Showing papers on "Myzus persicae published in 1994"

Endosymbiotic bacteria associated with circulative transmission of potato leafroll virus by Myzus persicae

Abstract: In order to understand the molecular mechanisms underlying circulative transmission of potato leafroll virus (PLRV) by aphids, we screened Myzus persicae proteins as putative PLRV binding molecules using a virus overlay assay of protein blots. In this way, we found that purified PLRV particles exhibited affinity for five aphid proteins. The one most readily detected has an M(r) of 63K, and was identified as symbionin. This is the predominant protein synthesized by the bacterial endosymbiont of the aphid and is released into the haemolymph. Since further studies clearly showed that PLRV particles also bind to native symbionin, it was envisaged that virus particles when acquired into the haemocoel of an aphid interact with symbionin. Inhibition of prokaryotic protein synthesis by feeding M. persicae nymphs on an antibiotic-containing artificial diet prior to PLRV acquisition reduced virus transmission by more than 70%. The major coat protein of the virus was found to be degraded in the antibiotic-treated aphids; this would obviously have resulted in an increased exposure of viral RNA to enzymic breakdown and concomitant loss of infectivity. For these reasons we conclude that endosymbiotic bacteria play a crucial role in determining the persistent nature of PLRV in the aphid haemolymph and that symbionin is probably the key protein in this interaction.

Biological characterisation of various geographical isolates of potato virus Y inducing superficial necrosis on potato tubers

Abstract: A range of selected PVY isolates that induce superficial necrosis on potato tubers, originating from several countries, were compared with standard strains of PVA, PVV and PVY. Biological properties (e.g., host range, aphid transmissibility and relationships based on cross-protection between virus isolates) were studied. PVYNN isolates differ from the normal PVYC, PVYN and PVO strains by their ability to infect Capsicum annuum but not Chenopodium amaranticolor and C. quinoa. All PVYNN isolates are transmissible by Myzus persicae, without any significant differences from one standard strain. These additional data confirm that these tuber-necrosing isolates belong to PVY. However, they could be ranged in a homogeneous and distinct group inside the PVYN group, based on the differences revealed in the host range, in addition to the specific ability naturally to induce necrosis on tubers.

Pathogenicity of the entomogenous fungi Metarhizium anisopliae and Beauveria bassiana against crucifer pests and the honey bee

Abstract: The susceptibility of the cabbage stem flea beetle (Psylliodes chrysocephala; Coleoptera: Chrysomelidae) to different isolates of the entomogenous, hyphomycete fungi Beauveria bassiana and Metarhizium anisopliae, all from heterologous hosts, was investigated. The most pathogenic isolates were of M. anisopliae (V208, V233, V234, V242, V245, and V248). Studies were conducted to determine the virulence of V208 and V245, and their specificity for three other crucifer pests, Phaedon cochleariae, Myzus persicae and Lipaphis erysimi and a beneficial insect, Apis mellifera. Flea beetle mortality rates increased with dose; the estimated LC50 S of V208 and V245 at 14 days post‐inoculation were c. 106 conidia ml‐1. The respective estimated LT50 values of V208 and V245 for P. chrysocephala at 1 × 107 conidia ml‐1 were 10.0 and 9.3 days, and at 1 × 1010 conidia ml LT50s were 3.8 and 4.2 days. Both V208 and V245 were pathogenic for P. cochleariaeM. persicae and L. erysimi. Myzus persicae and L. erysimi died within 4 da...

