+publisher:"Texas A&M University" +contributor:("Eubanks, Micky D.")

Texas A&M University

1. Hewlett, Jeremy Alan. THE EFFECTS OF PREDATION ON SUGARCANE APHIDS IN SORGHUM.

Degree: MS, Entomology, 2018, Texas A&M University

URL: http://hdl.handle.net/1969.1/173962

► The sugarcane aphid, Melanaphis sacchari Zehntner (Hemiptera: Aphididae), is an emerging pest in sorghum, Sorghum bicolor (L.), in the USA. Lady beetles and green lacewings… (more)

▼ The sugarcane aphid, Melanaphis sacchari Zehntner (Hemiptera: Aphididae), is an emerging pest in sorghum, Sorghum bicolor (L.), in the USA. Lady beetles and green lacewings are abundant in sugarcane aphid-infested sorghum fields, but little is known about the effects of these predators on the establishment and growth of sugarcane aphid populations in sorghum. I quantified the effect of two species of lady beetles (Coccinella septempunctata L. and Harmonia axyridis Pallas) (Coleoptera: Coccinellidae) and green lacewings (Chrysoperla rufilabris Burmeister) (Neuroptera: Chrysopidae) on aphid colony growth across several aphid densities. I incorporated these predator effects into a dynamic predator-prey model to predict the impact of predators on the short-term population dynamics of sugarcane aphids and their ability to suppress aphids below action thresholds in sorghum. I also compared the effects of aphid-resistant sorghum on predation by lacewing larvae. All predators were able to significantly reduce the growth of sugarcane aphid populations at low to intermediate aphid densities (20, 40, and 80 aphids per colony). At the highest aphid density (160 aphids), H. axyridis larvae were much less effective and lacewing larvae did not suppress sugarcane aphid colony growth. The model found that all predators prevented aphid densities between 20-40 per leaf from reaching action thresholds and at densities of 80 aphids per colony, all predators suppressed aphids below threshold in two to four days. However, at the highest initial aphid density (160), H. axyridis larvae required seven days to suppress aphids below threshold and lacewing larvae never suppressed aphids below threshold. Aphid-resistant cultivars sustained smaller populations of aphids compared to susceptible. However, predators were an overall more effective tool to reduce aphid densities than use of only resistant varieties. As there is some evidence that predators may be more attracted to aphid-infested resistant varieties, predator effects may be enhanced on these varieties. My results suggest that common predators have the potential to reduce the number of insecticide applications needed to control sugarcane aphids and should be incorporated into Integrated Pest Management (IPM) programs. The simultaneous use of biological control and resistant varieties may yield synergistic suppression of sugarcane aphids in sorghum. Advisors/Committee Members: Eubanks, Micky D (advisor), Kerns, David (committee member), Schnell, Ronnie W (committee member).

Subjects/Keywords: Integrated Pest Management; Biological Control; Host Plant Resistance; Coccinella septempunctata; Harmonia axyridis; Chrysoperla rufilabris; Melanaphis sacchari

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APA (6^th Edition):

Hewlett, J. A. (2018). THE EFFECTS OF PREDATION ON SUGARCANE APHIDS IN SORGHUM. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/173962

Chicago Manual of Style (16^th Edition):

Hewlett, Jeremy Alan. “THE EFFECTS OF PREDATION ON SUGARCANE APHIDS IN SORGHUM.” 2018. Masters Thesis, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/173962.

MLA Handbook (7^th Edition):

Hewlett, Jeremy Alan. “THE EFFECTS OF PREDATION ON SUGARCANE APHIDS IN SORGHUM.” 2018. Web. 13 Apr 2021.

Vancouver:

Hewlett JA. THE EFFECTS OF PREDATION ON SUGARCANE APHIDS IN SORGHUM. [Internet] [Masters thesis]. Texas A&M University; 2018. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/173962.

Council of Science Editors:

Hewlett JA. THE EFFECTS OF PREDATION ON SUGARCANE APHIDS IN SORGHUM. [Masters Thesis]. Texas A&M University; 2018. Available from: http://hdl.handle.net/1969.1/173962

Texas A&M University

2. Nally, Deseri Dawn. Growth, Development, and Vertebrate and Invertebrate Herbivory of the Federally Endangered Spiranthes parksii Correll and Sympatric Congener Spiranthes cernua.

Degree: MS, Ecosystem Science and Management, 2016, Texas A&M University

URL: http://hdl.handle.net/1969.1/158627

► ABSTRACT Spiranthes parksii Correll, a terrestrial orchid protected under the Endangered Species Act, and its congener Spiranthes cernua (L.) Rich, were studied in the Post… (more)

▼ ABSTRACT Spiranthes parksii Correll, a terrestrial orchid protected under the Endangered Species Act, and its congener Spiranthes cernua (L.) Rich, were studied in the Post Oak Savanna Ecoregion of Central Texas in 2014 and 2015. The species are sympatric and each produces a single inflorescence in the fall with emergence of a basal rosette during flower senescence or early spring. Objectives of this study were to 1) assess variation in annual and seasonal growth 2) determine the impact of vertebrate and invertebrate herbivores on the rosette and flower phases, and 3) identify invertebrate herbivores that utilize S. parksii and S. cernua. To assess variation in annual growth patterns between years an analysis of precipitation, demographic (presence or absence), and growth data (leaf area and inflorescence height) was performed. From 2014 to 2015 there was a reduction in precipitation, plants present, plant height, and the number of flowering plants that survived to seed production. To determine the difference between vertebrate and invertebrate herbivores, a 2 x 3 factorial experiment was conducted. Plants were randomly assigned to one of five treatments: Control (accessible to Vertebrates and Invertebrates), Insecticide with no cage (Vertebrate Only), Cage with no insecticide (Invertebrate Only), Caged with insecticide (Cage+Insecticide; no vertebrate or invertebrate), and cage with mesh cover and no insecticide (Mesh; access by only small invertebrates). During the flower season, herbivory was visually estimated for plant stalk and inflorescence by 5 percent increments. For rosettes, herbivory was visually estimated for each leaf in 5 percent increments and averaged over the whole rosette. During the first flowering season, vertebrates consumed more reproductive tissue (46%) than invertebrates (3%), while in the second season there was no significant difference between the two at 19% and 2%, respectively. There was no significant difference in percent herbivory of rosettes by vertebrates or invertebrates at 9% and 14% in 2014 and 16% and 11% in 2015. Invertebrates that were observed consuming Spiranthes sp. inflorescences and rosettes were armyworms (Order Lepidoptera: Family Noctuidae), grasshoppers (Family Acrididae), and an unidentified member of the Actiinae subfamily. This experiment confirms that vertebrates have a direct effect on Spiranthes sp. fitness through removal of reproductive tissue and an indirect impact by consuming rosettes. In addition, it documents that invertebrate herbivores can have a similar effect on inflorescence and rosettes. This knowledge can be important in understanding the influence of plant-herbivore interactions on conservation and management plans for S. parksii. Advisors/Committee Members: Smeins, Fred E (advisor), Rogers, William E (committee member), Eubanks, Micky D (committee member).

