Absence of Mitochondrial DNA Sequence Variation in Russian Wheat Aphid (Hemiptera: Aphididae) Populations Consistent with a Single Introduction into the United States
Bibliographic record
Abstract
Russian wheat aphid, Diuraphis noxia (Kurdjumov), was introduced into North America in Mexico during 1980 and by 1988 had spread north across the Western US into Southern Canada. South Africa has been suspected as the source of the introduction. Russian wheat aphid is the major insect pest of wheat and barley in the southern and central plains states. Resistant wheat with the Dn4 gene was the primary management tactic from 1996 to 2003. During 2003, a biotype able to injure Dn4 wheat (designated RWA2) appeared in Colorado. The source of the biotype is unclear, that is whether it represents a new introduction from another country or if it arose from the extant population in the US. We examined a 332 bp portion of the cytochrome oxidase subunit I gene (COI) in the mtDNA of Russian wheat aphid collected in the US from 1986 through 2006. Also included were specimens from Mexico and South Africa. Except for two nucleotides in two individual aphids, no COI sequence variation was found in US populations over a 20 yr period. US populations had COI sequences which were identical to those found in Mexico, Turkey, France, and one aphid from South Africa. A second aphid from South Africa differed by only two bp. The lack of COI nucleotide variation suggested that biotype RWA2 did not represent a second introduction of a genetically distinct population from another country. The data are consistent with a single introduction from South Africa and no other introductions of virulent biotypes into the US occurred since 1986.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".