Transmission efficiency of Papaya ringspot virus by three aphid species

The transmission efficiency of Papaya ringspot virus (PRSV) by three aphid vectors (i.e., Aphis gossypii, A. craccivora, and Myzus persicae) was studied. Efficiency was measured by single-aphid inoculation, group inoculation (using five aphids), duration of virus retention, and the number of plants following a single acquisition access period (AAP) to which the aphids could successfully transmit the virus. Single-aphid inoculation studies indicated that M. persicae (56%) and A. gossypii (53%) were significantly more efficient in transmitting PRSV than A. craccivora (38%). Further, in the former two species, the time required for initiation of the first probe on the inoculation test plant was significantly shorter compared to A. craccivora. PRSV transmission efficiency was 100% in all three species when a group of five aphids were used per plant. There was a perceptible decline in transmission efficiency as the sequestration period increased, although M. persicae successfully transmitted PRSV after 30 min of sequestration. A simple leaf-disk assay technique was employed for evaluating the transmission efficiency of three species of aphids. The results of leaf-disk assays also indicated that A. gossypii (48%) and M. persicae (56%) were more efficient PRSV vectors than A. craccivora. Using leaf-disk assays, the ability of individual aphids to inoculate PRSV serially to a number of plants was studied. Following a single AAP on an infected leaf, M. persicae was more efficient than the other two species with 52.5% transmission after the first inoculation access period (IAP). However, its inoculation efficiency significantly decreased with the second and subsequent IAPs. A. gossypii was able to transmit PRSV sequentially up to four successive leaf disks, but with significantly declining efficiency. Since A. gossypii is reported to be the numerically dominant vector in south India in addition to being a more efficient vector capable of inoculating PRSV to multiple plants, it should be the target vector for control strategies.     

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。     

Plum pox in north america: identification of aphid vectors and a potential role for fruit in virus spread

ABSTRACT Thirteen aphid species were tested for their ability to transmit Pennsylvania isolates of Plum pox virus (PPV) collected in Columbia (PENN-3), Franklin (PENN-4), and York (PENN-7) Counties, PA. Four species, Aphis fabae, A. spiraecola, Brachycaudus persicae, and Myzus persicae, consistently transmitted PPV in preliminary transmission tests. Two species, Metopolophium dirhodum and Rhopalosiphum padi, were occasional inefficient vectors. Toxoptera citricida, from Florida, also was an effective vector but it does not occur in major stone-fruit-growing states. Species not transmitting PPV in parallel tests included Acyrthosiphon pisum, Aphis glycines, Aulacorthum solani, Macrosiphum euphorbiae, Rhopalosiphum maidis, and Sitobion avenae. When given a 3-day probing access period simultaneously on PPV-infected peach seedlings and healthy peach seedlings, Myzus persicae, Aphis spiraecola, A. fabae, and B. persicae transmitted PPV to 63, 31, 38, and 32% of the healthy peach seedlings, respectively. When given a similar probing period on PPV-infected peach fruit and healthy peach seedlings, the same aphid species transmitted PPV to 50, 35, 0, and 0% of seedlings, respectively. Results support the hypothesis of secondary PPV spread by indigenous aphids in Pennsylvania, and suggest that PPV-infected fruit has the potential to function as a virus source for long-distance dispersal.     

基于EPG分析无翅型和有翅型柑橘蚜虫的取食行为

为明确无翅型、有翅型柑橘蚜虫取食行为的差异,采用EPG技术对褐色橘蚜Toxoptera citricida(Kirkaldy)和棉蚜Aphis gossypii Glover的有翅型、无翅型成蚜在柑橘苗上的取食行为进行测定。结果表明,褐色橘蚜无翅型和有翅型的EPG均记录到7种取食波形,依次为非刺探波np、路径波A、B和C、电位下降波pd、韧皮部取食波E1和E2;棉蚜无翅型和有翅型的EPG记录到9种取食波形,除上述7种外,还包括木质部主动吸食波G和口针阻碍波F。褐色橘蚜有翅型和无翅型的np波持续时间为25.73 min和8.39 min,二者间差异显著;棉蚜有翅型的np波持续时间、刺探次数、C波次数分别为27.34 min、19.16次、20.21次,显著高于无翅型,而刺探总持续时间为332.66 min,显著低于无翅型。棉蚜的C波次数及总持续时间、刺探次数、pd波次数及总持续时间均显著高于褐色橘蚜,而E2波总持续时间及平均持续时间均显著小于褐色橘蚜。表明棉蚜无翅型比有翅型在柑橘上更容易取食,影响有翅型蚜虫取食的抗性因子可能位于柑橘表面;褐色橘蚜比棉蚜对柑橘的适应性更强。     

