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Phenology, Olfactory Response, And Tritrophic Interactions Of Helicoverpa Zea And Chloridea Virescens On Hemp, Cannabis Sativa, Julian B. Cosner

Doctoral Dissertations

Industrial hemp, Cannabis sativa L., production has been revived in the United States following its legalization through the Agricultural Improvement Act of 2018 (a.k.a. 2018 Farm Bill). The corn earworm, Helicoverpa zea (Boddie), has been considered one of the most harmful insect pests in outdoor hemp production as larvae feed on the marketable grain and inflorescences where cannabinoid concentrations are highest. However, in Tennessee, a Heliothine complex, including corn earworm and the tobacco budworm, Chloridea virescens (F.), occurs on hemp. To investigate the seasonal incidence of these hemp pests, larvae were collected from hemp grown in different regions of Tennessee …

Data Driven Models Of Hemlock Woolly Adelgid Impacts And Biological Control, Hannah M. Thompson

Doctoral Dissertations

We present two models of the Adelges tsugae, the hemlock woolly adelgid, an invasive insect pest of Tsuga canadensis, eastern hemlock, in the eastern United States. An A. tsugae infestation often results in the death of T. canadensis within years, and has caused significant changes to hemlock forests. We construct two models composed of systems of ordinary differential equations with time dependent parameters to represent seasonality. The first model captures the coupled cycles in T. canadensis health and A. tsugae density. We use field data from Virginia to develop the model and to perform parameter estimation. The mechanisms …

Benefits And Risks Of Imidacloprid-Based Management Programs For Hemlock Woolly Adelgid, Elizabeth Paige Benton

Doctoral Dissertations

Hemlock woolly adelgid, Adelges tsugae (Annand) (HWA) (Hemiptera: Adelgidae), has caused widespread decline of eastern hemlock, Tsuga canadensis (L.) Carriére. This collaborative retrospective analysis with Great Smoky Mountains National Park (GRSM) provides research-based management guidance on imidacloprid treatments and nontarget risks to aquatic systems.

Imidacloprid and olefin concentrations were assessed in foliage from different diameter at breast height (DBH) size hemlocks 4 – 7 yr post-imidacloprid treatment. Imidacloprid concentrations were below the LC₅₀ [lethal concentration] for HWA, but olefin was above the LC₅₀ 4 yr post-treatment. HWA populations were suppressed, and hemlock canopies were healthy. Treatment efficacy can …

Linking Physiology And Biogeography: Disentangling The Constraints On The Distributions Of Ant Species, Lacy Danikas Chick

Doctoral Dissertations

Understanding the factors that limit the distribution of species is at the core of ecological and biogeographical research, and is critical if we are to predict the responses of key ecosystem components to ongoing climatic changes. My doctoral research seeks to provide an understanding of how thermal physiology influences species’ distributions and better define the mechanisms underlying geographic variation in biodiversity. By using natural temperature gradients (both elevational and latitudinal) and coupling controlled laboratory experiments with field observations and null modeling approaches, I was able to document the role of inter-specific variation in thermal physiology and, more interesting, inter-population variation …

Evolution And Phylogeny Of The Parasitoid Subfamily Phasiinae (Diptera: Tachinidae), Jeremy Daniel Blaschke

Doctoral Dissertations

The first molecular phylogenetic analysis of the agriculturally important parasitoid subfamily Phasiinae (Diptera: Tachinidae) is presented, estimated from 128 worldwide taxa (80 genera) and approximately 7.6 kilobases of nuclear data. Special emphasis is placed on taxa with controversial taxonomic placement. The resultant phylogenetic tree is used to reconstruct ancestral character states, trace the evolution of significant adaptive traits within the Tachinidae, and test hypotheses about the classification of Phasiinae. Subfamily placements of the taxa Eutherini, Epigrimyiini, Litophasia, Strongygastrini, and Parerigonini are confidently resolved, the former three within Dexiinae and the latter two within Phasiinae. Due to sparse molecular evidence, …