Subjects/Keywords: Herbivory; Herbivores; Vertebrate; Invertebrate; Insects; Plant-Herbivore interactions; Plant-insect interactions; Orchids; Endangered species; Spiranthes parksii; Spiranthes cernua; Armyworm; Grasshopper; Roly Poly; Feral Hogs; Mice

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APA (6^th Edition):

Nally, D. D. (2016). Growth, Development, and Vertebrate and Invertebrate Herbivory of the Federally Endangered Spiranthes parksii Correll and Sympatric Congener Spiranthes cernua. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/158627

Chicago Manual of Style (16^th Edition):

Nally, Deseri Dawn. “Growth, Development, and Vertebrate and Invertebrate Herbivory of the Federally Endangered Spiranthes parksii Correll and Sympatric Congener Spiranthes cernua.” 2016. Masters Thesis, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/158627.

MLA Handbook (7^th Edition):

Nally, Deseri Dawn. “Growth, Development, and Vertebrate and Invertebrate Herbivory of the Federally Endangered Spiranthes parksii Correll and Sympatric Congener Spiranthes cernua.” 2016. Web. 13 Apr 2021.

Vancouver:

Nally DD. Growth, Development, and Vertebrate and Invertebrate Herbivory of the Federally Endangered Spiranthes parksii Correll and Sympatric Congener Spiranthes cernua. [Internet] [Masters thesis]. Texas A&M University; 2016. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/158627.

Council of Science Editors:

Nally DD. Growth, Development, and Vertebrate and Invertebrate Herbivory of the Federally Endangered Spiranthes parksii Correll and Sympatric Congener Spiranthes cernua. [Masters Thesis]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/158627

Texas A&M University

3. Bockoven, Alison A. Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant.

Degree: PhD, Entomology, 2015, Texas A&M University

URL: http://hdl.handle.net/1969.1/155760

► Organisms vary at the individual and population level in many ecologically relevant traits. This study documents and quantifies colony-level variation in ecologically important behaviors of… (more)

▼ Organisms vary at the individual and population level in many ecologically relevant traits. This study documents and quantifies colony-level variation in ecologically important behaviors of a widespread invasive social insect, demonstrates multitrophic ecological effects of this colony-level variation, and explores genetic factors that may affect and predict behavior at the colony-level. I quantified significant, persistent regional and colony-level variation in the red imported fire ant (Solenopsis invicta) in behaviors such as extra-nest activity, exploration, and resource discovery speed and recruitment effort. Colony behavior correlated with both colony productivity and colony growth. Using single-lineage colonies, I estimated broad-sense heritability of between 0.45 and 0.5 for the observed colony behaviors. I created experimental microcosms comprised of fire ant colonies, plants, and insect herbivores. Differences in fire ant colony behavior linked to carbohydrate attraction directly impacted herbivore mortality and indirectly impacted plant damage. I quantified colony differences colony differences in the expression of the fire ant foraging gene (sifor) as well as colony-level differences in behavior for fire ant colonies collected from across a large area of Texas. Expression of sifor was more than three-fold higher in fire ant foragers than in fire ant workers in the interior of the nest, and colony-level differences in sifor expression of foragers and interior workers correlated with colony behavior. Higher sifor expression in foragers correlated with higher foraging activity, exploratory activity, and recruitment to nectar in fire ant colonies. Finally, I explored the hypothesis that fire ant foundress groups could maximize inclusive fitness benefits and alter cooperative and competitive behaviors in response to cues indicating higher relatedness of foundresses. I found that group and queen performance was significantly affected by group composition. Groups composed of foundresses that were less likely to be related produced no more workers than queens founding alone, while groups composed of foundresses from the same site produced the most workers of all group types. The conclusions of this study have widespread implications for many social insects and their ecological interactions. By further exploring these effects at the mechanistic, organismal, and ecological level we will improve our understanding of collective behavior, social evolution, and intraspecific variation. Advisors/Committee Members: Eubanks, Micky D (advisor), Carney, Ginger (committee member), Coates, Craig (committee member), Slotman, Michel (committee member).

Subjects/Keywords: foraging; solenopsis invicta; behavior; superorganism; personality

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Bockoven, A. A. (2015). Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/155760

Chicago Manual of Style (16^th Edition):

Bockoven, Alison A. “Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant.” 2015. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/155760.

MLA Handbook (7^th Edition):

Bockoven, Alison A. “Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant.” 2015. Web. 13 Apr 2021.

Vancouver:

Bockoven AA. Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant. [Internet] [Doctoral dissertation]. Texas A&M University; 2015. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/155760.

Council of Science Editors:

Bockoven AA. Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant. [Doctoral Dissertation]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/155760

Texas A&M University

4. Bockoven, Alison A. Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant.

Degree: PhD, Entomology, 2015, Texas A&M University

URL: http://hdl.handle.net/1969.1/155761

► Organisms vary at the individual and population level in many ecologically relevant traits. This study documents and quantifies colony-level variation in ecologically important behaviors of… (more)

▼ Organisms vary at the individual and population level in many ecologically relevant traits. This study documents and quantifies colony-level variation in ecologically important behaviors of a widespread invasive social insect, demonstrates multitrophic ecological effects of this colony-level variation, and explores genetic factors that may affect and predict behavior at the colony-level. I quantified significant, persistent regional and colony-level variation in the red imported fire ant (Solenopsis invicta) in behaviors such as extra-nest activity, exploration, and resource discovery speed and recruitment effort. Colony behavior correlated with both colony productivity and colony growth. Using single-lineage colonies, I estimated broad-sense heritability of between 0.45 and 0.5 for the observed colony behaviors. I created experimental microcosms comprised of fire ant colonies, plants, and insect herbivores. Differences in fire ant colony behavior linked to carbohydrate attraction directly impacted herbivore mortality and indirectly impacted plant damage. I quantified colony differences colony differences in the expression of the fire ant foraging gene (sifor) as well as colony-level differences in behavior for fire ant colonies collected from across a large area of Texas. Expression of sifor was more than three-fold higher in fire ant foragers than in fire ant workers in the interior of the nest, and colony-level differences in sifor expression of foragers and interior workers correlated with colony behavior. Higher sifor expression in foragers correlated with higher foraging activity, exploratory activity, and recruitment to nectar in fire ant colonies. Finally, I explored the hypothesis that fire ant foundress groups could maximize inclusive fitness benefits and alter cooperative and competitive behaviors in response to cues indicating higher relatedness of foundresses. I found that group and queen performance was significantly affected by group composition. Groups composed of foundresses that were less likely to be related produced no more workers than queens founding alone, while groups composed of foundresses from the same site produced the most workers of all group types. The conclusions of this study have widespread implications for many social insects and their ecological interactions. By further exploring these effects at the mechanistic, organismal, and ecological level we will improve our understanding of collective behavior, social evolution, and intraspecific variation. Advisors/Committee Members: Eubanks, Micky D (advisor), Carney, Ginger (committee member), Coates, Craig (committee member), Slotman, Michel (committee member).

