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PubMed2001

Molecular evidence that the aphid-transmitted Tomato mild mottle virus belongs to the Potyviridae family but not the Potyvirus genus.

Molecular studies have been carried out on Tomato mild mottle virus (TMMV) and 2322 nucleotides of the aphid-transmitted virus have been sequenced. This translates to a 2187 nucleotide open reading frame and a 135 nucleotide untranslated region (UTR) followed by a poly A tail. The sequence is consistent with the NIb and coat protein regions of a member of the Potyviridae family of viruses. Sequence comparisons show this virus to have no close relationship with any previously sequenced aphid-transmitted virus; the highest identity was found with the whitefly-transmitted Ipomoviruses. The vector of transmission and the low level of sequence identity with other aphid-transmitted viruses suggest TMMV does not belong to any existing genus of the Potyviridae family.

Animals↗
PubMed2006

Phloem alkaloid tolerance allows feeding on resistant Lupinus angustifolius by the aphid Myzus persicae.

We examined the hypothesis that the polyphagous green peach aphid (Myzus persicae) shows clone-specific adaptation to the narrow-leafed lupin (Lupinus angustifolius) containing toxic quinolizidine alkaloids. We compared the performance of a lupin-feeding clone of M. persicae from Western Australia to that of nine clones of the same species collected from eastern Australian locations, where narrow-leafed lupins rarely occur. Mean relative growth rate (MRGR) and colonization ability varied among the M. persicae clones on one aphid-susceptible and two aphid-resistant lupin varieties. The performance of the lupin-feeding clone was better than that of all other clones on the resistant narrow-leafed lupin varieties "Tanjil" and "Kalya", indicating that successful lupin feeding is not a characteristic of the species. Gas chromatography-mass spectrometry analyses (GC-MS) of phloem from the different lupin varieties detected differences in the quantities of two alkaloid compounds identified as 13-OH-lupanine and lupanine. The lupin-feeding M. persicae clone also showed better performance on artificial diet amended with lupanine. The results suggest that the M. persicae clone collected from Western Australia is adapted to feed successfully on narrow-leafed lupin, and that this adaptation may involve improved tolerance of lupanine in its diet.

Adaptation, Physiological↗
PubMed2005

Wheat containing snowdrop lectin (GNA) does not affect infection of the cereal aphid Metopolophium dirhodum by the fungal natural enemy Pandora neoaphidis.

Studies were carried out to determine if susceptibility of the cereal aphid Metopolophium dirhodum to the fungus Pandora neoaphidis was affected by wheat expressing snowdrop lectin (GNA). Aphid infection did not differ significantly between the transgenic GNA and non-transformed lines (91 and 82%, respectively). Fecundity also did not differ between aphids on the two lines, and was ca. 18 nymphs adult(-1). Time to infection was ca. 5 days for M. dirhodum on both lines in two of three assays. Our results indicate that wheat expressing GNA would not compromise the efficacy of P. neoaphidis as a biocontrol agent.

Animals↗
PubMed2026

Molecular and transcriptional regulation of plant defense responses to aphid infestation.

Aphids are one of the important agricultural pests causing substantial yield losses in crops grown across the globe. Aphids are known to cause direct feeding damages and indirect losses due to sooty mold development and plant virus transmission. Plants respond to these attacks by mounting a complex defense response at the infested sites and systemic levels. This multilayered defense response involves a highly coordinated network of phytohormones and other signalling components like Ca2+, mitogen activated protein kinases and reactive oxygen species. Key to these complex responses is a well-regulated gene expression involving several transcription factors. A wide range of transcription factors are structurally and functionally characterized across some model plants and in a few agronomically important crops. These transcription factors play diverse roles such as defense gene expression modulation, regulation of hormone signaling, secondary metabolism, oxidative stress response, cell wall modifications, and phloem-based defense. Understanding the integration of signaling pathways, hormone crosstalk, and transcription factor mediated regulation provides a framework for practical applications, including breeding, genome editing, and elicitor-based strategies. This review highlights how plant defense signaling and transcriptional regulation against aphids can be harnessed to develop sustainable and novel pest management solutions.

