Software bugs can cost millions and affect people's daily lives. However, many bug detection tools are not always practical in reality, which hinders their wide adoption. There are three main concerns regarding existing bug detectors: 1) run-time overhead in dynamic bug detectors, 2) space overhead in dynamic bug detectors, and 3) scalability and precision issues in static bug detectors. With those in mind, we propose to: 1) leverage commodity hardware to reduce run-time overhead, 2) reuse metadata maintained by one bug detector to detect other types of bugs, reducing space overhead, and 3) apply programming idioms to static analyses, improving scalability and precision. We demonstrate the effectiveness of three approaches using data race bugs, memory safety bugs, and permission check bugs, respectively. First, we leverage the commodity hardware transactional memory (HTM) selectively to use the dynamic data race detector only if necessary, thereby reducing the overhead from 11.68x to 4.65x. We then present a production-ready data race detector, which only incurs a 2.6% run-time overhead, by using performance monitoring units (PMUs) for online memory access sampling and offline unsampled memory access reconstruction. Second, for memory safety bugs, which are more common than data races, we provide practical temporal memory safety on top of the spatial memory safety of the Intel MPX in a memory-efficient manner without additional hardware support. We achieve this by reusing the existing metadata and checks already available in the Intel MPX-instrumented applications, thereby offering full memory safety at only 36% memory overhead. Finally, we design a scalable and precise function pointer analysis tool leveraging indirect call usage patterns in the Linux kernel. We applied the tool to the detection of permission check bugs; the detector found 14 previously unknown bugs within a limited time budget. / Doctor of Philosophy / Software bugs have caused many real-world problems, e.g., the 2003 Northeast blackout and the Facebook stock price mismatch. Finding bugs is critical to solving those problems. Unfortunately, many existing bug detectors suffer from high run-time and space overheads as well as scalability and precision issues. In this dissertation, we address the limitations of bug detectors by leveraging commodity hardware and common programming patterns. Particularly, we focus on improving the run-time overhead of dynamic data race detectors, the space overhead of a memory safety bug detector, and the scalability and precision of the Linux kernel permission check bug detector. We first present a data race detector built upon commodity hardware transactional memory that can achieve 7x overhead reduction compared to the state-of-the-art solution (Google's TSAN). We then present a very lightweight sampling-based data race detector which re-purposes performance monitoring hardware features for lightweight sampling and uses a novel offline analysis for better race detection capability. Our result highlights very low overhead (2.6%) with 27.5% detection probability with a sampling period of 10,000. Next, we present a space-efficient temporal memory safety bug detector for a hardware spatial memory safety bug detector, without additional hardware support. According to experimental results, our full memory safety solution incurs only a 36% memory overhead with a 60% run-time overhead. Finally, we present a permission check bug detector for the Linux kernel. This bug detector leverages indirect call usage patterns in the Linux kernel for scalable and precise analysis. As a result, within a limited time budget (scalable), the detector discovered 14 previously unknown bugs (precise).

