Edamame, also known as edible soybean, is a crop with growing demand in the United States. Currently much of the edamame consumed in the United States is imported, but it has potential to be grown domestically, in Virginia and other mid-Atlantic states. With the introduction of a new crop, however, comes new challenges, such as novel pests. The broad-headed bugs (Hemiptera: Alydidae), a relatively insignificant pest of conventional soybean, have been observed in high numbers on edamame in Virginia. Their piercing-sucking feeding may produce dark marks on edamame beans that could result in economic losses. However, little research has been conducted on the pest status or management of these bugs in edamame. This study aims to determine their pest potential to edamame by investigating their distribution throughout the state, damage to the crop, and avenues for chemical control. An important element in determining the pest potential of an insect is its distribution throughout an area. The distribution of broad-headed bugs in Virginia was last thoroughly investigated in 1975, and the research has scarcely been updated since. With advances in technology, however, it is now possible to crowd-source data from citizen scientists to supplement museum and field collection data. The first portion of this study explores the species of broad-headed bugs present in Virginia, and their distribution throughout the state. This was achieved using museum specimens, field-collected specimens, and photographs from the social network iNaturalist. By manually checking iNaturalist identifications of broad-headed bugs using a key, I was able to determine that iNaturalist is 96% accurate at identifying North American broad-headed bugs to species. Through the combination of museum, field, and iNaturalist data, I also found evidence of two species of broad-headed bug at elevations never before seen in Virginia, the first broad-headed bug ever found on the Eastern Shore of Virginia, as well as the first documented sighting of Hyalymenus tarsatus Fabricus in Virginia. The level of injury that broad-headed bugs cause to edamame is presently unknown. The second portion of this study compares the density-damage relationship of broad-headed bugs on edamame to that of the brown marmorated stink bug (Halyomorpha halys Stahl), a known pest of edamame. Through a cage study conducted in Whitethorne, Virginia, I found that broad-headed bugs cause significant damage to edamame at densities of 10 insects per plant, but still less damage than that of brown marmorated stink bugs. Currently, no economic injury thresholds exist for broad-headed bugs, or brown marmorated stink bugs on edamame. Determining the density-damage relationship of these insects on edamame may contribute to the creation of these thresholds in the future. The third portion of this study is the first attempt at evaluating chemical control of the broad-headed bugs on edamame. I performed a bioassay evaluation of four commercial selective insecticides including the following: flupyradifurone and sulfoxaflor, both with a mode of action similar to neonicotinoids, but with reduced non-target effects; the diamide cyclaniliprole, and a novel venom-like peptide insecticide, GS-omega/kappa-Hxtx-Hv1a. Each of the insecticides caused significant mortality of Alydus eurinus (Say) adults. This thesis serves as a starting point in evaluating the potential threat of broad-headed bugs to Virginia's edamame production. / Master of Science in Life Sciences / Alydids are a group of true bugs, often referred to as broad-headed bugs. Not many species are known to occur in Virginia. However, after research began in Virginia in 2018 to develop edible soybean (edamame) for production in the state, we observed high densities of broad-headed bugs feeding on edamame pods on research farms and commercial fields. Broad-headed bug feeding may produce dark marks that leave edamame beans unmarketable. Very little is known about the pest status or management of broad-headed bugs as a crop pest, or about their distribution and biology in general. This study aims to address these questions. An important element in determining the pest potential of an insect is its distribution throughout an area. The distribution of broad-headed bugs in Virginia was last thoroughly investigated in 1975, and the research has scarcely been updated since. With advances in technology, however, it is now possible to crowd-source data from citizen scientists to supplement museum and field collection data. The first portion of this study explores the species of broad-headed bugs present in Virginia, and their distribution throughout the state. This was achieved using museum specimens, field-collected specimens, and photographs from the web and mobile application iNaturalist. By manually checking iNaturalist identifications of broad-headed bugs using an identification key, I was able to determine that iNaturalist is 96% accurate at identifying North American broad-headed bugs to species. Through the combination of museum, field, and iNaturalist data, I also found evidence of two species of broad-headed bug at elevations not previously reported, the first broad-headed bug ever found on the Eastern Shore of Virginia, as well as the first documented sighting of Hyalymenus tarsatus (Fabricus) in Virginia. The second portion of this study compares the damage of broad-headed bugs on edamame to that of the brown marmorated stink bug, a known pest of edamame. By caging broad-headed bugs on edamame plants in Whitethorne, Virginia, I found that they cause significant damage to edamame at 10 insects per plant, but still less damage than that of brown marmorated stink bugs. Determining the density-damage relationship of these insects on edamame may determine their potential as a pest, as well as inform growers when to apply insecticides. The third portion of this study is the first attempt at determining avenues of chemical control of the broad-headed bug Alydus eurinus (Say), one of the two most likely species to be a pest of edamame. I performed a laboratory evaluation of four commercial selective insecticides including the following: flupyradifurone and sulfoxaflor, both with a mode of action similar to neonicotinoids, but with reduced non-target effects; the diamide cyclaniliprole, and a novel venom-like peptide insecticide, GS-omega/kappa-Hxtx-Hv1a. These insecticides have limited detrimental effects on beneficial organisms. Each of the insecticides was effective against A. eurinus. This study serves as a starting point in evaluating the potential threat of broad-headed bugs to Virginia's edamame production.

