Transmission of plum pox potyvirus in Spain1

Transmission tests were conducted in the laboratory to determine which are the aphid species responsible for the great natural spread of plum pox potyvirus (PPV) observed in the field in Spain. Woody hosts were used in these tests and different transmission techniques were compared. The aphid species tested were Myzus persicae, Aphis gossypii, A. spiraecola, A. fabae, Hyalopterus pruni and Brachycaudus prunicola. Although the transmission rates obtained were, in general, quite low, it can be stated that, except for B. prunicola (pending confirmation of results), all species tested transmitted PPV under the conditions of the trial.     

Transmission efficiency of Cucumber mosaic virus by aphids associated with virus epidemics in snap bean

Cucumber mosaic virus (CMV) is a major component of the virus complex that has become more pronounced in snap bean in the midwestern and northeastern United States since 2001. Multiple-vector-transfer tests were done to estimate the CMV transmission efficiencies (p) of the main aphid species identified in commercial snap bean fields in New York and Pennsylvania. The four most efficient vectors (p > 0.05) were Aphis gossypii, A. glycines, Acyrthosiphon pisum, and Therioaphis trifolii, which were all significant species in the migratory aphid populations in snap bean. Moderately efficient vectors (0.01 < p < 0.04) were A. spiraecola, A. craccivora, Macrosiphum euphorbiae, and Rhopalosiphum maidis. Poor vectors (p < 0.01) included A. fabae, Nearctaphis bakeri, and Myzus persicae. Only one species, Sitobion avenae, failed to transmit CMV in replicated tests. Estimates of p were consistent between different clones of the same aphid species and among three different field isolates of CMV tested. Single-vector-transfer test results for a subset of the species supported those obtained via the multiple-vector-transfer approach. Our results are consistent with the notion that A. glycines is a major vector of recent CMV epidemics in snap bean, but that species is only one of several that are involved.     

Molecular, ultrastructural, and biological characterization of Pennsylvania isolates of Plum pox virus

Plum pox virus (PPV) was identified in Pennsylvania in 1999. The outbreak was limited to a four-county region in southern Pennsylvania. Initial serological and molecular characterization indicated that the isolates in Pennsylvania belong to the D strain of PPV. The Pennsylvania isolates were characterized by sequence analysis, electron microscopy, host range, and vector transmission to determine how these isolates related to their previously studied European counterparts. Genetically, Pennsylvania (PPV-Penn) isolates were more closely related to each other than to any other PPV-D strains, and isolates from the United States, Canada, and Chile were more closely related to each other than to European isolates. The PPV-Penn isolates exist as two clades, suggesting the possibility of multiple introductions. Electron microscopy analysis of PPV-Penn isolates, including cytopathological studies, indicated that the virions were similar to other Potyvirus spp. PPV-Penn isolates had a herbaceous host range similar to that of European D isolates. There were distinct differences in the transmission efficiencies of the two PPV-Penn isolates using Myzus persicae and Aphis spiraecola as vectors; however, both PPV-Penn isolates were transmitted by M. persicae more efficiently than a European D isolate but less efficiently than a European M isolate.     

Stability of the aphid transmission phenotype in cucumber mosaic virus

The stability of the aphid transmission phenotype in seven field isolates of cucumber mosaic virus (CMV) was studied, using aphids Aphis gossypii and Myzus persicae . Field isolates, obtained from four vegetable crops, were propagated in squash and Nicotiana glutinosa , and passaged by either aphid transmission or mechanical transfer. All seven isolates were transmissible by both aphids and this aphid transmission phenotype was stable after 20–24 mechanical passages. Upon further mechanical passaging, one of the seven isolates, CMV-2 A1-MT 60x, lost its transmissibility by Myzus persicae but was still transmissible by Aphis gossypii , although at a reduced rate. Isolates maintained by both aphid transmission and mechanical transfer were transmitted more efficiently by Aphis gossypii than by Myzus persicae . A comparison of the RNA profiles showed no major differences among the CMV isolates before and after mechanical passage.     

Evaluation of peach and nectarine cultivars in Bulgaria for their resistance to plum pox potyvirus

In spring and summer 1989, it was established that plum pox potyvirus (PPV) was present in certain peach cultivars in Bulgaria. At the same time, we started to investigate the distribution of PPV in naturally infected 4–5 year-old peach and nectarine cultivars and hybrids in order to optimize PPV detection. Over 160 peach and nectarine cultivars and hybrids were evaluated. In about 40% of the genotypes, typical plum pox symptoms were observed. The latter were estimated and divided into groups depending on their susceptibility to PPV. Observations were made on the population density of seven aphid species established in the peach orchards. Five proved to be vectors of the virus. Myzus persicae was the vector that played the main role in spreading the virus on peach.     

