Supercooling Capacity and Survival of Low Temperatures by a Pyrethroid-Resistant Strain of<i>Typhlodromus pyri</i>(Acari: Phytoseiidae)
Bibliographic record
Abstract
An organophosphate/pyrethroid resistant strain of the phytoseiid mite Typhlodromus pyri Scheuten was imported from New Zealand in 1988 for use in biological control of European red mite, Panonychus ulmi (Koch), and apple rust mite, Aculus schlechtendali (Nalepa), in Nova Scotia. To better understand the overwintering strategy of T. pyri and the likelihood the New Zealand strain would withstand winter conditions in Canada, we measured supercooling points and mortality of diapausing females held at subzero temperatures. Mites in quartz crucibles were placed in the liquid nitrogen-cooled stage of a cryostage microscope, and temperature was lowered 1°C/min until the mites froze, as indicated by an instantaneous darkening of their body contents. Supercooling points of the New Zealand strain averaged −18.2°C for July to September, were −23.2°C in October, and averaged −28.2°C in the colder months from November to March. The mean supercooling points for December 1994 did not differ from the mean for the native Nova Scotian strain. However, the mean supercooling point of the New Zealand strain for March 1995 was higher than the means for the native strain and for a T. pyri strain that was imported from Geneva, NY. New Zealand strain T. pyri taken from cloth bands affixed to orchard trees were placed on apple leaves in plastic vials and exposed to low temperatures for various periods of exposure. At −5°C, mortality at 24 h was less for mites collected in February than for those collected in November (6% versus 44%) but at −10°C trends were similar, reaching 100% by 24 h in both trials. For the February trial, a logistic function with a coefficient for the product of time and temperature explained 61% of the variation in mortality. If these results are applied to populations in Nova Scotian orchards, where winter temperatures of −10°C are common, one would predict complete annihilation of the New Zealand strain. However, populations of the New Zealand strain, first released in orchards in 1988, have survived every winter since that date and have proven effective in biological control of European red mite and apple rust mite. Possible reasons for survival and increase of populations of this exotic strain of T. pyri, despite apparent susceptibility to cold-induced mortality, are discussed.
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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) | 0.003 | 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".