The biological transmission of potato leafroll virus by Myzus persicae

The ability of the green peach aphid,Myzus persicae, to transmit potato leafroll virus after a six-hours' acquisition feeding period on leafroll-diseased plants ofPhysalis floridana, followed by a feeding for different lengths of time on Chinese cabbage (Brassica pekinensis) was determined. Virus transmission was optimally efficient at about the ninth day after aphid birth. If after a one-hour acquisition feeding period on a virus source the aphids were starved for different numbers of days at 4°C, the efficiency increased with increasing starvation periods. Starvation at 4°C prior to the one-hour acquisition feeding period had no effect on the ability to transmit the virus. Starvation of larvae at 4°C did not prevent them completing their larval stage in about 9–10 days when transferred to plants at 20°C.Samenvatting Het vermogen van de groene perzikluis,Myzus persicae, om het aardappelbladrolvirus over te brengen werd gedurende haar leven nagegaan. Daartoe werden pasgeboren luizen zes uur op een bladrolzieke plant vanPhysalis floridana gezet en daarna op Chinese kool. Vervolgens werden de luizen op verschillende tijden gedurende 24 uur getoetst op zaailingen vanP. floridana. Het bleek dat maximale virusoverdracht doorM. persicae plaatsvond op de negende dag na infectie (Fig. 1). Tevens werd gevonden dat het vermogen van virusoverdracht door de luis werd verhoogd wanneer ze na een opneemperiode van 1 uur op een virusbron werden weggezet bij 4°C zonder voedsel. Werden de luizen vóór de opneemperiode van 1 uur op de virusbron weggezet bij 4°C zonder voedsel, dan bleek deze behandeling geen invloed te hebben op de virusoverdracht (Fig. 2, zie^*). Een opneemperiode op de virusbron van 4 uur of langer en een verblijf bij 4°C zonder voedsel, had eveneens géén invloed op de virusoverdracht (Tabel 1).     

Virus transmission by aphids in potato crops

This paper reviews the contribution of vector activity and plant age to virus spread in potato crops. Determining which aphid species are vectors is particularly important for timing haulm destruction to minimize tuber infection by potato virus Y (PVY). Alate aphids of more than 30 species transmit PVY, and aphids such asRhopalosiphum padi, that migrate in large numbers before flights of the more efficient vector,Myzus persicae, appear to be important vectors. Differences in methodology, aphid biotypes and virus strains prevent direct comparisons between estimates of vector efficiencies obtained for aphids in different countries in north western Europe. M. persicae is also the most efficient vector of potato leafroll virus (PLRV), but some clones ofMacrosiphum euphorbiae transmit PLRV efficiently toNicotiana clevelandii and potato test plants. The removal of infected plants early in the season prevents the spread of PLRV in cool regions with limited vector activity. The proportion of aphids acquiring PLRV from infected potato plants decreases with plant age, and healthy potato plants are more resistant to infection later in the season. Severe symptoms of secondary leafroll developed on progeny plants of cv. Maris Piper derived from mother plants inoculated with PLRV in June or July of the previous year. Progeny plants derived from mother plants inoculated in August showed only mild symptoms, but the concentration of PLRV in these plants was as high as that in the plants with severe symptoms.     

新疆大白菜病毒病与甘蓝蚜的关系

甘藍蚜、桃蚜和棉蚜的有翅型与无翅型,均能传播大白菜病毒病,其中以甘藍蚜为最主要的传毒介体。一头带毒蚜可使80％的健苗发病;一头无毒蚜經吸毒一分钟的传病率为35％;健苗經一头有毒蚜传毒一分钟,就有10％发病。病毒系非持久性的,蚜虫一次吸毒后的传毒期限为25分钟左右。在烏魯木齐地区,有翅甘藍蚜全年中的迁飞高峯期,都是在7月下旬。証实了这时期与大白菜病毒病的流行,有极密切的关系。当年春、夏季播种的甘蓝和苤藍,尤其是晚甘蓝和晚苤蓝,是大白菜(包括冬蘿卜)苗期的初次毒源和蚜源。初步認为,能感染病毒的几种十字花科及藜科杂草,不是本病病毒和甘藍蚜的重要越夏寄主。     