The brown marmorated stink bug, Halyomorpha halys (Stål), is an invasive species that has spread throughout the United States and become a serious agricultural pest. Studies were conducted in Virginia on the survival of H. halys nymphs on different vegetable hosts and on the oviposition preference of H. halys on common tree hosts in southwestern Virginia. To determine the effects of vegetable host on H. halys survival, nymphs were placed on one of five vegetable host plants and their corresponding vegetable fruit. Survival was highest on sweet corn, followed by bell pepper and snap bean. Eggplant and tomato were poor compared to other vegetable hosts tested, potentially due to secondary compounds released by the plant to reduce feeding. Of six common host trees sampled, H. halys laid the most egg masses on catalpa, Catalpa bignonioides, while aggregation lure had no effect on the number of eggs laid. Across host trees, egg masses were more commonly found in trees with fruiting structures present. An additional study was conducted on a red-sternum phenotype of H. halys. Mortality was recorded by sternum phenotype for each sex. There was no difference in survival between groups at two time points. Biochemical tests were used to determine if the red-sternum was associated with the potentially pathogenic red bacteria Serratia marcescens. Only one stink bug's gut contents had a confirmed infection of S. marcescens. Results from these studies offer insight into H. halys development on vegetable hosts and oviposition preferences on different host trees. / MSLFS / The brown marmorated stink bug (BMSB), is an invasive insect that has spread throughout the United States and become a serious pest. Current research is focused on reducing their populations without increasing insecticide use. Studies were conducted to determine if vegetable host type influenced survival and development of this insect. Nymphs were placed on one of five vegetable plants with the corresponding vegetable fruit. Overall, survival was highest on sweet corn, followed by bell pepper and snap bean. Eggplant and tomato were poor hosts, potentially due to chemicals released by the plant to reduce insect feeding. Six common host trees of BMSB were sampled to determine where females lay the most egg masses and the effect of using an attraction lure. Catalpa trees had the most egg masses throughout the season. Use of a lure had no effect on the number of eggs laid on any tree. A red colored abdomen was observed in some adult insects throughout these studies. To determine if this was associated with higher mortality, male and female insects were observed for two weeks. There were no mortality differences at either seven or 14 days between any of the groups. Tests were used to determine if the red abdomen was caused by a red-colored bacterium. Of the insects sampled, there was only one stink bug with a confirmed infection. Results from these studies provides information that increases knowledge of this pest’s ecology in Virginia.

Field experiments (2007-2009) and laboratory bioassays (2009) tested the efficacy of insecticides with short pre-harvest intervals, caneberry cultivar susceptibility, and geranium toxicity for reducing Japanese beetle (JB) activity on primocane-bearing caneberries. Deltamethrin, chlorantraniliprole, bifenthrin, lime-alum, and thyme oil reduced JB activity in the field. Deltamethrin, chlorantraniliprole, acetamiprid, an azadirachtin and pyrethrin mixture, an azadirachtin and neem oil extract mixture, and an extract of Chenopodium ambrosioides reduced JB activity during the bioassays. "Prelude" had significantly more JB than "Anne", "Caroline", "Heritage", "Dinkum", or "Himbo Top" and "Prime-Jan" had significantly more JB than "Prime-Jim". Compared to certain cultivars, "Heritage", "Caroline", "Himbo Top", and "Prime-Jan" had higher percentages of injured fruit and "Autumn Bliss", "Heritage", and "Caroline" produced greater marketable and overall yields. "Prime-Jan" produced more overall yield than "Prime-Jim"; marketable yields from both blackberry cultivars were similar. Defoliation was significantly less for "Dinkum", "Caroline", "Heritage", and "Anne" than for "Prelude" in 2008 and significantly less for "Caroline" and "Anne" than "Prelude" or "Fall Gold" in 2009. In field tests, previous consumption of geraniums lessened raspberry defoliation by JB. Bioassays indicated that JB activity was only reduced if JB were continually exposed to geranium. Therefore, the efficacy of geranium as a trap crop for JB may be limited. The stink bug species within the caneberries were identified (2008-2009) and Euschistus servus (Say) made up 48.1 % of the overall species composition. Stink bug injury to ripening raspberries was identified as small holes between drupelets; stink bug excretions also ruined fruit. / Master of Science in Life Sciences

This study investigates the potential of Large Language Models (LLMs) to automate and enhance software maintenance tasks, focusing on bug detection and code refactoring. Traditional software maintenance, which includes debugging and code optimization, is time-consuming and prone to human error. With advancements in artificial intelligence, LLMs like ChatGPT and Copilot offer promising capabilities for automating these tasks. Through a series of quasi-experiments, we evaluate the effectiveness of ChatGPT 3.5, ChatGPT 4 (Grimoire GPT), and GitHub Copilot. Each model was tested on various code snippets to measure their ability to identify and correct bugs and refactor code while maintaining its original functionality. The results indicatethat ChatGPT 4 (Grimoire GPT) outperforms the other models, demonstrating superior accuracy and effectiveness, with success percentages of 87.5% and 75% in bug detection and code refactoring respectively. This research highlights the potential of advanced LLMs to significantly reduce the time and cost associated with software maintenance, though human oversight is still necessary to ensure code integrity. The findings contribute to the understanding of LLM capabilities in real-world software engineering tasks and pave the way for more intelligent and efficient software maintenance practices.