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.     

Epidemiology of sharka disease in Spain

PPV was first detected in Spain in 1984 in Japanese plum ( Prunus salicina Lindl) cv. Red Beaut and spread very quickly to other Japanese and European plums and apricot cultivars but left peach cultivars unaffected. In the years following the detection of PPV, the predominant aphid species visiting Prunus orchards in Mediterranean areas were Aphis gossypii followed by Aphis spiraecola , the latter being the main aphid species found at present. Both species are considered to be the main vectors of PPV in Spanish early Prunus growing areas. Spatial analysis of the spread of PPV-D in Japanese plum and apricot trees confirmed the lack of significant association between immediately adjacent trees. The observed spatial pattern of sharka suggests a lack of movement of PPV-viruliferous aphid vectors to immediately adjacent trees and indicates their preferential movement to trees several tree spaces away. PPV-D is the only type currently present in Spain, with the exception of a PPV-M outbreak that was detected in and successfully eradicated from Aragón in 2002. The short-distance spread of PPV-M infection occurred as far as 12 m along the rows of peach trees. However, PPV-D has not been observed to spread through peach cultivars, despite being grown in the vicinity of heavily infected plots of apricot or Japanese plum trees.     

Aphid and host plant species in the Arava Valley of Israel: Epidemiological aspects

A survey of aphid species which colonize or reproduce on wild and cultivated plants in the Arava Valley of Israel was carried out at the end of winter 1986. Thirty-three aphid species were collected on wild plants and 23 in green tile or yellow traps exposed in cultivated plots. Aphids were recorded from 77 plant species in 22 botanical families.Myzus persicae, Aphis craccivora, Brachyunguis harmalae, Acyrthosiphon gossypii andAphis gossypii were present on plants in 19 botanical families. M. persicae was the most frequently trapped aphid species in both green tile and yellow traps. The possible origin of the aphid species found in the desert was considered in view of the ecology and geography of the region. The role of aphid species trapped in the Arava Valley, in the epidemiology of potato virus Y (PVY) and zucchini yellow mosaic virus (ZYMV), is discussed. Publication of the Agricultural Research Organization. No. 2305-E, 1988 series.     

芝麻上花生条纹病毒的发生规律

ＥＬＩＳＡ和生长法检测结果表明,芝麻种不种传ＰＳｔＶ,感染ＰＳｔＶ的花生是芝麻黄花叶病毒病的主要初侵染源。桃蚜、豆蚜和大事蚜能传播芝麻上ＰＳｔＶ,传毒率分别为３７％、１９．３％和１３．８％,而经为０。黄花叶病害流行程度肥芝麻生育期蚜虫发生量互作作用影响。芝麻黄花叶病害年度间流行程度差异大,发病率与６月下旬７月上旬平均气温、降雨量及雨日在。芝麻苗期至蕾期为感病生育期,进入开花后期,芝麻对ＰＳｔＶ 表     

Characterization of an isolate of beet mosaic virus from South Kazakhstan

A filamentous virus isolated from a sugar-beet plant showing systemic mosaic collected in South Kazakhstan was identified as an isolate of beet mosaic virus (BMV-K). BMV-K was transmitted by the green peach aphid Myzus persicae in a non-persistent manner, and by sap inoculation to 11 out of 19 species from seven families tested. The virus could not be transmitted to Nicotiana tabacum, N. debneyi, N. glutinosa and N. clevelandii, cither mechanically or with M. persicae. The thermal inactivation point of BMV-K in sugar-beet sap was 55-60 C, dilution end point 1:1000 and longevity in vitro 2 days at 20 C. A purification procedure produced 1-5-3 mg of purified virus from 100 g of infected Stellaria media plants. Purified virus contained a single protein species of molecular weight 34 700 Da. In ELISA tests, BMV-K reacted positively with BMV-specifc antisera obtained from Japan. Germany and Portugal. By competitive DAS- ELISA, the virus isolate was shown to be closely serologically related to all the three isolates of BMV, and very distantly related to bean yellow mosaic and soy bean mosaic viruses.     

