Effects of two grasshopper control insecticides on food resources and reproductive success of two species of grassland songbirds
Notice bibliographique
Résumé
Abstract Wconducteda field experimenttodetermine the direct and indirect effects of spraying two broad-spectrum insecticides with widely differing avian toxicities in grassland habitat on the survival and reproductive success of nesting songbirds. Three 56-ha plots were sprayed with Decis 5F™, three plots were sprayed with Furadan 480F™, and three plots were left unsprayed. Insecticides were applied at rates recommended for grasshopper control. Grasshopper (Orthoptera: Acrididae) density was measured throughout the spring and summer. Nests of chestnut-collared longspurs (Calcarius ornatus) were monitored to determine survival rates and nestling growth. Food habits of nestlings and parental foraging parameters were measured using esophageal ligatures and observations of parental foraging flights. Applications of both insecticides decreased grasshopper populations by more than 90%. Nevertheless, the number of grasshoppers in nestling diets was significantly decreased only in nests in Decis-sprayed plots. Total arthropod biomass delivered to the nestlings did not decrease in plots sprayed with either insecticide. Nestling weight and size were unaffected by insecticide spraying. Rate of prey delivery also did not change; however, by two weeks after spraying with Decis, parent longspurs were foraging almost twice as far from their nests as were birds in control plots (p < 0.05) to maintain prey delivery rates. Clutch size and egg and nestling success were similar among treated and control plots within specific two-week periods during the season. Age-corrected brain acetylcholinesterase activities of longspur nestlings in plots sprayed with Furadan were significantly depressed compared to controls; a single case of insecticide-induced mortality was detected in a nestling that was severely infested with blowfly larvae. Nevertheless, success of nests with Furadan-exposed nestlings (n = 20) was greater than that in control plots during the two-week period following spray (n = 19, p = 0.03). The Baird's sparrow (Ammodramus bairdii), an uncommon prairie species of conservation concern, was monitored using an index of productivity. The number of 3.14-ha census circles having productive Baird's sparrow territories was significantly lower in Furadan-sprayed plots than in unsprayed and Decis-sprayed plots; a larger number of sparrow territories were abandoned in Furadan plots.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».