Digital Commons Network^™

Improving The Deployment Of Insecticidal Seed Treatments In Louisiana Rice In Accordance With Integrated Pest Management, Megan Marie Mulcahy

LSU Doctoral Dissertations

Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), is the most destructive insect pest of rice in the United States. Lissorhoptrus oryzophilus larvae feed on rice roots, reducing yields by up to 25 %. Lepidopteran stem borers, in the family Crambidae, are also economically important pests of rice in Louisiana.

Currently, insecticidal seed treatments are used throughout the U.S. Mid-south rice industry to prophylactically control L. oryzophilus. Chlorantraniliprole seed treatments are also effective against stem borers. Thus, insecticidal seed treatments are used on >80 % of Louisiana rice acreage. Although seed treatments reduce damage inflicted by these pests, they are applied preventatively …

Investigation Of Arabidopsis Extremophyte Relatives, Schrenkiella Parvula And Eutrema Salsugineum Reveals Different Roads Leading To Salt Stress Tolerance, Kieu-Nga Thi Tran

LSU Doctoral Dissertations

How plants adapt to salt stress has been a central question in plant biology for decades. Yet we have not been able to fully understand the molecular networks and genetic mechanisms underlying this complex trait. Most of the genetic work on salinity stress has focused on understanding salt stress responses in the leading, yet a salt-sensitive model Arabidopsis thaliana. With the recent availability of genomes for wild-relatives of A. thaliana, we can now investigate how naturally salt adapted plants may have evolved modified or novel molecular networks to adapt to salt stress. Therefore, my research utilizes a comparative …

Insights Into Abscisic Acid And Phosphatidic Acid Signal Transduction Dynamics In Arabidopsis Thaliana, Ruth Wanjiru Ndathe

LSU Doctoral Dissertations

Abscisic acid (ABA) is a plant hormone that triggers a signaling transduction in response to drought, salinity, and cold. The core components in the ABA signaling pathway that lead to downstream ABA responses have been identified.

Phosphatidic acid (PA) is a membrane phospholipid that is involved in the signaling pathway for ABA-induced stomatal closure. We tested whether PA is involved in the signaling pathway for ABA-induced gene expression as well, using model plant Arabidopsis thaliana. We selected the RD29A gene which is a canonical drought gene that is induced by ABA. We found that PA is not involved in …

Genetic Structuring And Community Assembly In Neotropical Birds, Oscar Johnson

LSU Doctoral Dissertations

The factors that influence how species form is of fundamental interest to biology. Under the framework of the speciation cycle, the process begins by population subdivision creating structured populations that then diverge until two new species form. Following speciation, however, continued divergence is necessary for these new species to be able to coexist without adverse interactions, known as the transition to secondary sympatry. At this point the speciation cycle is complete and the process can begin anew. Many of the factors influencing these processes remain poorly understood. Here, I explore the factors that influence speciation and community assembly in Neotropical …

Casting A Critical Lens On Global Development: A Multimethod Investigation Of The Masculine Hegemonic Forces That Marginalize Women In Agriculture, Morgan Alyse Richardson Gilley

LSU Doctoral Dissertations

A critical link between gender equality and agricultural development has been established in the literature. However, disparities between genders have persisted in many areas of the developing world. One strategy that has been used to reduce gender inequalities has been educational outreach opportunities through agricultural extension, which has provided women a critical pathway to empowerment. Despite this, a lack of knowledge on the experiences of women in agriculture throughout Southeast Asia has served as a barrier to the advancement of such work. This investigation sought to better understand the issues facing this region’s fight to attain gender equality. To achieve …

Investigating Plant Tolerance For The Management Of Insect Pests In Rice, James Michael Villegas

LSU Doctoral Dissertations

The rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), is the most destructive and widespread insect pest of rice (Oryza sativa L., Poaceae) in the USA. This insect poses a global threat to rice production, having invaded rice-producing regions of Asia and Europe. Moreover, lepidopteran stemborers, particularly the invasive Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), are increasingly becoming problematic in Louisiana rice. Although insecticidal seed treatments have been widely used against weevils and stemborers, alternative management strategies are needed. Plants possess defense-related traits that both reduce injury from herbivores (resistance) and the amount of yield loss per …

Assessment Of Cash Value Benefits And The Effects On Participant Vegetable Consumption In The Louisiana Wic Program, Celia Rene Bridgeforth

