 1 and 5 DAE was higher than acquisition at 10 and 20 DAE. Subsequent transmission competence of adult cohorts was studied by vector transmission assays. All adult thrips tested that had an acquisition access period as an adult were unable to transmit the virus. These results indicate the susceptibility of adult TT and WFT to infection of midgut cells by TSWV and subsequent virus replication and confirm earlier studies that adult thrips that feed on virus-infected plants do not transmit the virus. The role of a tissue barrier in TSWV movement and infection from midgut muscle cells to the salivary glands is discussed.     

Characteristics of Beet Yellows Closterovirus Transmission to Sugar Beets by Aphis fabae

ABSTRACT Laboratory studies were conducted on the characteristics of beet yellows closterovirus (BYV) transmission to sugar beets by the bean aphid, Aphis fabae. The relative transmission efficiency and the retention, acquisition, and inoculation thresholds were evaluated using clonal aphid colonies. Transmission efficiency was studied between different apterous aphid species (A. fabae and Myzus persicae ), between alate and apterous morphs of A. fabae and M. persicae, and among five clonal aphid colonies of A. fabae. Results indicated, on average, that apterous M. persicae transmitted twice as efficiently as apterous A. fabae (60 and 34%, respectively), apterous forms of A. fabae were equally efficient in transmitting BYV as compared with alate A. fabae (28 and 29%, respectively), and the five clonal colonies of A. fabae ranged from 28 to 40% transmission efficiency with an average of 34%. The maximum retention time recorded for BYV by A. fabae was between 24 and 48 h. After a 1-h acquisition access, a transmission efficiency of 10% was obtained, with maximum transmission efficiency (the highest average percent transmission that is statistically different from all other previous averages) of 39% reached after 6 h of acquisition access. Inoculation thresholds occurred within 1 h, with maximum transmission efficiency (42%) reached after a 6-h inoculation access. Using an electronic monitoring system, a range of 9 to 38 min (20.5 mean) was recorded for the stylets of A. fabae to reach the phloem sieve elements. This was consistent with our threshold of a 20-min acquisition access recorded through direct observation.     

加州新小绥螨对猎物的选择行为及其扩散行为

本文研究了柑橘全爪螨Panonychus citri （McGregor）不同螨态及其丝网对加州新小绥螨Neoseiuluscalifornicus的吸引作用和影响加州新小绥螨扩散行为的因素。结果表明,柑橘全爪螨完整丝网对加州新小绥螨吸引最强,在试验的5 h中,对加州新小绥螨吸引作用在第1 h效果显著,第2~5 h效果极显著,其中第3 h时的吸引作用最强达78.33%;柑橘全爪螨雌成螨、若螨和幼螨对加州新小绥螨均具有不同强度的吸引能力,吸引作用最强时分别达76.67%、71.67%和68.33%;猎物密度影响不同取食经历下加州新小绥螨的扩散行为,其扩散时间与生境中的柑橘全爪螨卵初始密度呈正相关,处于饥饿状态和自身密度较高时会加速加州新小绥螨的扩散行为,加州新小绥螨雌后若螨扩散时间低于加州新小绥螨雌成螨。     

Yellow leaf curl and other virus diseases of tomato in Cyprus

Outdoor and greenhouse tomato plantings in the main production centres of Cyprus were surveyed for virus diseases during 1978–1982. A disease characterized by prominent leaf yellowing and curling was the most prevalent and damaging. The causal agent was identified as tomato yellow leaf curl virus (TYLCV) because it infected Datura stramonium but not the tobacco cultivars Havana 423 or Virginia, was graft-transmissible but not mechanically or seed-transmissible, and was transmitted persistently by the tobacco whitefly, Bemisia tabaci. Minimum acquisition and inoculation feeding periods were 20–30 and 10–20 min. respectively; the latent period was 21–24 h. The vector was infective for about 12 days, but there was no transovarial transmission to progeny.
Four other, mechanically transmissible, viruses were also isolated from tomato and identified on the basis of symptomatology, indicator host reactions and serology; tobacco mosaic virus (TMV), potato virus Y (PVY). potato virus X (PVX), and cucumber mosaic virus (CMV). These viruses, especially TMV, were commonly associated with mosaic symptoms and occasionally with other leaf or fruit disorders; coinfection with TYLCV occurred frequently.