Characterization Of The Role Of Alpha-Arylphorin In The Heliothis Virescens Midgut Response To Cry1ac Toxin From Bacillus Thuringiensis, Jerreme Jamael Jackson

Doctoral Dissertations

Homeostasis of the intestinal epithelium in Heliothis virescens is mediated by the proliferation and differentiation of multipotent intestinal stem cells (ISCs) that lie adjacent to the basal lamina. In response to extrinsic and intrinsic signals, ISC proliferation and differentiation promotes epithelial growth and regeneration following the loss of integrity. We tested the in vivo effects of the ISC mitogen, a [alpha]-arylphorin, on ISC proliferation and the morphological changes of the midgut during larval development. Additionally, we examined how these changes affected the intestinal epithelium response to Cry1Ac toxin from Bacillus thuringiensis. Histological and in vitro evidence supported two distinct …

Ant Community Dynamics And The Effects Of Global Warming, Katharine Lisa Stuble

Doctoral Dissertations

This dissertation seeks to provide an understanding of how species coexist and, further, how climate change may alter communities by acting on the mechanisms that promote coexistence. Specifically, I examined coexistence among ant species in eastern deciduous forests and the effects that warming may have on foraging activity. Through a series of field observations, I sought evidence for the importance of four of the most commonly cited mechanisms for coexistence among ant species: the dominance – discovery tradeoff, the dominance – thermal tolerance tradeoff, spatial segregation, and niche partitioning. In this system, I did not find evidence for any of …

Assessment Of Factors Affecting Establishment Of Biological Control Agents Of Hemlock Woolly Adelgid On Eastern Hemlock In The Great Smoky Mountains National Park, Abdul Hakeem

Doctoral Dissertations

Eastern hemlock in the Great Smoky Mountains National Park (GRSM) is threatened by hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae). To manage this invasive pest in GRSM, ca. 550,000 Sasajiscymnus tsugae (Sasaji and McClure) (Coleoptera: Coccinellidae) and 7,857 Laricobius nigrinus Fender (Coleoptera: Derodontidae) have been released. Limited information is available on their establishment in GRSM. To fill this gap, a study was initiated to assess establishment of these predators and their impact on hemlock health. To determine factors affecting establishment of these predators, 65 release sites were sampled from 2008 to 2012. Several factors were evaluated for their …

Characterization Of Field Evolved Resistance To Transgenic Cry1fa Maize In Spodoptera Frugiperda (J. E. Smith), Siva Rama Krishna Jakka

Doctoral Dissertations

Transgenic Bt crops expressing Cry and Vip toxins from Bacillus thuringiensis (Bt) have been increasingly planted to manage insect pest damage on agricultural crops. The high adoption of Bt-based insecticidal technologies suggests an increase selection pressure for the evolution of resistance in insect populations. So far, nine insect species have developed field evolved resistance to Bt crops, yet the mechanisms involved in field evolved resistance are unknown. In the present study, the resistance mechanism in field evolved resistance to maize producing Cry1Fa in Spodoptera frugiperda collected in fields from Puerto Rico was characterized. High levels of resistance to …

Characterization Of Bipolaris Species, Their Effects On Switchgrass Biomass Yield And Chemical Components, Oluseyi Lydia Fajolu

Doctoral Dissertations

Switchgrass (Panicum virgatum L.) is a promising biofuel crop; however, limited attention has been directed toward switchgrass pathogens and their impact on biomass yield. Bipolaris is one of the fungal pathogens that pose a potential threat to switchgrass production in the U.S. This research is focused on the impact of Bipolaris on switchgrass. The research objectives were 1) Assessment of isolates of four Bipolaris species for morphology and virulence diversity on switchgrass and impact on biomass yield, 2) Assessment of Bipolaris infection on switchgrass chemical components, 3) Assessment of switchgrass germplasm for disease resistance, and 4) Genetic characterization of …