LSU Doctoral Dissertations

The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) is administered by the United States Department of Agriculture (USDA) Food and Nutrition Service (FNS). The WIC program serves low-income women, infants, and children by providing supplemental foods, nutrition education, breastfeeding support and promotion, and referrals to healthcare and social service programs (Oliveira & Frazão, 2015). Revisions of the WIC food packages to include cash value benefits (CVB) that provided WIC participants the opportunity to purchase fruits and vegetables with their WIC benefits. There is significant research that indicates the benefit of F.V. consumption and the impact on diet-related …

Integrated Nutrient Management And Cover Cropping Practices In Louisiana Sugarcane Production Systems, Daniel Erneso Forestieri

LSU Doctoral Dissertations

Integrating effective fertilizer management with conservation practices is essential to improve farm income and promote environment friendly sugarcane production systems. A study was conducted in multiple to document the impact of nitrogen (N) source and cover cropping on sugarcane yield and quality components. The treatment consisted of different N sources: urea, knife-in urea ammonium nitrate (UAN) solution, calcium nitrate-CaNO3, ammonium sulfate-NH4SO4, and knife-in UAN. + foliar N, applied at 90 kg ha-1 and control (0 N). The cover crops included: crimson clover (Trifolium incarnatum), hairy vetch (Vicia villosa), and oilseed radish (Raphanus sativus L.) planted at 13, 17, and 1 …

Population Structure In Two Imperiled Sparrows With Differing Vagility, Amie Elizabeth Settlecowski

LSU Doctoral Dissertations

Characterizing population structure and genetic differentiation can inform the management of imperiled species and the relative influences of ecological and evolutionary factors on species evolution. One trait that is expected to influence the amount of population structure a species exhibits is vagility, or the ability to move across the landscape. Species with higher vagility may be more likely to disperse, potentially facilitating gene flow among populations and limiting population structure. My dissertation focuses on characterizing population structure in 2 imperiled sparrows that are both largely nonmigratory with broad distributions in eastern North America: Seaside Sparrow (Ammospiza maritima) and Bachman’s Sparrow …

Gene (Co)Expression Networks And Alternate Transcripts Induced In Cotton In Response To Aspergillus Flavus Infection, Mohit Verma

LSU Doctoral Dissertations

Cotton (Gossypium hirsutum L) is an economically important crop that generates billions of dollars in annual revenue worldwide. However, contamination of cottonseed with a highly carcinogenic aflatoxin produced by Aspergillus flavus limits the use of cottonseed in the oil and animal feed industries. Much success has been achieved by the application of atoxigenic strains of A. flavus for controlling aflatoxin contamination in cotton, peanut, and maize. Understanding the gene (co)expression network in response to A. flavus infection with both toxigenic and atoxigenic strains of A. flavus pericarp and seed of cotton through genome-wide transcriptome profiling will not only unravel …

Indicators Of Senescence And Their Relationship With The Antioxidant Response Element In Ovarian Cancer Cells—Toward A More Encompassing View Of Enzyme Activity Levels In Cells, Shaniqua Analycia Hayes

LSU Doctoral Dissertations

Enzymes and other related proteins are promising targets as biomarkers for cancer diagnostics, and it is therefore important to be able to quantify intracellular enzyme activity levels, not just presence of enzyme. Thus, there is a great need for the development of methods that offer spatiotemporal quantification of intracellular enzyme activity levels in respiring 2- and 3-dimensional cultures or their sample-processed variants. Previous studies have demonstrated that ß-gal is upregulated in senescence and in select ovarian cancers, and its expression/activity is upregulated when cells are under oxidative stress conditions. To that end, the primary goal of this work was to …

Palynology And Paleoclimatology Of The Chicxulub Impact Crater In The Early Paleogene, Vann Smith

LSU Doctoral Dissertations

At the end of the Cretaceous Period, a large bolide impacted the Earth and formed the Chicxulub impact crater in the Yucatán Peninsula, Mexico. In 2016, International Ocean Discovery Program (IODP) Expedition 364 Site M0077 drilled into the buried peak ring of the crater, recovering a marine Paleocene to early Eocene post-impact section deposited on top of the impact breccia. Palynological analysis of 195 samples from the post-impact section has yielded the first pre-Holocene vegetational record from inside the Chicxulub impact crater and the first palynological record of the recovery of life following the end-Cretaceous mass extinction from inside the …

Determinants Of Fine-Scale Heterogeneity In Mosquito-Borne Virus Systems, Elizabeth Handly Mayton

