蚜虫传播非持久性病毒的取食行为调控机制

蚜虫能够传播上百种植物病毒，是最重要的农业介体昆虫之一。蚜虫在刺探和取食植物过程中，唾液组分会连同附着在口针中的病毒粒子一同被分泌进入植物内，在调节植物诱导抗性、病毒侵染扩散、介体昆虫行为等过程中均有重要作用。本文围绕蚜虫传播病毒和获取病毒2个关键过程，总结分析了蚜虫独特的刺吸取食行为与传毒效率和获毒效率之间的联系；针对取食活动中关键的唾液蛋白在调控植物免疫抗性、帮助病毒侵染过程中的功能，阐述了蚜虫高效传播非持久病毒的分子基础；针对蚜虫的获毒过程，综述了病毒侵染植物间接调控蚜虫趋向和行为的作用方式。这些研究的开展将为解释蚜虫和病毒协同侵染的分子机制以及有效开展基于蚜虫取食行为调控的病虫害防控新技术提供思路。     

NS-83对桃蚜传播芜菁花叶病毒(TuMV)的作用

 1% NS-83乳剂喷布饲毒毒源芥菜(Brassica juncea)病株与检测植物油青菜(Brassica chinensis)植株,桃蚜传播TuMV受到了显著抑制,抑制效果为39.0%左右,但用乳化剂处理的植株未表现抑制作用。NS-83的抑制效果随使用乳剂中NS-83浓度升高而增加,随接种压力(每株传毒蚜虫数)增大而降低。桃蚜在传毒前、饲毒时和传毒时口针接触NS-83后,传播TuMV分别受到了41.8,29.4和14.1%的抑制。NS-83以不同方式处理饲毒株与传毒株,抑制效果不同,结果表明NS-83在TuMV一桃蚜复合关系中起作用。用1% NS-83乳剂涂抹芥菜叶片6、12、24、48小时后,桃蚜在上面的探食(试探取食)行为发生了显著的改变,表现在所观察的探食时间的缩短及两次探食间爬行时间的延长。     

Divergent effects of PVY-infected potato plant on aphids

Host plant selection by aphids can be positively or negatively affected when plants are infected by phytoviruses. Potato plants infected by Potato virus Y (PVY), a non-persistent virus, are reported to affect settling behaviour and growth parameters of Myzus persicae Sulzer and Macrosiphum euphorbiae Thomas. Using the Electrical penetration graph system (EPG), we demonstrated that PVY-infection of potato plants influences the feeding behaviour of these two aphid species. Myzus persicae exhibited increased phloem sap ingestion and reduced non-probing duration. Macrosiphum euphorbiae showed delayed stylet insertion, reduced activity in the phloem vessels and an enhanced non-probing duration. In addition, we showed that these two species exhibited different transmission rates. The opposite effects of PVY-infected potato plant on these two aphids are discussed in terms of PVY spreading in the field.     

Lethal and Sublethal Effects of Imidacloprid on Nicotine-Tolerant Myzus nicotianae and Myzus persicae

Bioassays of nicotine and imidacloprid against clones of Myzus persicae (Sulzer) and Myzus nicotianae (Blackman) from around the world demonstrated that some had low levels of resistance to both compounds. This was expressed not only as a reduced mortality, but more markedly as differential inhibition of feeding by imidacloprid concentrations in the parts per billion range. Such concentrations also reduced aphid fecundity by inhibiting the production and viability of nymphs, and this effect was more marked for susceptible aphids than for those showing reduced direct lethal and antifeedant effects.     

Pymetrozine,a Fast-Acting and Selective Inhibitor of Aphid Feeding. In-situ Studies with Electronic Monitoring of Feeding Behaviour

Pymetrozine, a pyridine azomethine compound, represents a novel insecticide with a selective activity against homopteran insects. It acts in a unique way: aphids are not knocked down on contact but seem to die of starvation. This implies an effect of pymetrozine on feeding behaviour. The aim of the present work was to elucidate how and at which step pymetrozine interferes with the complex mechanisms underlying phloem feeding. The effect of pymetrozine, applied in various ways, on different phases of stylet penetration and feeding activity of individual aphids was studied using the Electrical Penetration Graph technique (EPG). Initial choice experiments indicated that pymetrozine does not have a deterrent or antifeedant action. Topical application (150 ng pymetrozine mg^-1 fresh weight) inhibited stylet insertion into the plant. When injected, less than 30 ng mg^-1 was sufficient to produce the same effect. When pymetrozine was systemically applied via plant spraying or root uptake, aphids started feeding normally. After some time, however, they withdrew their stylets from the phloem and walked around with unaffected locomotion. At low doses aphids eventually recovered and resumed feeding. High doses, however, irreversibly disrupted feeding and prevented stylet reinsertion. Aphid motility was not affected up to an estimated haemolymph concentration of 1 mM pymetrozine. Aphids which eventually stopped feeding on pymetrozine-treated plants showed EPGs with distorted salivation/ingestion patterns. It is concluded that pymetrozine does not have a general toxic effect on aphids but selectively interferes with the nervous regulation of feeding behaviour which consequently results in death due to starvation after a few days. © 1997 SCI.     