Effect of temperature, vector life stage, and plant access period on transmission of banana bunchy top virus to banana

The study of the transmission biology of insect-borne plant viruses is important to develop disease control practices. We characterized the transmission of a nanovirus, Banana bunchy top virus (BBTV), by its aphid vector Pentalonia nigronervosa Coquerel (Hemiptera, Aphididae) with respect to temperature, vector life stage, and plant access time. Adult aphids transmitted BBTV more efficiently than third instar nymphs at all temperatures tested. Adult aphids transmitted the virus more efficiently at 25 and 30 degrees C than at 20 degrees C, but temperature had no impact on transmission efficiency by nymphs. By decoupling the relationship between temperature and aphid BBTV acquisition or inoculation, we determined that temperature affected inoculation events more strongly than acquisition. Longer plant access periods increased viral acquisition and inoculation efficiencies in a range of 60 min to 24 h. Both BBTV acquisition and inoculation efficiencies peaked after 18 h of plant access period. We also show that BBTV transmission by P. nigronervosa requires a latent period. Our results demonstrate that vector transmission of BBTV is affected by temperature, vector life stage, and plant access period.     

The yellow rose aphid <Emphasis Type="Italic">Rhodobium porosum</Emphasis>: a new pest of Damask rose in Turkey

Apterous and alate viviparous females of the yellow rose aphid, Rhodobium porosum (Sanderson) (Hemiptera: Aphididae), were collected on Damask rose, Rosa damascena Mill., in Isparta Province, Turkey. The aphid is recorded for the first time from Turkey. Brief information about the invasive yellow rose aphid, including its distribution in Isparta Province and a key to the apterous females of aphid species known to infest Damask rose in Turkey, is provided.     

Early intracellular punctures by two aphid species on near-isogenic melon lines with and without the virus aphid transmission (Vat) resistance gene

The Vat resistance gene (in Cucumis melo L.) inhibits the transmission of non-persistent viruses by Aphis gossypii Glover, but does not affect transmission by Myzus persicae (Sulz.). To see whether this difference was behaviourally determined, we investigated the stylet penetration behaviour of these two aphid species by recording EPGs (Electrical Penetration Graphs) of 8 and 20 min on two sets of susceptible and resistant isogenic melon lines. During the 20 min EPG study, inoculation with CMV (Cucumber Mosaic Virus) was also investigated. For both sets of isogenic lines, the two aphid species were able to detect the presence of Vat. The mean duration of individual intracellular punctures on the resistant genotypes was significantly reduced for both M. persicae and A. gossypii (-10% and -8% respectively for duration of pattern ‘pd’ in the 20 min experiment); this reaction appeared faster for M. persicae, a species for which melon was not a suitable host-plant. Therefore, in contrast to Vat's anti-transmission effect, this behavioural effect was not aphid species-specific. Also, the frequency of intracellular punctures on the resistant genotypes was significantly reduced in A. gossypii (but not in M. persicae): on average, this frequency dropped from ≈0.65 pd.min^-1 on the susceptible genotypes to ≈0.5 pd.min^-1 on the resistant ones. It was concluded that (intracellular?) chemical cues were detected very early by aphids probing on the resistant genotypes carrying the Vat gene. However, a comprehensive analysis of the behavioural traits of both aphids on the two genotypes could not alone account for the complete inhibition of transmission which was found only to occur for A. gossypii on resistant genotypes. None of the differences detected (between aphid species or between plant genotypes) could account for the Vat phenotype, although they may explain quantitative differences in transmission efficiencies between aphid species. It was thus concluded that Vat effect was primarily chemically mediated. Finally, some intracellular punctures bearing typical subphases have been identified in both aphid species and were designated as ‘long potential drops’ (pd-L). For A. gossypii, these were observed early after plant contact and their mean duration was twice that of standard intracellular punctures (≈8.5 s vs ≈4.2 s). Although not necessary for CMV inoculation, the duration of such phases was positively correlated with a high transmission efficiency by A. gossypii on the susceptible genotype. The nature of this pattern and a putative mechanism of action of the Vat gene are discussed.     

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.     

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.     

The grapevine aphid <Emphasis Type="BoldItalic">Aphis illinoisensis</Emphasis>: an invasive pest in Israel

Apterous and alate viviparous females of Aphis illinoisensis Shimer (Hemiptera: Aphididae) were collected on grape, Vitis vinifera L., in three different regions of Israel. Detailed information is given about this species distribution in Israel. A key is provided to the apterous females of aphid species known to infest grape in Israel.     