Subjects/Keywords: foraging; solenopsis invicta; behavior; superorganism; personality

Record Details Similar Records Cite « Share

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Bockoven, A. A. (2015). Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/155761

Chicago Manual of Style (16^th Edition):

Bockoven, Alison A. “Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant.” 2015. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/155761.

MLA Handbook (7^th Edition):

Bockoven, Alison A. “Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant.” 2015. Web. 13 Apr 2021.

Vancouver:

Bockoven AA. Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant. [Internet] [Doctoral dissertation]. Texas A&M University; 2015. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/155761.

Council of Science Editors:

Bockoven AA. Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant. [Doctoral Dissertation]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/155761

Texas A&M University

5. Dickey, Aaron. Host-Associated Differentiation in an Insect Community.

Degree: PhD, Entomology, 2011, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8695

► Host-Associated Differentiation (HAD) is the formation of genetically divergent hostassociated lineages maintained by ecological isolation. HAD is potentially an important route to ecological speciation in… (more)

▼ Host-Associated Differentiation (HAD) is the formation of genetically divergent hostassociated lineages maintained by ecological isolation. HAD is potentially an important route to ecological speciation in parasites including many insects. While HAD case studies are accumulating, there is a dearth of negative results in the literature making it difficult to know how common the phenomenon really is or whether there are specific traits of parasites which promote HAD. To address these two problems, studies are needed which both publish negative results (i.e., parasites not showing HAD) and test for HAD in multiple parasite species on the same pair of host species (i.e., control for host plant effects). In this study, HAD was tested in three species of herbivorous insects and one parasitoid species on the same two host tree species: pecan and water hickory. The insects were selected based on the presence or absence of two traits, parthenogenesis and endophagy. A test for HAD was considered “positive” when population substructure was explained by host-association. To test for the presence of HAD, insects were sampled sympatrically to eliminate geographical isolation as a confounding factor, sampling was replicated spatially to assure that HAD persisted, and multiple loci were sampled from each individual. Genetic data was analyzed using cluster analyses. HAD was found in both pecan leaf phylloxera and yellow pecan aphid but not in pecan bud moth or in the parasitoid of the yellow pecan aphid, Aphelinus perpallidus. Interestingly, both taxa showing HAD are parthenogenetic and both taxa not showing HAD reproduce sexually. Species showing HAD were tested for the presence of a pre-mating reproductive isolating mechanism (RIM) which could be maintaining HAD despite the potential for gene flow. Selection against migrants to the alternative host was tested in yellow pecan aphid using a no-choice fitness experiment. The overall contribution of this RIM to total isolation was positive and ranged from 0.614 to 0.850. The RIM of “habitat preference” was tested in pecan leaf phylloxera using a dual-choice preference experiment. In this species, preference was only detected for phylloxera originating from water hickory suggesting that host discrimination ability may be a less important factor promoting differentiation in phylloxera. Advisors/Committee Members: Medina, Raul F. (advisor), Eubanks, Micky D. (committee member), Harris, Marvin K. (committee member), DeWitt, Thomas J. (committee member).

Subjects/Keywords: Parthenogenesis; Endophagy; Aphids; Carya, Solidago, Genetic Differentiation; Amplified Fragment Length Polymorphisms; Host-Parasite Interactions; Reciprocal Transplant; Host Plant Discrimination; Sequential Radiation

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Dickey, A. (2011). Host-Associated Differentiation in an Insect Community. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8695

Chicago Manual of Style (16^th Edition):

Dickey, Aaron. “Host-Associated Differentiation in an Insect Community.” 2011. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8695.

MLA Handbook (7^th Edition):

Dickey, Aaron. “Host-Associated Differentiation in an Insect Community.” 2011. Web. 13 Apr 2021.

Vancouver:

Dickey A. Host-Associated Differentiation in an Insect Community. [Internet] [Doctoral dissertation]. Texas A&M University; 2011. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8695.

Council of Science Editors:

Dickey A. Host-Associated Differentiation in an Insect Community. [Doctoral Dissertation]. Texas A&M University; 2011. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8695

6. Tracy, James L. Random Subset Feature Selection for Ecological Niche Modeling of Wildfire Activity and the Monarch Butterfly.

Degree: PhD, Entomology, 2018, Texas A&M University

URL: http://hdl.handle.net/1969.1/174342

► Correlative ecological niche models (ENMs) are essential for investigating distributions of species and natural phenomena via environmental correlates across broad fields, including entomology and pyrogeography… (more)

▼ Correlative ecological niche models (ENMs) are essential for investigating distributions of species and natural phenomena via environmental correlates across broad fields, including entomology and pyrogeography featured in this study. Feature (variable) selection is critical for producing more robust ENMs with greater transferability across space and time, but few studies evaluate formal feature selection algorithms (FSAs) for producing higher performance ENMs. Variability of ENMs arising from feature subsets is also seldom represented. A novel FSA is developed and evaluated, the random subset feature selection algorithm (RSFSA). The RSFSA generates an ensemble of higher accuracy ENMs from different feature subsets, producing a feature subset ensemble (FSE). The RSFSA-selected FSEs are novelly used to represent ENM variability. Wildfire activity presence/absence databases for the western US prove ideal for evaluating RSFSA-selected MaxEnt ENMs. The RSFSA was effective in identifying FSEs of 15 of 90 variables with higher accuracy and information content than random FSEs. Selected FSEs were used to identify severe contemporary wildfire deficits and significant future increases in wildfire activity for many ecoregions. Migratory roosting localities of declining eastern North American monarch butterflies (Danaus plexippus) were used to spatially model migratory pathways, comparing RSFSAselected MaxEnt ENMs and kernel density estimate models (KDEMs). The higher information content ENMs best correlated migratory pathways with nectar resources in grasslands. Higher accuracy KDEMs best revealed migratory pathways through less suitable desert environments. Monarch butterfly roadkill data was surveyed for Texas within the main Oklahoma to Mexico Central Funnel migratory pathway. A random FSE of MaxEnt roadkill ENMs was used to estimate a 2-3% loss of migrants to roadkill. Hotspots of roadkill in west Texas and Mexico were recommended for assessing roadkill mitigation to assist in monarch population recovery. The RSFSA effectively produces higher performance ENM FSEs for estimating optimal feature subset sizes, and comparing ENM algorithms and parameters, and environmental scenarios. The RSFSA also performed comparably to expert variable selection, confirming its value in the absence of expert information. The RSFSA should be compared with other FSAs for developing ENMs and in data mining applications across other disciplines, such as image classification and molecular bioinformatics. Advisors/Committee Members: Coulson, Robert N (advisor), Knutson, Allen E (advisor), Eubanks, Micky D (committee member), Lawing, A. Michelle (committee member).