Flonicamid, a novel insecticide with a rapid inhibitory effect on aphid feeding

Flonicamid (IKI220; N-cyanomethyl-4-trifluoromethylnicotinamide), a pyridinecarboxamide compound, is a novel systemic insecticide with selective activity against hemipterous pests, such as aphids and whiteflies, and thysanopterous pests. The purpose of this study is to clarify the biological properties of flonicamid against aphids. Flonicamid is very active against aphids, regardless of differences in species, stages and morphs. This compound inhibited the feeding behaviour of aphids within 0.5 h of treatment without noticeable poisoning symptoms such as convulsion, and this antifeeding activity was not recoverable until death. The nymphs born from adults exposed to flonicamid for 3 h showed high mortality. The effect of flonicamid on the feeding activity of an individual aphid was studied using electronic monitoring of insect feeding behaviour (EMIF). Although the treated aphid attached the head of its proboscis to the leaf surface, salivation and sap feeding were strongly inhibited. These results suggest that the main insecticidal mechanism of flonicamid is starvation based on the inhibition of stylet penetration to plant tissues.     

Transmission of barley yellow dwarf virus by cereal aphids collected from different habitats on cereal farms

Cereal aphids were collected from cereal crops, from Poa annua within cereal fields, from Lolium perenne pastures and from wild grasses in hedge bottoms and around farm buildings. The frequency of barley yellow dwarf virus (BYDV) transmission was assessed by aphid transmission tests. There were differences in transmission rates between aphid species, between host species and between years. The transmission rates of Rhopalosiphum padi from the different host species were broadly similar whereas for Sitobion avenae, P. annua within cereal fields was significantly better than the other host species. Wild grasses other than P. annua were relatively poor sources of virus. A large percentage of aphids frequently transmitted more than one strain, suggesting that host plants are often infected with more than one BYDV strain.     

人工饲料条件下大麦黄矮病毒GAV株系对麦长管蚜种群适合度的直接影响

植物病毒与介体蚜虫存在复杂的互作关系。前人关于植物病毒对蚜虫调控作用的研究主要集中在植物病毒通过寄主植物对蚜虫的间接影响上,未见植物病毒对介体蚜虫适合度直接调控的报道。鉴于此,我们以麦长管蚜Sitobion miscanthi (Takahashi)为试虫,以其传播的大麦黄矮病毒-GAV(Barley yellow dwarf virus GAV,BYDV-GAV)为测试病毒,以全纯人工饲料加入BYDV-GAV病毒提取液饲养麦长管蚜4 d,使之在不接触寄主植物条件下获毒,然后分别在全纯人工饲料和无毒小麦叶片上继续饲养,直至死亡。利用生命表技术分析麦长管蚜生长发育和繁殖参数。研究结果表明:在无毒小麦叶片饲养条件下,与未获毒对照麦长管蚜相比,获毒后麦长管蚜生活史参数成虫历期和产仔天数显著降低,繁殖力显著增加;种群参数内禀增长率、净繁殖率、周限增长率显著增加,平均世代周期显著降低。在全纯人工饲料条件下,与未获毒对照相比,获毒后麦长管蚜仅成虫历期和产仔天数显著下降,而其他生活史参数及种群参数均无显著差异。说明BYDV-GAV使得介体麦长管蚜在小麦叶片上的适合度显著提高,这是由麦长管蚜与寄主植物互作引起的,而病毒对介体麦长管蚜的适合度无直接调控作用。     

Transmissibility of Cucumber mosaic virus by Aphis gossypii Correlates with Viral Accumulation and Is Affected by the Presence of Its Satellite RNA

