Abstract
The Russian wheat aphid, Diuraphis noxia (Kurdjumov), is a pest on wheat and barley in the Western United States. Management is achieved primarily by resistant varieties. In 2003, the Russian wheat aphid caused damage to wheat with the Dn4 resistance gene in Southeastern Colorado. The damaging biotype was designated RWA-2 and the extant population RWA-1. Plant response experiments showed variation within RWA-2 clones based on chlorosis, plant height, and shoot dry weight to wheat with the Dn4 resistance gene. Phenotypic variation found within RWA-2 argues against the hypothesis that RWA-2 populations consist of a single, genetically identical clone. I conducted studies to observe variation between and within Russian wheat aphid biotypes using 12 clones of RWA-1 and RWA-2 biotype, and a single clone of: RWA-3; RWA-4; and RWA-5 biotypes, determined according to plant response to Dn genes. Using RAPD-PCR, three single band polymorphisms were detected distinguishing RWA-5 and clone 7 (RWA-2) after screening all Russian wheat aphids with 58 primers. I found no sequence variation within or between biotypes in a 436 bp fragment of the COI gene in the mtDNA. Seven microsatellite DNA markers were used to evaluate clonal diversity, but no variation was found. In addition, cuticular hydrocarbon analysis was performed on multiple aphids belonging to a single clone of RWA-1, RWA-2, RWA-3, RWA-4, and RWA-5. This method showed RWA-1 and RWA-2 had unique hydrocarbon mixtures, based on principal component analysis. Ultimately all five biotypes could be separated according to canonical variables. Using genotypic markers, Russian wheat aphid biotypes are homogenous, and consist of a single introduction into the United States. Using phenotypic markers, RWA-1 and RWA-2 are more distinctive of the five Russian wheat aphid biotypes. Lack of genotypic variation could have resulted from a founder effect upon introduction into North America, followed by bottlenecking of populations in the United States.
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Claims 11
Claim · model-written summary
Russian wheat aphids damaged wheat carrying the Dn4 resistance gene in southeastern Colorado.
- Taxon
- wheat
Triticum aestivume0 - Interactor
- Russian wheat aphid
Diuraphis noxiae0pest - Gene
- Dn4e0
- Outcome
- damage to wheate0
- Setting
- Southeastern Coloradoe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the Russian wheat aphid caused damage to wheat with the Dn4 resistance gene in Southeastern Colorado”
Claim · model-written summary
RWA-2 clones caused variable chlorosis, height and shoot dry weight responses in Dn4 wheat.
- Taxon
- wheatTriticum aestivume0
- Interactor
- RWA-2 clonese0pest
- Gene
- Dn4e0
- Outcome
- chlorosis, plant height, and shoot dry weighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“variation within RWA-2 clones based on chlorosis, plant height, and shoot dry weight to wheat with the Dn4 resistance gene”
Claim · model-written summary
The authors infer that phenotypic variation contradicts a single identical RWA-2 clone.
- Taxon
- wheatTriticum aestivume1
- Interactor
- RWA-2e0pest
- Outcome
- Phenotypic variatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Phenotypic variation found within RWA-2 argues against the hypothesis that RWA-2 populations consist of a single, genetically identical clone”
e1“The Russian wheat aphid, Diuraphis noxia (Kurdjumov)”
Claim · model-written summary
Three RAPD band polymorphisms distinguished RWA-5 and RWA-2 clone 7.
- Taxon
- wheatTriticum aestivume1
- Interactor
- RWA-5e0pest
- Outcome
- three single band polymorphismse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“three single band polymorphisms were detected distinguishing RWA-5 and clone 7 (RWA-2)”
e1“The Russian wheat aphid, Diuraphis noxia (Kurdjumov)”
Claim · model-written summary
No COI sequence variation was found within or between aphid biotypes.
- Taxon
- wheatTriticum aestivume2
- Interactor
- Russian wheat aphidDiuraphis noxiae1pest
- Gene
- COI genee0
- Outcome
- no sequence variatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no sequence variation within or between biotypes in a 436 bp fragment of the COI gene in the mtDNA”
e1“The Russian wheat aphid, Diuraphis noxia (Kurdjumov)”
e2“pest on wheat and barley”
Claim · model-written summary
Seven microsatellite markers found no clonal variation in aphid biotypes.
- Taxon
- wheatTriticum aestivume2
- Interactor
- Russian wheat aphidDiuraphis noxiae1pest
- Outcome
- no variatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seven microsatellite DNA markers were used to evaluate clonal diversity, but no variation was found”
e1“The Russian wheat aphid, Diuraphis noxia (Kurdjumov)”
e2“pest on wheat and barley”
Claim · model-written summary
RWA-1 and RWA-2 had distinct cuticular hydrocarbon mixtures.
- Taxon
- wheatTriticum aestivume1
- Interactor
- RWA-1 and RWA-2e0pest
- Outcome
- unique hydrocarbon mixturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“RWA-1 and RWA-2 had unique hydrocarbon mixtures”
e1“The Russian wheat aphid, Diuraphis noxia (Kurdjumov)”
Claim · model-written summary
Canonical variables separated all five aphid biotypes.
- Taxon
- wheatTriticum aestivume2
- Interactor
- Russian wheat aphidDiuraphis noxiae1pest
- Outcome
- all five biotypes could be separatede0
- Value
- five biotypese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“all five biotypes could be separated according to canonical variables”
e1“The Russian wheat aphid, Diuraphis noxia (Kurdjumov)”
e2“pest on wheat and barley”
Claim · model-written summary
Genotypic markers indicated homogeneous aphid biotypes and a single introduction into the United States.
- Taxon
- wheatTriticum aestivume1
- Interactor
- Russian wheat aphidDiuraphis noxiae0pest
- Outcome
- homogenous, and consist of a single introductione0
- Setting
- United Statese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Using genotypic markers, Russian wheat aphid biotypes are homogenous, and consist of a single introduction into the United States”
e1“The Russian wheat aphid, Diuraphis noxia (Kurdjumov)”
Claim · model-written summary
Phenotypic markers made RWA-1 and RWA-2 the most distinctive of five biotypes.
- Taxon
- wheatTriticum aestivume1
- Interactor
- Russian wheat aphidDiuraphis noxiae0pest
- Outcome
- more distinctivee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Using phenotypic markers, RWA-1 and RWA-2 are more distinctive of the five Russian wheat aphid biotypes”
e1“The Russian wheat aphid, Diuraphis noxia (Kurdjumov)”
Claim · model-written summary
The authors suggest founder effect and bottlenecks as possible explanations for absent genotypic variation.
- Taxon
- wheatTriticum aestivume2
- Interactor
- Russian wheat aphidDiuraphis noxiae1pest
- Outcome
- Lack of genotypic variatione0
- Qualifier
- a founder effect upon introduction into North America, followed by bottlenecking of populations in the United Statese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lack of genotypic variation could have resulted from a founder effect upon introduction into North America, followed by bottlenecking of populations in the United States”
e1“The Russian wheat aphid, Diuraphis noxia (Kurdjumov)”
e2“pest on wheat and barley”