Spread and occurrence of tulip tree aphid in Europe: new record of Illinoia liriodendri (Monell, 1879) (Hemiptera: Aphididae) from Hungary

The genus Illinoia is found primarily in North America. Illinoia liriodendri (Monell, 1879), the tulip tree aphid, was observed and identified for the first time in Hungary. Nymphs, apterous and alate viviparous females in colonies of I. liriodendri were found on a tulip tree, Liriodendron tulipifera L. (Magnoliaceae), in Debrecen, Hungary. Tulip tree aphids feed on the underside of tulip tree leaves. The consequences of this are honeydew and associated black sooty mould which is unsightly and causes sticky residues to drop onto footpaths and parked cars. If the infestation is very severe this may reduce photosynthesis. A short report is presented here on the first finding of this pest in Hungary, and its characteristics.     

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.     

桃蚜卵巢小管数量的变异及其与起飞行为的关系

本文以卵巢解剖的方法观察了不同来源及蚜型的桃蚜卵巢小管数量的变异,其中来源于春季桃树上的干母的卵巢小管数最多,平均达12.93根,而晚秋桃树上的无翅雌性蚜则最少,平均仅4.67根,在孤雌胎生蚜中无翅蚜较有翅蚜多。桃蚜的起飞行为包括起飞角度和起飞时间两方面。作者测定有翅桃蚜的起飞势能,结果表明,有翅蚜卵巢小管数的多少影响其起飞势能的大小,卵巢小管数越少,起飞角度越大,起飞时间越短。     

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.     

The host range of beet yellowing viruses among common arable weed species

Twenty common arable weed species were inoculated using Myzus persicae to transmit beet yellows virus (BYV), beet mild yellowing virus (BMYV), and an isolate of beet western yellows viruses (BWYV) that did not infect beet. The viruses were detected by enzyme-linked immunosorbent assay (ELISA), in which monoclonal antibodies distinguished between BMYV and BWYV, and by aphid transmissions to indicator host plants. Spergula arvensis, Stellaria media, Lamium purpureum and Papaver rhoeas were susceptible to all three viruses whereas Senecio vulgaris, Capsella bursa-pastoris, Anagallis arvensis and Chrysanthemum segetum were susceptible to both BMYV and BWYV, and Matricaria perforata, Raphanus raphanistrum, Veronica persica, Urtica urens and Viola arvensis were susceptible to BWYV only. Atriplex patula, Chenopodium album and Portulaca oleracea were susceptible to BYV only. Myosotis arvensis, Silene alba, Poa annua and Solanum nigrum were not susceptible to any of the viruses. Portulaca oleracea was shown for the first time to be a host of BYV, and C. segetum a host of BMYV and BWYV. In spring 1991, 8% of weeds sampled in a field of autumn-sown oilseed rape contained BWYV. Tests on weeds collected from an area of 'set-side' adjacent to sugar beet showed that 3% contained BMYV and 3% BWYV. No sampled weeds were infected with BYV. The role of weeds in the epidemiology of sugar beet virus yellows is discussed.     

Behavioural responses of Aphis fabae to isothiocyanates in the laboratory and field

Isothiocyanates have been shown to stimulate olfactory receptors on the antennae of the black bean aphid, Aphis fabae Scop. Single-cell recording techniques show that this aphid has receptors at the proximal primary rhinarium which are sensitive to n-butyl isothiocyanate. In laboratory assays, 4-pentenyl and n-butyl isothiocyanates were repellent at similar threshold concentrations. A. fabae was attracted to host-plant odour, but addition of either isothiocyanate to the airstream masked this attraction. Field trials on spring beans did not produce any consistent reduction in numbers of alate or apterous aphids on the crop, and yields were not improved by either compound.     

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.     

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.     

蚕豆蚜日龄、翅型和寄生对其共生菌胞变化的影响

初生内共生菌与宿主蚜虫的营养代谢密切相关.本文观察了蚕豆蚜Aphis fabae不同翅型的共生菌胞随宿主蚜虫生长发育的变化规律,以及饥饿和混合柄瘤蚜茧蜂Lysiphlebus confusus寄生对共生菌胞的影响.菌胞数量和体积随发育进程和翅型的变化而呈现有规律的变化:随若蚜发育而逐渐增大,然后随胎生蚜产生而逐渐减少;无翅蚜的菌胞数量和体积均显著大于有翅蚜.随饥饿时间的延长,菌胞数量和体积迅速直线下降,而重新取食后又可迅速恢复.蚕豆蚜被混合柄瘤蚜茧蜂寄生后的第3d,菌胞数量显著多于未寄生蚜虫,此后则明显少于未寄生蚜虫,从第4d的119个·头-1降至第6d的46个·头-1.研究结果说明,蚜虫共生菌胞的变化与宿主蚜虫翅型、发育、外源营养以及蚜茧蜂寄生等密切关联.