Aphid↗
PubMed1990

Indirect double antibody sandwich ELISA for detecting alfalfa mosaic virus in aphids after short probes on infected plants.

An indirect double antibody sandwich enzyme-linked immunosorbent assay (IDAS-ELISA) system using antibodies elicited in rabbits and chickens is described for the detection of alfalfa mosaic virus (AMV). The method is capable of detecting 40 pg of homologous purified AMV and was shown to be suitable for detecting the virus in aphids. AMV in the order of 150 pg was detected in single aphids. It was shown that a significant proportion of insects could acquire this or higher amounts of virus during 1 min probes on the leaves of infected plants. The IDAS-ELISA should find applicability in research on the acquisition of viruses by aphids and in epidemiological studies for detecting viruses in insects from traps.

Animals↗
PubMed1991

Visualization of a luteovirus in the vector aphid's body by two gold immunolabelling techniques: a comparative study.

Two gold immunolabelling techniques using electron microscopy were compared to examine the in situ localization of a luteovirus, potato leafroll virus (PLRV), inside its main aphid vector, Myzus persicae SULZ. With Gildow's technique, virus particles were labelled prior to fixation, embedding by injecting PLRV-specific IgGs into the living aphids. This facilitated the detection of extracellular particles located between the basal lamina and plasmalemma by trapping them in aggregates. The heavy coating of particles by antibodies and gold indicated good labelling sensitivity. Isometric virus-like particles were also observed inside the cytoplasm, but they were non decorated because the cell membrane prevented labelling reagents from entering the cell. With the second technique, ultrathin sections were immunolabelled after fixation-embedding. Since PLRV lost its antigenicity when aphid tissues were normally treated for electron microscopy, the successful application of this technique required fixation in 4% formaldehyde before embedding in Lowicryl at low temperature; it was also necessary to use PLRV-specific monoclonal antibodies to eliminate non-specific reactions. In these conditions, all intra- and extra-cytoplasmic virions present on the surface of sections were surrounded by gold particles, but the antibody coating was not discernible, and, because the resin limited the access of markers to antigens, the inner virus particles were not labelled. In conclusion, both techniques must be applied on the same material to give complementary information.

Acrylic Resins↗
PubMed1985

Protein synthesis by intracellular symbionts in two closely interrelated aphid species.

An aphid endosymbiont in vivo synthesizes symbionin almost exclusively which is not produced in vitro by the same symbiont. While symbionin produced by the endosymbiont of the pea aphid is an acidic protein with a molecular weight of 63,000, that by the symbiont of the kondo aphid, the closest relative to the former, is a distinct, less acidic, molecule. While the two endosymbionts in vivo in old insects synthesize about 11 protein species in common, they produce many different proteins when incubated extracellularly.

Animals↗
PubMed1993

Buchnera aphidicola (a prokaryotic endosymbiont of aphids) contains a putative 16S rRNA operon unlinked to the 23S rRNA-encoding gene: sequence determination, and promoter and terminator analysis.

The aphid Schizaphis graminum is dependent on an association with Buchnera aphidicola, an eubacterial endosymbiont located in specialized host cells. Past studies have indicated that Escherichia coli is the closest known relative of the endosymbiont which has many genetic attributes of free-living bacteria. In order to obtain information on the properties of highly expressed genes, we have chosen for study the single-copy rrs (gene encoding 16S rRNA) of B. aphidicola. A 4.4-kb DNA fragment was cloned into E. coli and the nucleotide (nt) sequence determined. Several ORFs were identified; the order of genes was argS-rrs-ORF1-rnh-dnaQ. ArgS, RNase H and DnaQ had 36-57% amino acid (aa) identity to the homologous proteins of E. coli. B. aphidicola rrs appears to be part of an operon consisting of a putative promoter, rrs and two inverted repeats resembling Rho-independent terminators. Comparisons of the sequences of argS-rrn DNA fragments from endosymbionts of six additional aphid species indicated conservation of sequences corresponding to a single -35 (TTGACA) and -10 (TGTAAT) promoter region, as well as boxA (sequence involved in antitermination) and boxC. The B. aphidicola argS-rrn DNA fragments from endosymbionts from seven species of aphids had promoter activities in E. coli which ranged from 6 to 135% of that observed with a comparable DNA fragment of E. coli rrnB. Similarly, the putative B. aphidicola terminator was functional in E. coli. In most eubacteria, the rRNA-encoding genes are arranged in the order, 16S, 23S, 5S, and are part of a single operon.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMedDate not supplied

