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Computing education for learning to program has made great strides in the current century. Exciting educational technologies are now available and active learning pedagogies are increasingly used. Interest is strong, but the longstanding problem remains: learning to program as an analytical endeavor is quite frustrating for many. The purpose of this study is to discover ways to mitigate this frustration. It researches ways to help students comprehend code by guiding them to take it apart (through reading, tracing, completing, and debugging) as they learn to write code on their own. This study contributes to the understanding of learning from errors. It also builds upon and further develops the emergent pedagogy of de-constructionism. The de-constructionist approach involves taking things apart, practice, and learning from errors. This study applies a de-constructionist approach in an experiment with ~80 undergraduates learning Python in an introductory programming class. During weekly lab periods, students engaged with web-based interactive practice problems that emphasize reading, tracing, completing, and in some cases, debugging code. Students also wrote code for lab and homework assignments. Approximately half of the students were given some that involved learning from bugs that were intentionally placed in the provided code, while the others were not. Learning gains were assessed using pre/post tests and exams. Surveys were used to measure attitudes. Learning gains and attitudes were compared according to condition (Bugs, NoBugs), prior experience, gender, minority status, and class size. This study demonstrates that bugs can be intentionally incorporated into practice problems that students like to solve, without detrimental effects on learning or attitudes about computing. It also contributes to the literature on code comprehension. / Math & Science Education

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.

The brown marmorated stink bug (BMSB), Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is an invasive insect from Asia that has recently become a major pest of agricultural crops and a nuisance to home and business owners in the Mid-Atlantic U.S. Since 2010, H. halys has been reported in many vineyards in Virginia, but the pest significance in this crop is unknown. Sampling was conducted in four commercial vineyards across Virginia in 2012 and 2013 to study the seasonal phenology and pest status of H. halys in vineyards. Adults moved into vineyards as early as May and laid eggs usually on the undersurface of leaves, but occasionally on the berry or the rachis. Grapevines were an early season reproductive host for H. halys. A vineyard adjacent to a sub-urban area with homes and buildings in proximity had an early season peak of H. halys as compared to vineyards adjacent to woods. However, populations declined sharply in late season due to the possible movement of bugs to more preferable host plants such as soybean and corn. In contrast, H. halys was recorded throughout the grape growing period in a vineyard that was surrounded by forests. Significantly more H. halys were recorded from border than interior section of vineyards. A degree-day model suggested that there were enough degree-days to complete a generation of H. halys in Virginia vineyards. H. halys caused direct injury to the grape berries at veraison and pre-harvest berries. Injury expression in the veraison berry can be described as an appearance of a small necrotic spot at the site of the stylets insertion. The spot gradually increased in size and the berries became deformed. H. halys is an economic pest of raspberry, causing direct injury to the berries. Sampling of stink bugs in raspberry plantings in southwestern Virginia showed that the Euschistus species were the most abundant stink bugs in 2008, 2009, 2011 and 2012. However, H. halys became the most abundant in 2013. / Master of Science in Life Sciences

Fruit abscission is a natural occurrence in cotton. Fruiting retention is very important since yields are highly correlated with number of bolls produced. There are many factors contributing to the abscission of squares by cotton, including environmental conditions, heavy boll load, diseases, and insect feeding. An experiment was designed to evaluate the compensation capacity of cotton at various levels of square removal using two cotton cultivars at two planting dates over two Virginia locations; the effect of mechanical square removal on cotton yield components and quality; and to evaluate the use and effectiveness of COTMAN in tracking major phenological stages PHS, FF, and Cutout of cotton at various rates of square removal. In 1998, DPL 51 was planted on May first at the Tidewater Agricultural Research and Extension Center in Suffolk, Virginia. This was an ideal location, planting date, and variety, so in 1999, the experiment was expanded to ascertain whether cotton would have the same compensation capacity in less ideal conditions. In 1999, two varieties were planted, DPL 51 (early maturing) and DPL 5111 (late maturing), on two planting dates (two weeks apart), and in a location outside the traditional cotton growing region, the Southern Piedmont AREC in Blackstone, Virginia. Five levels of manual desquaring treatments (0%, 12-15%, 20-25%, and 30-40% of first position squares, and 20% of small bolls [Suffolk, 1999 only]) were used in both years. The physiological progress of the crop was monitored using the COTMAN cotton monitoring system and compared to the Target Development Curve (TDC). Over both years, there were no significant differences in boll numbers or yield among any of the square removal treatments. Comparison of fruiting curves with the TDC showed that in both 1998 and 1999, the influence of square removal in excess of 30-40% resulted in a lower apogee and premature cut-out. Also, though not statistically significant, yield was greatly reduced at the 30-40% square removal rate, often by as much as 448 kg/ha. In many cases, a lower level of square removal (varying between the 12-15% and the 20-25% rates) seemed to stimulate the growth and development of the crop. It may also contribute to a higher level of square retention. The results of this study suggest that cotton plants will compensate for up to 30% of first position square loss, with no reduction in yields. / Master of Science

Computer security attacks take place due to the presence of vulnerabilities and bugs in software applications. Bugs and vulnerabilities are the result of weak software architecture and lack of standard software development practices. Despite the fact that software companies are investing millions of dollars in the research and development of software designs security risks are still at large. In some cases software applications are found to carry vulnerabilities for many years before being identified. A recent such example is the popular Heart Bleed Bug in the Open SSL/TSL. In today’s world, where new software application are continuously being developed for a varied community of users; it’s highly unlikely to have software applications running without flaws. Attackers on computer system securities exploit these vulnerabilities and bugs and cause threat to privacy without leaving any trace. The most critical vulnerabilities are those which are related to the integrity of the software applications. Because integrity is directly linked to the credibility of software application and data it contains. Here I am giving solution of maintaining web applications integrity running on RADIUM by using daikon. Daikon generates invariants, these invariants are used to maintain the integrity of the web application and also check the correct behavior of web application at run time on RADIUM architecture in case of any attack or malware. I used data invariants and program flow invariants in my solution to maintain the integrity of web-application against such attack or malware. I check the behavior of my proposed invariants at run-time using Lib-VMI/Volatility memory introspection tool. This is a novel approach and proof of concept toward maintaining web application integrity on RADIUM.