ABSTRACT Satellite RNAs (satRNAs) are associated with Cucumber mosaic virus (CMV) in tomato, most often causing severe epidemics of necrotic plants, and not associated with specific host symptoms. Laboratory studies on virus transmission by the aphid vector Aphis gossypii were performed to better understand the dynamics of field populations of CMV. The presence of satRNAs correlated with lower concentrations of virus in infected plants and with a decrease in the efficiency of transmission from satRNA-infected plants. Both the concentration of virus in CMV-infected tomato and the efficiency of transmission varied more extensively with nonnecrogenic satRNAs than with necrogenic satRNAs. A negative effect of satRNAs on virus accumulation can account, in part, for a decrease in the field transmission and recovery of CMV + satRNAs. Aphids behaved differently and probed less readily on plants infected with CMV + necrogenic satRNAs compared with plants containing non-necrogenic satRNAs. Aphid-mediated satRNA-free CMV infections were observed in test plants when aphids were fed on source plants containing CMV + nonnecrogenic satRNA; no comparable satRNA-free test plants occurred when aphids were fed on source plants containing necrogenic satRNAs. These results indicate that factors associated with transmission can be a determinant in the evolution of natural populations of CMV and its satRNA.     

Reducing the spread of aphid-transmitted viruses in peppers by coarse-net cover

Spread of the aphid-transmitted cucumber mosaic virus (CMV) and potato virus Y (PVY) in pepper plots was markedly reduced by growing the plants under a white coarse-net cover permitting normal development of the plants. This net also reduced the winged aphid population on the plants by more than 40 times. Light grey and yellow nets also reduced virus spread and aphid populations, but were much less effective than white ones. The nets do not act as a mechanical barrier to aphids. It is suggested that under white and grey netting, aphid repellency and microclimatic conditions are the primary causes of virus check, while the controlling effect of the yellow nets may be explained by their being more attractive to aphids than the plants. A reduction of “background effect” and a limiting of the aphids’ vision range by nets are probably other factors involved in the protective mechanism.     

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.     

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。     

Variation in Transmission Efficiency Among Barley yellow dwarf virus-RMV Isolates and Clones of the Normally Inefficient Aphid Vector, Rhopalosiphum padi

The RMV strain of Barley yellow dwarf virus (BYDV-RMV) is an unassigned member of the Luteoviridae that causes barley yellow dwarf in various cereal crops. The virus is most efficiently vectored by the aphid Rhopalosiphum maidis, but can also be vectored with varying efficiency by R. padi and Schizaphis graminum. Field collections of alate aphids migrating into the emerging winter wheat crop in the fall of 1994 in central New York identified a high proportion of R. padi transmitting BYDV-RMV. This prompted a comparison of the BYDV-RMV isolates and the R. padi populations found in the field with type virus and aphid species maintained in the laboratory. A majority of the field isolates of BYDV-RMV were similar to each other and to the type BYDV-RMV isolate in disease severity on oat and in transmission by the laboratory-maintained population of R. maidis and a field-collected population of R. maidis. However, several field populations of R. padi differed in their ability to transmit the various BYDV-RMV isolates. The transmission efficiency of the R. padi clones was increased if acquisition and inoculation feeding periods were allowed at higher temperatures. In addition, the transmission efficiency of BYDV-RMV was significantly influenced by the aphid that inoculated the virus source tissue. In general, BYDV-RMV transmission by R. padi was higher when R. padi was the aphid that inoculated the source tissue than when R. maidis was the inoculating aphid. The magnitude of the change varied among virus isolates and R. padi clones. These results indicate that, under certain environmental conditions, R. padi can play a significant role in the epidemiology of BYDV-RMV. This may be especially significant in regions where corn is a major source of virus and of aphids that can carry virus into a fall-planted wheat crop.     

Glutenin and gliadin contents of flour derived from wheat infested with different aphid species

