| genetic variation and phylogenetic relationships among worldwide collections of the russian wheat aphid, diuraphis noxia (mordvilko), inferred from allozyme and rapd-pcr markers. | genetic analyses were conducted on diuraphis noxia (mordvilko) populations collected from wheat, barley and other grasses from various countries throughout the world. these collections had been found to contain clones that differed in virulence from various cultivars, cuticular hydrocarbon profiles and life cycle characters. discrete genetic markers analysed in this study included allozymes and arbitrary regions of the genome amplified by the polymerase chain reaction (rapd-pcr). in all, 23 enzy ... | 1993 | 8335479 |
| the endosymbiont (buchnera sp.) of the aphid diuraphis noxia contains plasmids consisting of trpeg and tandem repeats of trpeg pseudogenes. | most aphids are dependent for their survival on prokaryotic endosymbionts assigned to the genus buchnera. among the functions of buchnera species is the synthesis of tryptophan, which is required by the aphid host. in buchnera species from the aphid diuraphis noxia, the genes for anthranilate synthase (trpeg) were found on a plasmid which consisted of seven tandem repeats of a 3.2-kb unit and one 2.6-kb unit which differed in containing a 0.6-kb deletion. one of the 3.2-kb units contained open r ... | 1996 | 8593038 |
| endosymbionts (buchnera) from the aphids schizaphis graminum and diuraphis noxia have different copy numbers of the plasmid containing the leucine biosynthetic genes. | the prokaryotic endosymbiont (buchnera) of the aphid schizaphis graminum contains 24 copies of a plasmid that has genes encoding enzymes of the leucine biosynthetic pathway while the endosymbiont of the related aphid diuraphis noxia has only one copy of this plasmid. these results, in conjunction with similar results for the trpeg-containing plasmids, suggest that d. noxia has a reduced demand for endosymbiont-derived essential amino acids. | 1998 | 9504992 |
| the endosymbiont (buchnera) of the aphid diuraphis noxia contains all the genes of the tryptophan biosynthetic pathway. | previously it has been shown that the prokaryotic endosymbiont (buchnera) of the aphid diuraphis noxia contains a plasmid consisting of one copy of the gene for anthranilate synthase (trpeg) and seven trpeg pseudogenes. in the present communication we show that this endosymbiont contains the remaining genes of the tryptophan biosynthetic pathway [trpdc(f)ba] which appear to be functional in that they code for the complete enzyme proteins and are not pseudogenes. as in the case of buchnera from o ... | 1998 | 9625791 |
| genetic characterization of plasmids containing genes encoding enzymes of leucine biosynthesis in endosymbionts (buchnera) of aphids. | the prokaryotic endosymbionts (buchnera) of aphids are known to provision their hosts with amino acids that are limiting in the aphid diet. buchnera from the aphids schizaphis graminum and diuraphis noxia have plasmids containing leuabcd, genes that encode enzymes of the leucine biosynthetic pathway, as well as genes encoding proteins probably involved in plasmid replication (repa1 and repa2) and an open reading frame (orf1) of unknown function. the newly reported plasmids closely resemble a pla ... | 1999 | 9873079 |
| genetic transformation and mutagenesis of the entomopathogenic fungus paecilomyces fumosoroseus | we have developed a dna-mediated transformation system for the entomopathogenic fungus paecilomyces fumosoroseus based on resistance to the herbicide glufosinate ammonium. the resistance is provided by the bar gene from streptomyces hygroscopicus and is under the control of the aspergillus nidulans trpc promoter and terminator sequences. frequencies of up to 110 transformants/&mgr;g of linearized plasmid dna were obtained aided by the addition of the nuclease inhibitor, aurintricarboxylic acid ( ... | 1999 | 10534416 |
| molecular characterization of the leucine plasmid from buchnera aphidicola, primary endosymbiont of the aphid acyrthosiphon pisum. | the complete sequence of the leucine plasmid of buchnera aphidicola from the aphid acyrthosiphon pisum (pleu-bap) is reported. its gene organization was concordant with those of other leucine plasmids of buchnera from aphids of the aphidini and macrosiphini tribes. three inverted repeats are present in pleu-bap. two of them are also present in pleu from the family aphididae: (i) sir1, located downstream the leucine operon, resembles a rho-independent terminator of transcription, and (ii) lir1, l ... | 2000 | 10688696 |
| seasonal dynamics of cereal aphids on russian wheat aphid (homoptera: aphididae) susceptible and resistant wheats. | field experiments were conducted in 1997 and 1998 to evaluate the impact of resistance to russian wheat aphid, diuraphis noxia (mordvilko), on the cereal aphid complex in wheat. two spring wheats were planted: the variety "centennial" (russian wheat aphid susceptible) and the advanced line ido488 (russian wheat aphid resistant). ido488 incorporates the resistance found in pi 294994 into a centennial background. field plots were artificially infested with adult d. noxia and sampled weekly. the mo ... | 2000 | 10902358 |
| decay of mutualistic potential in aphid endosymbionts through silencing of biosynthetic loci: buchnera of diuraphis. | buchnera, the primary bacterial endosymbiont of aphids, is known to provision essential amino acids lacking in the hosts' diet of plant sap. the recent discovery of silenced copies of genes for tryptophan biosynthesis (trpeg) in certain buchnera lineages suggests a decay in symbiotic functions in some aphid species. however, neither the distribution of pseudogenes among lineages nor the impact of this gene silencing on amino-acid availability in hosts has been assessed. in buchnera of the aphid ... | 2000 | 10983826 |
| 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 ... | 2003 | 12701703 |
| nutritional enhancement of host plants by aphids - a comparison of three aphid species on grasses. | three aphid species were compared with respect to ability of enhancing the nutritional quality of their host plants. rhopalosiphum padi, which does not induce macroscopic changes in its host plants, was compared with schizaphis graminum and diuraphis noxia, both of which induce distinctive types of chlorotic lesions. phloem sap samples were collected from severed stylets of feeding aphids and from exudates of cut leaves of plants uninfested or infested with each aphid species. samples were analy ... | 2000 | 12770256 |
| biotypic and pest status differences between hungarian and south african populations of russian wheat aphid, diuraphis noxia (kurdjumov) (homoptera: aphididae). | russian wheat aphid, diuraphis noxia (kurdjumov) is a severe pest of cereals in south africa and in the usa. in order to reduce d noxia damage, intensive resistance breeding programs have been undertaken, resulting in d noxia-resistant cultivars that are now widely used in south africa and in the usa. however, there appear to be differences in the ability of different populations of d noxia to damage these resistant cereal cultivars. to determine whether different biotypes of d noxia are present ... | 2003 | 14561073 |
| proton-transfer-reaction mass spectrometry as a new tool for real time analysis of root-secreted volatile organic compounds in arabidopsis. | plant roots release about 5% to 20% of all photosynthetically-fixed carbon, and as a result create a carbon-rich environment for numerous rhizosphere organisms, including plant pathogens and symbiotic microbes. although some characterization of root exudates has been achieved, especially of secondary metabolites and proteins, much less is known about volatile organic compounds (vocs) released by roots. in this communication, we describe a novel approach to exploring these rhizosphere vocs and th ... | 2004 | 15141066 |