LSU Doctoral Dissertations

ABSTRACT

Arthropod-borne viruses (arboviruses) are the etiological agents of much morbidity and mortality, especially in low- and middle-income countries. Many of these viruses are spread and maintained by mosquitoes, particularly the urban mosquito Aedes aegypti. Zika virus (ZIKV) is responsible for one of the largest vector-borne disease outbreaks in the past decade, affecting millions in Central and South America including a wave of microcephaly among newborns. Mayaro virus (MAYV) is a mosquito-borne virus endemic to South America and is predicted to become an emergent public health threat. Describing the vector-virus transmission systems are critical for understanding the potential spread …

The Evolution Of Dietary Adaptations In Small Mammals: From Muscles To Microbes, Mark Thomas Swanson

LSU Doctoral Dissertations

My dissertation provides critical insights on the pattern and process of evolution in front-end and back-end dietary adaptations of mammals. I found that the position of the rodent masseter muscle, a complex front-end adaptation that improves the efficiency of mechanical digestion, has convergently evolved numerous times, suggesting that selective pressure for this adaptation has been strong. For back-end adaptations, I found gut bacterial taxa that likely aid in chemical digestion of food have predictable associations with host diet across host species in natural environments. To detect patterns in gut microbial community structure that are related to host factors such as …

Neuromuscular Control Strategy During Object Transport While Walking: Adaptive Integration Of Upper And Lower Limb Movements, Ahyoung Song

LSU Doctoral Dissertations

When carrying an object while walking, a significant challenge for the central nervous system (CNS) is to preserve the object’s stability against the inter-segmental interaction torques and ground reaction forces. Studies documented several strategies used by the CNS: modulation of grip force (GF), alterations in upper limb kinematics, and gait adaptations. However, the question of how the CNS organizes the multi-segmental joint and muscle coordination patterns to deal with gait-induced perturbations remains poorly understood. This dissertation aimed to explore the neuromuscular control strategy utilized by the CNS to transport an object during walking successfully. Study 1 examined the inter-limb coordination …

Understanding Potassium Toxicity Stress Responses Of The Extremophyte Schrenkiella Parvula Using Systems Biology Approaches, Pramod Pantha

LSU Doctoral Dissertations

Schrenkiella parvula is an extremophyte model closely related to Arabidopsis thaliana and Brassica crops. Its natural habitat includes shores of saline lakes in the Irano-Turanian region. It has adapted to grow in soils rich in multiple salts including Na⁺ and K⁺. I have investigated the genetic basis for high K⁺ tolerance in plants using S. parvula as a stress tolerant model compared to the premier plant model, Arabidopsis thaliana which is highly sensitive to salt stresses using physiological, ionomic, transcriptomic, and metabolomic approaches. Under high K⁺ stress, root system architecture changes significantly compared to control …

Late Embryogenesis Abundant Proteins And Mitochondrial Membranes From An Animal Extremophile: Insights Into Severe Water Stress, John Marcus Anderson

LSU Doctoral Dissertations

This dissertation focuses on two major topics germane to mechanisms by which animals tolerate extreme water stress. First, the impact of transgenic expression of late embryogenesis abundant proteins (LEA) on water stress tolerance of the fruit fly Drosophila melanogaster was investigated. The overall aim was to extend current understanding of the protective properties of LEA proteins documented with isolated cells to a desiccation-sensitive organism during exposure to drying and hyperosmotic stress. Four lines of D. melanogaster were created that expressed transgenes encoding selected LEA proteins originally identified in embryos of the extremophile Artemia franciscana. After 80% tissue water loss, …

Leveraging Multiple Data Sources: How Catch Data, Metadata, And Genetic Samples Can Aid The Recovery Of Endangered Smalltooth Sawfish (Pristis Pectinata), Kelcee Smith

LSU Doctoral Dissertations

The small population sizes characteristic of many imperiled species means that they are vulnerable to both demographic and genetic extinction threats. Responses to these threats (e.g., population trends, genetic diversity estimates) are often difficult to obtain, but critical for conservation. Thus, researchers studying imperiled species may have to consult multiple data sources, collaborate with a wide variety of stakeholders, or ask new questions about previously collected data. I used this approach to understand more about the United States (U.S.) population of Pristis pectinata, an endangered elasmobranch that has declined up to 95% due to habitat loss and bycatch in …

