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a large-scale field study of bacterial communities in cereal aphid populations across morocco.insects are frequently associated with bacteria that can have significant ecological and evolutionary impacts on their hosts. to date, few studies have examined the influence of environmental factors to microbiome composition of aphids. the current work assessed the diversity of bacterial communities of five cereal aphid species (sitobion avenae, rhopalosiphum padi, r. maidis, sipha maydis and diuraphis noxia) collected across morocco and covering a wide range of environmental conditions. we aim ...201829346623
retraction: virulent diuraphis noxia aphids over-express calcium signaling proteins to overcome defenses of aphid-resistant wheat plants. 201829346432
rapid cold hardening capacity and its impact on performance of russian wheat aphid (hemiptera: aphididae).the russian wheat aphid, diuraphis noxia (kurdjumov), is one of the most important pests of wheat and barley in most wheat-producing countries. rapid cold hardiness (rch) is a capacity of insects to develop, within hours, protection against subfreezing temperatures that plays an important role in aphid survival in response to sudden decreases in air temperature. in this research, we investigated the duration and rate of cooling on the induction of rch of d. noxia and the costs of rch on aphid de ...201728541434
genome of russian wheat aphid an economically important cereal aphid.although the hemipterans (aphididae) are comprised of roughly 50,000 extant insect species, only four have sequenced genomes that are publically available, namely acyrthosiphon pisum (pea aphid), rhodnius prolixus (kissing bug), myzus persicae (green peach aphid) and diuraphis noxia (russian wheat aphid). as a significant proportion of agricultural pests are phloem feeding aphids, it is crucial for sustained global food security that a greater understanding of the genomic and molecular functioni ...201729299110
diversity and evolution of mariner-like elements in aphid genomes.although transposons have been identified in almost all organisms, genome-wide information on mariner elements in aphididae remains unknown. genomes of acyrthosiphon pisum, diuraphis noxia and myzus persicae belonging to the macrosiphini tribe, actually available in databases, have been investigated.201728662628
survival and feeding rates of four aphid species (hemiptera: aphididae) on various sucrose concentrations in diets.different concentrations of sucrose were used to investigate how survival and feeding was affected in four species of aphids (hemiptera: aphididae). seven sucrose concentrations were evaluated in feeding chambers fitted with parafilm membranes and infested with nymphs of aphis glycines matsumura, diuraphis noxia kurdjumov, myzus persicae sulzer, or schizaphis graminum rondani at 25 °c and a photoperiod of 14:10 (l:d) h. survival on each diet was recorded 1, 3, 5, 7, 9, and 11 d. diet volumes (μl ...201728637212
isolation of early-responsive microrna from diuraphis noxia (hemiptera: aphididae)-resistant wheat.the russian wheat aphid (diuraphis noxia kurdjumov) is an economically important pest of small grains in many countries. the past decades have seen the deployment of resistance-carrying wheat (triticum aestivum l.) cultivars to control d. noxia. however, the emergence of resistance-breaking biotypes is negating this strategy. the role that noncoding rna (ncrna) molecules play in the wheat-d. noxia interaction has not been studied to date. this study aimed to isolate differentially regulated micr ...201728407081
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 ...201728119199
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 ...201728334389
more virulent offspring result from hybridization of invasive aphid species, diuraphis noxia (hemiptera: aphididae), with diuraphis tritici endemic to the united states. 201728199674
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 ...201627049398
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 ...201626815857
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 ...201626803815
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 ...201626773849
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 ...201525243379
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 ...201526470192
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 ...201526453736
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 ...201524648393
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.201526044338
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 ...201526198254
chromosomal genomics facilitates fine mapping of a russian wheat aphid resistance gene.making use of wheat chromosomal resources, we developed 11 gene-associated markers for the region of interest, which allowed reducing gene interval and spanning it by four bac clones. positional gene cloning and targeted marker development in bread wheat are hampered by high complexity and polyploidy of its nuclear genome. aiming to clone a russian wheat aphid resistance gene dn2401 located on wheat chromosome arm 7ds, we have developed a strategy overcoming problems due to polyploidy and enabli ...201525862680
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 ...201424964057
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 ...201424095774
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 ...201424280006
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 ...201424617944
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 ...201426309288
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 ...201425373187
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 ...201425361582
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 ...201425195438
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 ...201425026693
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 ...201424874154
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 ...201424862828
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 ...201424665729
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 ...201324498762
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 ...201323786097
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 ...201223321099
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 ...201222812148
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 ...201222476464
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 ...201222422524
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 ...201222420276