| effectiveness of predators and parasitoids for the natural control of diuraphis noxia (homoptera: aphididae) on barley in central ethiopia. | the russian wheat aphid, diuraphis noxia (kurdj.), is a serious threat for the production of barley, hordeum vulgare l., in ethiopia. the pest can cause up to 100% yield losses in years of heavy infestation. natural control of d. noxia by using predators and parasitoids might be the best alternative both from economical and ecological point of view. in this regard, a field investigation was conducted during the 2001 spring cropping season at fitche, central ethiopia to determine abundance of d. ... | 2003 | 15149108 |
| identification of russian wheat aphid (homoptera: aphididae) populations virulent to the dn4 resistance gene. | the russian wheat aphid, diuraphis noxia (mordvilko), is a serious worldwide pest of wheat and barley. russian wheat aphid populations from hungary, russia, and syria have previously been identified as virulent to d. noxia (dn) 4, the gene in all russian wheat aphid-resistant cultivars produced in colorado. however, the virulence of russian wheat aphid populations from central europe, north africa, and south america to existing dn genes has not been assessed. experiments with plants containing s ... | 2004 | 15279298 |
| molecular phylogenetics and reproductive incompatibility in a complex of cryptic species of aphid parasitoids. | we infer the phylogeny of a complex of cryptic species and populations of parasitic wasps and examine how reproductive incompatibility maps onto the molecular phylogeny. we used four nuclear (28s-d2, its1, its2, argk) and two mitochondrial (coi, coii) gene regions to analyze relationships among populations in the aphelinus varipes species complex (hymenoptera: aphelinidae) from throughout eurasia (france, georgia, israel, china, korea and japan) and from three aphid hosts (aphis glycines, diurap ... | 2007 | 17702609 |
| sipha maydis: distribution and host range of a new aphid pest of winter cereals in argentina. | sipha maydis (passerini) is a new aphid pest of cereals and cultivated and wild grasses in argentina. this species was recently introduced into america, and nothing is known of its distribution or host range in south america. a better understanding of its biology is likely to facilitate control. this article records 1) the distribution and 2) the host range of s. maydis in argentina. over the period 2004-2006 samples were collected from 32 populations at several localities in argentina. the numb ... | 2007 | 18232394 |
| molecular mapping of the stb4 gene for resistance to septoria tritici blotch in wheat. | abstract breeding wheat for resistance is the most effective means to control septoria tritici blotch (stb), caused by the ascomycete mycosphaerella graminicola (anamorph septoria tritici). at least eight genes that confer resistance to stb in wheat have been identified. among them, the stb4 locus from the wheat cv. tadinia showed resistance to m. graminicola at both seedling and adult-plant stages. however, no attempt has been made to map the stb4 locus in the wheat genome. a mapping population ... | 2004 | 18944455 |
| limited genetic variation within and between russian wheat aphid (hemiptera: aphididae) biotypes in the united states. | insect biotypes are populations able to kill or injure crops with resistance genes and complicate pest management programs based on host plant resistance. biotypes occur in russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae), a worldwide pest of wheat, triticum aestivum l., and barley, hordeum vulgare l., that was introduced into mexico in 1980 and then spread into texas by 1986. five d. noxia biotypes were described in the united states and given the number designations 1 th ... | 2009 | 19253666 |
| plant responses to seven russian wheat aphid (hemiptera: aphididae) biotypes found in the united states. | the russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae), is a serious wheat, triticum aestivum l., and barley, hordeum vulgare l., pest throughout the small grain-producing areas in the western united states. the virulency and classification of recently described russian wheat aphid biotypes 1-7 (rwa1-7) were clarified using 24 plant differentials. these seven biotypes had been described previously using various methods and test environments; therefore, the purpose of this st ... | 2009 | 19886462 |
| aphid resistance in wheat varieties. | as an environmentally compatible alternative to the use of conventional insecticides to control cereal aphids, we have investigated the possibility to exploit natural resistance to insect pests in wheat varieties. we have tested a wide range of hexaploid (triticum aestivum), tetraploid (t. durum) and diploid (t. boeoticum and t. monococcum) wheat lines for resistance to the bird cherry oat aphid (rhopalosiphum padi). lines tested included russian wheat aphid (diuraphis noxia), greenbug (schizaph ... | 2009 | 20218532 |
| virus-induced gene silencing of wrky53 and an inducible phenylalanine ammonia-lyase in wheat reduces aphid resistance. | although several wheat genes differentially expressed during the russian wheat aphid resistance response have recently been identified, their requirement for and specific role in resistance remain unclear. progress in wheat-aphid interaction research is hampered by inadequate collections of mutant germplasm and difficulty in transforming hexaploid wheat. virus-induced gene silencing (vigs) technology is emerging as a viable reverse genetics approach in cereal crops. however, the potential of vig ... | 2010 | 20561246 |
| limited endosymbiont variation in diuraphis noxia (hemiptera: aphididae) biotypes from the united states and south africa. | symbiosis allows an insect access to imbalanced food sources on which other organisms cannot survive. a bacterial endosymbiont, buchnera aphidicola, gives aphids the ability to feed on phloem depleted of certain essential amino acids by producing those required. pseudogenes and lower plasmid copy numbers of essential amino acid genes in b. aphidicola, endosymbiont of the russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae), suggest that this symbiotic relationship is degenerat ... | 2010 | 20568636 |
| differential regulation of 3-aminomethylindole/n-methyl-3-aminomethylindole n-methyltransferase and gramine in barley by both biotic and abiotic stress conditions. | the expression of nmt (3-aminomethylindole/n-methyl-3-aminomethylindole n-methyltransferase; ec 2.1.1.), involved in the biosynthesis of the indole alkaloid gramine, was investigated in aphid-infested barley (hordeum vulgare l.). nmt is induced by methyl jasmonate and it was hypothesized that the gene would be more strongly upregulated in aphid-resistant barley. we examined the effects of feeding by three aphid species; russian wheat aphid (diuraphis noxia mordvilko), rose-grain aphid (metopolop ... | 2010 | 21074448 |
| the genome of diuraphis noxia, a global aphid pest of small grains. | the russian wheat aphid, diuraphis noxia kurdjumov, is one of the most important pests of small grains throughout the temperate regions of the world. this phytotoxic aphid causes severe systemic damage symptoms in wheat, barley, and other small grains as a direct result of the salivary proteins it injects into the plant while feeding. | 2015 | 26044338 |
| virus-induced gene silencing suggests (1,3;1,4)-β-glucanase is a susceptibility factor in the compatible russian wheat aphid-wheat interaction. | the russian wheat aphid (rwa), diuraphis noxia (kurdjumov), is a significant insect pest of wheat (triticum aestivum l.) and has a major economic impact worldwide, especially on winter wheat in the western united states. the continuing emergence of new rwa biotypes virulent to existing resistance genes reinforces the need for more durable resistance. studies have indicated that resistance in previously susceptible plants can be produced by knock-down of susceptibility genes or other genes involv ... | 2014 | 24964057 |