The peach‐potato aphid Myzus persicae and the tobacco aphid Myzus nicotianae have the same esterase‐based mechanisms of insecticide resistance

Abstract: Biochemical and molecular studies have established that in the peach-potato aphid, Myzus persicae, insecticide resistance is conferred by amplification of genes encoding the insecticide-detoxifying esterases E4 or FE4. Here we report that two insecticide-resistant clones of the closely related tobacco aphid Myzus nicotianae have elevated esterases indistinguishable from E4 and FE4 and amplified esterase DNA sequences, and flanking regions, with identical restriction maps to the M. persicae genes. Furthermore, the DNA sequences of c. 630 bp fragments of the E4 and FE4 genes of M. persicae are different from each other but identical to the fragment from corresponding M. nicotianae clones. The existence of apparently identical insecticide resistance genes in the two species can be best explained by the selection of the amplified genes in M. persicae, transfer to hybrids of M. persicae and M. nicotianae by sexual reproduction and subsequent spread through M. nicotianae populations.

Insect growth regulating effects of neem extract and azadirachtin on aphids

Abstract: Neem, Azadirachta indica (A. Juss.), seed oil (NSO) applied to leaf discs at a concentration of 1.0% resulted in 94% to 100% mortality of second instar nymphs of currant-lettuce aphid, Nasonovia ribis-nigri (Mosley), and green peach aphid, Myzus persicae (Sulzer), after nine days. The equivalent amount of pure azadirachtin (AZA) (a40 ppm), the principle active ingredient of neem, was as effective as NSO. The survival of adult aphids was unaffected by NSO or AZA, but the survival of offspring from treated adult M. persicae and N. ribis-nigri was reduced significantly. The lethal concentration of AZA resulting in 50% mortality of second instar nymphs of nine species of aphids ranged from 2.4 ppm for M. persicae on pepper to 635.0 ppm for the strawberry aphid, Chaetosiphon fragaefolii (Cockerell), on strawberry. For M. persicae, the growth regulating effect of AZA was influenced by the host plant and the nymphal instar treated.

Novel sucrose esters from Nicotiana gossei: effective biorationals against selected horticultural insect pests

Abstract: Leaf-surface extracts of Nicotiana gossei Domin, N. benthamiana Domin, and N. bigelovii (Torrey) Watson were the most active of those from 17 species of Nicotiana evaluated against late second/early third instars of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Four chromatographically purified sucrose esters of N. gossei resulted in 88-94% mortality of late second/early third instars of the sweetpotato whitefly, Bemisia tabaci (Gennadius). A less purified mixture of the four compounds was effective at 1.0 mg/ml (wt:vol) against nymphs of both whitefly species and the green peach aphid, Myzus persicae (Sulzer), and it deterred feeding and oviposition by the twospotted spider mite, Tetranychus urlicae Koch. These sucrose esters were not active against whitefly eggs; neonates of the Colorado potato beetle, Leptinotarsa decemlineata (Say); or second instars of the western flower thrips, Frankliniella occidentalis (Pergande). The selective activity against immature insects, and the feeding and ovipositional deterrence to spider mites suggest pesticidal activity. Activity of 1.0 mglml (wt:vol) aqueous mixtures of the four compounds was comparable with, or better than, label rates of currently available biorational products or pesticides. The purified product was stable for 1 yr.

Pest Status of Aphids and Other Insects in Winter Canola in Georgia

Abstract: Canola, Brassica napus L., is being evaluated as a winter grain crop in the southeastern United States. The damage potential of insect pests was studied during three growing seasons in the Piedmont and coastal plain regions of Georgia by controlling insects with insecticides at the rosette, beginning bloom, or pod-fill stages of plant development. Canola pod infestations by the cabbage seedpod weevil, Ceutorhynchus assimilis Paykull, reached 60% at some sites in northern Georgia indicating that this insect will be an important pest of canola in this area. However, C. assimilis was not collected in any year in southern Georgia. Yield responses to insecticide treatments were associated with a complex of aphids, primarily the turnip aphid, Lipaphis erysimi (Kaltenbach), and green peach aphid, Myzus persicae (Sulzer), which caused direct injury to leaves and stems. Aphid injury reduced plant height and winter survival and delayed plant development. Comparison of untreated and season-long treated plots indicated that aphid injury reduced yield by 9.9, 30.4, and 34.8% in 3 yr in the coastal plain region. In northern Georgia, yield losses caused by aphids were ≤2.0% in three of four trials, but aphid injury reduced yield by 32.7% in one trial. Insecticidal control of aphids had the greatest effect on yield during the rosette stage with treatments at first bloom also enhancing yield in some trials. Insecticide treatments at pod-fill stage did not affect canola growth and yield in any trial. Aphids most likely will be a limiting factor in canola production in the southern United States, particularly in the coastal plain region. Aphid management activities should be directed at seedling and rosette stages of plant development.