Subjects/Keywords: Random Feature Selection; Feature Subset Ensemble; Species Distribution Model; Pyrogeography; Danaus plexippus; Migratory Niche Model; Kernel Density Estimation Migratory Model; Insect Roadkill Niche Model

12 more images…

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APA (6^th Edition):

Tracy, J. L. (2018). Random Subset Feature Selection for Ecological Niche Modeling of Wildfire Activity and the Monarch Butterfly. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/174342

Chicago Manual of Style (16^th Edition):

Tracy, James L. “Random Subset Feature Selection for Ecological Niche Modeling of Wildfire Activity and the Monarch Butterfly.” 2018. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/174342.

MLA Handbook (7^th Edition):

Tracy, James L. “Random Subset Feature Selection for Ecological Niche Modeling of Wildfire Activity and the Monarch Butterfly.” 2018. Web. 13 Apr 2021.

Vancouver:

Tracy JL. Random Subset Feature Selection for Ecological Niche Modeling of Wildfire Activity and the Monarch Butterfly. [Internet] [Doctoral dissertation]. Texas A&M University; 2018. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/174342.

Council of Science Editors:

Tracy JL. Random Subset Feature Selection for Ecological Niche Modeling of Wildfire Activity and the Monarch Butterfly. [Doctoral Dissertation]. Texas A&M University; 2018. Available from: http://hdl.handle.net/1969.1/174342

Texas A&M University

7. Lenhart, Paul Alvarado. Nutrient Niches: an Investigation of Nutritional Ecology in a Generalist Herbivore Community.

Degree: PhD, Entomology, 2014, Texas A&M University

URL: http://hdl.handle.net/1969.1/152808

► Understanding how diversity is maintained is a classic question in ecology. A diverse group of organisms can often be found utilizing the same resource. For… (more)

▼ Understanding how diversity is maintained is a classic question in ecology. A diverse group of organisms can often be found utilizing the same resource. For example, in grasslands there are communities of grasshoppers containing many generalist species with overlapping diets that are likely competing for resources. To explore how species that overlap in host plant use can coexist, I investigated a recent hypothesis in nutritional ecology that species-specific macronutrient requirements in generalist insect herbivores could represent different nutrient niches. As a model system I used a community of grasshoppers in Central Texas. First, I surveyed variation in plant macronutrient content and compared this data to the grasshopper community. By assaying levels of digestible protein and carbohydrate in abundant forbs and grasses at different sites, I produced a ‘nutrient landscape’ available to foraging herbivores and found significant correlations between plant nutrients and grasshopper abundance. To further explore the role of plant macronutrient shifts in controlling grasshopper populations, I manipulated water availability in plots of grassland during a severe drought. Total grasshopper density and diversity were lower in water-stressed plots despite previous observations of drought-induced outbreaks. The effect of water stressed plants on grasshoppers depended on their diet, and how different plant groups responded to water stress. I then compared host plant use to macronutrient requirements among 11 dominant grasshopper species. I found differences associated with functional diet groupings. I also found intake differences among mixed-feeders with highly overlapping diets, which could potentially represent nutrient niches. Finally, I tested the nutrient niche hypothesis in a greenhouse competition experiment using three species of generalist grasshoppers with overlapping diets. I found mixed support for the nutrient niche hypothesis. Body size was more important for predicting competitive outcomes. Understanding community-wide patterns of nutrient regulation in insect herbivores is in its infancy. While the plant nutrient landscape plays a large role in consumer populations, we are far from understanding how species-specific nutrient regulation differences might impact communities. Perhaps the potential effects of nutrient intake differences are inconsequential next to other ecological factors. Future comparative studies should determine what evolutionary factors shape nutrient requirements. Advisors/Committee Members: Eubanks, Micky D (advisor), Behmer, Spencer T (advisor), Medina, Raul F (committee member), Rogers, William E (committee member).

Subjects/Keywords: grasshopper; nutrients; insect herbivore; geometric framework; community ecology; nutritional ecology; grassland

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APA (6^th Edition):

Lenhart, P. A. (2014). Nutrient Niches: an Investigation of Nutritional Ecology in a Generalist Herbivore Community. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/152808

Chicago Manual of Style (16^th Edition):

Lenhart, Paul Alvarado. “Nutrient Niches: an Investigation of Nutritional Ecology in a Generalist Herbivore Community.” 2014. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/152808.

MLA Handbook (7^th Edition):

Lenhart, Paul Alvarado. “Nutrient Niches: an Investigation of Nutritional Ecology in a Generalist Herbivore Community.” 2014. Web. 13 Apr 2021.

Vancouver:

Lenhart PA. Nutrient Niches: an Investigation of Nutritional Ecology in a Generalist Herbivore Community. [Internet] [Doctoral dissertation]. Texas A&M University; 2014. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/152808.

Council of Science Editors:

Lenhart PA. Nutrient Niches: an Investigation of Nutritional Ecology in a Generalist Herbivore Community. [Doctoral Dissertation]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/152808

Texas A&M University

8. Mohr, Rachel. Female Blow Fly (Diptera: Calliphoridae) Arrival Patterns and Consequences for Larval Development on Ephemeral Resources.

Degree: PhD, Entomology, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10759

► This investigation explored the environmental and physiological factors affecting adult blow fly (Diptera: Calliphoridae) arrival and attendance at pig (Sus scrofa domesticus L.) carcasses in… (more)

Subjects/Keywords: forensic entomology; Cochliomyia macellaria; Chrysomya rufifacies; PMI estimation; critical weight; competition; carrion

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APA (6^th Edition):

Mohr, R. (2012). Female Blow Fly (Diptera: Calliphoridae) Arrival Patterns and Consequences for Larval Development on Ephemeral Resources. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10759

Chicago Manual of Style (16^th Edition):

Mohr, Rachel. “Female Blow Fly (Diptera: Calliphoridae) Arrival Patterns and Consequences for Larval Development on Ephemeral Resources.” 2012. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10759.