| erwinia iniecta sp. nov., isolated from russian wheat aphid (diuraphis noxia). | short, gram-negative-staining, rod-shaped bacteria were isolated from crushed bodies of russian wheat aphid [diuraphis noxia (kurdjumov)] and artificial diets after russian wheat aphid feeding. based on multilocus sequence analysis involving the 16s rrna, atpd, infb, gyrb and rpob genes, these bacterial isolates constitute a novel clade in the genus erwinia, and were most closely related to erwinia toletana. representative distinct strains within this clade were used for comparisons with related ... | 2015 | 26198254 |
| effect of serial transfer of three strains of paecilomyces fumosoroseus on growth in vitro, virulence, and host specificity. | serial passage of entomopathogenic hyphomycetes has been shown to alter virulence and host specificity. we evaluated virulence, host specificity, biomass production, conidiation, conidial germination, and a genetic fingerprint of 3 strains of paecilomyces fumosoroseus after passage in vitro or in vivo in diuraphis noxia or plutella xylostella. strain 4461 did not change in virulence toward d. noxia or p. xylostella after 30 passages in vitro nor after 15 passages in d. noxia. however, it lost vi ... | 2004 | 14992859 |
| use of the green fluorescent protein for investigations of paecilomyces fumosoroseus in insect hosts. | the green fluorescent protein (gfp) from the jellyfish aequorea victoria has been expressed in a variety of prokaryotic and eukaryotic organisms and has been used extensively as a marker in the study of host-pathogen interactions. we have expressed gfp in the entomopathogenic fungus paecilomyces fumosoroseus through co-transformation with a vector that confers resistance to glufosinate ammonium. all cell types express gfp and were readily detected by fluorescence microscopy. no correlation was o ... | 1999 | 10486232 |
| relative efficacy of blastospores and aerial conidia of paecilomyces fumosoroseus against the russian wheat aphid. | | 1998 | 9709022 |
| diversity, frequency and geographic distribution of facultative bacterial endosymbionts in introduced aphid pests. | facultative bacterial endosymbionts in insects have been under intense study during the last years. endosymbionts can modify the insect's phenotype, conferring adaptive advantages under environmental stress. this seems particularly relevant for a group of worldwide agricultural aphid pests, because endosymbionts modify key fitness related traits, including host plant use, protection against natural enemies and heat tolerance. aimed to understand the role of facultative endosymbionts on the succe ... | 2016 | 26773849 |
| whole genome sequence of the soybean aphid, aphis glycines. | aphids are emerging as model organisms for both basic and applied research. of the 5,000 estimated species, only three aphids have published whole genome sequences: the pea aphid acyrthosiphon pisum, the russian wheat aphid, diuraphis noxia, and the green peach aphid, myzus persicae. we present the whole genome sequence of a fourth aphid, the soybean aphid (aphis glycines), which is an extreme specialist and an important invasive pest of soybean (glycine max). the availability of genomic resourc ... | 2017 | 28119199 |
| salivary proteins of plant-feeding hemipteroids - implication in phytophagy. | many hemipteroids are major pests and vectors of microbial pathogens, infecting crops. saliva of the hemipteroids is critical in enabling them to be voracious feeders on plants, including the economically important ones. a plethora of hemipteroid salivary enzymes is known to inflict stress in plants, either by degrading the plant tissue or by affecting their normal metabolism. hemipteroids utilize one of the following three strategies of feeding behaviour: salivary sheath feeding, osmotic-pump f ... | 2014 | 24280006 |
| comparisons of salivary proteins from five aphid (hemiptera: aphididae) species. | aphid (hemiptera: aphididae) saliva, when injected into host plants during feeding, causes physiological changes in hosts that facilitate aphid feeding and cause injury to plants. comparing salivary constituents among aphid species could help identify which salivary products are universally important for general aphid feeding processes, which products are involved with specific host associations, or which products elicit visible injury to hosts. we compared the salivary proteins from five aphid ... | 2011 | 22182624 |
| cross-species transferability of microsatellite markers from six aphid (hemiptera: aphididae) species and their use for evaluating biotypic diversity in two cereal aphids. | the abundance and distribution of microsatellites, or simple sequence repeats (ssrs) were explored in the expressed sequence tag (est) and genomic sequences of the pea aphid, acyrthosiphon pisum (harris), and the green peach aphid, myzus persicae (sulzer). a total of 108 newly developed, together with 40 published, ssr markers were investigated for their cross-species transferability among six aphid species. genetic diversity among six greenbug, schizaphis graminum (rondani) and two russian whea ... | 2007 | 17714463 |
| the mitochondrial genome of the russian wheat aphid diuraphis noxia: large repetitive sequences between trne and trnf in aphids. | to characterize aphid mitochondrial genome (mitogenome) features, we sequenced the complete mitogenome of the russian wheat aphid, diuraphis noxia. the 15,784-bp mitogenome with a high a+t content (84.76%) and strong c skew (-0.26) was arranged in the same gene order as that of the ancestral insect. unlike typical insect mitogenomes, d. noxia possessed a large tandem repeat region (644 bp) located between trne and trnf. sequencing partial mitogenome of the cotton aphid (aphis gossypii) further c ... | 2014 | 24095774 |
| oxidative responses of resistant and susceptible cereal leaves to symptomatic and nonsymptomatic cereal aphid (hemiptera: aphididae) feeding. | the impact of the leaf-chlorosis-eliciting russian wheat aphid, diuraphis noxia (mordvilko), and the nonchlorosis-eliciting bird cherry-oat aphid, rhopalosiphum padi (l.), feeding on d. noxia-susceptible and -resistant cereals was examined during the period (i.e., 3, 6, and 9 d after aphid infestation) that leaf chlorosis developed. after aphid number, leaf rolling and chlorosis ratings, and fresh leaf weight were recorded on each sampling date, total protein content, peroxidase, catalase, and p ... | 2001 | 11425032 |
| poisoning of canada geese in texas by parathion sprayed for control of russian wheat aphid. | approximately 200 canada geese (branta canadensis) died at a playa lake in the texas panhandle shortly after a winter wheat field in the basin adjacent to the lake was treated with parathion to control newly invading russian wheat aphids (diuraphis noxia). no evidence of infectious disease was diagnosed during necropsies of geese. brain che activities were depressed up to 77% below normal. parathion residues in gi tract contents of geese ranged from 4 to 34 ppm. based on this evidence, parathion ... | 1991 | 2067047 |
| olfactory responses of the parasitoiddiaeretiella rapae (hymenoptera: aphidiidae) to odor of plants, aphids, and plant-aphid complexes. | diaeretiella rapae (m'intosh) (hymenoptera: aphidiidae) is a parasitoid of several aphid species, including the russian wheat aphid (rwa),diuraphis noxia (mordvilko), and the cabbage aphid (ca).brevicoryne brassicae (l.). the response of matedd. rapae females to odors from wheat, cabbage, and plant-host complexes was investigated using a four-choice olfactometer. experienced parasitoids, but not inexperienced females, responded positively to odors of the wheat-rwa complex in a no-choice test. in ... | 1995 | 24234172 |