Comparison of short- and long-feed transmission of the cauliflower mosaic virus Cabb-S strain and S delta II hybrid by two species of aphid: Myzus persicae (Sulzer) and Brevicoryne brassicae (L.).

The cauliflower mosaic virus (CaMV) hybrid S delta II, partially deleted in ORFII, loses its transmissibility by the aphid Myzus persicae on 5-min acquisition feed. We have also shown that it is not transmitted after 8-h acquisition feed. The same occurs with Brevicoryne brassicae. Therefore, the aphid transmission factor (ATF) is involved in both means of transmission and in both aphid species. M. persicae can acquire CaMV Cabb-S strain in less than 20 s. M. persicae is a more efficient vector during a short feed than during a long feed, contrary to B. brassicae which transmits better during a long feed.

Animals↗
PubMed1996

The aphid sex pheromone cyclopentanoids: synthesis in the elucidation of structure and biosynthetic pathways.

Identification of a range of aphid sex pheromones as comprising the cyclopentanoids (4aS,7S,7aR)-nepetalactone, (1R,4aS,7S,7aR)-nepetalactol and the (1S)- and (1R,4aR,7S,7aS)-nepetalactols required samples authenticated by 1H and 13C NMR. These and related compounds were provided by small scale synthesis and extraction from plants in the genus Nepeta (Lamiaceae). The subsequent discovery that the synthetic sex pheromones could attract males, and also parasitic wasps that attack aphids, has created a need for large scale syntheses of the cyclopentanoids. This is afforded by cyclisation of the 8-oxo-1-enamine of citronellal as originally developed by Schreiber and co-workers (1986). Investigation into the biosynthesis of the cyclopentanoids by plants for exploiting aphid sex pheromones in crop protection by means of molecular biology required synthesis of putative biosynthetic intermediates, some with radioactive isotopic labelling, particularly 8-oxidised monoterpene alcohols and aldehydes.

Animals↗
PubMed2006

Plasmids in the aphid endosymbiont Buchnera aphidicola with the smallest genomes. A puzzling evolutionary story.

Buchnera aphidicola, the primary endosymbiont of aphids, has undergone important genomic and biochemical changes as an adaptation to intracellular life. The most important structural changes include a drastic genome reduction and the amplification of genes encoding key enzymes for the biosynthesis of amino acids by their translocation to plasmids. Molecular characterization through different aphid subfamilies has revealed that the genes involved in leucine and tryptophan biosynthesis show a variable fate, since they can be located on plasmids or on the chromosome in different lineages. This versatility contrasts with the genomic stasis found in three distantly related B. aphidicola strains already sequenced. We present the analysis of three B. aphidicola strains (BTg, BCt and BCc) belonging to aphids from different tribes of the subfamily Lachninae, that was estimated to harbour the bacteria with the smallest genomes. The presence of both leucine and tryptophan plasmids in BTg, a chimerical leucine-tryptophan plasmid in BCt, and only a leucine plasmid in BCc, indicates the existence of many recombination events in a recA minus bacterium. In addition, these B. aphidicola plasmids are the simplest described in this species, indicating that plasmids are also involved in the genome shrinkage process.

Amino Acids↗
PubMed2006

Effect of fungal infection on the reproductive potential of aphids and their progeny.