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 ...201222417053
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 ...201222348819
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 ...201122066205
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 ...201121499720
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 ...201121336570
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 ...201122182624
bac libraries from wheat chromosome 7d: efficient tool for positional cloning of aphid resistance genes.positional cloning in bread wheat is a tedious task due to its huge genome size and hexaploid character. bac libraries represent an essential tool for positional cloning. however, wheat bac libraries comprise more than million clones, which makes their screening very laborious. here, we present a targeted approach based on chromosome-specific bac libraries. such libraries were constructed from flow-sorted arms of wheat chromosome 7d. a library from the short arm (7ds) consisting of 49,152 clones ...201121318113
variation of resistance in barley against biotypes 1 and 2 of the russian wheat aphid (hemiptera: aphididae).the russian wheat aphid, diruaphis noxia (kurdjumov) (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. host plant resistance is the foundation for cereal insect pest management programs, and several sources of d. noxia resistance have been incorporated in cultivars to manage d. noxia damage. the emergence of d. noxia north american biotype 2 (rwa2) in colorado has made all k ...201020568641
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 ...201021061992
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 ...201020561246
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 ...201020568636
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 ...201021074448
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 ...201021086025
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 ...201022127172
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 ...201020568643
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 ...201020229216
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 ...201020146860
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 ...201019941673
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 ...200919689884
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 ...200919610450
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 ...200919610446
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 ...200919453509
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 ...200919449632
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 ...200919370091
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 ...200919253663
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 ...200919159500
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 ...200919055542
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 ...200918840314
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 ...200919253666
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 ...200919886462
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 ...200920218532
inheritance and categories of resistance in wheat to russian wheat aphid (hemiptera: aphididae) biotype 1 and biotype 2.the russian wheat aphid, diruaphis noxia (kudjumov) (hemiptera: aphididae), is globally one of the most devastating pests of wheat, tritium aestivum l., and barley, hordeum vulgare l. host plant resistance is the foundation of cereal insect pest management programs, and several d. noxia resistance (dn) genes from wheat have been introduced in commercial cultivars of wheat to manage russian wheat aphid (rwa). emergence of d. noxia biotype 2 (rwa2) in colorado has made all known dn genes, except t ...200919736781
microsatellite-based molecular diversity of bread wheat germplasm and association mapping of wheat resistance to the russian wheat aphid.genetic diversity of a set of 71 wheat accessions, including 53 biotype 2 russian wheat aphid (rwa2)-resistant landraces and 18 rwa2 susceptible accessions, was assessed by examining molecular variation at multiple microsatellite (ssr) loci. fifty-one wheat ssr primer pairs were used, 81 ssr loci were determined, and 545 ssr alleles were detected. these ssr loci covered all the three genomes, 21 chromosomes, and at least 41 of the 42 chromosome arms. diversity values averaged over ssr loci were ...200918392559
glycoproteins from russian wheat aphid infested wheat induce defence responses.elicitors are molecules which can induce the activation of plant defence responses. elicitor activity of intercellular wash fluid from russian wheat aphid, diuraphis noxia (mordvilko) infested resistant (cv tugela dn), and susceptible (cv tugela), wheat (triticum aestivum l.), was investigated. known russian wheat aphid resistance related responses such as peroxidase and beta-1,3-glucanase activities were used as parameters of elicitor activity. the intercellular wash fluid from infested resista ...200912440726
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 ...200818613599
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. ...200818459426
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 ...200818459422
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 ...200818426488
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 ...200717972650
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 ...200717972649
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 ...200717972648
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 ...200717598566
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 ...200717714463
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 ...200717702609
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 ...200718232394
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 ...200617195687
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 ...200617066823
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 ...200617066822
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) ...200617032617
molecular basis of plant gene expression during aphid invasion: wheat pto- and pti-like sequences are involved in interactions between wheat and russian wheat aphid (homoptera: aphididae).the russian wheat aphid, diuraphis noxia (mordvilko) (homoptera: aphididae), is a major pest of bread wheat, triticum aestivum l. (em thell), in most wheat-growing areas worldwide. aphid-resistant cultivars are used to combat this pest, but very little is known about the molecular basis of resistance. in this study, differential gene expression in d. noxia biotype 1-resistant wheat plants containing the dnx gene and d. noxia biotype 1 feeding on dnx plants was investigated using suppressive subt ...200616937702