| host associations of diuraphis noxia (homoptera: aphididae) biotypes in south africa. | the incidence and host associations of russian wheat aphid were investigated in the wheat-growing areas of south africa from 2009 to 2011. most russian wheat aphid samples were collected on dryland wheat, while few samples were collected on irrigation wheat. volunteer wheat and rescue grass were the preferred alternative host plants to cultivated wheat for all three biotypes. no rwasa1 samples were collected from oats, but rwasa2 seemed to be able to survive successfully on oats, with 12.26% of ... | 2013 | 24498762 |
| brain cholinesterase inhibition in songbirds from pecan groves sprayed with phosalone and disulfoton. | brain cholinesterase (che) activities of songbirds collected in pecan groves 6 to 7 hr after separate applications of the organophosphorus pesticides, phosalone and disulfoton, were compared to mean che activities of controls (normals) as a measure of insecticide exposure. in general, reduction of brain che activity greater than or equal to 2 standard deviations below the control mean indicates exposure to an anticholinesterase compound. phosalone had little effect on brain che activity of birds ... | 1990 | 2304190 |
| response of russian wheat aphid resistance in wheat and barley to four diuraphis (hemiptera: aphididae) species. | three diuraphis species, diuraphis frequens (walker), diuraphis mexicana (mcvicar baker), and diuraphis tritici (gillette), were known to exist in the united states before the 1986 appearance of the russian wheat aphid, diuraphis noxia kurdjumov. the russian wheat aphid soon became a significant pest of wheat although other endemic diuraphis species were known to infest wheat. wheat and barley entries resistant and susceptible to russian wheat aphid biotype 2 were evaluated against all four diur ... | 2013 | 23786097 |
| host associations and incidence of diuraphis spp. in the rocky mountain region of the united states, and pictorial key for their identification. | the russian wheat aphid, diuraphis noxia kurdjumov, is an introduced species first identified in 1986 into the united states. it has since become a major pest of wheat, triticum aestivum l., and other small grains in the western united states. three other diuraphis species, diuraphis frequens (walker), diuraphis mexicana (mcvicar baker), and diuraphis tritici (gillette), were already endemic to the united states before the introduction of d. noxia. the objective of this study was to determine th ... | 2010 | 21061992 |
| profiling diuraphis noxia (hemiptera: aphididae) transcript expression of the biotypes sa1 and sam feeding on various triticum aestivum varieties. | the intimate relationship between an aphid and its host is mediated by the composition of the secreted saliva. in the present study, aphid heads were sampled and transcript profiling conducted after aphids were fed on their preference host and transferred to a variety of preference and nonpreference hosts. it was found that the virulent diuraphis noxia (kurdjumov) (hemiptera: aphididae) biotype sam was able to selectively up-regulate more transcripts when confronted with feeding on a variety of ... | 2017 | 28334389 |
| more virulent offspring result from hybridization of invasive aphid species, diuraphis noxia (hemiptera: aphididae), with diuraphis tritici endemic to the united states. | | 2017 | 28199674 |
| reproduction and population dynamics as biotypic markers of russian wheat aphid diuraphis noxia (kurdjumov). | russian wheat aphid diuraphis noxia (kurdjumov) is widely established in wheat-growing countries where it causes significant economic losses. the development and use of russian wheat aphid (rwa)-resistant wheat varieties has been constrained by the variation in resident rwa populations and the evolution of virulent biotypes. an experiment was set up at the kenya agricultural and livestock research organization (kalro), njoro, to characterize rwa populations based on phenotypic characteristics of ... | 2016 | 27049398 |
| virulent diuraphis noxia aphids over-express calcium signaling proteins to overcome defenses of aphid-resistant wheat plants. | the russian wheat aphid, diuraphis noxia, an invasive phytotoxic pest of wheat, triticum aestivum, and barley, hordeum vulgare, causes huge economic losses in africa, south america, and north america. most acceptable and ecologically beneficial aphid management strategies include selection and breeding of d. noxia-resistant varieties, and numerous d. noxia resistance genes have been identified in t. aestivum and h. vulgare. north american d. noxia biotype 1 is avirulent to t. aestivum varieties ... | 2016 | 26815857 |
| changes in the russian wheat aphid (hemiptera: aphididae) biotype complex in south africa. | russian wheat aphid diuraphis noxia (kurdjumov) has spread from its native area in central asia to all the major wheat-producing countries in the world to become an international wheat pest. because the russian wheat aphid is a serious threat to the wheat industry in south africa, it is important to investigate the key factors involved in the distribution of russian wheat aphid biotypes and in the changes of the russian wheat aphid biotype complex in south africa. there are currently four known ... | 2016 | 26803815 |
| change in biotypic diversity of russian wheat aphid (hemiptera: aphididae) populations in the united states. | a key component of russian wheat aphid, diuraphis noxia (kurdjumov), management has been through planting resistant wheat cultivars. a new biotype, rwa2, appeared in 2003 which caused widespread damage to wheat cultivars containing the dn4 gene. biotypic diversity in russian wheat aphid populations has not been addressed since 2005 when rwa2 dominated the biotype complex. our objectives were to determine the biotypic diversity in the central great plains and colorado plateau at regional (2010, 2 ... | 2015 | 26470192 |
| electrical penetration graph recording of russian wheat aphid (hemiptera: aphididae) feeding on aphid-resistant wheat and barley. | biotypes of russian wheat aphid, diuraphis noxia (kurdjumov), have nullified d. noxia-resistant wheat. in this study, feeding of north american d. noxia was measured in aphids fed resistant and susceptible wheat and barley using electrical penetration graph (epg) recordings. interactions between barley genotypes and d. noxia biotypes were significant. epg recordings of biotype 1 aphids fed on d. noxia-resistant ibrwagp4-7 barley plants displayed significantly more non-phloem (pathway) phase move ... | 2015 | 26453736 |
| effects of planting date and barley variety on russian wheat aphid (hemiptera: aphididae) populations in colorado, kansas, and nebraska. | the russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae), is an important pest in the western great plains of the united states, where it causes hundreds of millions of dollars of losses to barley and wheat production through reduced yields. experiments to evaluate the effect of early planting and resistance in barley (hordeum vulgare l.) on d. noxia were conducted at fort collins, co; tribune, ks; and sidney, ne, in 2007, 2008, and 2009. treatments included two planting dates ... | 2014 | 26309288 |
| variation between ethiopian and north american barley varieties (hordeum vulgare) in response to russian wheat aphid (diuraphis noxia) populations. | the russian wheat aphid, diuraphis noxia (mordvilko) (hemiptera: aphididae), causes severe damage to barley, hordeum vulgare l. (poales: poaceae), in the highlands of ethiopia. little information is available on the control of this pest in ethiopia. an experiment aimed at evaluating the resistance of barley varieties from the usa to d. noxia populations and determining biotypic variation between ethiopian and north american d. noxia populations was conducted. the d. noxia-resistant barley variet ... | 2014 | 25373187 |