Virus transmission by aphids in potato crops

This paper reviews the contribution of vector activity and plant age to virus spread in potato crops. Determining which aphid species are vectors is particularly important for timing haulm destruction to minimize tuber infection by potato virus Y (PVY). Alate aphids of more than 30 species transmit PVY, and aphids such asRhopalosiphum padi, that migrate in large numbers before flights of the more efficient vector,Myzus persicae, appear to be important vectors. Differences in methodology, aphid biotypes and virus strains prevent direct comparisons between estimates of vector efficiencies obtained for aphids in different countries in north western Europe.M. persicae is also the most efficient vector of potato leafroll virus (PLRV), but some clones ofMacrosiphum euphorbiae transmit PLRV efficiently toNicotiana clevelandii and potato test plants. The removal of infected plants early in the season prevents the spread of PLRV in cool regions with limited vector activity. The proportion of aphids acquiring PLRV from infected potato plants decreases with plant age, and healthy potato plants are more resistant to infection later in the season. Severe symptoms of secondary leafroll developed on progeny plants of cv. Maris Piper derived from mother plants inoculated with PLRV in June or July of the previous year. Progeny plants derived from mother plants inoculated in August showed only mild symptoms, but the concentration of PLRV in these plants was as high as that in the plants with severe symptoms.     

The effects of <Emphasis Type="Italic">Gibberella zeae</Emphasis>, <Emphasis Type="Italic">Barley Yellow Dwarf Virus</Emphasis>, and co-infection on <Emphasis Type="Italic">Rhopalosiphum padi</Emphasis> olfactory preference and performance

Insect-borne viruses promote several changes in plant phenotype, which can modify plant-vector interactions in favor of virus survival and dissemination. Although co-infections commonly occur in the field, little is known about their effects on interactions with the vector. The ecological interactions between Barley Yellow Dwarf Virus (BYDV) and its aphid vector, Rhopalosiphum padi, have been investigated extensively, but the vector’s behavior in more complex scenarios has yet to be examined. We assessed olfactory response and performance of R. padi to wheat singly and doubly infected by the pathogenic fungus Giberella zeae and BYDV. Non-viruliferous aphids preferred odors of BYDV-infected wheat over healthy wheat, as previously reported in the literature, and they were still preferentially attracted to BYDV-infected plant during co-infection. However, around 35% more non-viruliferous aphids chose healthy wheat over G. zeae-infected wheat. Viruliferous aphids did not show any preference to the treatments. BYDV-infected wheat was a superior host than healthy wheat for the aphids whose population increased in 25%. We observed a synergistic effect of the co-infected wheat, which was the best host for aphids, and promoted an elevation of 42% on population growth. Our results indicate that co-infection might be beneficial for virus spread as does not interfere with aphid olfactory preference and provides greater colony growth than in singly infected plants.     

芜菁花叶病毒(白菜孤丁株系)对白菜生理的影响及其与桃蚜的关系

1962年飼养并系統观察桃蚜 Myzus persicae (Sulzer) 在感染蕪菁花叶病毒(TpMV)的和健康的大白菜上的发生結果表明,病株对桃蚜不利。接种后24天,健株上的蚜虫数量为病株的1.8倍;健株上有翅若蚜占总蚜量的9.8％,而病株上达16.3％。 1964年比較测定了健株与具有不同症状(初現明脉、明显花叶、叶片严重皺縮)白菜苗的(1)含糖量、(2)全氮(可溶性氮)及非蛋白氮,以此算出蛋白氮含量、(3)細胞渗透压、吸水压,并以此算出細胞膨压。結果表明,病株比健康植株含糖量增加36.59—41.95％;全氮量与非蛋白氮含量均下降,其中非蛋白氮減少更多:由初現明脉期降低5.0％至叶片严重皺縮期降低86.7％,而蛋白氮初期有下降,后期又逐渐回升。病株的細胞渗透压增加了2％—5％,吸水压增加14.3％—42.9％,細胞膨压則下降36.3％—500.7％。从結果分析和有关文献佐証,作者認为病株不利于桃蚜的发生是由于糖/氮比增高,細胞膨压下降的結果,前者影响蚜虫的营养,后者影响蚜虫的取食量。     