This bachelor’s thesis investigates the efficacy of cutting-edge Large Language Models (LLMs) — GPT-4, Code Llama Instruct (7B parameters), and Gemini 1.0 — in detecting and correcting bugs in Java and Python code. Through a controlled experiment using standardized prompts and the QuixBugs dataset, each model's performance was analyzed and compared. The study highlights significant differences in the ability of these LLMs to correctly identify and fix programming bugs, showcasing a comparative advantage in handling Python over Java. Results suggest that while all these models are capable of identifying bugs, their effectiveness varies significantly between models. The insights gained from this research aim to aid software developers and AI researchers in selecting appropriate LLMs for integration into development workflows, enhancing the efficiency of bug management processes.

Brown marmorated stink bug (BMSB), Halyomorpha halys (Stål), has become an important pest of soybean in the Mid-Atlantic US. To assess the influence of tree borders on BMSB infestations in soybean, twelve fields were sampled weekly using five 3-min visual counts of BMSB on tree of heaven (TOH) (Ailanthus altissima) and other host trees along a wooded border, on the adjacent soybean edge, 15 m and 30 m into the soybean field. At all locations, BMSB densities increased on TOH wooded borders in July, then, gradually moved into adjacent soybean borders later in the summer. BMSB did not move far from the field edge, with approximately half as many bugs being present at 15 m into the field and very few being detected 30 m into the field. These results validate the use of border sprays for BMSB control in soybean. Additional studies conducted in 2013 and 2014 compared a visual plant inspection method with a standard sweep net strategy for sampling BMSB. Overall, the two methods were highly correlated with a correlation coefficient of R=0.83. Visual inspection appears to be an effective method for assessing BMSB populations in soybean. One of the major factors affecting the distribution and establishment of invasive species is climate. The CLIMEX modeling software uses climatic and biological factors of species to predict the geographic risk for pest outbreaks. A climate simulation model was run with CLIMEX to determine the potential distribution of BMSB in Virginia based on temperature. To develop a more accurate model, factors like resource availability and source population would need to be considered. / Master of Science in Life Sciences / Brown marmorated stink bug (BMSB) is a major pest of many crops, including soybean. Before moving into soybean the bug has been observed on other preferred hosts (primarily tree of heaven) in neighboring forest edges. To determine the relationship of these hosts to BMSB and its movement into soybean fields we sampled these forest edges, the neighboring field edge, 15 m into the field, and 30 m into the field. Results showed that BMSB populations were high on the forest edges early in the season and increased rapidly on neighboring field edge when soybeans begin developing pods and seeds. Bugs rarely moved past the 15 m sample zone. These results validate the use of border sprays for BMSB control in soybean. Sampling for BMSB with a sweep net has proven to be a challenge as the insect has a strong “startle response” where it will drop from the plant after slight disturbance. To assess the relationship between a standard sweep net sampling strategy and a new 2-min visual inspection method we sampled soybean fields in Virginia, Maryland and Delaware in 2013 and 2014. Data suggested that the 2-min visual inspection method can be used as an alternative to sweep net sampling. Climate plays a critical role in the geographic distribution of species. We ran a climate simulation model with CLIMEX (modeling software) to determine the potential distribution of BMSB in Virginia based on temperature. To develop a more accurate model, additional factors like resource availability and distance from source population would need to be considered.