| near-isogenic lines of triticum aestivum with distinct modes of resistance exhibit dissimilar transcriptional regulation during diuraphis noxia feeding. | russian wheat aphid (diuraphis noxia, kurdjumov) feeding on susceptible triticum aestivum l. leads to leaf rolling, chlorosis and plant death - symptoms not present in resistant lines. although the effects of several d. noxia (dn) resistance genes are known, none have been isolated or characterized. wheat varieties expressing different dn genes exhibit distinct modes of d. noxia resistance, such as antibiosis (dn1), tolerance (dn2), and antixenosis (dn5). however, the mechanism whereby feeding a ... | 2014 | 25361582 |
| phi-class glutathione-s-transferase is involved in dn1-mediated resistance. | wheat dn genes afford resistance to the economically important pest, diuraphis noxia (kurdjumov, russian wheat aphid, rwa) and have been the topic of transcriptomic and proteomic studies aimed at unraveling the pathways involved in resistance. the antibiotic resistance conveyed by dn1 is characterized by a hypersensitive response (hr) followed by systemic acquired resistance (sar). although many candidate genes differentially expressed during the dn1-mediated resistance response have been identi ... | 2015 | 25243379 |
| examining the competitive advantage of diuraphis noxia (hemiptera: aphididae) biotype 2 over biotype 1. | the russian wheat aphid, diuraphis noxia (kurdjumov) is a serious pest of small grains, such as wheat and barley. high population growth rates and a broad gramineae host range have allowed this aphid to successfully establish and become pestiferous across much of north america since its invasion in the mid-1980s. resistant wheat cultivars were developed and provided control ofd. noxia until 2003, when a new biotype (designated rwa2, as contrasted with the original biotype's designation, rwa1) em ... | 2014 | 25195438 |
| characterization of eight russian wheat aphid (hemiptera: aphididae) biotypes using two-category resistant-susceptible plant responses. | eight biotypes of the russian wheat aphid, diuraphis noxia (kurdjumov), have been discovered in the united states since 2003. biotypes are identified by the distinct feeding damage responses they produce on wheat carrying different russian wheat aphid resistance genes, namely, from dn1 to dn9. each russian wheat aphid biotype has been named using plant damage criteria and virulence categories that have varied between studies. the study was initiated to compare the plant damage caused by all the ... | 2014 | 25026693 |
| hypervirulent diuraphis noxia (hemiptera: aphididae) biotype sam avoids triggering defenses in its host (triticum aestivum) (poales: poaceae) during feeding. | in the molecular arms race between aphids and plants, both organisms rely on adaptive strategies to outcompete their evolutionary rival. in the current study, we investigated the difference in elicited defense responses of wheat (triticum aestivum l.) near-isogenic lines with different dn resistance genes, upon feeding by an avirulent and hypervirulent diuraphis noxia kurdjumov biotype. after measuring the activity of a suite of enzymes associated with plant defense, it became apparent that the ... | 2014 | 24874154 |
| selection of reference genes for expression analysis in diuraphis noxia (hemiptera: aphididae) fed on resistant and susceptible wheat plants. | the russian wheat aphid (rwa), diuraphis noxia kurdjumov, is a major global pest of wheat and barley production that causes enormous economic damage. few studies have been conducted to explore and decipher the molecular basis of rwa strategies to evade plant defense mechanisms. gene expression studies of rwa in response to wheat genotypes carrying different rwa resistance genes have been initiated in our group; however, a secure and accurate understanding of rwa gene expression is dependent on i ... | 2014 | 24862828 |
| evaluation of tetraploid switchgrass (poales: poaceae) populations for host suitability and differential resistance to four cereal aphids. | switchgrass, panicum virgatum l., is being developed as a bioenergy feedstock. the potential for large-scale production has encouraged its evaluation as a host for important grass pests. eight no-choice studies were performed for two developmental stages of two switchgrass cultivars ('kanlow' and'summer') and two experimental strains, k x s, and s x k produced by reciprocal mating of these cultivars followed by selection for high yield. plants were evaluated for host suitability and damage diffe ... | 2014 | 24665729 |
| validating spatiotemporal predictions of an important pest of small grains. | arthropod pests are typically managed using tactics applied uniformly to the whole field. precision pest management applies tactics under the assumption that within-field pest pressure differences exist. this approach allows for more precise and judicious use of scouting resources and management tactics. for example, a portion of a field delineated as attractive to pests may be selected to receive extra monitoring attention. likely because of the high variability in pest dynamics, little attenti ... | 2015 | 24648393 |
| a multi-genome analysis approach enables tracking of the invasion of a single russian wheat aphid (diuraphis noxia) clone throughout the new world. | this study investigated the population genetics, demographic history and pathway of invasion of the russian wheat aphid (rwa) from its native range in central asia, the middle east and europe to south africa and the americas. we screened microsatellite markers, mitochondrial dna and endosymbiont genes in 504 rwa clones from nineteen populations worldwide. following pathway analyses of microsatellite and endosymbiont data, we postulate that turkey and syria were the most likely sources of invasio ... | 2014 | 24617944 |
| quantifying russian wheat aphid pest intensity across the great plains. | wheat, the most important cereal crop in the northern hemisphere, is at-risk for an approximate 10% reduction in worldwide production because of animal pests. the potential economic impact of cereal crop pests has resulted in substantial research efforts into the understanding of pest agroecosystems and development of pest management strategy. management strategy is informed frequently by models that describe the population dynamics of important crop pests and because of the economic impact of t ... | 2012 | 23321099 |
| cyclical parthenogenetic reproduction in the russian wheat aphid (hemiptera: aphididae) in the united states: sexual reproduction and its outcome on biotypic diversity. | in 1986, the russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae), became an invasive species of united states. nearly 20 yr later, new biotypes appeared that were capable of overcoming most sources of resistance and became a renewed threat to wheat, triticum aestivum l., production. cyclical (cp) and obligate (op) parthenogenesis enables aphids to both adapt to changing environments and exploit host resources. we documented these forms of reproduction for russian wheat aphid ... | 2012 | 22812148 |
| barley tolerance of russian wheat aphid (hemiptera: aphididae) biotype 2 herbivory involves expression of defense response and developmental genes. | the russian wheat aphid, diuraphis noxia (kurdjumov), is an invasive insect pest that causes serious yield losses in bread wheat, triticum aestivum l., durum wheat, t. turgidum l and barley, hordeum vulgare l. successful management of d. noxia has been achieved through resistant varieties via plant antixenosis (aphid non-preference), antibiosis (reduced aphid growth or fecundity), tolerance (plant compensatory growth after aphid feeding), or a combination of each. previous phenotyping experiment ... | 2012 | 22476464 |