MLA Handbook (7^th Edition):

Mohr, Rachel. “Female Blow Fly (Diptera: Calliphoridae) Arrival Patterns and Consequences for Larval Development on Ephemeral Resources.” 2012. Web. 13 Apr 2021.

Vancouver:

Mohr R. Female Blow Fly (Diptera: Calliphoridae) Arrival Patterns and Consequences for Larval Development on Ephemeral Resources. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10759.

Council of Science Editors:

Mohr R. Female Blow Fly (Diptera: Calliphoridae) Arrival Patterns and Consequences for Larval Development on Ephemeral Resources. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10759

Texas A&M University

9. Fitzgerald, Daniel Bruce. Community Assembly Dynamics of Rapids-adapted Fishes of the Xingu River.

Degree: PhD, Wildlife and Fisheries Sciences, 2016, Texas A&M University

URL: http://hdl.handle.net/1969.1/158976

► Increasing hydroelectric development in the tropics is beginning to place a large percentage of global freshwater diversity at risk. A prime example is the recently… (more)

▼ Increasing hydroelectric development in the tropics is beginning to place a large percentage of global freshwater diversity at risk. A prime example is the recently completed Belo Monte Hydroelectric Complex (BMHC) on the Xingu River in Brazil, which will have severe impacts on a highly endemic assemblage of rapids-adapted fishes. This dissertation uses community assembly theory as a lens to explore ecological dynamics within rapids of the Xingu prior to hydrologic alteration, with the goal of furthering empirical understanding of the assembly process, as well as providing necessary baseline data for conservation efforts. Focusing on both functional and taxonomic community structure, I use null model comparisons and multivariate statistical approaches to explore: 1) temporal dynamics between wet and dry-season assemblages, 2) variation across different functional traits, and 3) spatial variation along the impacted reach. Significant differences in functional diversity between wet and dry-season assemblages suggest that the relative influence of community assembly mechanisms vary seasonally in response to changing abiotic conditions, with expanded habitat and decreased density of aquatic organisms during the wet season likely limiting the influence of biotic assembly mechanisms, including competitive exclusion. Significant relationships between a trait’s deviation from null expectations and its correlation with trophic structure indicates that traits strongly associated with trophic ecology display greater dispersion from the mean and more even spacing of trait values. This suggests that traits associated with trophic ecology are more influential in niche differentiation affecting species coexistence. The dominant compositional pattern observed was the high number of rapids-adapted species found upstream of the main powerhouse, further highlighting this region of the Xingu as a hotspot of aquatic diversity and identifying the area that will be dewatered by the BMHC as critically important for the conservation of this unique fauna. These results emphasize the dynamic nature of the assembly process, but suggest that traits may respond to assembly mechanisms in predictable ways. Maintenance of a dynamic flow regime that contains key components of the historic hydrograph will be critical for the conservation of this globally unique habitat and its associated diversity. Advisors/Committee Members: Winemiller, Kirk O (advisor), Fujiwara, Masami (committee member), Eubanks, Micky D (committee member), Kreuter, Urs (committee member).

Subjects/Keywords: functional trait; functional diversity; null model; seasonal variation; stable isotope; Brazil; Neotropical

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APA (6^th Edition):

Fitzgerald, D. B. (2016). Community Assembly Dynamics of Rapids-adapted Fishes of the Xingu River. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/158976

Chicago Manual of Style (16^th Edition):

Fitzgerald, Daniel Bruce. “Community Assembly Dynamics of Rapids-adapted Fishes of the Xingu River.” 2016. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/158976.

MLA Handbook (7^th Edition):

Fitzgerald, Daniel Bruce. “Community Assembly Dynamics of Rapids-adapted Fishes of the Xingu River.” 2016. Web. 13 Apr 2021.

Vancouver:

Fitzgerald DB. Community Assembly Dynamics of Rapids-adapted Fishes of the Xingu River. [Internet] [Doctoral dissertation]. Texas A&M University; 2016. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/158976.

Council of Science Editors:

Fitzgerald DB. Community Assembly Dynamics of Rapids-adapted Fishes of the Xingu River. [Doctoral Dissertation]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/158976

Texas A&M University

10. Le Gall, Marion. Diet-mixing in a Generalist Herbivore: Trade-offs Between Nutrient and Allelochemical Regulation.

Degree: PhD, Entomology, 2014, Texas A&M University

URL: http://hdl.handle.net/1969.1/152778

► Despite decades of research, many key aspects related to the physiological processes and mechanisms insect herbivores use to build themselves remain poorly understood, and we… (more)

▼ Despite decades of research, many key aspects related to the physiological processes and mechanisms insect herbivores use to build themselves remain poorly understood, and we especially know very little about how interactions among nutrients and allelochemicals drive insect herbivore growth processes. Understanding the physiological effects of these interactions on generalist herbivores is a critical step to a better understanding and evaluation of the different hypothesis that have been emitted regarding the benefits of polyphagy. I used both lab and field experiments to disentangle the respective effect of protein, carbohydrates and allelochemicals on a generalist herbivore, the grasshopper Melanoplus differentialis. The effect of protein and carbohydrates alone were examined using artificial diets in choice and no-choice experiments. Results were plotted using a fitness landscape approach to evaluate how protein-carbohydrate ratio and/or concentration affected performance and consumption. Growth was best near the self-selected ratio obtained from the choice experiment, most likely due to the fact that the amount of food digested was also higher on that ratio. By contrast, development time was not best near the preferred ratio most likely due to the trade-off existing between size and development time. These results illustrate how nutrient availability can shape an ecological trade-off: growing big or growing fast. When an allelochemical (gramine, an alkaloid commonly found in grass) was introduced to the artificial diets, it had an interactive effect with protein and carbohydrates on performance and consumption and performance were generally improved on diets that contained higher amount of protein. Host plants of two wild populations were determined by gut content analysis and fed in choice and no-choice experiment. First the plant material was dried and ground and its protein, carbohydrate, terpenoid and phenolic content analyzed. Both populations regulated for the same protein-carbohydrate intake. However performance was different, due to variation in plant allelochemical content. This demonstrated for the first time that nutrient regulation, not toxin dilution, is directing food selection behavior in a generalist herbivore. Finally the role of macronutrients was analyzed in a context of cost of detoxification by measuring microsomal p450 production in the presence/absence of gramine. In the presence of choice, nutrient regulation was altered when gramine was present in the protein-biased diet. In the absence of choice, insects performed better on carbohydrate biased diet. I found that gramine elevated the level of microsomal protein in the fat body. Advisors/Committee Members: Behmer, Spencer T. (advisor), Eubanks, Micky D. (committee member), Rosenthal, Gil G. (committee member), Zhu-Salzman, Keyan (committee member), Harrison, Jon F. (committee member).