贵州省烟田蚜虫的种类和田间定殖情况

研究了贵州省烟田蚜虫的种类,结果表明:迁入到烟田的蚜虫隶属9种,其中桃蚜(Myzus persicae)、甘蓝蚜(Brevicoryne brassicae)、豆蚜(Aphis craccivora)、萝卜蚜(Lipaphis erysimi)、麦长管蚜(Macrosiphum miscanthi)占诱集蚜量的90%以上,尤以桃蚜数量最大,是烟田传播病毒病的主要蚜种,能传播多种烟草病毒病。试验结果还表明,单作烟田和毗邻油菜的烟田病毒病发病较高,麦套烟的发病较轻;甘蓝蚜、豆蚜和萝卜蚜基本上不能在烟叶上定殖。     

Serological detection of plant viruses in their aphid vectors and host plants in Tunisia

DAS-ELISA was used to study the presence of viruses in four aphid species ( Aphis gossypii , Aphis craccivora , Myzus persicae and Macrosiphum euphorbiae ) and in their host plants potato, capsicum and tomato. Samples were collected in different regions in Tunisia: north, Cap Bon, Sahel, centre and south. A. gossypii and M. persicae carried all the viruses detected: Cucumber mosaic cucumovirus , Tomato aspermy cucumovirus , Tobacco etch potyvirus , Potato Y potyvirus , Alfalfa mosaic alfamovirus and Potato leafroll polerovirus . These two aphids were also those that occurred most frequently on the crops concerned.     

Laboratory evaluation of temperature effects on the germination and growth of entomopathogenic fungi and on their pathogenicity to two aphid species

As part of an approach to select potential mycoinsecticides for aphid biocontrol, we investigated the effects of temperature on the growth, germination and pathogenicity of some hyphomycete fungi. Commercially available mycoinsecticides (based on Beauveria bassiana (Balsamo) Vuillemin and Verticillium lecanii (Zimmermann) Viegas) and other isolates of B bassiana, V lecanii, Metarhizium anisopliae (Metschnikoff) Sorokin and Paecilomyces fumosoroseus (Wize) Brown & Smith were evaluated. The rate of in vitro conidial germination of all isolates was slower at 10 and 15 degrees C than at 20 and 25 degrees C. Similarly, in vitro growth of most isolates was adversely affected at 10 and 15 degrees C. The greatest reduction at 10 degrees C in rates of conidial germination and colony growth, compared with other temperatures, was for M anisopliae isolates. Germination of V lecanii (isolate HRI 1.72) was fastest at 10 degrees C compared with the other fungi. It was also the most pathogenic of three isolates tested against Aphis fabae Scopoli and Myzus persicae Sulzer at 10, 18 and 23 degrees C. Generally, A fabae was more susceptible than M persicae to infection by the fungal isolates tested. A significant interaction between aphid species and temperature indicated that the pathogenic nature of an isolate was dependent not only on the target aphid species but also the temperature conditions of the bioassay. The series of studies, detailed above, allowed a temperature profile to be formed for the different isolates. Verticillium lecanii isolate HRI 1.72 (commercialised as Vertalec) was the most promising isolate selected from results of the series of experiments. Temperature profiles in conjunction with infectivity assays can be useful in selecting appropriate isolates for a particular thermal environment.     

一种蚜虫持久性传病的长豇豆黄化型病毒

 1983年6月,在南京郊区的长豇豆上采到1株表现植株矮缩症状的C-7病毒分离物。接种试验证明,它不能摩擦接种传病,但可以由豆蚜(Aphis craccivora)、棉蚜(A.gossypii)和桃蚜(Myzus persicae)以持久性方式传病。寄主范围测定的结果表明:分离物可以侵染长豇豆、豇豆、蚕豆、大豆、菜豆、豌豆、赤豆、利马豆、苜蓿、红三叶、地三叶、绛三叶、葫芦巴,紫云英和苕子等15种豆科植物和曼陀罗1种茄科植物。这些植物大都出现植株矮化,叶片扭曲,卷缩或僵缩,不能开花结实等症状。豆蚜的传病性状中,获毒饲育的最短传病时间为3小时,接毒饲育最短传病时间为10分钟,循回期是24小时左右。但是,传病率最高的获毒饲育时间是2~3天,接毒饲育时间在1天以上。接种1头蚜虫就具有传病能力,5头蚜虫能达到100%的传病率。蚜虫可以终身传毒,蜕皮不影响其传毒力,但传毒有间歇性。根据它的基本性状,病毒C-7分离物是一种豆科植物的黄化型病毒,可能是属于大麦黄矮病毒组(Luteovirus Group)的成员。     

Use of insect antifeedants against aphid vectors of plant virus disease

The probing and feeding behaviour of aphids can result in uptake of viruses from infected plants and subsequent transmission to healthy plants. It is possible to interfere with virus acquisition and transmission by influencing aphid host-selection and feeding behaviour with antifeedant chemicals. Published work is reviewed and new work is presented in this paper. The two most successful classes of antifeedants against aphids are (a) compounds derived from the aphid alarm pheromone and (b) plant-derived antifeedants such as the sesquiterpene (-)-polygodial. Results with these and other compounds are discussed in terms of antifeedant activity against Myzus persicae, their effects on resistant aphids and the evidence for dec?ease in virus spread by aphids in laboratory and field.     