| antifeedant activity of fatty acid esters and phytosterols from echium wildpretii. | crude extracts and fractions from echium wildpretii h. pearson ex hook. f. subsp. wildpretii (boraginaceae) have been tested against insect species spodoptera littoralis, leptinotarsa decemlineata, and the aphids myzus persicae, diuraphis noxia, metopolophium dirhodum, rhopalosiphum maidis, and rhopalosiphum padi. the etoh extract and the lipid and steroidal fractions of e. wildpretii exhibited significant antifeedant activities against the aphids and l. decemlineata. two bioactive mixtures comp ... | 2012 | 22422524 |
| polymorphism and methylation of four genes expressed in salivary glands of russian wheat aphid (homoptera: aphididae). | dna methylation is a general epigenetic mechanism for plants, animals, and fungi to adapt to environmental variation. two biotypes of the russian wheat aphid (diuraphis noxia), biotype 1 and biotype 2, have different virulence to host plants. in this study, in addition to a high polymorphism, dna methylation at cytosines were observed in genomic fragments of four genes in biotype 1 and biotype 2, after the genomic dna was treated with sodium bisulfite. these genes presumably encode proteins and ... | 2012 | 22420276 |
| russian wheat aphids (diuraphis noxia) in china: native range expansion or recent introduction? | in this study, we explore the population genetics of the russian wheat aphid (rwa) (diuraphis noxia), one of the world's most invasive agricultural pests, in north-western china. we have analysed the data of 10 microsatellite loci and mitochondrial sequences from 27 populations sampled over 2 years in china. the results confirm that the rwas are holocyclic in china with high genetic diversity indicating widespread sexual reproduction. distinct differences in microsatellite genetic diversity and ... | 2012 | 22417053 |
| proteomic analysis of secreted saliva from russian wheat aphid (diuraphis noxia kurd.) biotypes that differ in virulence to wheat. | diuraphis noxia, russian wheat aphid (rwa), biotypes are classified by their differential virulence to wheat varieties containing resistance genes. rwa salivary proteins, unlike those of most aphid species, cause foliar damage and physiological alterations in plants. a comparative proteomic analysis of secreted saliva from four differentially virulent rwa biotypes identified thirty-four individual proteins. the five major proteins were glucose dehydrogenase, lipophorin, chitinase, civ16.8g1-like ... | 2012 | 22348819 |
| distribution and diversity of russian wheat aphid (hemiptera: aphididae) biotypes in south africa and lesotho. | russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae) was recorded for the first time in south africa in 1978. in 2005, a second biotype, rwasa2, emerged, and here we report on the emergence of yet another biotype, found for the first time in 2009. the discovery of new russian wheat aphid biotypes is a significant challenge to the wheat, triticum aestivum l., industry in south africa. russian wheat aphid resistance in wheat, that offered wheat producers a long-term solution to ... | 2011 | 22066205 |
| wheat gene expression is differentially affected by a virulent russian wheat aphid biotype. | an improved understanding of the complex interactions between plants and aphids is emerging. recognition of aphid feeding in plant tissues involves production of several defense response signaling pathways and downstream production of defense and detoxification compounds. feeding by russian wheat aphid, diuraphis noxia (kurdjumov), a serious pest of cereal crops worldwide, induces foliar deformity and chlorophyll loss during compatible wheat-d. noxia interactions. experiments described here reve ... | 2011 | 21499720 |
| karyotype analysis of the russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae) reveals a large x chromosome with rrna and histone gene families. | the russsian wheat aphid (rwa), diuraphis noxia (kurdjumov), is a worldwide pest of cereals. despite its economic importance, little is known about its genome. here we investigated physical genomic features in rwa by karyotype analysis using differential staining with agno(3), cma(3), and dapi, by chromosomal localization of ribosomal dna (rdna), h3 and h4 histone genes, and the "arthropod" telomeric sequence (ttagg)(n) using fluorescence in situ hybridization (fish), and by measuring the rwa ge ... | 2011 | 21336570 |
| inhibition of xanthine oxidase activity results in the inhibition of russian wheat aphid-induced defense enzymes. | the role of xanthine oxidase (xo) in the defense response of wheat (triticum aestivum l.) against the russian wheat aphid (rwa) (diuraphis noxia) was studied. xanthine oxidase catalyzes the oxidation of hypoxanthine to xanthine to uric acid, and oxygen radicals that are formed as a by-product at both of these oxidation steps may participate in plant defense reactions. a resistant wheat cultivar (tugela dn), and a close isogenic susceptible cultivar (tugela), were infested with 20-30 aphids per p ... | 2010 | 21086025 |
| transcript profiling of wheat genes expressed during feeding by two different biotypes of diuraphis noxia. | diuraphis noxia (kurdjumov)(russian wheat aphid) has severe economic impacts on wheat and barley production in the united states. the interaction between the russian wheat aphid and its cereal hosts is poorly understood. however, the recent appearance of new biotypes in the united states showed that specific interactions exist between wheat resistance loci and russian wheat aphid biotypes. at present, dn7 is the only known gene in hexaploid wheat that confers resistance against all u.s. russian ... | 2010 | 22127172 |
| global phylogenetics of diuraphis noxia (hemiptera: aphididae), an invasive aphid species: evidence for multiple invasions into north america. | the russian wheat aphid, diruaphis noxia (kudjumov) (hemiptera: aphididae), is globally one of the most devastating pests of bread wheat, tritium aestivum l., durum wheat, triticum turgidum l., and barley, hordeum vulgare l. several sources of d. noxia resistance have been incorporated in commercial wheat and barley genotypes, but up to eight virulent biotypes, defined based on their ability to damage different wheat and barley genotypes, now occur across the western united states since the firs ... | 2010 | 20568643 |
| aphid feeding activates expression of a transcriptome of oxylipin-based defense signals in wheat involved in resistance to herbivory. | damage by the russian wheat aphid (rwa), diuraphis noxia, significantly reduces wheat and barley yields worldwide. in compatible interactions, virulent rwa populations flourish and susceptible plants suffer extensive leaf chlorophyll loss. in incompatible interactions, rwa reproduction and population growth are significantly reduced and rwa-related chlorophyll loss in resistant plants is minor. the objectives of this study were to develop an understanding of the molecular and phytochemical bases ... | 2010 | 20229216 |
| salivary proteins of russian wheat aphid (hemiptera: aphididae). | salivary secretions play critical roles in aphid-host plant interactions and are responsible for damage associated with aphid feeding. the objectives of this study were to evaluate aspects of salivation and the salivary constituents of diuraphis noxia (hemiptera: aphididae). salivary proteins were isolated and compared from three aphid probed diets: pure water, 15% sucrose, or amino acids (100 mm serine, 100 mm methionine, 100 mm aspartic acid, and 15% sucrose). after 6 h, more aphids settled on ... | 2010 | 20146860 |