Systena frontalis (F.) (Coleoptera: Chrysomelidae), the red headed flea beetle (RHFB), is a ubiquitous pest of ornamental nursery crops in the eastern United States. Defoliation by adults renders plants unsaleable. Control costs and economic losses from injured plants have become a top concern among Virginia nurseries in the past decade. Current management tactics include spraying insecticides up to three times a week during the adult active season. The frequent use of insecticides poses a risk to the environment, non-target organisms, and evolution of resistance within the targeted beetle population. To develop a sustainable pest management program, more information is needed to understand pest biology, quantify the injury potential, and explore control tactics. Methods to monitor this beetle were used to observe peak activity throughout the growing season as well as the adult daily activity levels. There were three observed generations with population peaks in late June, late July, and late August into early September. Within the scale of one day, adult beetles were found to be diurnal with peaks in activity in the middle of the day. These findings will inform growers of the most efficient times to scout and spray, ultimately reducing insecticide usage. Quantification of feeding damage to individual leaves, the entire plant, and preference between older and newer growth may relate plant injury with specific population densities. The use of phenyl ethyl alcohol as an attractant lure, was explored to bolster pest control. Finally, insecticide bioassays were performed to compare those currently used to others yet untested. / Master of Science in Life Sciences / The red headed flea beetle (RHFB) is an important pest of ornamental crops in open-field nurseries along the Eastern United States. Defoliation caused by adult feeding renders plants unsellable. Japanese hollies, hydrangeas, and sweetspire iteas are among the most affected plants. Infested nurseries suffer severe economic losses due to insecticide costs and plant inventory reductions. Growers are spraying insecticides up to three times a week to manage RHFB. Frequent use of insecticides poses risks to the environment non-target organisms. This study will help improve control tactics for this pest and potentially minimize non-target effects by reducing insecticide usage. Understanding when beetles are active throughout the day, and throughout the growing season, may inform timing of scouting and insecticide sprays to maximize effectiveness. With populations highest in late June, late July, and late August, RHFB is estimated to have three generations per year. Adults are most active in the middle of the day and sedentary at night. It was observed how different densities of beetles cause injury to individual leaves and entire plants, and compared feeding preference on older versus newer growth. Chemical control tactics were explored including insecticides labeled and not labeled for RHFB such as iscycloseram. Finally, the effectiveness of phenyl ethyl alcohol as an attractant lure for RHFB was assessed and found ineffective within the open-field nursery ecosystem.

