Leaf‐roll gall formation in <i>Reynoutria</i> × <i>bohemica</i> and its implications for biological control with <i>Aphalara itadori</i>
Bibliographic record
Abstract
Abstract The psyllid Aphalara itadori Shinji (Hemiptera: Psyllidae) is a biocontrol agent against invasive knotweed species (Polygonaceae) in Europe and North America. Despite an extensive release program, successful establishment of the agent has never been confirmed. The slow establishment of A. itadori in its introduced range appears to be predominantly the result of nymphal mortality, either through desiccation, predation, or the adaptation of captive populations to low‐stress environments. In 2016, CABI UK collected a new line of psyllids from Murakami, Niigata Prefecture, in Japan, where it was observed causing severe leaf‐roll galling on one of the many varieties of native knotweeds. The induction of leaf‐roll galls by Murakami psyllids on invasive Bohemian knotweed, Reynoutria × bohemica, has the potential to alleviate some or all of the observed nymphal mortality factors. We conducted a series of growth chamber experiments to explore the psyllid behaviors that initiate leaf‐roll galls, and the ways in which the galls might benefit the psyllids and inhibit invasive knotweed. Reynoutria × bohemica exposed to A. itadori for 4 weeks suffered reduced stem elongation and leaf area compared to control plants. Artificial leaf‐roll galls were consistently utilized by developing A. itadori nymphs, and contributed to their survival. Leaf‐roll galling in R. × bohemica was predominantly initiated by early instar nymphs of A. itadori, and only occurred when leaves were attacked at a very early stage in their development. Our results can inform the knotweed biocontrol program in several key ways. Releases of A. itadori should be timed so that developing nymphs have access to newly emerging leaves. Monitoring efforts at release sites should focus on the growing tips of R. × bohemica, where the highly mobile nymphs appear to migrate. Finally, our results provide motivation to seek additional lines of A. itadori that may affect other invasive knotweed species in similar ways.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".