Potato germplasm with combined resistance to leafroll virus and viruses X and Y

Abstract: Potato germplasm with high levels of combined resistance to potato viruses X, Y, and leafroll was identified and used to produce improved parental clones with similarly high levels of resistance. Resistance was determined from the amount of tuber infection following inoculation of plants in the field. Parental germplasm with the best multiple resistance came from two backgrounds, eitherSolanum tuberosum group Andigena derived from the Cornell University neo-tuberosum program, or from complex hybrids ofS. tuberosum and wild solanums that were produced by the Max Planck Institute and the Polish Institute for Potato Research. Two Aberdeen, ID selections, A85519-6 and A85530-10, with gp. Andigena ancestry, have had no tuber-borne infection of PVX, PVY, or PLRV during four years of intensive field testing. We have not been successful in combining virus S resistance with resistance to the other viruses.

A New Strain of Sweet Potato Feathery Mottle Virus That Causes Russet Crack on Fleshy Roots of Some Japanese Cultivars of Sweet Potato

Abstract: A new filamentous virus (designated VC) was isolated from sweet potato plants that seemed to be tolerant to russet crack. It infected Ipomoea spp., Chenopodium quinoa and C. amaranticolor. Ipomoea nil infected with the virus developed typical vein-clearing on the first true leaf. The infectivity of VC in sap was lost at dilutions between 1:10, 000 and 1:100, 000 and after storage for one day at 20°C. Its thermal inactivation point was between 50 and 60°, and virus particles were 850-880nm long and 13nm wide. VC was nonpersistently transmitted by the aphid Myzus persicae, and was serologically related but not identical to sweet potato feathery mottle virus (SPFMV, abbreviated as Mo) that belongs to Potyvirus. Coat proteins of both purified VC and Mo migrated as three major bands of proteins with Mr 32, 000, 30, 000 and 29, 000. However, electro-blot immunoassay revealed one major protein of Mr 38, 000 and an additional, more slowly migrating protein of Mr 97, 000 in leaves infected with VC, and one major protein of Mr 38, 000 in leaves infected with Mo. Sweet potato inoculated with VC developed symptoms of russet crack on the fleshy roots. These results indicate that VC is the causative agent of russet crack that occurs in some Japanese cultivars of sweet potato and that VC is a new strain of SPFMV. Therefore, we named VC and Mo severe strain (SPFMV-S) and ordinary strain (SPFMV-O), respectively, of SPFMV.

The effects of azadirachtin‐treated diets on the feeding behaviour and fecundity of the peach‐potato aphid, Myzus persicae

Abstract: Adult apterous Myzus persicae, which had fed for 26 h on diet containing azadirachtin at concentrations of 25–100 ppm, produced nymphs at less than half the rate of aphids on control diets. After 50 h on azadirachtin-treated diets nymph production had virtually ceased. After this period, any nymphs produced by adults that had fed on azadirachtin-treated diets were born dead with undeveloped appendages. Honeydew production on azadirachtin-treated diets was unaffected during the first 26 h period but was approximately three times less than on control diets during the subsequent 24 h period.