Aphid feeding in cereals results in both quantitative and qualitative yield losses; moreover aphid-transmitted viruses are responsible for other quantitative and qualitative damage so that direct or indirect effects of aphid infection are always of interest. At the beginning of stem elongation, wheat plants were caged regardless of the presence or absence of indigenous cereal aphids. Half of the caged plants were artificially infected with Diuraphis noxia. The number of D noxia and Rhopalosiphum padi individuals on plants destined for flour preparation was approximately 150 aphids per tiller at peak population. The number of Sitobion avenae individuals was ca 25 aphids per tiller. Bread-making quality of wheat flour is determined primarily by the protein content, the gluten proteins (gliadins, glutenins) being the prime factors. The absolute amounts and/or the relative proportion of gliadins and glutenins are very important in dough making and in determining baking quality. Flour from grains originating from plants infected naturally with cereal aphids indigenous to Hungary, and flour infected artificially with D noxia, were analysed for glutenin and gliadin content using size exclusion HPLC. It was found that aphid infection had a significant effect on the gliadin/glutenin ratio, which was significantly lower in wheat flour prepared from aphid-infected plants than in that from uninfected control. The most significant decrease in gliadin/glutenin ratio was caused by D noxia infection, followed by R padi and then S avenae. As the gliadin/glutenin ratio was significantly lower in flour made from aphid-infected wheat seeds, it can be supposed that aphid feeding results in decreased bread making quality of wheat flour.     

Species composition and abundance of aphids in Australian hop gardens and their impact on spatiotemporal patterns of Carlavirus epidemics

The species composition and abundance of aphids in commercial cv. Agate and cv. Super Pride hop gardens in Tasmania, Australia, were characterized over three seasons (1999–2001). Gunns Plains recorded 14 aphid species and Bushy Park 11 species, with nine of these common to both sites. The majority of aphids were trapped in the first 2 months (October and November) of active hop growth in all three seasons. Cultivar and geographical location had significant effects on the abundance of total aphids (species pooled) trapped and several individual aphid species in the three seasons. In general, significantly more aphids (total and individual species) were trapped in cv. Agate than cv. Super Pride gardens, and higher numbers were trapped at Bushy Park than at Gunns Plains. This coincided with a higher incidence of plants infected by carlaviruses in cv. Agate gardens at both locations. Differences in the spatiotemporal dynamics of Carlavirus epidemics were described by fitting a stochastic model to the data, with parameters for local spread within the garden (contagion) and background infection (disease increase unrelated to infected plants within the gardens). Local spread of Hop latent virus (HpLV) and Hop mosaic virus (HpMV) was indicated within all gardens. For HpMV in cv. Agate at Gunns Plains, however, infections caused by immigrant viruliferous aphids were also apparent. Using join-count statistics, spatial aggregation of both virus diseases was found for all years, except for the initial year (1999) when incidence was low. Clusters of diseased plants extended to greater distances for HpLV than for HpMV. Based on spatial and spatiotemporal analyses, local spread (mechanical transmission and/or aphid movement within the garden) appears to be the dominant factor in the epidemics of HpLV. Aphid immigration from outside the crop over time may play a more significant role for HpMV epidemics, at least for one location.     

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.     

RNAi‐mediated plant protection against aphids

Aphids (Aphididae) are major agricultural pests that cause significant yield losses of crop plants each year by inflicting damage both through the direct effects of feeding and by vectoring harmful plant viruses. Expression of double‐stranded RNA (dsRNA) directed against suitable insect target genes in transgenic plants has been shown to give protection against pests through plant‐mediated RNA interference (RNAi). Thus, as a potential alternative and effective strategy for insect pest management in agricultural practice, plant‐mediated RNAi for aphid control has received close attention in recent years. In this review, the mechanism of RNAi in insects and the so far explored effective RNAi target genes in aphids, their potential applications in the development of transgenic plants for aphid control and the major challenges in this regard are reviewed, and the future prospects of using plant‐mediated RNAi for aphid control are discussed. This review is intended to be a helpful insight into the generation of aphid‐resistant plants through plant‐mediated RNAi strategy. © 2016 Society of Chemical Industry     

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.     

Identification of barley yellow dwarf virus and cereal aphid Infestations In winter wheat by aerial photography

In 1976 distinctive patterns were identified on aerial photographs of winter wheat crops in East Anglia. The patterns consisted of numerous dark foci which were found to be associated with sooty moulds (mostly Cladosporium spp.) in the crops. Both green and mature crops were photographed in 1977 and the patterns were matched with crop inspection data. These suggested that barley yellow dwarf virus (BYDV) was the cause of the patterns and that sooty moulds secondarily invaded the infected plants. A different type of focal pattern appeared to be associated with damage caused by aphid feeding. All crops showing the pattern associated with BYDV were sown before 13 October but there was no relationship with sowing date for the crops damaged directly by aphids. Yield losses within foci were estimated by sampling and the total crop areas affected were calculated using an image analysis computer: yield losses were estimated to range from 10% (BYDV) to 2% (aphid feeding). The epidemiology of BYDV is discussed and reasons are suggested for the development and appearance of the foci.