Spatial, Temporal, And Tri-Trophic Distribution Of Imidacloprid, Olefin And 5-Hydroxy And Their Effect On Hemlock Woolly Adelgid, Adelges Tsugae Annand, (Hemiptera: Adelgidae)., Carla Irene Coots

Doctoral Dissertations

Extensive mortality of eastern hemlock, Tsuga canadensis (L.) Carrière, resulting from infestation by hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae) (HWA), has occurred throughout the eastern United States. Imidacloprid, a systemic insecticide, is used to control hemlock woolly adelgid. The metabolism of imidacloprid in eastern hemlock produces two metabolites of toxicological interest, olefin and 5-hydroxy. The objectives of this study were to 1.) determine the distribution and persistence of the metabolites in eastern hemlock in the southern Appalachians, 2.) their effect on hemlock woolly adelgid mortality, 3.) assess the tri-trophic movement of these compounds, 4.) evaluate the effects of …

Efficacy Of Biopesticides For Organic Management Of Cucumber Beetles, Mary A. Rogers

Doctoral Dissertations

Organic growers are limited in crop protection techniques for cucumber beetle management. Spotted (Diabrotica undecimpunctata howardi) and striped (Acalymma vitatta) cucumber beetles and are significant pests of cucurbits in the U.S. Feeding results in aesthetic damage and reduction in marketable yields as well as transmission of bacterial wilt that can result in plant mortality. Biopesticides are products formulated from naturally occurring organisms such as fungi and bacteria that are pathogenic or toxic to insect pests. Advantages to these products are that they have low environmental risk, low risk to non-target organisms including mammals and beneficial insects, …

Comparing The Midgut Regenerative Responses In Bacillus Thuringiensis-Susceptible And Resistant Heliothis Virescens Larvae, Anais Severiana Castagnola

Doctoral Dissertations

The crystal (Cry) toxins from Bacillus thuringiensis (Bt) display high specificity and toxicity against relevant insect pests and the use of Bt-based products continues to contribute to insect pest management. To protect this investment, further its potential, and investigate possible unintended effects, various research questions have been proposed. One issue related to Bt usage is the evolution of pest resistance to Bt toxins. The midgut epithelium is targeted by Cry toxins killing enterocytes, facilitating invasion of the hemocoel, leading to septicemia and mortality. While resistance may emerge from alterations to these steps, most research efforts have been focused on reduced …

Production And Roles Of Volatile Secondary Metabolites In Interactions Of The Host Plant Tomato (Solanum Lycopersicum L.) With Other Organisms At Multi-Trophic Levels., Gitika Shrivastava

Doctoral Dissertations

Tomato (Solanum lycopersicum L.) produces an array of volatile secondary metabolites that act as constitutive and induced defenses against a variety of insect pests and diseases. We studied the effect of beneficial microorganisms, an arbuscular mycorrhiza fungus (AM), Glomus intraradices, an entomopathogenic fungus (Bb), Beauveria bassiana and a combination of both (AM+Bb), as well as, pests, such as rootknot nematode (RKN) (Meloidogyne incognita) and beet armyworm (BAW) (Spodoptera exiguae H.) on the production of volatile compounds in the leaves and roots of tomato. Benzyl alcohol, 3-hexenoic acid, total other compounds and β-myrcene were significantly increased ( …

Riparian Ecosystem Response To Hemlock Woolly Adelgid (Adelges Tsugae) Induced Eastern Hemlock (Tsuga Canadensis) Mortality In The Great Smoky Mountains National Park, Usa, Misty Dawn Huddleston

Doctoral Dissertations

An invasive insect, hemlock woolly adelgid (HWA), has initiated widespread hemlock decline and mortality in the Great Smoky Mountains National Park (GSMNP). Riparian hemlock mortality impacts on vegetative and aquatic systems of first-order, headwater streams were evaluated. Reference sites for this study were representative of the best available conditions within the GSMNP, with initial stages of HWA presence. Impacted sites were defined as areas with over 90 percent hemlock mortality. Impacted streams had decreased canopy coverage and increased light availability. Residual red maple, yellow birch, and sweet birch capitalized on the loss of hemlock, with increases in relative basal area …