positive correlation of fitness with group size in two biotypes of russian wheat aphid (homoptera: aphididae).changes in fitness parameters as a function of colony size (one versus 10 aphids) were measured in two biotypes (rwa1 and rwa2) of the russian wheat aphid, diuraphis noxia (mordvilko) (homoptera: aphididae), feeding on three cultivars of wheat, triticum aestivum l., at two temperatures. 'trego' is a cultivar with no specific resistance to d. noxia, whereas, 'stanton' and 'halt' express dny and dn4 resistance sources, respectively. feeding in a group accelerated the development of rwa1 on trego a ...200616937675
diuraphis noxia and rhopalosiphum padi (hemiptera: aphididae) interactions and their injury on resistant and susceptible cereal seedlings.interspecific interactions between the symptomatic (chlorosis-eliciting) russian wheat aphid, diuraphis noxia (mordvilko), and the asymptomatic (nonchlorosis-eliciting) bird cherry-oat aphid, rhopalosiphum padi (l.), on four cereal genotypes were examined by simultaneous infestations. four cereals (i.e., diuraphis noxia-susceptible 'arapahoe' wheat and 'morex' barley, and d. noxia-resistant 'halt' wheat and 'border' oat) and four infestations (i.e., control, d. noxia, r. padi, and d. noxia/r. pa ...200616686159
resistance to biotype 2 russian wheat aphid (homoptera: aphididae) in two wheat lines.biotype 2 of the russian wheat aphid, diuraphis noxia (mordvilko), was identified in the united states in 2003 and is virulent to all commercially available cultivars of winter wheat, triticum aestivum l., that are resistant to biotype 1. we compared the development and reproduction of biotype 2 d. noxia at 21.7 +/- 0.12 degrees c on 'trego' (pi 612576), a susceptible commercial cultivar, and on lines ci 2401 and 03gd1378027 that represent putative resistance sources. ci 2401 is a pure wheat lin ...200616686158
is photosynthetic transcriptional regulation in triticum aestivum l. cv. 'tugeladn' a contributing factor for tolerance to diuraphis noxia (homoptera: aphididae)?diuraphis noxia (russian wheat aphid, rwa) is a major pest on wheat in south africa and most other wheat growing countries. being a probing-sucking insect, rwas insert their stylets into the phloem sieve elements and feed on the phloem sap. this feeding causes necrotic lesions in resistant varieties, or decoloration of leaves and death in susceptible varieties. in an effort to broaden our understanding on the response of the plant to rwa feeding, we synthesized and analyzed expressed sequence ta ...200616328390
comparative biology of a novel strain of russian wheat aphid (homoptera: aphididae) on three wheat cultivars.in spring 2003, several outbreaks of the russian wheat aphid, diuraphis noxia (mordvilko), were reported in fields of supposedly resistant wheat cultivars ('stanton', 'halt', and 'prairie red') in eastern colorado. we conducted two laboratory experiments to compare the biological performance of this new biotype 2 (b2) to that of two d. noxia collections of biotype 1 (b1) from western kansas by using three wheat cultivars as host plants: 'trego', a susceptible cultivar, and stanton and halt, two ...200516022336
resistance to rhopalosiphum padi (homoptera: aphididae) in three triticale accessions.experiments were conducted to identify and characterize host plant resistance to bird cherry-oat aphid, rhopalosiphum padi (l.), in various wheat and wheat-grass hybrids. initial tests screened for resistance to r. padi among 12 grass accessions (eight wheat [triticum aestivum l.], three triticale [xtriticosecale wittmack], and 1xelytricum [elytrigia elongata [host] nevski x triticum aestivum hybrid]). r. padi had less population growth on triticale accessions '8ta5l' (pi 611760) and 'stniism 3' ...200515889754
yield response and categories of resistance to russian wheat aphid in four dn4 hard red winter wheat cultivars.a field experiment was conducted to determine whether resistance to russian wheat aphid, diuraphis noxia (mordvilko), conferred by the dn4 gene is affected by genetic background. this was done by comparing the yield responses to russian wheat aphid-resistant wheat containing dn4, derived through the backcross method, to those of the corresponding recurrent parents. infested resistant cultivars had fewer russian wheat aphids per tiller than infested susceptible cultivars at the lamar and fort col ...200515889752
influence of three resistance sources in winter wheat derived from tam 107 on yield response to russian wheat aphid.a study to determine yield response to the russian wheat aphid, diuraphis noxia (mordvilko), was conducted during the 1997-1998 and 1998-1999 growing seasons at three eastern colorado locations, akron, fort collins, and lamar, with three wheat lines containing either russian wheat aphid-resistant dn4 gene, dn6 gene, or resistance derived from pi 222668, and tam 107 as the susceptible control. russian wheat aphids per tiller were greater on tam 107 than the resistant wheat lines at the 10x infest ...200515889729
interactions among three species of cereal aphids simultaneously infesting wheat.interactions among greenbug, schizaphis graminum (rondani), russian wheat aphid, diuraphis noxia (mordvilko), and bird cherry-oat aphid rhopalosiphum padi (l.) were examined on wheat plants (triticum aestivum l., cultivar tam 107). nymphs were released on the plants as conspecific and heterospecific pairs of either first or fourth instars and evaluated for survival, developmental time, fecundity, intra-plant movement, and affinity to plant tissues. survival from first instar to onset of reproduc ...200516341245
comparison of dn4- and dn7-carrying spring wheat genotypes artificially infested with russian wheat aphid (homoptera: aphididae) biotype 1.genetic resistance is a useful control strategy for managing russian wheat aphid, diuraphis noxia (mordvilko), in wheat, triticum aestivum l. in 2003, a russian wheat aphid population (denoted as biotype 2) identified in colorado was virulent to genotypes carrying the dn4 russian wheat aphid resistance gene, necessitating the rapid identification and deployment of new sources of resistance. although the dn7 gene had shown excellent resistance to russian wheat aphid biotypes 1 and 2 in evaluation ...200516334342
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