Transmission biology of Raspberry latent virus, the first aphid-borne reovirus

Raspberry latent virus (RpLV) is a newly characterized reovirus found in commercial raspberry fields in the Pacific Northwest (PNW). Thus far, all members of the plant reoviruses are transmitted in a replicative, persistent manner by several species of leafhoppers or planthoppers. After several failed attempts to transmit RpLV using leafhoppers, the large raspberry aphid, commonly found in the PNW, was tested as a vector of the virus. The virus was transmitted to new, healthy raspberry plants when inoculated with groups of at least 50 viruliferous aphids, suggesting that aphids are vectors of RpLV, albeit inefficient ones. Using absolute and relative quantification methods, it was shown that the virus titer in aphids continued to increase after the acquisition period even when aphids were serially transferred onto fresh, healthy plants on a daily basis. Transmission experiments determined that RpLV has a 6-day latent period in the aphid before it becomes transmissible; however, it was not transmitted transovarially to the next generation. To our knowledge, this is the first report of a plant reovirus transmitted by an aphid. Phylogenetic analyses showed that RpLV is related most closely to but distinct from Rice ragged stunt virus (RRSV), the type member of the genus Oryzavirus. Moreover, the conserved nucleotide termini of the genomic segments of RpLV did not match those of RRSV or other plant reoviruses, allowing us to suggest that RpLV is probably the type member of a new genus in the Reoviridae comprising aphid-transmitted reoviruses.     

水稻锯齿叶矮缩病毒对褐飞虱生长发育和生殖的影响

为明确水稻锯齿叶矮缩病毒（rice ragged stunt virus,RRSV）对褐飞虱Nilaparvata lugens生长发育和生殖的影响,分别比较带毒褐飞虱与未带毒褐飞虱的若虫发育历期、成虫寿命、性比、翅型及产卵量,并利用实时荧光定量PCR（real-time quantitative PCR,RT-qPCR）技术分析RRSV侵染后褐飞虱体内卵黄原蛋白（vitellogenin,Vg）与其受体（vitellogenin receptor,VgR）以及海藻糖代谢途径中相关基因表达量的情况。结果显示,带毒褐飞虱的若虫历期显著高于未带毒褐飞虱的若虫历期,分别为17.56 d和15.90 d;带毒褐飞虱的成虫寿命、雌虫比例和短翅比例均高于未带毒褐飞虱的,但两者间均无显著差异;带毒褐飞虱较未带毒褐飞虱单雌日产卵量显著提升,分别为11.26粒和6.45粒;带毒褐飞虱的Vg、VgR和海藻糖转运蛋白基因（trehalose transporter,TRET）表达量均显著高于未带毒褐飞虱的。表明RRSV侵染会显著延长褐飞虱若虫发育历期,同时可能通过上调Vg、VgR以及TRET的表达量以促进褐飞虱生殖。     

Korte overdrachttijd van bladrolvirus

Conclusie Uit de bovenbeschreven infectieproeven is dus wel duidelijk aan het licht gekomen, dat de overdracht van het bladrolvirus in zeer korte tijd kan plaats vinden, naarPhysalis in ieder geval in een half uur. Hiermee zal rekening moeten worden gehouden bij de virusbestrijding. Hoe men deze snelle overdracht zal moeten interpreteren in verband met de verdere eigenschappen van het bladrolvirus, dat in allerlei opzichten overeenkomt met andere persistente viren, zal nader moeten worden onderzocht.Summary Groups of 5 virus freeMyzus persicae (Sulz.), which were not starved, were used in experiments to transmit leafroll virus. An acquisition period of 15 minutes on leafroll-infectedPhysalis floridana, followed immediately by an inoculation-period of 15 minutes onP. floridana seedlings, proved to be long enough for the transmission of leaf-roll virus: 31 out of 45 test plants ofP. floridana became infected. In the same way 11 out 18 of healthyP. floridana plants were infected when potato was used as a leafroll-source.     

Evidence of no horizontal or vertical transmission of tomato severe rugose virus by Bemisia tabaci MEAM1