In this project, we synthesized a new homologous series of five long-chain, two-headed amphiphiles [2CAm13, 2CAm15, 2CAm17, 2CAm19, 2CAm21; CH3(CH2)n-1CONHC(CH3)(CH2CH2COOH)2, n = 13, 15, 17, 19, 21]. The synthesis of the 2CAmn series was accomplished in four steps. The first step involves a reaction of nitroethane and two equivalents of tert-butyl acrylate to create the nitrodiester synthon [O2NC(CH3)(CH2CH2COOtBu)2] by successive Michael additions. The second step in the synthesis consists of a reduction of nitrodiester with H2 and Raney nickel to give the diesteramine [H2NC(CH3)(CH2CH2COOtBu)2]. The third step is the condensation of an acid chloride with diesteramine to give an alkanamido diester [2EAmn; CH3(CH2)n-1CONHC(CH3)(CH2CH2COOtBu)2, n = 13, 15, 17, 19, 21]. The final step is the removal of the tert-butyl protecting groups to give 2CAmn. Critical micelle concentration measurements were collected by the pendant drop method for measuring surface tension for a series of triethanolamine/2CAmn solutions to establish the concentration required for detergency. The CMCs for the 2CAmn series were found to decrease in value from 3.0 Ã 10â 2 M (2CAm13) to 1.7 Ã 10â 4 M (2CAm21) in a linear fashion [log CMC = (â 0.28 ± 0.01)n + (2.2 ± 0.1)]. The CMCs for the 2CAmn series falls in between the CMCs for three series of homologues three-headed amphiphiles (3CAmn, 3CCbn, 3CUrn) and the CMCs for fatty acids, with fatty acids having the lowest CMCs. Antibacterial activity (minimal inhibitory concentrations, MICs) for a series of homologous dendritic two-headed amphiphiles and three series of homologous, three-headed amphiphiles against Staphylococcus aureus and methicillin-resistent S. aureus (MRSA) were measured by broth microdilution to compare the effect of chain length and, hence, hydrophobicity. Inoculum density affected antibacterial activity of the 2CAmn series against both S. aureus and MRSA. MIC measurements at different cell densities showed that activity decreased with higher cell densities. For all four series, the MICs were relatively flat at low inoculum densities. This flat region defines the intrinsic activity, MIC0. The MIC0 results revealed that inoculum density, chain-length, and hydrophobicity all influenced antibacterial activity and that activity correlates strongly with clogp, an established measure of hydrophobicity. The most hydrophobic members from each homologous series exhibited antibacterial activity. The most active homologue of the 2CAmn series was 2CAm21 with MIC0 of 2.0 ± 1.0 and 3.2 ± 1.0 μM against S. aureus and MRSA, respectively. The CMCs and MIC0s of the two- and three-headed amphiphiles were compared for both S. aureus and MRSA to gauge the effect that micelles may have on activity. Amphiphile 2CAm19 has the largest ratio between CMC and MIC0 (CMC/MIC0 = 205) against S. aureus and 3CUr20 has the largest ratio (CMC/MIC0 = 339) against MRSA. These ratios suggest that micelle formation is not a mechanism of action for anti-Staphylococcal activity. / Master of Science