Subjects/Keywords: diet-mixing; generalist; herbivore; nutrients; allelochemical; protein; carbohydrate; physiological ecology

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APA (6^th Edition):

Le Gall, M. (2014). Diet-mixing in a Generalist Herbivore: Trade-offs Between Nutrient and Allelochemical Regulation. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/152778

Chicago Manual of Style (16^th Edition):

Le Gall, Marion. “Diet-mixing in a Generalist Herbivore: Trade-offs Between Nutrient and Allelochemical Regulation.” 2014. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/152778.

MLA Handbook (7^th Edition):

Le Gall, Marion. “Diet-mixing in a Generalist Herbivore: Trade-offs Between Nutrient and Allelochemical Regulation.” 2014. Web. 13 Apr 2021.

Vancouver:

Le Gall M. Diet-mixing in a Generalist Herbivore: Trade-offs Between Nutrient and Allelochemical Regulation. [Internet] [Doctoral dissertation]. Texas A&M University; 2014. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/152778.

Council of Science Editors:

Le Gall M. Diet-mixing in a Generalist Herbivore: Trade-offs Between Nutrient and Allelochemical Regulation. [Doctoral Dissertation]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/152778

Texas A&M University

11. Pechal, Jennifer. The Importance of Microbial and Primary Colonizer Interactions on an Ephemeral Resource.

Degree: PhD, Entomology, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11016

► Carrion decomposition is an essential ecosystem function as it is an important component of nutrient cycling. Carrion decomposition has primarily been attributed to insect consumption,… (more)

▼ Carrion decomposition is an essential ecosystem function as it is an important component of nutrient cycling. Carrion decomposition has primarily been attributed to insect consumption, with little attention given to microbial communities or their potential interactions with insects. The first objective was to use passive insect-trapping methods to assess primary colonizer communities on swine carcasses between two treatments: 1) carrion with access to insects and 2) carrion excluded from insect access for five days using exclusion cages. Despite similarities between succession patterns within each treatment, carcasses initially exposed to insects had significantly fewer insect taxa. Therefore, collections of adult insect communities associated with carrion are promising as an indication of whether or not there has been a delay in insect colonization of a resource. There has yet to be a study documenting bacterial communities during carrion decomposition. The second objective was to describe bacterial community succession and composition during decomposition in the presence and absence of naturally occurring insects. Total genomic DNA was used to identify bacterial community composition via a modified bacterial tagged encoded FLX amplicon pyrosequencing. I obtained 378,904 sequences and documented distinct bacterial community successional trajectories associated with insect access and exclusion carcasses. By the fifth day of decomposition, Proteus was the dominant (72%) bacterial genus on exclusion carcasses while Psychrobacillus (58%) and Ignatzschineria (18%) were dominant bacterial genera on insect carcasses. These data are the first to document bacterial community composition and succession on carrion. My final objective was to assess microbial community function in response to carrion insect colonization using metabolic profiling. I characterized microbial community metabolic function in the presence and absence of the primary necrophagous insects. I documented significant microbial community metabolic profile changes during active decomposition of carcasses. Mean carcass microbial community metabolic function with insect access continuously decreased over decomposition during both field seasons. Thus demonstrating microbial metabolic activity may have discriminatory power to differentiate early and late stages of decomposition. Overall, my data contributes to an understudied area of microbial research important to organic matter decomposition, forensic entomology, and microbial-insect ecological interactions. Advisors/Committee Members: Tomberlin, Jeffery K. (advisor), Tarone, Aaron M. (committee member), Eubanks, Micky D. (committee member), Crippen, Tawni L. (committee member), Benbow, Mark E. (committee member).

Subjects/Keywords: decomposition ecology; carrion; forensic entomology; microbial communities; Biolog ECOplates; 454-pyrosequencing

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APA (6^th Edition):

Pechal, J. (2012). The Importance of Microbial and Primary Colonizer Interactions on an Ephemeral Resource. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11016

Chicago Manual of Style (16^th Edition):

Pechal, Jennifer. “The Importance of Microbial and Primary Colonizer Interactions on an Ephemeral Resource.” 2012. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11016.

MLA Handbook (7^th Edition):

Pechal, Jennifer. “The Importance of Microbial and Primary Colonizer Interactions on an Ephemeral Resource.” 2012. Web. 13 Apr 2021.

Vancouver:

Pechal J. The Importance of Microbial and Primary Colonizer Interactions on an Ephemeral Resource. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11016.

Council of Science Editors:

Pechal J. The Importance of Microbial and Primary Colonizer Interactions on an Ephemeral Resource. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11016

Texas A&M University

12. Roach, Katherine. Large River Food Webs: Influence of Nutrients, Turbidity, and Flow, and Implications for Management.

Degree: PhD, Wildlife and Fisheries Sciences, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11633

► Humans impact rivers in many ways that modify ecological processes yielding ecosystem services. In order to mitigate anthropogenic impacts, scientists are challenged to understand interactions… (more)

▼ Humans impact rivers in many ways that modify ecological processes yielding ecosystem services. In order to mitigate anthropogenic impacts, scientists are challenged to understand interactions among physicochemical factors affecting large river food webs. An understanding of socioeconomic factors also is critical for ecosystem management. In this dissertation, I explore spatiotemporal patterns in floodplain river food webs and political barriers to management of environmental flows, an important factor influencing river ecology. In Chapter II, I reviewed the scientific literature to test conceptual models of river food webs and predictions of environmental factors that might produce variation in basal production sources supporting consumer biomass. My review indicates that algae are the predominant production source for large rivers worldwide, but consumers assimilate C3 plants in rivers 1) with high sediment loads and low transparency during high flow pulses, 2) with high dissolved organic matter concentrations, and 3) following periods of high discharge or leaf litter fall that increase the amount of terrestrial material in the particulate organic matter pool. In Chapter III, I descrobe field research conducted to examine relationships among hydrology, nutrient concentrations, turbidity, and algal primary production and biomass in the littoral zone of five rivers in Texas, Peru, and Venezuela differing in physicochemical conditions. I used stable isotope signatures to estimate contributions of algal-versus terrestrial-based production sources to consumers during different hydrologic periods. My research indicates that during flow pulses in floodplain rivers, a decrease in algal biomass and productivity, combined with increased inputs of terrestrial organic matter, can result in increased terrestrial support of metazoan consumers in the aquatic food web. In 2007, Texas Senate Bill 3 directed that environmental flow recommendations be developed for river basins. Despite emphasis on use of the "best available science" to develop environmental flow regimes and "stakeholder involvement" to address needs of all water users, for the first two basins to complete the SB3 process, final environmental flow rules did not mimic a natural flow regime. In Chapter IV, I reviewed this process, concluding that incentives for river authorities to increase compromise with diverse stakeholders should result in more sustainable management of freshwater. Advisors/Committee Members: Winemiller, Kirk O. (advisor), Davis III, Stephen E. (committee member), Eubanks, Micky D. (committee member), Fitzgerald, Lee A. (committee member), Stronza, Amanda L. (committee member).