| survival analysis approach to insect life table analysis and hypothesis testing: with particular reference to russian wheat aphid (diuraphis noxia (mordvilko)) populations. | the goal of this paper is to examine and demonstrate that survival analysis, which has been a de facto standard in biomedical research since the 1990s but has not been widely adopted in entomology yet, should possess similar potential in entomological research. the following three objectives are set to achieve this goal: (i) addressing a fundamental issue - censoring or incomplete observations; (ii) demonstrating the application of survival analysis to analyze insect life tables; and (iii) apply ... | 2010 | 19941673 |
| diuraphis noxia reproduction and development with a comparison of intrinsic rates of increase to other important small grain aphids: a meta-analysis. | the russian wheat aphid, diuraphis noxia (kurdjumov), is a significant pest of small grains in the united states and worldwide. there is an increasing need for quality population dynamic models to aid in development of integrated pest management strategies. unfortunately, there exists high variability in published data regarding basic life history traits that frequently direct model parameterization. metadata were analyzed to develop relationships between temperature and reproductive and develop ... | 2009 | 19689884 |
| feeding behavior of russian wheat aphid (hemiptera: aphididae) biotype 2 in response to wheat genotypes exhibiting antibiosis and tolerance resistance. | in this study, wheat, triticum aestivum l. (em thell), genotypes containing the dnx, dn7, dn6, and dn4 genes for resistance to the russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae), along with dn0, a susceptible control, were assessed to determine the categories of d. noxia biotype 2 (rwa2) resistance in each genotype and rwa2 feeding behaviors on dnx and dn0 plants by using the electronic penetration graph technique. at 14 d postinfestation, dn0 plants exhibited intense ch ... | 2009 | 19610450 |
| resistance to russian wheat aphid biotype 2 in cimmyt synthetic hexaploid wheat lines. | the russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae), devastates wheat and barley production on all continents except australia. although d. noxia-resistant cultivars exist, virulent d. noxia populations exist in asia, north america, and south america that have the ability to overcome resistance. in this study, synthetic hexaploid wheat genotypes created at the international maize and wheat improvement center (cimmyt) were evaluated and characterized for resistance to nort ... | 2009 | 19610446 |
| dissimilar molecular defense responses are elicited in triticum aestivum after infestation by different diuraphis noxia biotypes. | for sustainable solutions to the problem of insect infestation, the study of molecular plant-insect interactions is integral to resistance breeding strategies. this also holds true in the case of wheat (triticum aestivum), where the russian wheat aphid (diuraphis noxia, kurdjumov, rwa) is responsible for significant crop losses in most major wheat producing countries around the world. our study is focused on gaining a greater understanding of the resistance mechanisms activated by the rwa resist ... | 2009 | 19453509 |
| modeling spatial variation of russian wheat aphid overwintering population densities in colorado winter wheat. | the russian wheat aphid, diuraphis noxia (kurdjumov), is a pest of small grain crops that has caused hundreds of millions of dollars of damage since it was first reported in the united states in 1986. much is known about d. noxia population dynamics during the spring and early summer when most of the crop damage occurs, whereas little is known about the system during the overwintering period. using a spatially explicit model developed from field observations in a wheat/fallow agro-ecosystem, we ... | 2009 | 19449632 |
| molecular cytogenetic and agronomic characterization of advanced generations of wheat x triticale hybrids resistant to diuraphis noxia (mordvilko): application of gish and microsatellite markers. | the pi 386148 triticale from russia is among the highest resistant line to the russian wheat aphid (rwa) (diuraphis noxia (mordvilko)). this triticale line was used as the male parent in crosses with lamar wheat (triticum aestivum l.). the f1 plants were backcrossed to lamar wheat. the progenies were tested for rwa biotype 1 reaction for at least eight backcross and selfing generations. five lines from these selections were identified for their resistance to the rwa and their seeds were increase ... | 2009 | 19370091 |
| impact of diuraphis noxia and rhopalosiphum padi (hemiptera: aphididae) on primary physiology of four near-isogenic wheat lines. | the impact of feeding injury by the russian wheat aphid, diuraphis noxia (mordvilko) (hemiptera: aphididae), and bird cherry-oat aphid, rhopalosiphum padi (l.) (hemiptera: aphididae) on susceptible and resistant wheat, triticum aestivum l., near-isogenic lines 'tugela' (susceptible), tugela-dn1 (antibiotic), tugela-dn2 (tolerant), and tugela-dn5 (antixenotic) was evaluated by assessing photosynthetic parameters. photosynthesis and closely related parameters, pigment composition, and nonstructura ... | 2009 | 19253663 |
| a new modelling approach to insect reproduction with same-shape reproduction distribution and rate summation: with particular reference to russian wheat aphid. | same-shape distribution model and rate summation approach are widely used to describe the insect developmental process. in this approach, by integrating a nonlinear deterministic developmental rate model and a probabilistic same-shape distribution model, the proportion of the cohort completing development is quantified as a function of accumulating developmental rates, which themselves are temperature dependent. this method is considered to be more accurate in modelling insect phenology because ... | 2009 | 19159500 |
| stronger induction of callose deposition in barley by russian wheat aphid than bird cherry-oat aphid is not associated with differences in callose synthase or beta-1,3-glucanase transcript abundance. | the effects of infestation by the bird cherry-oat aphid (bca), (rhopalosiphum padi l) and the russian wheat aphid (rwa) (diuraphis noxia mordvilko) on callose deposition and transcription of genes related to callose accumulation were investigated in barley (hordeum vulgare l. cv. clipper). the bca, which gives no visible symptoms, induced very limited callose deposition, even after 14 days of infestation. in contrast, rwa, which causes chlorosis, white and yellow streaking and leaf rolling, indu ... | 2009 | 19055542 |
| gene expression profiling of tolerant barley in response to diuraphis noxia (hemiptera: aphididae) feeding. | aphids are, arguably, the single most damaging group of agricultural insect pests throughout the world. plant tolerance, which is a plant response to an insect pest, is viewed as an excellent management strategy. developing testable hypotheses based on genome-wide and more focused methods will help in understanding the molecular underpinnings of plant tolerance to aphid herbivory. as a first step in this process, we undertook transcript profiling with affymetrix genechip barley genome arrays usi ... | 2009 | 18840314 |
| induced life cycle transition from holocycly to anholocycly of the russian wheat aphid (homoptera: aphididae). | the russian wheat aphid (rwa),diuraphis noxia (mordvilko), exists with holocyclic life cycle in tacheng, xinjiang in northwest china. it produces males and oviparae to mate and oviposit for overwintering by eggs. under laboratory conditions with 14 h/d photophase and temperature not lower than 15 degrees c, rwa occurred in parthenogenesis and produced no males. the laboratory populations of russian wheat aphid, which were kept under natural conditions in fall by 15th, 49th and 81st generation wh ... | 2001 | 18763082 |
