INVESTIGATING BIRDS AS DISPERSAL VECTORS OF LITYLENCHUS CRENATAE SUBSP. MCCANNII (ANGUINIDAE), THE NEMATODE ASSOCIATED WITH BEECH LEAF DISEASE
Bibliographic record
Abstract
Beech leaf disease (BLD) is an emerging forest pathogen primarily affecting American beech (Fagus grandifolia, Ehrh.) in North America and has been attributed to tree mortality of sapling sized trees within five to seven years of infection. Symptoms typically occur in regenerating American beech thickets sprouting from roots of trees killed by beech bark disease. Scientists first observed BLD in Ohio in 2012 and currently has spread to 15 states in the USA and one Canadian province. The nematode Litylenchus crenatae subsp. mccannii (Lcm) is highly associated with BLD symptoms, interveinal chlorosis and defoliation of leaves, and is currently recognized as the major causal agent of BLD (Carta et al. 2020). Methods of dispersal are still being examined. Animal vectors could be responsible for the spread of Lcm and thus BLD. This was the first survey investigating birds as possible dispersal vectors of Lcm through endozoochory and ectozoochory. From 2021 to 2023 we collected 219 fecal, feather, and ectoparasite samples from 156 birds in infected BLD areas in Ohio and Pennsylvania. We kept birds in cages, fed them Lcm nematodes and collected fecal matter to determine if we could observe Lcm via endozoochory. We collected ectoparasite and feather samples to determine if Lcm nematodes could be observed via ectozoochory. We used PCR and microscopy to determine the presence of Lcm. Results confirmed presence in 21 samples from six avian species: tufted titmouse [Baeolophus bicolor], black-capped chickadee [Poecile atricapillus], white-breasted nuthatch [Sitta carolinensis], dark-eyed junco [Junco hyemalis], American goldfinch [Spinus tristis], and downy woodpecker [Dryobates pubescens]. We detected Lcm DNA from both endozoochory and endozoochory samples suggesting birds could act as vectors of Lcm. This study successfully used existing and novel methodologies to detect nematode DNA in avian biological samples. These methods can be adopted for future BLD research as well as animal vector and forest pathogen studies. If birds are dispersal vectors of BLD state, federal, or local agencies could create predictive models and implement preventative management to protect uninfected American beech stands.
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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 | 0.000 |
| 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".