不同温度下转换寄主对桃蚜生态学特征的影响

在5种温度、4组寄主与蚜源组合处理条件下研究了温度对转换寄主后的桃蚜的影响。同一寄主间移植的桃蚜在有效积温、发育起点温度、生殖率、死亡率、寿命以及抗逆性上与不同寄主间移植的桃蚜有明显的差异;寄主对桃蚜生物学、生态学特征有明显的影响,表明长期生活在一种寄主上的桃蚜获得了一定的专化性。若将其移植到另一种寄主上,则会表现出种种不适反应,但这种反应还未进化至型或寄主生殖隔离。     

四种杀虫剂对桃蚜和异色瓢虫的选择毒性及 害虫生物防治与化学防治的协调性评价

测定了吡虫啉、鱼藤酮、阿维菌素和印楝素4种杀虫剂对桃蚜及其捕食性天敌异色瓢虫成虫的相对毒力。4种药剂对桃蚜的毒力大小依次为阿维菌素＞吡虫啉＞鱼藤酮＞印楝素,其LC50分别为0.042、1.96、6.54和10.17 mg/L。对异色瓢虫的LC50则分别为1009.42、201.89、8202.90和大于7500 mg/L,益害毒性比分别为24033.81、103.01、1254.27和大于786.63。4种药剂在有效防治桃蚜的前提下对天敌异色瓢虫的安全性依次为阿维菌素＞鱼藤酮＞印楝素＞吡虫啉。阿维菌素、吡虫啉、印楝素和鱼藤酮这4种药剂均可在蚜虫综合治理中发挥有效的作用。     

Effects of liquid vermicompost and synthetic NPK fertilizer sources on Myzus persicae Sulzer (Aphididae: Hemiptera) fed on tobacco

Journal of Plant Diseases and Protection - Green peach aphid (Myzus persicae Sulzer (Aphididae: Hemiptera)) is a polyphagous&nbsp;pest that causes economic losses in the tobacco. In addition to...     

Hairy nightshade as a potential Potato leafroll virus (Luteoviridae: Polerovirus) inoculum source in Pacific Northwest potato ecosystems

Hairy nightshade, Solanum sarrachoides, is a solanaceous weed found abundantly in Pacific Northwest potato ecosystems. It serves as a reservoir for one of the important potato viruses, Potato leafroll virus (PLRV) (Luteoviridae: Polerovirus), and its most important vector, the green peach aphid, Myzus persicae (Homoptera: Aphididae). Laboratory research indicated an increased green peach aphid settling and performance on S. sarrachoides than on potato. It also revealed that green peach aphids transmitted PLRV more efficiently from S. sarrachoides to potato than from potato to potato. To test the efficiency of S. sarrachoides as an inoculum source in the field, a two season (2004 and 2005) trial was conducted at Kimberly, Idaho. Two inoculum sources, PLRV-infected potato and PLRV-infected S. sarrachoides, were compared in this trial. Green peach aphid density and temporal and spatial PLRV spread were monitored at weekly intervals. Higher densities of green peach aphids were observed on plots with S. sarrachoides and inoculum sources (PLRV-infected S. sarrachoides and potato) than on plots without S. sarrachoides and inoculum sources. PLRV infection in plots with PLRV-infected S. sarrachoides was similar to or slightly higher than in plots with PLRV-infected potato as an inoculum source. Temporal and spatial PLRV spread was similar in plots with either inoculum source. Thus, S. sarrachoides is as efficient as or a better PLRV inoculum source than potato.     

Analysis of insecticide-resistant Myzus persicae (Sulzer) populations collected in Italian peach orchards

Several populations of the green peach aphid, Myzus persicae (Sulzer), were collected in the most important Italian peach-growing areas. In these populations, collected as primary colonies or as secondary ones, total esterase content and acetylcholinesterase sensitivity towards pirimicarb was assessed using biochemical assays. Most of the individuals analysed generally exhibited an elevated esterase content, and in some cases acetylcholinesterase insensitivity. The implications of resistance levels and distribution on M persicae control strategies are discussed.