Subjects/Keywords: food web; instream flow; nutrients; primary production; river; Texas Senate Bill 3; turbidity

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APA (6^th Edition):

Roach, K. (2012). Large River Food Webs: Influence of Nutrients, Turbidity, and Flow, and Implications for Management. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11633

Chicago Manual of Style (16^th Edition):

Roach, Katherine. “Large River Food Webs: Influence of Nutrients, Turbidity, and Flow, and Implications for Management.” 2012. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11633.

MLA Handbook (7^th Edition):

Roach, Katherine. “Large River Food Webs: Influence of Nutrients, Turbidity, and Flow, and Implications for Management.” 2012. Web. 13 Apr 2021.

Vancouver:

Roach K. Large River Food Webs: Influence of Nutrients, Turbidity, and Flow, and Implications for Management. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11633.

Council of Science Editors:

Roach K. Large River Food Webs: Influence of Nutrients, Turbidity, and Flow, and Implications for Management. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11633

13. Marquezini Leite, Pedro Afonso. Influences of Forest Regrowth and Ants on the Recovery of Soil Hydraulic Properties in a Semiarid Region of Brazil.

Degree: MS, Ecosystem Science and Management, 2016, Texas A&M University

URL: http://hdl.handle.net/1969.1/157822

► Dryland tropical forests are at risk globally because of accelerated deforestation and the consequent losses of hydrological functions. The Caatinga shrublands in Brazil, for example,… (more)

▼ Dryland tropical forests are at risk globally because of accelerated deforestation and the consequent losses of hydrological functions. The Caatinga shrublands in Brazil, for example, are dry tropical forests undergoing rapid deforestation, which is often followed by conversion to pasturelands. When overgrazed, these pastures become degraded and are often abandoned, allowing forests to regrow. Studies in the humid tropics have shown that natural regrowth of forest promotes a gradual recovery of soil hydraulic properties and also protect the soil against erosion. One of the mechanisms through which forests might improve soil structure is by the promoting the activity of ecosystem engineers, such as ants. However, there are some knowledge gaps in the literature of tropical dry forests about the effects of forest regrowth on the recovery infiltration and soil loss, as well as on the effects of ants on infiltration. Soil hydraulic properties and soil erosion were evaluated on a secondary succession continuum in the Caatinga. Rainfall simulation was used to assess infiltrability and susceptibility to erosion, and saturated hydraulic conductivity was determined in the field and in the laboratory using two different methods. A relation between forest age and erosion was not found. However, there was gradual increase of hydraulic conductivity with increasing forest age, and infiltrability was only higher at the older forested site. The results suggest that a complete recovery of soil hydraulic properties might take several decades. Soil modifications by fauna can critically affect water infiltration, which is particularly important on dryland ecosystems. Modification of soil hydraulic properties by two ant species in the Caatinga– one found at preserved forest and the other at a degraded pasture– were evaluated. Soil bulk density, texture, and infiltration were assessed on their nests and on non-nest soils. Both ants significantly modified these soil properties, but while modifications by the forest species might increase soil water available to plants, the other species had an overall negative effect on soil hydraulic properties. Such modifications could be impacting forest resilience and recovery in opposite ways. Advisors/Committee Members: Wilcox, Bradford P (advisor), Eubanks, Micky D (committee member), Boutton, Thomas W (committee member).

Subjects/Keywords: ecohydrology; Caatinga; chronosequence; soil recovery; hydraulic conductivity; macropore; ecosystem engineer

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APA (6^th Edition):

Marquezini Leite, P. A. (2016). Influences of Forest Regrowth and Ants on the Recovery of Soil Hydraulic Properties in a Semiarid Region of Brazil. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/157822

Chicago Manual of Style (16^th Edition):

Marquezini Leite, Pedro Afonso. “Influences of Forest Regrowth and Ants on the Recovery of Soil Hydraulic Properties in a Semiarid Region of Brazil.” 2016. Masters Thesis, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/157822.

MLA Handbook (7^th Edition):

Marquezini Leite, Pedro Afonso. “Influences of Forest Regrowth and Ants on the Recovery of Soil Hydraulic Properties in a Semiarid Region of Brazil.” 2016. Web. 13 Apr 2021.

Vancouver:

Marquezini Leite PA. Influences of Forest Regrowth and Ants on the Recovery of Soil Hydraulic Properties in a Semiarid Region of Brazil. [Internet] [Masters thesis]. Texas A&M University; 2016. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/157822.

Council of Science Editors:

Marquezini Leite PA. Influences of Forest Regrowth and Ants on the Recovery of Soil Hydraulic Properties in a Semiarid Region of Brazil. [Masters Thesis]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/157822

14. Jing, Xiangfeng. Effects of Sterol Structure on Insect Herbivore Physiology, Biochemistry and Molecular Biology.

Degree: PhD, Entomology, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10426

► Sterols serve two important biological functions in animals - they act as cellular membrane components, and as the precursor to steroid hormones. Insects require a… (more)

