• Login
    View Item 
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UA Campus RepositoryCommunitiesTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournalThis CollectionTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournal

    My Account

    LoginRegister

    About

    AboutUA Faculty PublicationsUA DissertationsUA Master's ThesesUA Honors ThesesUA PressUA YearbooksUA CatalogsUA Libraries

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    An Ontogenetic Perspective on the Timing of Maturation in Insects with Special Consideration of Physical and Resource Thresholds

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    azu_etd_12872_sip1_m.pdf
    Size:
    3.211Mb
    Format:
    PDF
    Download
    Author
    Helm, Bryan Robert
    Issue Date
    2013
    Keywords
    Ecology & Evolutionary Biology
    Advisor
    Davidowitz, Goggy
    
    Metadata
    Show full item record
    Publisher
    The University of Arizona.
    Rights
    Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
    Abstract
    All animals progress through a series of functionally discrete life stages from fertilization through adulthood and often into senescence. Reproduction in the adult stage can only occur after maturation--the final life history transition during ontogeny--from juvenile to adult. Despite a robust literature that predicts the optimal body size and development time at which this transition should occur, the ontogenetic factors that are responsible for determining metamorphosis and the manner in which they are translated into the hormonal mechanisms regulating maturation remain unresolved in most species. In this dissertation, I first review the theoretical context and importance of understanding maturation from both life history and physiological/developmental perspectives. Then I review the literature that describes various ontogenetic factors thought to determine the onset of maturation in insects. Finally, I present four studies that examine two of the major hypotheses that have been proposed to explain the onset of metamorphosis in insects using Manduca sexta larvae (Lepidoptera: Sphingidae) as a model organism. In the first study, I show that physical thresholds are unlikely to be the factor that determines maturation in larval M. sexta because larval insects do not seem to be growth constrained in the manner assumed in the literature. Next, I present three chapters that examine the possibility that attainment of a resource storage threshold is the determining factor for the onset of metamorphosis. In the first of these studies, I show that there is a hemolytic factor present after metamorphic commitment that can induce precocious metamorphosis in larval M. sexta, indicating that maturation can be coordinated at least partially from developing tissues throughout the body. The following study examines resource storage during metamorphic commitment in the final larval instar of M. sexta. I show that resource storage is of critical importance during the final period of larval growth in terms of mass allocation. Even with environmentally-induced variability in resource storage, growing M. sexta appear to have a target amount of stored resources near the body weight at which metamorphic commitment occurs. Individuals reared on reduced quality diet store proportionally more resources with a higher caloric value than individuals reared on in terms of fat growth, which is consistent with a decrease in the body weight at metamorphic commitment observed in other studies. Individuals reared at different temperatures invest differently in resource storage during growth; however, resource storage content tends to converge at the critical weight, which may explain invariance of the critical weight in response to rearing temperature found in other studies. Finally, I examine resource storage in the context of allocation tradeoffs with growth and metabolic rate. I demonstrate that storage increases substantially as growth rate declines in the final larval instar of M. sexta.
    Type
    text
    Electronic Dissertation
    Degree Name
    Ph.D.
    Degree Level
    doctoral
    Degree Program
    Graduate College
    Ecology & Evolutionary Biology
    Degree Grantor
    University of Arizona
    Collections
    Dissertations

    entitlement

     
    The University of Arizona Libraries | 1510 E. University Blvd. | Tucson, AZ 85721-0055
    Tel 520-621-6442 | repository@u.library.arizona.edu
    DSpace software copyright © 2002-2017  DuraSpace
    Quick Guide | Contact Us | Send Feedback
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.