The effects of temperature on the availability and acquisition of potato leafroll luteovirus by Myzus persicae

Abstract: Summary The concentration of potato leafroll luteovirus (PLRV) did not differ in potato plants with secondary infections grown at 15°C or 27°C. Detached leaves of plants grown at 15°C or 27°C were used as sources of PLRV for peach-potato aphids (Myzus persicae Sulz.) both at 15°C and 27°C. At comparable temperature during virus acquisition, aphids which fed on leaves of plants kept previously at 15°C contained more viral antigen detected by ELISA than aphids which fed on leaves of plants grown at 27°C. The aphids which acquired PLRV at 27°C contained evidently more viral antigen than those which acquired PLRV at 15°C. The greatest amount of PLRV was found in the aphids which acquired the virus at 27°C from the leaves of plants kept at 15°C. The ability of M. persicae to transmit PLRV to Physalis ftoridana Rydb. generally decreased with decrease in the amount of PLRV in vectors.

The role of the plant in host acceptance by the parasitoid Aphidius rhopalosiphi (Hymenoptera: Braconidae)

Abstract: Female Aphidius rhopalosiphi De Stefani Perez reared on Rhopalosiphum padi (Linnaeus) made equal numbers of encounters with another suitable host aphid (Sitobion avenae (Fabricius (both Homoptera: Aphididae))) in arenas where the aphids were on either pieces of wheat leaf or moist filter paper. However, the number of oviposition stabs made in arenas with wheat was far higher than with filter paper, demonstrating the importance of host-plant cues in the acceptance of the aphids by the parasitoid. Diet reared aphids (even if subsequently fed on wheat) appeared to be accepted more readily than totally wheat reared individuals. In another arena experiment, there were more encounters with and more stabs made into both S. avenae and a non-host aphid (Myzus persicae (Sulzer)) on wheat than on Brussels sprouts (a host plant of M. persicae), again showing the over-riding importance of host-plant cues.

Transmission of plum pox potyvirus in Spain.

Abstract: 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.

A potyvirus isolated from solanaceous hosts

Abstract: A potyvirus was isolated from Datura stramonium, Lycopersicon esculentum (tomato) and Solanum nigrum in the Yemen. It was transmitted mechanically and by Myzus persicae in a non-persistent manner. Its flexuous rod-shaped particles had a mean length of 719 nm and some of its pinwheel inclusion bodies in infected Nicotiana clevelandii leaves were unusual in that they were dichotomously branched. The virus infected various solanaceous species, but the symptoms it induced were distinct from those of pepper veinal mottle (PVMV) and potato Y viruses. Its particles were purified from N. glutinosa and their coat protein had an atypically high molecular mass a potyvirus of 41·5 kDa. They showed a distant serological relationship to those of PVMV and potato virus V in ISEM decoration tests, but did not react with antisera to particles of any other potyvirus tested. The virus has been tentatively named tomato mild mottle virus.

Effects of extended and repeated exposures to low temperature on mortality of the peach-potato aphid Myzus persicae

Abstract: 1. The survival of adult and first-instar Myzus persicae reared at 20-degrees-C and 10-degrees-C was investigated after brief (1 min) exposure in the absence of plant material to temperatures between -5-degrees-C and -25-degrees-C, and extended exposures on plants of 1-10 days at a constant 5-degrees-C, 3-degrees-C and -5-degrees-C and a 24 h cycling regime between 5-degrees-C (18 h) and -5-degrees-C (6h). 2. Life stage, rearing temperature, period of exposure and temperature regime all had a significant effect on the ability of aphids to survive cold. The effects of life stage and rearing temperature were most noticeable following exposure to cycling temperatures and extended exposures at -5-degrees-C, and least apparent after 1 min exposures at lower sub-zero temperatures. 3. Mortality following exposure to temperatures cycling between -5-degrees-C and 5-degrees-C was greater than that at 3-degrees-C (the mean of the cycling temperatures) and less than at a constant -5-degrees-C, suggesting that when temperatures fluctuate by a few degrees around 0-degrees-C the minimum temperature may affect survival to a greater extent than the mean. 4. These results suggest that an overwintering population of acclimated M. persicae would persist without significant mortality after a period of 7-10 days with -5-degrees-C frosts each night.