Effect Of Forage Management Strategies And Land Use Change On Nitrogen Budget And Soil Health Parameters In Pasture Systems, Yili Meng

LSU Doctoral Dissertations

Pastures produce hay for livestock, and they conserve soil, water, and air resources. However, high nitrogen (N) fertilizer demands in pasture production have significant implication on greenhouse gas emission and environmental pollution. Appropriate forage management strategies can reduce environmental N loss and improve soil health, to enhance the long-term pasture productivity. Therefore, this study was carried out to investigate the effects of management strategies on N budgets and soil health parameters in subtropical pastures. Both field and laboratory experiments were conducted to evaluate the effects of N stabilizers including urease inhibitor and nitrification inhibitor on pasture yield, greenhouse gas emission, …

Fisheries Food Webs: Quantifying Habitat-Use, Trophic Structure, And Energetic Pathways In Coastal Tanzania, Mario Fernando Hernandez

LSU Doctoral Dissertations

Commercial and recreational fisheries are a valuable resource to millions of people around the world. Developing countries are particularly dependent on the revenue provided by locally harvested fish with total exports from these nations valued at $80 billion USD. For Tanzania, fisheries provide not only a source of revenue but an important source of protein with an estimated 25 to 30kg of fish consumed per person every year. There is no doubt that high fisheries production is critical to the well-being of millions of livelihoods along the Tanzanian coast. An important but poorly understood driver of fisheries production is the …

Habitat Use And Morphology Of Birds In "Intact" Amazonia Under Changing Climate, Vitek Jirinec

LSU Doctoral Dissertations

Neotropical forests contain the core of global avian diversity. Of these, the Amazon rainforest is the largest, but ~20% has already been lost to deforestation, inspiring research into the effects of clearing and fragmentation on forest birds. These studies have consistently shown that insectivorous birds that forage on or near the ground are the most sensitive species to forest disturbance. As a preamble to our study, we synthesized bird capture data collected over 40 years within continuous forest far from human disturbance. Remarkably, we found that terrestrial and near-ground insectivores have shown substantial abundance declines even within primary forest. The …

Functional And Phenotypic Evaluation Of Murine Cytomegalovirus Infection Of The Heart, Cassandra Marie Bonavita

LSU Doctoral Dissertations

Human Cytomegalovirus (HCMV) is a ubiquitous pathogen which infects 50-90% of the world population and results in lifelong latent infection with periodic transient reactivations. In immunocompetent populations acute infection is generally asymptomatic but seropositivity is associated with many chronic diseases, including cardiovascular disease. Despite 139 years of research into HCMV pathogenesis there is still no licensed vaccine and many gaps in the general knowledge of the virus. This includes the role of long term infection as it pertains to chronic diseases. In these studies, murine cytomegalovirus (MCMV) was used as a model of HCMV pathogenesis in the heart. MCMV shares …

Evidence For Perchlorate-Coupled Molybdenum And Nickel Carbon Monoxide Dehydrogenase Co Oxidation And Characterization Of Novel Perchlorate-Reducing Haloarchaea, Marisa Russell Myers

LSU Doctoral Dissertations

Carbon monoxide (CO) has been exploited as a microbial energy source for much of life’s evolutionary history. A phylogenetically diverse array of microorganisms can oxidize CO using two distinct CO dehydrogenases, molybdenum-dependent (Mo-CODH) and nickel-dependent (Ni-CODH). Aerobes and facultative organisms contain Mo-CODHs which allow them to utilize oxygen as an electron acceptor in addition to alternatives such as nitrate and sulfate. Obligate anaerobic organisms contain Ni-CODHs, which oxidize CO at elevated concentrations, but cannot utilize oxygen. In systems where organic matter deposits are limited or absent, atmospheric trace gases such as CO are thought to assist in supporting the growth …

Evolution Of Extreme Habitat Specialists In The Dark: Cavefishes And Anglerfishes, Pamela Hart

LSU Doctoral Dissertations

Extremophilic organisms are fascinating in that they thrive in physiologically demanding environments. Extreme habitats include subsurface caves and the deep sea, which share several qualities like low light and cold temperatures. Extremophiles have adapted bizarre characteristics that allow them to thrive in such harsh environments including eye and pigment loss (cavefishes) and development of a lure in anglerfishes. These traits are integral to the health and fitness of these organisms, yet the evolutionary history of these traits is unclear.