The effect of infection by Pandora neoaphidis and Beauveria bassiana on the reproductive potential of the pea aphid, Acyrthosiphon pisum, and their progeny was assessed. Infection by either P. neoaphidis or B. bassiana reduced the number of nymphs produced within 24 h of inoculation and over the entire infection period compared to uninfected aphids. However, infection by either P. neoaphidis or B. bassiana for 24 or 72 h did not alter the intrinsic rate of increase of the host aphid's progeny. Therefore, fungal infection appears to have no indirect effects on the fitness of the host's progeny.

Animals↗
PubMed2005

Virion stability and aphid vector transmissibility of Cucumber mosaic virus mutants.

The physical stability of virions of Cucumber mosaic virus (CMV) mutants was investigated to determine if relative stability correlated with efficiency of aphid transmission. Virion stability was evaluated by a urea disruption assay and by testing the infectivity of virus following purifications. All viruses were infectious when purified using a low salt buffer without organic solvent, whereas two of seven viruses were less stable and inactivated following purification with a high salt buffer and chloroform. These two viruses were both reassortants derived from the spontaneous transmission-defective mutant CMV-M (F1F2M3 and F1F2M3-L129P). F1F2M3 was relatively unstable, being disrupted between 0 and 1 M urea versus the wild-type CMV-Fny (F1F2M3) that was destabilized at 3-4 M urea. Modifications of F1F2M3 at three amino acid positions (129, 162, 168), singly or in combination, increased the relative stability of virions. A second class of transmission-defective CMVs with engineered mutations in the betaH-betaI surface loop of the CMV-Fny capsid protein (CP) exhibited near wild-type levels of stability. Lastly, a single Pro to Leu substitution at CP position 129 of CMV-Fny (F1F2M3-P129L) conferred the induction of necrosis in tobacco plants and reduced aphid transmissibility, but did not markedly alter the physical stability of virions. Thus, only among CMV-M derivatives harboring the CP mutation of Thr to Ala at position 162 were increases in stability correlated with restoration of transmissibility by the aphid Aphis gossypii.

Amino Acid Substitution↗
PubMed2003

Effects of DIMBOA on detoxification enzymes of the aphid Rhopalosiphum padi (Homoptera: aphididae).

The presence of glutathione transferases and esterase activity was investigated in Rhopalosiphum padi and the effects of the cereal hydroxamic acid, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) on these detoxification enzymes was studied. Activity of glutathione S-transferases and general esterases was determined for adult aphids feeding on a natural diet lacking DIMBOA and on an artificial DIMBOA-containing diet for 48 hours. In vivo, DIMBOA in the diet inhibited the activities of esterases by 50-75% at all concentrations tested (0.5-4 mM). The activity of glutathione transferase was inhibited to a lesser extent (30%) at the higher concentrations of DIMBOA. In vitro, DIMBOA generally inhibited the activity of esterases with an IC(50) of 33 micro M, and had a slight inhibitory effect on glutathione S-transferases. These effects of DIMBOA could make the aphids vulnerable to electrophilic agents and insecticides which may be metabolized via esterases and GSTs. In cereals, therefore, DIMBOA may act by interfering with esterase- or GST-mediated detoxification of xenobiotics by aphids.

Animals↗
PubMed2003

Effects of long-term storage at -14 degrees C on the survival of Neozygites fresenii (Entomophthorales: Neozygitaceae) in cotton aphids (Homoptera: Aphididae).