Bemisia tabaci is important in agriculture worldwide, mainly because it is a vector of numerous plant viruses, probably the most important of which are members of the genus Begomovirus. Dozens of begomoviruses have been reported to infect tomato plants in Brazil, although tomato severe rugose virus (ToSRV) predominates in tomato crops. ToSRV, found so far only in Brazil, is efficiently transmitted by B. tabaci MEAM1. However, no studies have assessed the occurrence of vertical and horizontal transmission of the virus in the insect, which may have epidemiological consequences affecting disease management. This study evaluated the possibility of transmission of ToSRV between whiteflies during copulation and transovarial transmission from viruliferous females of B. tabaci MEAM1 to their progeny. Transmission of ToSRV did not occur during mating between males and females of B. tabaci MEAM1. Aviruliferous males and females confined with viruliferous insects of the opposite sex were also unable to transmit the virus to tomato plants. ToSRV was detected, by PCR, in the ovaries of viruliferous females of B. tabaci MEAM1 but not in eggs, nymphs, or adults of the progeny of viruliferous females. Adult progeny of viruliferous females also did not transmit ToSRV to tomato plants. Together, the results indicate that vertical and horizontal transmission of ToSRV by B. tabaci MEAM1 is unlikely. Sustainable management of the tomato golden mosaic disease caused by ToSRV should continue to focus on using resistant varieties, managing sources of inoculum around tomato fields, and rational chemical control of the vector.     

柑桔黄龙病的媒介昆虫及指示植物的试验初报

根据試驗結果,初步認为柑桔黃龙病可借东方桔蚜传病,其指示植物为由力克檸檬、北京香檸檬和墨西哥来檬等1—2月龄的实生幼苗。在这些指示植物和蕉柑幼苗上,用东方桔蚜传病以及用嫁接法传病所引起的症状均相同:在由力克檸檬和蕉柑上表現矮化及梢叶黄化;在北京香檸檬和墨西哥来檬上表現矮化、明脉和“嵌紋”等。同时,在北京香檸檬上,以蚜传发病植株的組織,进行回接的試株和以广州及普宁县病株的組織进行嫁接的試株,有些发生木质部陷点及木质部陷紋的症状。根据这些特点,虽然不能肯定柑桔黄龙病与南美洲柑桔衰退病的病原病毒相同,但它們很可能屬于同一类病毒(却柑桔衰退病毒类)。此病在指示植物上的潛育期最短为27天。在11月气温較低时的潛育期长达二个月以上。5月分在网罩内气温高达42℃,发病試株在一周内消失症状并恢复生长,但試株移到树蔭下(气温降低到25°—30℃左右),一个月内症状又重新出現。     

小麦丛矮病毒对传毒介体灰飞虱影响的研究

 小麦丛矮病毒对传毒介体灰飞虱的有害影响,表现在:使带毒若虫历期延长5.3天,羽化前死亡率比无毒虫高一倍以上,并有3.3%的不羽化个体;使雌虫产卵前期延长1.4和3.5天,产卵天数少8.2和11天,寿命缩短6.5和15.4天,日平均产卵量少1.9粒,每头雌虫平均产卵量少95.4和107.7粒。病毒对子代无影响。
获得丛矮病毒的介体表现抗御低温能力差,如在田间、不加温的温室越冬,长期在0~-4℃及-16~19℃、-21~-24℃各3小时的低温处理,带毒虫死亡率比无毒虫高25~35%。对湿度敏感,在RH 50% 24小时后带毒虫死亡率比无毒虫高10%。耐饥五天,春天带毒若虫死亡率比无毒虫高20%,夏天带毒成虫死亡率比无毒虫高25%,而雄虫耐饥力又比雌虫要差。     

Screening Lactuca for resistance to Myzus persicae

A macrotest was developed to screen rapidly many genotypes ofLactuca in the greenhouse for resistance toMyzus persicae. In this test the estimated number of aphids on certain leaves of plants artificially exposed to aphid infestation was representative for the total number of aphids per plant. Significant differences in resistance between genotypes were observed and several partially resistant PIVT numbers were found among 645 accessions tested in 1973 and 1974. Also a microtest with leaf cages was developed in which biomass after seven to eight days of larval development and net larvae production during four to seven days functioned as criteria of resistance. Besides differences between genotypes, also within plants and between plants of the same genotype significant differences were found to occur. After testing nineteen genotypes with different levels of resistance it appeared that there was a clear relationship between results from both types of tests.     