The caseloads of food stamp program and welfare program experienced sharp drops among non-metropolitan single female-headed families with children (SFHFwC) after welfare reform in 1996. There is concern that leaving welfare program has led to nonparticipation in food stamp program due to multiple reasons. This study conducts an empirical analysis of non-metropolitan SFHFwC's participation in food stamp program and welfare program, using the 1993 and 1999 CPS data. Results from using reduced-form probit model, bivariate probit model and structural probit model are compared. The reduced-form probit model considers participation in both programs as functions of all exogenous variables. The bivariate probit model allows correlation between the participation in the two programs. The structural probit model considers participation in welfare as an endogenous variable of FSP participation. Empirical analysis is also conducted through the comparison across years and between southern and the remaining U.S. states. We found that welfare participation has a significant and positive impact on FSP participation. Households leaving welfare are more likely not to participate in FSP. Further, welfare participation is more important in determining FSP participation in 1999 than in 1993. Residence in South has a significant and negative impact in welfare participation in 1999, but has no significant impact on FSP participation in either year. Incomes and number of young children are the other major determinants of participation in both programs. Policy suggestions include improving economic situation to reduce FSP caseloads on one side, and providing more information about FSP eligibility to welfare leavers to ensure their food safety on the other side. / Master of Science

This project is about the synthesis of homologous series of two-headed, long-chain amphiphiles (the 2CCbn series, where n = 16, 18, 20, 22, 30, 5α-cholestan-3Ã -ol). The 2CCbn series was synthesized in five steps. The first step involves a reaction of nitroethane and two equivalents of tert-butyl acrylate to form nitrodiester by successive Michael addition reaction. The second step is the reduction of nitrodiester with Raney nickel to form aminodiester. The third step involves a reaction of aminodiester with di-tert-butyl dicarbonate [(Boc)2O] to form isocyanatediester. The fourth step is addition of iscocyanatediester with aliphatic alcohol to give alkyl carbamate diester (2ECbn) series. The fifth step is the removal of the tert-butyl protecting group to give the 2CCbn series. The critical micelle concentrations (CMC) were measured by the pyrene-based fluorescent probe method. The pyrene excited at 345 nm and fluoresces with maxima at 374 nm (I1) and 385 nm (I3). The stock solution and the dilution series for each amphiphiles were made in 0.9% triethanolamine solution. The CMCs were measured at two pH ~9.2 and 7.4. The CMCs were determined by plotting I1/I3 vs. concentrations. The CMCs were decreasing with increasing chain length. The CMCs for the 2CCbn series are lower than the 3CCbn series but higher than the fatty acids. The minimal inhibitory concentrations were measured against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. These strains were grown on BHIB+S with 5% triethanolamine. The MICs of the 2CCbn series amphiphiles were measured by using microtiter plate reader and by looking turbidity. The cutoff effect was found for the 2CCbn series. The MIC decreased up to C20 chain length and started rising for C22. The 2CCb18 (MICâ 2.2 µg/mL) of the 2CCbn series was the most effective amphiphile against S. aureus and MRSA. The CMC/MIC ratio was used to determine the safety of an amphiphile as a drug use. The amphiphile 2CCb18 has given the largest safety ratio (CMC/MIC = 273) against S. aureus and MRSA. It suggests that micelle formation is not a mechanism of action for anti-Staphylococcal activity. / Master of Science

No / In steel-concrete composite construction, headed stud shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface. Present knowledge of the load-slip behavior of the shear stud in composite beam is limited to data obtained from the experimental push-off tests. A finite element model to simulate the structural behavior of headed stud shear connector in steel-concrete composite beam is described in the chapter. The model is based on finite element method and takes into account linear and nonlinear behavior of the materials. The model has been validated against test results and compared with data given in the current Code of Practices, for which both demonstrate the accuracy of the model used. Parametric studies using the model to investigate variations in concrete strength and shear stud diameter are also discussed in the chapter. The model takes into account the linear and nonlinear material properties of the concrete and shear stud. The FE results compare well with the experimental push-off test results and specified data from the codes. The FE model accurately predicts the mode of failure.