Detecting concurrency bugs can be challenging due to the intricacies associated with their manifestation. These intricacies correspond to identifying the methods that need to be invoked concurrently, the inputs passed to these methods and the interleaving of the threads that cause the erroneous behavior. Neither fuzzing-based testing techniques nor over-approximate static analyses are well positioned to detect subtle concurrency defects while retaining high accuracy alongside satisfactory coverage. While dynamic analysis techniques have been proposed to overcome some of the challenges in detecting concurrency bugs, we observe that their success is critically dependent on the availability of effective multithreaded clients. Without a priori knowledge of the defects, manually constructing defect-revealing multithreaded clients is non-trivial. In this thesis, we design an approach to address the problem of automatically generate clients for detecting concurrency bugs in multithreaded libraries. The key insight underlying our design is that a subset of the properties observed when the defects manifest in a concur-rent execution can also be observed in a sequential execution. The input to our approach is a library implementation and a sequential testsuite, and the output is a set of multithreaded clients that can be used to reveal defects in the input library implementation. Dynamic defect detectors can execute the clients and analyze the resulting traces to report various kinds of defects including deadlocks, data races and atomicity violations. Furthermore, the clients can also be used by testing frameworks to report assertion violations. We propose two variants of our design – (a) path-agnostic client generation, and (b) path-aware client generation. The path-agnostic client generation process helps in detection of potential bugs present in the paths executed by the input sequential testsuite. It does not attempt to explore newer paths by satisfying path conditions either by modifying the input or by scheduling the threads appropriately. The generated clients are used to expose deadlocks, data races and atomicity violations. Our analysis analyzes the execution traces obtained from executing the input sequential clients and produces a concurrent client program that drives shared objects via library methods calls to states conducive for triggering deadlocks, data races or atomicity violations. For path-aware client generation, our approach explores newer paths that are not covered by the input sequential testsuite to generate clients. For this purpose, we design a directed, iterative and scalable engine that combines the strengths of static and dynamic analysis to help synthesize both multithreaded clients and schedules that violate complex correctness conditions expressed by the developer. Apart from the library implementation and the sequential testsuite as input, this engine also accepts a specification of correctness as input. Then, it iteratively refines each client from the input sequential testsuite to generate an ex-ecution that can break the input specification. Each step of the iterative process includes statically identifying sub-goals towards the goal of failing the specification, generating a plan toward meeting these goals, and merging of the paths traversed dynamically with the plan computed statically via constraint solving to generate a new client. The engine reports full reproduction scenarios, guaranteed to be true, for the bugs it finds. We have implemented prototypes that incorporate the aforementioned ideas and validated them by applying them on 29 well-tested concurrent classes from popular Java libraries, including the latest version of JDK. We are able to automatically generate clients that helped expose more than 300 concurrency bugs including deadlocks, data races, atomicity violations and assertion violations. We reported many previously unknown bugs to the developers of these libraries resulting in either fixes to the code or changes to the documentation pertaining to the thread-safe behavior of the relevant classes. On average, the time taken to analyze a class and generate clients for it is less than two minutes. We believe that the demonstrated effectiveness of our prototypes in helping expose deep bugs in popular Java libraries makes the design, proposed in this thesis, a vital cog in the future development and deployment of dynamic concurrency bug detectors.

In this day and age, the Internet provides the biggest linkage of information, personal data and information, social contact facilities, entertainment and electronic repository for all things including software downloads and tools, online books and technical descriptions, music and movies - both legal and illegal [Clarke, 1994]. With the increasing bandwidth in the last few years worldwide, it is possible to access the so-called "Triple-Play-Solutions" - Voice over lP, High-Speed-Internet and Video on Demand. More than 100 million subscribers have signed on across Asia, Europe, and the Americas in 2007, and growth is likely to continue steadily in all three. As broadband moves into the mainstream, it is reshaping the telecommunications, cable and Internet access industrie [Beardsley, Scott and Doman, Andrew, and EdinMC Kinsey, Par, 2003]. Cisco [Cisco, 2012], one of the biggest network companies, will expect more than 966 exabytes (nearly 1 zettabyte) per year or 80.5 exabytes per month in 2015 and the "Global IP traffic has increased eightfold over the past 5 years, and will increase fourfold over the next 5 years. Overall, IP traffic will grow at a compound annual growth rate (CAGR) of 32 percent from 2010 to 2015" . More and more types of sensible data flow between different recipients. News from around the world are transferred within seconds from the one end to the other end of the world, and affect the financial market, stock exchange [Reuters, 2012] and also bring down whole governments. For instance, worldwide humoil might ensue if a hacker broke into the web-server of an international newspaper or news channel like N-TV in Germany or BBC in England and displayed messages of a political revolution in Dubai or the death of the CEO from Microsoft or IBM.