▼ Sterols serve two important biological functions in animals - they act as cellular membrane components, and as the precursor to steroid hormones. Insects require a dietary source of sterol because they cannot synthesize sterols de novo. Cholesterol is the most common sterol in plant-feeding insects, but because plants contain very little cholesterol, plant-feeding insects must convert plant sterols into cholesterol. In this dissertation I investigate the effect of common and novel plant sterols and steroids found in a transgenic tobacco line on several caterpillar species. I also explore the metabolism of these sterols and steroids, and use a microarray approach to identify genes involved in sterol use and metabolism in plant-feeding insects. I also study cholesterol homeostasis using a grasshopper species. Modified tobacco plants containing a novel sterol profile negatively affected performance three different caterpillar species, especially in the second generation. Insects reared on modified plants contained less total sterols and cholesterol than those on control plants having normal sterol profile. Similar results were found using artificial diets containing atypical steroids, e.g., cholestanol and cholestan-3-one, identified in the tobacco plants that were fed to my experimental caterpillars. More importantly, the sterol/steroid ratio, but not their absolute amount in the diets, determined the negative effects. Caterpillar species could convert stigmasterol, a common plant sterol, into cholesterol. They could also convert cholestan-3-one into cholestanol and epicholestanol, although this ability varied among different species. A microarray study, that focused on gene expression in midgut tissue, indicated that stigmasterol, cholestanol and cholestan-3-one could induce different gene expression level, and that cholestan-3-one caused a the largest pool of genes to be regulated. The genes possibly involved in the metabolism of stigmasterol and cholestan-3-one were reported. These findings are important in directing further research on the potential application of plant sterol modification to control pests in agricultural systems. Insect herbivores could behaviorally regulate the intake of several nutrients, but they could not regulate their sterol intake. They did, however, practice cholesterol homeostasis, by postingestively regulating tissue sterol levels, even when feeding on diets with high cholesterol content. Collectively, the results from this dissertation provide unique insight into cholesterol regulation, which is difficult to achieve in mammals that are capable of synthesizing their own sterols. Advisors/Committee Members: Behmer, Spencer T. (advisor), Davies, Frederick T. (committee member), Eubanks, Micky D. (committee member), Zhu-Salzman, Keyan (committee member).

Subjects/Keywords: phytosterol; metabolism; insect; cholesterol; homeostasis

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APA (6^th Edition):

Jing, X. (2012). Effects of Sterol Structure on Insect Herbivore Physiology, Biochemistry and Molecular Biology. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10426

Chicago Manual of Style (16^th Edition):

Jing, Xiangfeng. “Effects of Sterol Structure on Insect Herbivore Physiology, Biochemistry and Molecular Biology.” 2012. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10426.

MLA Handbook (7^th Edition):

Jing, Xiangfeng. “Effects of Sterol Structure on Insect Herbivore Physiology, Biochemistry and Molecular Biology.” 2012. Web. 13 Apr 2021.

Vancouver:

Jing X. Effects of Sterol Structure on Insect Herbivore Physiology, Biochemistry and Molecular Biology. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10426.

Council of Science Editors:

Jing X. Effects of Sterol Structure on Insect Herbivore Physiology, Biochemistry and Molecular Biology. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10426

15. Bellota Villafuerte, Edwin. Effects of Life History, Domestication, and Breeding of Zea on the Specialist Herbivore Dalbulus maidis (Hemiptera: Cicadellidae).

Degree: MS, Entomology, 2013, Texas A&M University

URL: http://hdl.handle.net/1969.1/149221

► A suite of plants from the maize genus Zea L. (Poaceae) and the specialist herbivore Dalbulus maidis (DeLong and Wolcott, 1923) (Hemiptera: Cicadellidae) were used… (more)

▼ A suite of plants from the maize genus Zea L. (Poaceae) and the specialist herbivore Dalbulus maidis (DeLong and Wolcott, 1923) (Hemiptera: Cicadellidae) were used to test the hypotheses that anti-herbivore defenses are affected by plant life-history evolution and human intervention through domestication and breeding for high yield. The suite of plants included a commercial hybrid maize (Zea mays ssp. mays L.), a landrace maize, two populations of annual Balsas teosinte (Z. mays ssp. parviglumis Iltis & Doebley), and perennial teosinte (Z. diploperennis Iltis, Doebley & Guzman). Leaf toughness and pubescence, oviposition preference, and feeding and oviposition acceptance parameters were compared among the suite of host plants looking for effects of transitions in life history (perennial to annual teosinte), domestication (annual teosinte to landrace maize), and breeding (landrace maize to hybrid maize) on defenses against D. maidis. Observations on leaf toughness suggested that the life history and domestication transitions weakened the plant’s resistance to penetration by the herbivore’s mouthparts and ovipositor, as expected, while observations on pubescence suggested that the breeding transition led to stronger defense in hybrid maize compared to landrace maize, contrary to expectation. Observations on oviposition preference of D. maidis coincided with the expectations that life history and domestication transitions would lead to preference for Balsas teosinte over perennial teosinte, and of landrace maize over Balsas teosinte. A negative correlation suggested that oviposition preference is significantly influenced by leaf toughness. Observations on host plant feeding and iii oviposition acceptance under no-choice conditions suggested that D. maidis equally accepts all host plants considered in this study, thus these observations did not support the hypotheses associated with the life history, domestication, and breeding transitions evident in the herbivore’s host genus. Overall, the results of this study suggested that plant defenses against specialist herbivores are variably affected by plant life history evolution, domestication, and breeding. Additionally, the study’s results suggested that chemical defenses may play a role in Zea antiherbivore defense because the two physical defenses that were evaluated (i.e. leaf toughness and pubescence) only partially explained host preference of D. maidis Advisors/Committee Members: Bernal, Julio S (advisor), Medina, Raul F (advisor), Eubanks, Micky D (committee member), Kolomiets, Michael V (committee member).

Subjects/Keywords: plant defense; domestication; Zea mays; Dalbulus maidis

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APA (6^th Edition):

Bellota Villafuerte, E. (2013). Effects of Life History, Domestication, and Breeding of Zea on the Specialist Herbivore Dalbulus maidis (Hemiptera: Cicadellidae). (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/149221

Chicago Manual of Style (16^th Edition):

Bellota Villafuerte, Edwin. “Effects of Life History, Domestication, and Breeding of Zea on the Specialist Herbivore Dalbulus maidis (Hemiptera: Cicadellidae).” 2013. Masters Thesis, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/149221.

MLA Handbook (7^th Edition):

Bellota Villafuerte, Edwin. “Effects of Life History, Domestication, and Breeding of Zea on the Specialist Herbivore Dalbulus maidis (Hemiptera: Cicadellidae).” 2013. Web. 13 Apr 2021.

Vancouver:

Bellota Villafuerte E. Effects of Life History, Domestication, and Breeding of Zea on the Specialist Herbivore Dalbulus maidis (Hemiptera: Cicadellidae). [Internet] [Masters thesis]. Texas A&M University; 2013. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/149221.

Council of Science Editors:

Bellota Villafuerte E. Effects of Life History, Domestication, and Breeding of Zea on the Specialist Herbivore Dalbulus maidis (Hemiptera: Cicadellidae). [Masters Thesis]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/149221

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