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

Abstract: 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.

Feeding Activity of Green Peach Aphid (Homoptera: Aphididae) on Transgenic Potato Expressing a Bacillus thuringiensis ssp. tenebrionis B-Endotoxin Gene

Abstract: Probing behavior and feeding activities of green peach aphids, Myzus persicae (Sulzer), were electronically monitored on potato leafroll virus-infected transgenic 'Russet Burbank' potatoes expressing a delta-endotoxin gene of Bacillus thuringiensis ssp. tenebrionis, potato leafroll virus-infected normal 'Russet Burbank', and uninfected normal 'Russet Burbank' potatoes. The waveforms corresponding to probing, salivation, sieve element penetration, and ingestion were recorded. During 2 h of plant access, we found no significant difference in the time to initiate the first probe on a potato leaf, number of probes (or stylet insertions) before phloem ingestion (defined as ingestion from phloem lasting at least 25 min), time to reach the first X-wave (diagnostic of sieve element penetration by the stylets), time to the last probe before phloem ingestion, time to phloem ingestion, or total duration of phloem ingestion of green peach aphid on potato leafroll virus-infected transgenic, potato leafroll virus-infected normal, and uninfected normal potatoes. Transgenic potatoes had no effect on green peach aphid feeding behavior, suggesting that transmission of green peach aphid-borne viruses would not be affected.

Increase in Cucurbit Aphid–Borne Yellows Virus Concentration by Co–infection with Sap–transmissible Viruses does not Increase its Aphid Transmissibility

Abstract: The cucurbit aphid–borne yellows virus (CABYV) is a new tentative member of the luteovirus group which is transmitted persistently by Myzus persicae and Aphis gossypii. In muskmelon plants, mixed infection with CABYV and zucchini yellow mosaic virus (ZYMV) induced an increase in CABYV concentration estimated by double antibody sandwich–enzyme linked immunosorbent assay (DAS–ELISA), which was maximum after 3 weeks, of co–infection. Assays, conducted with other cucurbit hosts and sap–transmissible viruses showed that a similar increase occurred with most of the potyviruses tested. However, cucumber mosaic virus (CMV) and squash mosaic virus (SqMV) were inefficient for less efficient than potyviruses) in increasing CABYV concentration. Aphid transmission experiments were conducted to check whether increased virus multiplication could either enhance transmission rates or modify the mode of CABYV acquisition by aphids. However, when A. gossypii was used, no increases in CABYV, transmissibility nor in its acquisition mode were detected.

Brushing Reduces Thrips and Aphid Populations on Some Greenhouse-grown Vegetable Transplants

Abstract: «Sunny» tomato (Lycopersicon esculentum Mill.), «BlackBeauty» eggplant (Solanum melongena var. esculentum L. Nees.), or «Sugar Baby» watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] were nontreated, subjected to brushing (20 strokes twice daily) or drought conditioning (2 hours daily wilt), or maintained undisturbed using ebb-and-flow irrigation. One week after brushing or drought conditioning, plants were inoculated with western Dowerthrips (Frankliniella occidentalis Pergande) or green peach aphid (Myzus persicae Sulzer). Brushing and drought conditioning reduced plant height and shoot dry weight of all crops. Brushing of all three species generally reduced the number of thrips, as indicated by number of feeding scars or percent leaf area damaged

Prevalence of natural fungal mortality of green peach aphid (Homoptera: Aphididae) on potatoes and nonsolanaceous hosts in Washington and Idaho