O objetivo geral desta pesquisa foi avaliar a fisiologia reprodutiva de Nezara viridula (L, 1758) (Hemiptera: Pentatomidae) e os fatores que influenciam o seu processo reprodutivo, como a frequência de cópula, a associação a bactérias simbiontes e a utilização de recursos nutricionais. Análises da composição bioquímica da hemolinfa durante o processo de maturação reprodutiva das fêmeas indicaram que a concentração de proteína total aumentou gradativamente durante o período de maturação dos ovários, sendo que as proteínas ligadas ao desenvolvimento de oócitos, as vitelogeninas, tornaram-se disponíveis na hemolinfa a partir do décimo dia de idade, período que corresponde à fase de pré-cópula. O desenvolvimento e a maturação de oócitos ocorreram de forma gradativa em função do aumento das proteínas disponíveis na hemolinfa das fêmeas. A cópula não foi essencial para o desenvolvimento dos ovários, indicando a inexistência de estímulos fisiológicos associados à distensão da espermateca ou à transferência de moléculas associadas ao fluído seminal de machos. Entretanto, a freqüência com que as fêmeas copularam afetou a capacidade reprodutiva de N. viridula, sendo as fêmeas que copularam por duas vezes as mais fecundas em relação àquelas que copularam múltiplas vezes. Este fato também indica a existência de custos fisiológicos associados à cópula para fêmeas, sendo ainda evidente a inexistência de relação positiva entre os possíveis benefícios da transferência de nutrientes pelo macho a fêmea e o número de cópulas realizadas. Análises relacionadas à utilização de recursos nutricionais indicaram que o desenvolvimento do ovário de N. viridula é basicamente dependente de nutrientes adquiridos na fase adulta, sendo que a fecundidade de fêmeas oriundas de ninfas criadas em dieta de valor nutricional reduzido, foi recuperada quando adultos foram alimentados em dieta de valor nutricional adequado. Foi verificado ainda uma rica diversidade de bactérias associadas ao aparelho reprodutor masculino de N. viridula, com predominância da Enterobacteriaceae Klebsiella sp, a qual foi anteriormente relatada associada ao intestino de N. viridula. Fêmeas copuladas com machos infectados ou não por estas bactérias não apresentaram qualquer efeito em sua capacidade reprodutiva. / The objective of this research was to evaluate the reproductive physiology of Nezara viridula (L., 1758) (Hemiptera: Pentatomidae) and the factors that influence their reproductive process, such as mating frequency, association to symbiotic bacteria and the use of food resources. Analysis on biochemical composition of haemolymph during the reproductive maturation process of females indicated that the total protein concentration increased gradually during ovary maturation the proteins related to oocyte development, the vitellogenins, became available in the hemolymph from the tenth day of age, corresponding to the pre-copulation. Oocyte development and maturation occurred gradually due to the increase of protein available in hemolymph of females. Copulation was not requered for ovary development, indicating the absence of physiological stimuli associated with spermatheca distension or molecules with on male seminal fluids. However, the frequency females mated affected the reproductive capacity of N. viridula, to females that mated twice were the most fecund if compared to those mated multiple times. This also indicates that there are physiological cost associated with mating frequency, and that there is no positive relationship between the potential benefits from the transfer of nutrients from male to female and the number of mates performed. Analysis related to the use of food resources indicated that ovary development of N. viridula is basically dependent on nutrients acquired during adulthood. Fecundity of females obtained from nymphs reared on a low nutritional value diet was recovered when adults were fed on an adequate-nutritional diet. We further verified a rich diversity of bacteria associated with the male reproductive system of N. viridula, with predominance of the Enterobacteriaceae Klebsiella sp, which was previously reported associated with the gut of N. viridula. Females copulated by males infected or not by these bacteria did not show any effect on their reproductive capacity.