甘蓝蚜危害油菜产量损失的研究

作者用一种衡量蚜虫危害的新尺度——“累计蚜量(头/天)”,对油菜不同生育阶段的单株损失及补偿作用分别作了研究。结果表明:油菜苗期、苔花期、荚果期都存在着一个造成损失的临界危害量(C)。苗期 C 为360～440(头/天),苔花期 C 为13500～16500(头/天),荚果期 C 为2700～3300(头/天)。危害量与损失率的关系符合 logistic 曲线。根据研究结果提出“有害株”的概念,既有蚜虫而又影响产量的植株。并结合蚜虫消长规律及累计蚜量的计算原理推导出确定“有害株”蚜量标准的公式B=C/(1/2)T(1+Q~n)+ITQ(1-Q~(n-1))/(1-Q)经比较,认为“危害株率”是蚜虫防治指标理想的尺度,它不仅明确可靠,而且简单易行。     

Effect of azadirachtin applied systemically through roots of plants on the mortality,development and fecundity of the cabbage aphid (<Emphasis Type="Italic">Brevicoryne brassicae</Emphasis>)

The effect of low concentrations of azadirachtin applied systemically through root tissues of rape plants (Brassica napus subsp.napus) on the mortality, period of development, longevity and fecundity of the cabbage aphid (Brevicoryne brassicae L.) (Sternorrhyncha: Aphididae) was studied. The concentrations of azadirachtin A tested were: 0.25, 0.05, 0.005, 0.0005 and 0.00005 mg ml⁻¹. The mortality of cabbage aphid nymphs, particularly during the period of ecdysis, increased significantly with increasing concentrations. Azadirachtin had no effect on the length of the development period of the respective immature stages of cabbage aphids. The average longevity of the cabbage aphids decreased with increasing azadirachtin concentration and time spent feeding. The fecundity of aphids decreased after the application of azadirachtin. http://www.phytoparasitica.org posting May 6, 2004.     

Host plant preference of Diuraphis noxia (Kurdj.) (Hom., Aphididae)

Host plant preference of the Russian wheat aphid Diuraphis noxia (Kurdj.) was studied on 11 cultivars of 9 plant species: winter barley, spring barley, winter wheat, spring wheat, rye, oat, Triticale, canary grass, red millet yellow millet and maize. Seeds of the host plants were sown in a circle near the edge of pots. The host plant choice was evaluated 24 hours after releasing 55 Diuraphis noxia female adults in the middle of each pot. The suitability of different hosts for aphid development was evaluated 2, 7 and 14 days after infestation based on the mean number of Russian wheat aphid individuals per plant. Red millet, yellow millet and maize were chosen by significantly fewer aphids than grain crops. Winter and spring barley were chosen as hosts most frequently, and the progeny production was also the highest on these plants. The growth rate of D. noxia was significantly affected by the host plants and the date of assessment and their interaction.     

油菜品种抗蚜性多目标模糊综合决策

作者采用模糊统计回归法，建立了油菜品种的自然感蚜量、蚜虫在品种上的“累积存活率”，平均发育历期、平均产仔量、内禀增长率及品种耐害性、干扰效应等抗性指的模糊隶属函数，建立了品种抗蚜性的模糊综合决策模型。结果表明，１２个品种抗性强弱为：红叶芥＞咸阳７４－１＞甘油５号＞８８６３１＞７２１１＞７５－１＞波力木耳＞８８６３８＞德国１５选株＞华油９号＞秦油３号＞秦油２号。同时作者提出的一套衡量品种抗性的指禁     

The effects of co‐infection by different Potato virus Y (PVY) isolates on virus concentration in solanaceous hosts and efficiency of transmission

The influence of co‐infection on concentration and accumulation of genetically different isolates of Potato virus Y (PVY) in potato and tobacco plants and the efficiency of transmission by Myzus persicae of PVY isolates from doubly versus singly infected plants were evaluated. The vector ability to simultaneously transmit two virus isolates was examined. Eight PVY isolates represented three strain groups: PVY^O (pathotype and serotype O), PVY^NW (pathotype N and serotype O), and PVY^NTN (pathotype and serotype N). Different diagnostic methods, including DAS‐ELISA, multiplex RT‐PCR, aphid transmission tests and bioassays, were applied to detect the presence of PVY isolates in source and assay plants. Significant reductions in concentrations of certain PVY isolates during co‐infection with other isolates were found both in potato and tobacco plants. The observed effects were both isolate‐ and host‐dependent in form. The highest rates of virus transmission by single aphids were recorded with PVY^NTN isolates, and the lowest ones with PVY^O isolates. Individual aphids of M. persicae were able to simultaneously transmit two PVY isolates. The frequency of transmission was generally low, but it reached as high as 20% for one of the isolate combinations. The findings presented in the work provide proof for antagonistic within‐plant interactions between isolates of PVY, with some implications of these interactions for virus transmission by aphid vectors. Consequently, this research contributes to a better understanding of the epidemiology of the disease caused by PVY.     

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。