Phylogenetic Analysis Of The Nearctic Blepharicera Macquart (Diptera: Blephariceridae) With An Emphasis On The Eastern Blepharicera Tenuipes Group Hogue, Amanda Jane Jacobson

Doctoral Dissertations

The eastern Nearctic fauna of Blepharicera Macquart (Diptera: Blephariceridae) is revised to include twenty-three species, six of which are new to science. Descriptions of the larvae, pupae, and adults of B. amnicula n. sp., B. conifera n. sp., B. crista n. sp., B. enoristera n. sp., B. hillabee n. sp., and B. opistera n. sp. are presented. Keys to instar IV larvae, pupae, and adults of all eastern Blepharicera (except B. caudata Courtney) are provided. Phylogenetic studies were conducted to determine the relationships between eastern and western Nearctic Blepharicera and among species within these groups. Larvae, pupae, and adults were …

Identification And Phylogenetic Characterization Of Select Species Of Buprestidae (Coleoptera) And Sesiidae (Lepidoptera) Wood Boring Insect Families Occuring Across The Southeastern United States., Jason A. Hansen

Doctoral Dissertations

A brief overview of the importance of wood boring insects is provided. Background on the two wood boring insect families Buprestidae (Coleoptera) and Sesiidae (Lepidoptera) is given. Keys and checklists to Tennessee’s buprestid fauna as presently known are furnished. Photomicrographs depicting characteristics separating Tennessee buprestid taxa to the level of species are provided for select couplets to aid those unfamiliar with buprestid morphology and terminology. Distribution and flight data of many species within the state are also featured. Results of a phylogenetic analysis of the Chrysobothris femorata (Olivier) species complex is presented based on the nuclear gene arginine kinase and …

Between Population Comparison Of Resource Acquisition In The Long Jawed Orb Weaving Spider Tetragnatha Elongata, Rosemary Grace Gillespie

Doctoral Dissertations

Behavioral adaptations for resource acquisition in the long jawed orb weaving spider Tetragnatha elongata Walckenaer (Araneae: Tetragnathidae) are documented in this study. It examines the form and mechanism of spider foraging behavior, an essential prerequisite to the realization of the commercial use of spiders in integrated pes t management. Being the most common and ubiquitous of insect predators, spiders offer tremendous potential as stabilizers in agro ecosystems with unstable cycling of phytophagous insects. The initial part of this study examines the mechanisms employed by T. elongata in selecting a habitat, and demonstrates that spiders do not build webs where the …

Some Environmental Features Of Hallett Station, Antarctica, With Special Reference To Soil Arthropods, Madison E. Pryor

Doctoral Dissertations

Introduction: Since Cook's voyage of 1772-1775, numerous expeditions, nationally and independently supported, have explored coastal and inland areas of Antarctica. The primary purpose of most early scientific expeditions was directed toward a study of the physical nature of the continent. In most instances, biologists were not included as expedition personnel and a large portion of the information concerning the flora and fauna of the continent has been contributed by investigators trained in a variety of scientific disciplines. A very few systematic investigations of land flora and soil fauna have been made. In spite of the obvious inadequacy of such investigations, …

The Strawberry Leaf Roller Complex In Tennessee, Stelmon Emerson Bennett

Doctoral Dissertations

This study was undertaken in order to learn the basic biology of the strawberry leaf roller Ancylis comptana fragariae in Tennessee. Shortly after the initiation of the study, it was found that not one, but several forms of leaf roller larvae were involved in the damage being done to strawberries. The study was therefore broadened to include the entire complex of leaf roller species and subspecies which inflict damage to strawberries and sometimes to other host plants in Tennessee. Three of the eleven forms making up the complex were selected as being most important because of their abundance and the …