No / In steel¿concrete composite beams, the longitudinal shear force is transferred across the steel flange/concrete slab interface by the mechanical action of the shear connectors. The ability of the shear connectors to transfer these longitudinal shear forces depends on their strength, and also on the resistance of the concrete slab against longitudinal cracking induced by the high concentration of shear force. Most of the research in composite construction has concentrated on the more traditional reinforced concrete and metal deck construction, and little information is given on shear capacity of the headed studs in precast hollowcore slabs. In this paper, a standard push test procedure for use with composite beams with precast hollowcore slabs is proposed. Seven exploratory push tests were carried out on headed studs in solid RC slabs to validate the testing procedures, and the results showed that the new test is compatible with the results specified in the codes of practice for solid RC slabs. Once a standard procedure is established, 72 full-scale push tests on headed studs in hollowcore slabs were performed to determine the capacities of the headed stud connectors in precast hollowcore slabs and the results of the experimental study are analysed and findings on the effect of all the parameters on connectors¿ strength and ductility are presented. Newly proposed design equations for calculating the shear connectors¿ capacity for this form of composite construction are also be given.

Women are over-represented among the rural poor in developing countries, and the difficulties they face in raising themselves out of poverty are well established. This thesis examines how gender structures trade in local markets and forms of sociability in rural Ethiopia, using survey data from four rural communities and three local market places. Over 600 male and female farmers were surveyed, and qualitative data from interviews and observations was used to interpret and analyze the results. The thesis is in four parts: Part I introduces the research questions, and presents the theory and research methodology. The thesis posits that women’s access to resources is mediated via men, making it difficult for them to head their own households. Part II links the theoretical concepts to conditions in the field, showing how the the less valued activities are assigned to women, and develops a resource index that establishes the inequality in resource access. Part III proves that gender structures local markets and that the inequality in access to resources is reproduced in these. Yet trading offers an important livelihood for women, challenging their isolation and expanding their choices and markets are arenas in which they can exercise their agency. Part IV shows that local forms of sociability are also structured by gender and influence access to other resources. Density of social network ties and access to rural resources are strongly linked, particularly for female household heads. The final chapter shows how the gendered structure of local markets and sociability allows men to capitalize on resources more effectively than women. But women can carve out space and authority for themselves, lead local organizations and become active traders, and are actually less embedded in communities and more embedded in markets than men. The thesis problematizes the livelihood options open to female household heads, and how they balance these between markets and communities. The thesis concludes that future attempts to strengthen local markets and institutions must acknowledge that women and men face different constraints and opportunities. Women's room for maneuver could then translate into real empowerment.

This study assembles COI barcodes from 1814 specimens from the shorebird order, Charadriiformes and examines variation relative to time, rate of evolution and taxonomic level. In the suborder Scolopaci, 95% of sampled species were identified correctly. COI barcode variation within monotypic species was low (0-1% maximum distance) but showed a wide range within polytypic species (0-5%). Preliminary Charadrii results suggest similar trends but success is reduced in the third suborder, Lari. Rates of COI evolution are found to be lowest in the Lari and this leads to reduced species identification in recently radiated families: just 49% of the Laridae and 57% of the Stercoraridae are identified but 100% of the older Alcidae. In the faster Scolopaci, subspecies are at the limit of resolution with some well differentiated subspecies not distinguished by barcodes. The interplay of evolutionary rates, divergence dates and gene flow appears to determine COI barcode differentiation between taxa.

This study assembles COI barcodes from 1814 specimens from the shorebird order, Charadriiformes and examines variation relative to time, rate of evolution and taxonomic level. In the suborder Scolopaci, 95% of sampled species were identified correctly. COI barcode variation within monotypic species was low (0-1% maximum distance) but showed a wide range within polytypic species (0-5%). Preliminary Charadrii results suggest similar trends but success is reduced in the third suborder, Lari. Rates of COI evolution are found to be lowest in the Lari and this leads to reduced species identification in recently radiated families: just 49% of the Laridae and 57% of the Stercoraridae are identified but 100% of the older Alcidae. In the faster Scolopaci, subspecies are at the limit of resolution with some well differentiated subspecies not distinguished by barcodes. The interplay of evolutionary rates, divergence dates and gene flow appears to determine COI barcode differentiation between taxa.