Abstract: Green peach aphid, Myzus persicae (Selzer), populations were monitored and examined for pathogens at Moscow and Troy, ID, in 1991 and near Yakima, WA, in 1991–1992. M. persicae infesting a peach orchard, broadleaf weeds within and around the periphery of the orchard, and nearby potato fields near Yakima were observed from March until November. Potatoes and nonsolanaceous plants in home gardens in Moscow and Troy also were monitored for M. persicae and examined for pathogens during the growing season. In 1991, aphid numbers reached a maximum of 6,070 per 5–15-cm peach twig segments on 29 May but only nine per 15–0.15-m twig segments in 1992. Fungal pathogen activity was barely discemable on tree-borne aphids in the orchard but was observed more frequently from aphids infesting weeds beneath the trees. An epizootic of Entomophthorales occurred on aphids infesting solanaceous (potatoes) and nonsolanaceous hosts in home gardens in Moscow and Troy, (Latah County), Idaho, in 1991. Verticillium lecanii (Zimmerman) Viegas was identified from M. persicae on peach leaves; Beauveria bassiana (Bals.) Vuillemin and Conidiobolus sp. were identified from aphids on potatoes. Aphids collected from weeds growing in and near the peach orchard were infected with Entomophthora chromaphidis Cornu, Conidiobolus coronatus (Constantin) Batko, C. obscurus (Petch) Hall & Dunn, and V. lecanii. Aphids on potatoes and nonsolanaceous hosts at Moscow and Troy were infected with Pandora neoaphidis (Remaudiere & Hennebert) Humber, E. chromaphidis , and Conidiobolus spp. Aphid populations were much lower in 1992 both within the orchard and in potatoes.

Development of resistance in the bean aphid, Aphis craccivora Koch. to various insecticides used for nearly a quarter century

Abstract: The toxicity of commonly used insecticides was evaluated against Aphis craccivora Koch. to ascertain the trend of its susceptibility towards them. There has been a considerable shift in the level of susceptibility of A. craccivora to common insecticides after nearly a quarter century. The LC50 values of malathion, dimethoate, phosphamidon, methyl demeton, lindane, pyrethrin, endosulfan, fenitrothion, metthyl parathion and nicotine sulphate increased 46, 28, 22, 21, 20, 15, 14, 12, 11 and 9 times, respectively. Amongst the three aphid species, Myzus persicae Sulz. was relatively resistant than A. craccivora to all the ten insecticides tested, whereas Lipaphis erysimi Kalt. was more susceptible than A. craccivora except to methyl parathion.

A potyvirus causing mosaic disease of sesame (Sesamum indicum)

Abstract: A virus causing chlorosis of veins, mosaic, green banding along veins, and downward leaf rolling in sesame (Sesamum indicum) was isolated from sesame plants grown from seed imported from the Sudan. The virus was sap-transmissible to species of Amaranthaceae, Chenopodiaceae, Cucurbitaceae, Leguminosae, and Solanaceae. Chenopadium amaranticolor was used as a local lesion assay host and Pisum sativum cv. Little Marvel, as the propagation host for purification. The virus was nonpersistently transmitted by Aphis craccivora and Myzus persicae but was not transmitted through the seed of sesame. The virus remained infective in buffered leaf sap of Nicotiana benthamiaza at a dilution of 10 -5 after storage for 9 days at 25 C and heating for 10 min to 55 C (but not to 60 C)

Selection of compounds acting as aphid development and reproduction regulators: Laboratory screening

Abstract: Newly synthesized compounds were examined in screening tests with the pea aphid, Acyrthosiphon pisum (Harris) for juvenilizing effects. usign the spray-residue method. Two derivatives of 2-(4-hydroxvbenzyl)eyclohexanone bearing a carbamate or an ether group were found to be the most active inhibitors of development and reproduction. Tests with the hop aphid, Phorodon humuli (Schrank) of insecticide-susceptible and multi-resistant biotypes and with the green peach aphid, Myzus persicae (Sulzer) confirmed their biological activity. Cross-resistance between conventional insecticides and juvenoids was not indicated. The formation of supernumerary larvae, where retention of larval cauda and corresponding larval characters were observed and reproduction was entirely suppressed, was recognized as the critical result of the juvenilizing effect. The production of viable progeny was not affected in those aphids which survived treatment and developed normal adult external genitalia.