Biennial aerial application of Bacillus thuringiensis Berliner var. kurstaki is the most cost-effective approach of protection against spruce budworm (Choristoneura fumiferana [Clemens])
Bibliographic record
Abstract
Abstract Key message Aerial application of Bacillus thuringiensis Berliner var. kurstaki (Btk) every second year to stands of white spruce ( Picea glauca (Moench)Voss.), black spruce ( Picea mariana Mill.) and balsam fir ( Abies balsamea (L.) Mill.) is the most cost-effective spraying scenario for reducing the impact of spruce budworm ( Choristoneura fumiferana Clemens) on wood production, providing a similar level of forest protection, but at lower cost, to the standard scenario currently used in which 50% of current year’s foliage is protected every year. Context Insect outbreaks can have significant effects on forest productivity and various formulations of Bacillus thuringiensis Berliner var. kursta ki ( Btk ) are used to reduce their damage. In the Province of Québec, Canada, control programs aim to protect at least 50% of current-year foliage to limit tree mortality, but little information exists on the long-term cost-effectiveness of such programs. Aims Our goal was to evaluate the benefit/cost ratio and the efficacy of different Btk protection scenarios in reducing coniferous tree mortality and growth losses over a 11-year period. We hypothesized that less-intensive protection approaches ( Btk applications every 2 or 3 years) may provide similar levels of protection but with higher cost-effectiveness ratios than the standard program currently used in Quebec. Methods In 2007, we established nineteen 100-ha experimental units in Quebec’s Côte-Nord region to determine the efficacy and cost-effectiveness of different Btk spraying scenarios for reducing tree mortality and volume losses in coniferous stands dominated by mature balsam fir trees ( Abies balsamea (L.) Mill., with white spruce ( Picea glauca (Moench) Voss.) and black spruce ( P. mariana Mill.) as companion species. Tree mortality was monitored annually in three circular plots of 400 m 2 within each experimental unit. Growth losses were evaluated using stem analyses. Results Mortality was much higher in balsam fir than in black spruce and white spruce (respectively 74.4%, 13.8% and 5.9% in untreated stands) in all protection scenarios. The application of Btk every 2 years reduced balsam fir mortality to a level similar to the standard scenario (10.3% vs 7.15%, respectively) at a much lower cost. Growth losses have also been reduced but not to the same extent as in the standard scenario. Conclusion Spraying Btk every 2 years provides effective protection to balsam fir and is the most cost-effective scenario. A less intensive use of Btk would mitigate impact on non-target lepidoptera and allow protecting other areas, such as habitat of the woodland caribou, a threatened species which avoids disturbed areas.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".