Na região Centro-Oeste do Brasil, o aparecimento de percevejos migrantes da cultura da soja como Nezara viridula (Linnaeus, 1758) e Piezodorus guildinii (Westood,1873), após o processo de colheita , em lavouras de algodão, tem aumentado o interesse dos produtores em relação ao seu controle. Este trabalho teve o objetivo de verificar os tipos de danos que podem ser causados pelos percevejos N. viridula e P. guildinii nas maçãs e nas fibras do algodoeiro em três fases de desenvolvimento: até 10 dias após a florada, até 20 dias após a florada e até 30 dias após a florada. Para tanto, foram realizadas coletas na região Piracicaba, SP, além da criação em laboratório das duas espécies de pentatomídeos citadas. Os resultados obtidos evidenciaram as injúrias causadas às maçãs (externas, internas e também às fibras) por meio das sucessivas picadas dos percevejos, e permitem concluir que tanto N. viridula como P. guildinii causam queda significativa de maçãs até 10 dias após a florada e que independente da densidade de infestação, provocam danos nas características de produção e tecnológicas da fibra e do fio do algodoeiro, tendo como conseqüência não só a perda de produtividade como também da qualidade da fibra destinada à indústria. / The occurrence of migrant bugs from soybean e.g. Nezara viridula (Linnaeus, 1758) and Piezodorus guildinii (Westood, 1873), in the Centro-Oeste region of Brazil, soon after harvest in cotton farms has increased the farmers interest about tatics to control these pests. This work was carried out to verify the damage that N. viridula and P. guildinii cause in bolls and fiber at three developmental stages: until 10, 20 and 30 days after flowering. So, samples were taken at Piracicaba, State of São Paulo, Brazil, and a laboratory rearing of these two pentatomid species was set up. The results showed the damages to the bolls (external, internal and fibers) by sucessive sting bites and lead to the conclusion that N. viridula and P. guildinii cause significantly boll drop until 10 days after flowering and without relation with infestation density they damage the technological and production characteristics of cotton fiber and strings, therefore reducing yield and also the fiber industrial quality.

Na região Centro-Oeste do Brasil, o aparecimento de percevejos migrantes da cultura da soja como Nezara viridula (Linnaeus, 1758) e Piezodorus guildinii (Westood,1873), após o processo de colheita , em lavouras de algodão, tem aumentado o interesse dos produtores em relação ao seu controle. Este trabalho teve o objetivo de verificar os tipos de danos que podem ser causados pelos percevejos N. viridula e P. guildinii nas maçãs e nas fibras do algodoeiro em três fases de desenvolvimento: até 10 dias após a florada, até 20 dias após a florada e até 30 dias após a florada. Para tanto, foram realizadas coletas na região Piracicaba, SP, além da criação em laboratório das duas espécies de pentatomídeos citadas. Os resultados obtidos evidenciaram as injúrias causadas às maçãs (externas, internas e também às fibras) por meio das sucessivas picadas dos percevejos, e permitem concluir que tanto N. viridula como P. guildinii causam queda significativa de maçãs até 10 dias após a florada e que independente da densidade de infestação, provocam danos nas características de produção e tecnológicas da fibra e do fio do algodoeiro, tendo como conseqüência não só a perda de produtividade como também da qualidade da fibra destinada à indústria. / The occurrence of migrant bugs from soybean e.g. Nezara viridula (Linnaeus, 1758) and Piezodorus guildinii (Westood, 1873), in the Centro-Oeste region of Brazil, soon after harvest in cotton farms has increased the farmers interest about tatics to control these pests. This work was carried out to verify the damage that N. viridula and P. guildinii cause in bolls and fiber at three developmental stages: until 10, 20 and 30 days after flowering. So, samples were taken at Piracicaba, State of São Paulo, Brazil, and a laboratory rearing of these two pentatomid species was set up. The results showed the damages to the bolls (external, internal and fibers) by sucessive sting bites and lead to the conclusion that N. viridula and P. guildinii cause significantly boll drop until 10 days after flowering and without relation with infestation density they damage the technological and production characteristics of cotton fiber and strings, therefore reducing yield and also the fiber industrial quality.

Two intermediate wheatgrass seedings with different levels of grass bug infestation were evaluated for herbage production, seedhead production, percent dry matter, crude protein, and cell contents. Study sites were located at different elevations on mountain summer ranges in northern (Site I) and central (Site II) Utah. Study plots at Site I and Site II were infested with 113 and 210 bugs per sweep, respectively. Herbage production appeared to be reduced in early spring on the site with the higher infestation; however, no effect on season-long herbage production could be detected on either site. Seedhead production on infested plots was reduced 45 percent at Site I and 56 percent at Site II. No important effect on dry matter content of infested plants was detected even though the leaves appeared to be dry and in a condition of moisture stress. Crude protein of infested plants was significantly higher (one to two percent) than control plants on the site with the higher infestation. The percentage of cell contents of plants on the more highly infested plot was eight percent less than the percentage of cell contents of control plants in the early spring. This reduction coincided with the period of peak damage. Later in the season this difference diminished as plant growth continued after the bug population completed its life cycle.