Neozygites fresenii-infected Aphis gossypii cadavers, containing dormant hyphal bodies of N. fresenii, were stored in 4 ml glass vials at -14 degrees C in a standard consumer-type refrigerator/freezer for 1, 21, 30, 43, 51, and 68 months to determine the effect of storage on fungal survival. When the cadavers were removed from the freezer and placed in 25+/-1 degrees C, 100% relative humidity, and 12:12 (L:D) conditions, N. fresenii survival, as shown by fungal sporulation from the cadavers, was high at all storage periods. The average percentage of cadavers from which the fungus sporulated were 93, 47, 100, 100, 80, and 60% from 1, 21, 30, 43, 51, and 68 months storage periods, respectively. The number of primary conidia discharged from each sporulating cadaver was estimated using a scale of 1 (low, ca. 1000 primary conidia), 2 (medium, ca. 2000 primary conidia) and 3 (high, ca. 3000 primary conidia). The median scores for the number of primary conidia produced per sporulating cadaver were 3, 2, 3, 3, 2.5, and 1 for 1, 21, 30, 43, 51, and 68 months, respectively. Therefore, except for the longest storage period, most cadavers produced medium to high numbers of primary conidia. Mean germination of primary conidia produced from N. fresenii-infected-aphid cadavers from each time period varied significantly from 66.3 to 86.1% in the 21 and 43 months categories, respectively. Infectivity of capilliconidia, produced from frozen N. fresenii, to live healthy cotton aphids varied significantly from 16.7 to 68.7% from cadavers stored 68 months and 1 month, respectively. Overall N. fresenii survived well in dried frozen cotton aphid cadavers for up to 6 years with little reduction in sporulation, numbers of spores produced, germination of primary conidia, or infectivity.

Animals↗
PubMed2003

Characterization of a new densovirus infecting the green peach aphid Myzus persicae.

A new icosahedral DNA virus was isolated from aphids (Myzus persicae) that showed abnormal growth and development. The purified virus particles have a diameter of 20 nm and contain a single-stranded DNA molecule of approximately 5.7 kb. The viral particles are composed of five structural proteins (92, 85, 68, 64, and 57 kDa). As the main biophysical properties of this virus are similar to those of the members of the genus Densovirus it was tentatively named Myzus persicae densovirus (MpDNV). A PCR-based detection method and a polyclonal antiserum raised against MpDNV allowed the detection of the virus in a single-infected aphid. MpDNV is immunologically related to Junonia coenia densovirus, but not to other members of the subfamily Densovirinae. Biological assays showed that MpDNV could be both transmitted transovarially and horizontally via honeydew and saliva. MpDNV was able to infect whiteflies but not other aphid species tested.

Animals↗
PubMed2003

A novel computerised image analysis method for the measurement of production of conidia from the aphid pathogenic fungus Erynia neoaphidis.

A semi-automated method has been developed for the quantification and measurement of conidia discharged by the aphid pathogen Erynia neoaphidis. This was used to compare conidiation by E. neoaphidis-mycosed pea aphid cadavers, mycelial plugs cut from agar plates, mycelial pellets from shake flasks and by mycelial pellets from different phases of liquid batch fermenter culture. Aphid cadavers discharged significantly more and significantly smaller conidia than plugs or pellets. The volume of conidia discharged was stable over the period of discharge (80 h), but more detailed analysis of the size frequency distribution showed that more very small and very large conidia were discharged after 5 h incubation than after 75 h incubation. Biomass harvested at the end of the exponential growth phase in batch fermenter culture produced significantly more conidia than biomass from any other growth phase. The implications of these findings for the development of production and formulation processes for E. neoaphidis as a biological control agent are discussed.

Animals↗
PubMed1999

Activity of glutathione transferase and reductase in tissues of bird cherry-oat aphid during its host-plant alternation.

Changes in activity of detoxifying enzymes, involved in metabolism of glutathione in bird cherry-oat aphid during its host alternation have been investigated. Glutathione transferase (GST) and glutathione reductase (GR) activity was found in homogenates from tissues of the bird cherry-oat aphid, Rhopalosiphum padi (L.). The highest activity of the enzymes was recorded in winged migrants that fly from bird cherry (Prunus padus L.), the winter host onto cereals a summer host. Before the migration an increase in activity of the glutathione transferase and glutathione reductase within tissues of winged migrants was observed. When the migrants started to feed on cereals, GST activity further increased and GR activity decreased. The significance of the R. padi glutathione transferase and reductase in detoxification of plant allelochemicals while the aphid host-plants alternation is discussed.

Animals↗