| reproductive rates of russian wheat aphid (hemiptera: aphididae) biotypes 1 and 2 on a susceptible and a resistant wheat at three temperature regimes. | the reproductive rates of russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae), biotype 1 (rwa 1) and biotype 2 (rwa 2) were compared in the laboratory at three temperature regimes on a russian wheat aphid resistant cultivar ('prairie red') and a susceptible cultivar ('tam 107'). the objective of this study was to expose rwa 1 and rwa 2 to three temperature regimes and two levels of resistance to find whether there were reproductive differences that may occur within each bioty ... | 2008 | 18613599 |
| biotypic diversity in colorado russian wheat aphid (hemiptera: aphididae) populations. | the biotypic diversity of the russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae), was assessed in five isolates collected in colorado. three isolates, rwa 1, rwa 2, and an isolate from montezuma county, co, designated rwa 6, were originally collected from cultivated wheat, triticum aestivum l., and obtained from established colonies at colorado state university. the fourth isolate, designated rwa 7, was collected from canada wildrye, elymus canadensis l., in baca county, co. ... | 2008 | 18459426 |
| reproduction and development of russian wheat aphid biotype 2 on crested wheatgrass, intermediate wheatgrass, and susceptible and resistant wheat. | the russian wheat aphid, diuraphis noxia (kurdjumov), is an economically important pest of small grains. since its introduction into north america in 2003, russian wheat aphid biotype 2 has been found to be virulent to all commercially available winter wheat, triticum aestivum l., cultivars. our goal was to examine differences in russian wheat aphid reproduction and development on a variety of plant hosts to gain information about 1) potential alternate host refuges, 2) selective host pressures ... | 2008 | 18459422 |
| antioxidative enzymes and the russian wheat aphid (diuraphis noxia) resistance response in wheat (triticum aestivum). | a crucial function of antioxidative enzymes is to remove excess reactive oxygen species (ros), which can be toxic to plant cells. the effect of russian wheat aphid (rwa), diuraphis noxia (mordvilko), infestation on the activities of antioxidative enzymes was investigated in the resistant (cv. tugela dn) and the near-isogenic susceptible (cv. tugela) wheat (triticum aestivum l.). rwa infestation significantly induced the activity of superoxide dismutase, glutathione reductase and ascorbate peroxi ... | 2008 | 18426488 |
| physiological and biochemical responses of resistant and susceptible wheat to injury by russian wheat aphid. | we examined the physiological and biochemical responses of resistant ('halt' and 'prairie red') and susceptible ('tam 107') wheat, triticum aestivum l., to injury by the russian wheat aphid, diuraphis noxia (mordvilko). photosynthetic capacity was evaluated by measuring assimilation/internal co2 (a/ci) curves, chlorophyll fluorescence, chlorophyll, and nonstructural carbohydrate content. total protein and peroxidase specific activity also were determined. no significant differences were detected ... | 2007 | 17972650 |
| variation to cause host injury between russian wheat aphid (homoptera: aphididae) clones virulent to dn4 wheat. | biotypes are infraspecific classifications based on biological rather than morphological characteristics. cereal aphids are managed primarily by host plant resistance, and they often develop biotypes that injure or kill previously resistant plants. although molecular genetic variation within aphid biotypes has been well documented, little is known about phenotypic variation, especially virulence or the biotype's ability to cause injury to cultivars with specific resistance genes. five clones (si ... | 2007 | 17972649 |
| distribution and diversity of russian wheat aphid (hemiptera: aphididae) biotypes in north america. | wheat, triticum aestivum l., with russian wheat aphid, diuraphis noxia (kurdjumov) (hemiptera: aphididae) resistance based on the dn4 gene has been important in managing russian wheat aphid since 1994. recently, five biotypes (rwa1-rwa5) of this aphid have been described based on their ability to differentially damage rwa resistance genes in wheat. rwa2, rwa4, and rwa5 are of great concern because they can kill wheat with dn4 resistance. in 2005, 365 russian wheat aphid clone colonies were made ... | 2007 | 17972648 |
| fractionated extracts of russian wheat aphid eliciting defense responses in wheat. | it is hypothesized that the interaction between aphids and plants follows a gene-for-gene model. the recent appearance of several new russian wheat aphid, diuraphis noxia (kurdjumov) (homoptera: aphididae), biotypes in the united states and the differential response of wheat, triticum aestivum l., genotypes containing different resistance genes also suggest a gene-for-gene interaction. however, aphid elicitors remain unknown. this study was conducted to identify fractionated russian wheat aphid ... | 2007 | 17598566 |
| response of resistant and susceptible barley to infestations of five diuraphis noxia (homoptera: aphididae) biotypes. | since 2003, four new biotypes of the russian wheat aphid, diuraphis noxia (kurdjumov) (homoptera: aphididae), rwa2-rwa5, have been discovered that have the ability to damage most of the wheat germplasm resistant to the original russian wheat aphid population (rwa1). barley germplasm lines with resistance to rwa1 have not yet been evaluated against the newest biotypes. our study compared how biotypes rwa1-rwa5 affected the growth and leaf damage of rwa1-resistant germplasm (stars 9301b, stars 957 ... | 2006 | 17195687 |
| biotypic variation among north american russian wheat aphid (homoptera: aphididae) populations. | the russian wheat aphid, diuraphis noxia (mordvilko) (homoptera: aphididae), has been a major economic pest of small grains in the western united states since its introduction in 1986. recently, a new russian wheat aphid biotype was discovered in southeastern colorado that damaged previously resistant wheat, triticum aestivum l. biotype development jeopardizes the durability of plant resistance, which has been a cornerstone for russian wheat aphid management. our objective was to assess the rela ... | 2006 | 17066823 |
| categories and inheritance of resistance to russian wheat aphid (homoptera: aphididae) biotype 2 in a selection from wheat cereal introduction 2401. | the russian wheat aphid, diuraphis noxia (kurdjumov) (homoptera: aphididae), is one of the most devastating insect pests of wheat (triticum spp.) and barley (hordeum spp.) in the world. yield losses and control costs are valued at several hundred million dollars each year. the use of d. noxia-resistant cultivars is an ecologically, economically, and biologically sound method of managing this pest. several d. noxia resistance (dn) genes from wheat have been used to develop cultivars resistant to ... | 2006 | 17066822 |
| the reactive oxygen species are involved in resistance responses of wheat to the russian wheat aphid. | the effect of russian wheat aphid (rwa), diuraphis noxia (mordvilko), infestation on the hydrogen peroxide (h(2)o(2)) content and nadph oxidase (ec 1.6.3.1) activity was studied in the resistant (cv. tugela dn) and near-isogenic susceptible (cv. tugela) wheat (triticum aestivum l.). the objective of this study was to investigate the involvement of the reactive oxygen species (ros) during the resistance responses against the rwa. infestation significantly induced an early accumulation of the h(2) ... | 2006 | 17032617 |