Mechanisms underlying spruce budworm outbreak processes as elucidated by a 14‐year study in New Brunswick, Canada
Bibliographic record
Abstract
Abstract We conducted a 14‐yr intensive study of spruce budworm (Choristoneura fumiferana (Clem.)) survivorship at three study plots in largely balsam fir (Abies balsamea (L.) Mill.) stands in New Brunswick, Canada, to elucidate certain key mechanisms underlying spruce budworm outbreak cycles. The study covered a peak‐to‐declining phase (from 1981 and 1994) of the budworm outbreak cycle that had started in the early 1960s. Frequent sampling was carried out in each plot‐year to construct a practically continuous survivorship curve, and the annual variation in population density was estimated. We found a high level of correlation between the studied phase of the outbreak cycle and annual variations in the survivorship over the postdiapause period, suggesting that postdiapause survivorship was the chief determinant of the cycle. We found the annual changes in population density in the present study to be closely similar in pattern to those from the provincial budworm surveys conducted in much larger areas. This implies that the mechanism underlying the population process found in the few study plots in largely balsam fir stands also applies to the process in much larger areas of diverse stand types. The main source of postdiapause mortality is found to be natural enemies. The impacts of parasitoids and disease are evaluated by rearing budworm samples in the laboratory. Hymenopteran and dipteran parasitoids are by far the major sources of mortality, and microsporidians are the most prevalent pathogen. Occurrences of other entomopathogenic fungi and viruses were insignificant throughout the study. Seasonal changes in laboratory survivorship are compared with the corresponding field survivorship to estimate the effect of predation. No major mortality factor is found to singly play a predominant role in determining the outbreak cycle. Conversely, some minor factors are shown to have played significant roles. Thus, the importance of recognizing the action of natural enemies as a complex is emphasized for understanding the budworm outbreak cycle. Finally, centered on the roles played by the chronological succession of natural enemies in the present study, the results of budworm research in New Brunswick since the mid‐1940s are synthesized to outline basic mechanisms underlying the outbreak processes as a guide for further studies.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".