We investigated the population dynamics of the giant water bug, Belostoma angustum, across highland sin the Pampas of southern Brazil. We evaluated genetic and morphological variation, as well as the demographic history of 18 populations. The overall range includes two highlands and a lowland between them, overall exceeding 400 kilometers along the longitudinal gradient. Genetic variation was assessed from mitochondrial and nuclear markers. The morphological variation was estimated using linear measurements of males and females, and from male genitalic structures using geometric morphometrics approaches. We evaluated the effect of the highland topography, drainage basins, and past climate changes on the population structure. Our results from multiple analyses of molecular variance (AMOVA) show that Belostoma angustum structures as a large panmictic population across the Pampas highlands range. Every most frequent haplotype is shared by individuals from all three sampled areas in genetic markers from the mitochondrial as well as from the nuclear locus. Differentiation among haplotypes was very low, not greater than two mutation steps. The congruent phylogeographical pattern in both markers indicate absent sex-biased migration rates. Furthermore, there was no evidence for isolation-by-distance (IBD) based on the mitochondrial data. The pairwise st was low and not significant, indicating historical gene flow among populations of the giant water bug studied throughout Pampas highlands. Our findings about the demographic history of panmictic population throughout Pampas highlands suggest it experienced recent and rapid population expansion that started in the Late Pleistocene period, approximately 15,000 years old after Last Glacial Maximum. The recent marked demographic expansion could explain the high percentage of the exclusive haplotypes and the very low mutational steps among them. We did not find morphological variation among populations of B. angustum throughout Pampas highlands reflected, except for some body dimensions. The overall phenotypic uniformity among populations becomes more likely if gene flow is hypothesized to homogenize populations. However, in the body size, specially, there was variation among populations potentially explained by phenotypic plasticity, thereby generating phenotypic diversity without genetic differentiation. Our genetic findings suggest indirectly that individuals of B. angustum are strong fliers able to overcome the topographical barriers of the sampled area. / Neste trabalho, investigamos a dinâmica populacional de uma barata d\' água, Belostoma angustum, ao longo do Pampa no sul do Brasil. Foram avaliadas a variação genética, morfológica e a história demográfica de 18 populações. A área total amostrada inclui duas serranias e uma planície entre elas, excedendo 400 quilômetros ao longo de um gradiente longitudinal. A variação genética foi avaliada a partir de marcadores mitocondriais e nucleares. A variação morfológica foi avaliada utilizando medidas lineares de machos e fêmeas, e de estruturas genitais masculinas usando abordagens de morfometria geométrica. Testamos o efeito da topografia das serranias, das bacias de drenagem e das mudanças climáticas passadas sobre a estrutura das populações. Os resultados de múltiplas análises de variância molecular (AMOVA) mostram que Belostoma angustum forma uma grande população panmítica ao longo das serranias do Pampa. Todos os haplótipos mais frequentes são compartilhados por indivíduos de todas as três grandes áreas amostradas em marcadores genéticos dos loci mitocondrial e nuclear. A diferenciação entre haplótipos foi muito baixa, não excedendo dois passos mutacionais. O padrão filogeográfico congruente em ambos os marcadores indica taxas de migração não enviesada para um dos sexos. Além disso, não encontramos evidência de isolamento por distância (IBD) com base nos dados mitocondriais. Os valores de st par a par foram baixos e não significativos, indicando fluxo gênico histórico entre as populações da barata d\'água estudada ao longo das serranias Pampianas. Os resultados sobre a história demográfica da população panmítica ao longo do planalto do Pampa sugerem que essa população experimentou uma expansão populacional recente e rápida que teve início no fim do período Pleistoceno (há aproximadamente 15.000 anos), após a última máxima glacial. A expansão demográfica recente e acentuada poderia explicar a alta porcentagem de haplótipos exclusivos e o número reduzido de passos mutacionais entre eles. Não encontramos variação morfológica entre as populações de B. angustum amostradas ao longo das serranias do Pampa, exceto em algumas dimensões corporais. A uniformidade fenotípica entre as populações torna-se mais provável na medida em que o fluxo de genes atue homogeneizando as populações. Entretanto, no caso do tamanho do corpo, especialmente, há variação entre populações potencialmente explicada por plasticidade fenotípica, gerando assim diferenciação fenotípica sem diferenciação genética. Nossos resultados genéticos sugerem indiretamente que os indivíduos de B. angustum possuem capacidade de voo suficiente para transpor as barreiras topográficas na área amostrada.