Cave adaptation has evolved repeatedly across the Tree of Life, famously leading to eye degeneration and loss, yet its macroevolutionary implications …

Mental Imagery In The Regulation Of Differential Fear Conditioning: A Multimodal Investigation Involving Self-Report, Psychophysiology, And Brain Imaging, Tyler Daniel Robinson

LSU Doctoral Dissertations

Mental imagery is a common component in a range of emotion regulation techniques. However, the effectiveness and neural mechanisms of regulation via mental imagery are underexplored due to a lack of studies targeting mental imagery specifically. This discrepancy results in uncertainty regarding the mechanism of regulation in existing paradigms. Biased competition for attentional resources presents a plausible model by which a mental imagery-based distracter can downregulate response to an emotional stimulus. If visualizing an imagined distracter effectively regulates emotional response, the inclusion of mental imagery components in other techniques represents a potential confound. To address this discrepancy, this dissertation investigates …

Genomic Studies Of Beaf-32 In Drosophila, John Keller Mckowen Iii

LSU Doctoral Dissertations

Compared to humans, the model organism Drosophila melanogaster is particularly gene dense and encodes several insulator binding proteins (IBP) to aid in its genome organization. Our focus of research is a particular IBP, Boundary Element-Associated Factor of 32kD (BEAF). BEAF primarily binds near the promoters of constitutively active housekeeping genes. It is thought to help maintain the active state of these genes by preventing the spread of repressive chromatin. Additionally, the enhancer blocking activity of BEAF is thought to prevent aberrant activation or silencing of genes. BEAF appears to be ubiquitously expressed among cells and tissues, albeit at varying levels. …

Three Essays On Mahatma Gandhi National Rural Employment Guarantee Scheme, Rakhe Balachandran

LSU Doctoral Dissertations

India’s Mahatma Gandhi National Rural Employment Guarantee Scheme (MGNREGs) is the largest public works program in the world with an objective to ensure rural livelihood security by generating employment through infrastructure projects. This thesis is comprised of three essays investigating the MGNREGs’ impact on rural communities and the labor market. The first essay examined the targeting accuracy of the program. I simultaneously controlled for the self-selection bias and endogeneity bias between poverty and program participation using an extended probit model. Using data from National Sample Survey (NSS) 2014, I find that households closer to the poverty line are more likely …

The Effect Of Fallow Season Cover Crops On Nutrient Cycling And Soil Health In Row Crop Production In The Mid-South, Kritsanee Iamjud

LSU Doctoral Dissertations

The reliance on conventional cropping has profoundly impacted agricultural sustainability and resulted in soil degradation. Winter cover crops can preserve the soil surface, recycle soil nutrients, and improve soil health. Hence, the role of cover crops in Louisiana row-crop production was examined in small-scale plots and large-scale on-farm studies at three sites in Northeast Louisiana from 2017 to 2020. Additionally, mixed cover crops degradation and nutrient release were evaluated at Macon Ridge and Dean Lee sites to determine the optimum time of nutrient availability after cover crop termination. The small-scale results showed that integrating cover crops for corn (Zea …

Exercise And Bone: Older Adults, Type Ii Diabetes, And Ketogenic Diets, Matthew Casey Scott

LSU Doctoral Dissertations

Exercise is a well-appreciated modulator of bone and has other positive implications for overall fitness and health. The purpose of this dissertation was to determine the effects of exercise on bone in conjunction with other known modifiers: old age, type II diabetes mellitus (T2DM), and ketogenic diets. The three studies discussed in this dissertation utilized multiple methods of measuring bone to examine the effect of exercise on bone in individuals with type II diabetes, rodents consuming a ketogenic diet, and older adults participating in a novel resistance training intervention. The first study examined the effects of a 9-month resistance, aerobic, …

Micro- And Macroevolution Of Drab Plumage Color In Birds, Rafael Marcondes

LSU Doctoral Dissertations

I address the evolution of drab bird colors at micro- and macroevolutionary scales. I use as a study system the Furnariida, a clade of >600 Neotropical passerine species that, despite tremendous ecological and morphological diversity, are colored almost exclusively in shades of brown and grey produced by melanin pigments.

In chapters two and three, I took a macroevolutionary approach and showed that (1) plumage colors in the Furnariida evolve at similar rates in a monochromatic clade, males of a dichromatic clade, and females of a dichromatic clade; (2) ventral plumage color evolves faster than dorsal; (3) bird species that occupy …