Assessing adaptive winter behaviors of beneficial arthropods, with a focus on the long-distance migratory ecology of Nearctic hover flies (Diptera: Syrphidae)
Notice bibliographique
Résumé
Temperate climates present significant challenges for many insects. During the winter, insects are met with freezing temperatures and lack of resources that are normally accessible during warmer months. Consequently, insects have evolved behavioral and physiological strategies for surviving winter. Some seek refugia and enter a state of diapause as eggs, larvae, pupae, and/or adults, while others may migrate to more favorable locations. In this dissertation, I examine several aspects of winter survival among beneficial predacious, parasitic, and pollinating arthropods. Chapters 1 and 2 are focused on the long-distance migratory ecology of Nearctic hover flies (Diptera: Syrphinae), while Chapter 3 examines the effects of field borders on arthropod natural enemy communities. \nSyrphid hover flies of the subfamily Syrphinae are an important group of arthropods. Adults are pollinators for a variety of crop and non-crop plant species, while larvae act as biological control agents for major crop pests such as aphids. Despite these benefits, major aspects of their life histories remain unknown, especially for taxa outside of Europe. For example, while several Palearctic hover fly species are known to migrate, this behavior is almost entirely unresearched in Nearctic hover flies. \nIn Chapter 1, I examine evidence and mechanisms of migration among four hover fly species (Allograpta obliqua, Eupeodes americanus, Syrphus rectus, and Syrphus ribesii) common throughout eastern North America using a novel combination of stable hydrogen isotope (δ2H) analyses, morphological assessments, abundance estimations, and cold-tolerance assays. Non-local δ2H values obtained from hover fly specimens collected in central Illinois support the existence of long-distance fall migratory behavior among Eu. americanus and to a lesser extent S. rectus and S. ribesii. Elevated abundance of Eu. americanus during the expected autumn migratory time period further supports the existence of such behavior. Moreover, morphological analyses suggest that migratory Eu. americanus may exhibit a unique suite of morphological traits that decrease costs associated with long-distance flight. Finally, compared to the ostensibly non-migratory A. obliqua, Eu. americanus was significantly less cold-tolerant, a factor that may be related to migratory behavior. In Chapter 2, I examined how far these hover flies travel by assessing natal origins of the migratory Eu. americanus and non-migratory A. obliqua collected in northern Alabama. I built hover fly δ2H isoscapes using a calibration algorithm of water and hover fly tissues. I then used these isoscapes to assign grouped natal origins of hover flies using an IsoriX workflow. Consistent with Chapter 1, Eu. americanus was highly migratory whereas A. obliqua was mostly non-migratory. Several Eu. americanus specimens were estimated to have traveled between 1,000 and 3,000 km from the midwestern United States and Canada to Alabama.\nIn Chapter 3, I examined the capacity of semi-natural field borders to support overwintering predacious and parasitic arthropods. Semi-natural field borders are frequently used in midwestern U.S. sustainable agriculture. These habitats are meant to help diversify otherwise monocultural landscapes and provision them with ecosystem services, including biological control. Predatory and parasitic arthropods (i.e., potential natural enemies) often flourish in these habitats and may move into crops to help control pests. However, detailed information on the capacity of semi-natural field borders for providing overwintering refuge for these arthropods is poorly understood. In this study, I used soil emergence tents to characterize potential natural enemy communities (i.e., predacious beetles, wasps, spiders, and other arthropods) overwintering in cultivated organic crop fields and adjacent field borders. I found higher abundance, greater species richness, and a distinct community composition of predatory and parasitic arthropods in field borders compared to communities in arable crop fields, which were generally poorly suited as overwintering habitat. Furthermore, potential natural enemies tended to be positively associated with forb cover and negatively associated with grass cover, suggesting that grassy field borders with less forb cover are less suitable as winter refugia. These results demonstrate that semi-natural habitats such as field borders can act as a source for many natural enemies on a year-to-year basis and are important for conserving arthropod diversity in agricultural landscapes.
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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 ».