Agricultural landscape composition affects the development and life expectancy of colonies of <i>Bombus impatiens</i>
Bibliographic record
Abstract
Abstract Bumble bees are essential, efficient pollinators of numerous crops, and scientists are increasingly concerned about their global decline. Although several potential causes have been put forward, the concurrent modification of landscape structure and pesticide use by agriculture are often pointed out as the main drivers of the decline. Yet, the mechanisms through which these factors cause species to decline remain elusive. Most field studies have been conducted at the individual level, and the few studies that addressed higher levels of organization only covered narrow ecological conditions. We undertook a field experiment in spring 2016 to overcome these limitations by placing four commercial Bombus impatiens colonies in each of 20 sites located along a gradient of agricultural intensity in southern Québec, Canada. We hypothesized that landscape habitat composition and configuration, as well as local floral resources, would affect colony development. We expected colonies surrounded by low‐intensity and/or flowering crops in heterogeneous landscapes to develop better and live longer, partly linked to more abundant and diversified food resources, than colonies embedded in landscapes dominated by high‐intensity crops. Colonies were weighed once a week, and workers were captured to assess pollen load diversity. Final colony weight, queen production, and presence of depredators ( Aphomia sociella , Lepidoptera: Pyralidae) were also recorded. Landscape habitat composition and configuration were characterized within 1 km of colonies. Local availability of floral resources was assessed within 100 m of colonies every two weeks. As predicted, colony weight and longevity decreased with the proportion of intensive crops and increased with the amount of flowering crops, but queen production and the occurrence of A. sociella were not affected by landscape composition. Contrary to our prediction, local availability of floral resources also did not affect colonies. The pollen richness brought back to colonies decreased with the proportion of flowering crops and varied according to the proportion of intensive crops interacting with local floral resources. Our work contributes to generalize the more restrictive conclusion of local‐scale, crop‐specific studies that intensive crop farming undermines bumble bee colony development and that it may thus play a role in the large‐scale population decline of these insects.
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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 | 0.000 | 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 | 0.000 |
| 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".