University of Lethbridge Theses
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- ItemA time series analysis of trending dengue cases in Sri Lanka.(Lethbridge, Alta. : University of Lethbridge, Faculty of Health Sciences, 2025) Kurukulasuriya Perera, Ruvani; Oosterbroek, Tracy; Patel, NimeshThe study aimed to predict dengue case numbers in Sri Lanka from January 2024 to December 2025. The prediction will assist the National Dengue Control Unit of Sri Lanka in assessing the potential dengue case numbers before a seasonal dengue crisis. This allows the Ministry of Health of Sri Lanka to plan effective healthcare mobilization and manage its resources during dengue seasons. Secondary data on all island dengue cases was obtained from the National Dengue Control Unit's national surveillance system from 2015 to 2023. A seasonal ARIMA(0,1,1)(0,0,2)[12] model was generated in R software by the forecast package’s time series function based on the Box-Jenkins method. The ARIMA model was validated as a good fit for prediction with the Ljung-Box (p-value >0.05), Shapiro-Wilk (p-value >0.05), and ADF (p-value <0.05) tests. The prediction’s MAPE was estimated as accurate for forecasting (4.46). The seasonal ARIMA model demonstrated the ability to make a short-term prediction in univariate analyses.
- ItemPredictors of detoxification services use in Alberta: a provincial socio-demographic and utilization analysis(Lethbridge, Alta. : University of Lethbridge, Faculty of Health Sciences, 2025) Mekonnen, Abreham M.; University of Lethbridge. Faculty of Health Sciences; Lee, BonnieDetoxification is the first step in the substance use and addictive behaviours recovery process, serving as the transition between dependency and reduced use or abstinence. Completing detoxification is an important milestone in initiating recovery and remission of withdrawal symptoms, as well as facilitating follow-up treatment. However, high non-completion rates, low transition to residential treatment, and frequent use of detoxification services pose significant challenges to substance use disorder and behavioural addiction treatment and detox programs. This is the first study of the predictors in detoxification programs in Alberta, marking a significant step in understanding the predictors of completion and non-completion rates of detoxification, transfer to residential treatment, and repeated use of detox services based on data from five residential withdrawal management services in Alberta, Canada. The thesis consists of three manuscripts: (1) The first manuscript identifies the factors that predict detoxification service use, estimates program completion and non-completion rates, and the proportion of clients who cycle between completion and non-completion; (2) The second manuscript estimates clients' transition rates from detoxification to residential treatment services and identifies predictors of such transitions; (3) The third manuscript estimates the prevalence of repeated use of residential withdrawal management services in Alberta, Canada and identifies predictors of frequent use.
- ItemEntomopathogenic fungi: an alternative for the biological control of aphids (Phorodon cannabis) in cannabis (Cannabis sativa) plants(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2024) Lopez Restrepo, Daniel A>; University of Lethbridge. Faculty of Arts and Science; Kovalchuk, IgorThe rapid expansion of the cannabis industry in Canada post-legalization has heightened the prevalence of pests, particularly the cannabis aphid Phorodon cannabis,which poses significant threats to crop health. This study investigates the immediate effects of P. cannabis on Cannabis sativa plants and explores biological control strategies utilizing entomopathogenic fungi. The research aims to test the antagonistic activity of various fungal isolates against aphids, analyze the immune responses of cannabis plants to infection, assess the impact on metabolite production and yield, and develop effective application strategies for these biocontrol agents. Fungal isolates of Beauveria and Metarhizium were isolated and characterized. Infection tests on aphids demonstrated the potential of these fungi to control aphid populations without the environmental drawbacks associated with chemical insecticides. Bioassays revealed that both fungi achieved 100% aphid mortality at high conidial concentrations (1×10⁷ conidia/mL), with Beauveria bassiana demonstrating faster efficacy. In greenhouse trials, Beauveria bassiana maintained aphid populations below 20 aphids throughout the experiment across all varieties and maintaining cannabis growth parameters comparable to the chemical insecticide. Untreated aphid infections substantially reduced plant height and biomass across three cannabis varieties tested, reaching heights of 40-48 cm and under 4 g of dry biomass. Cannabinoid and terpene analyses revealed that Beauveria bassiana-treated plants exhibited higher concentrations of key metabolites, including THCa, CBDa, and total terpenes, compared to chemically treated plants. The findings highlight Beauveria bassiana as an eco-friendly alternative for pest management that not only effectively controls aphids but also supports the biochemical quality of cannabis plants. Findings suggest that entomopathogenic microorganisms can significantly mitigate the impact of P. cannabis on cannabis seedlings, offering a sustainable alternative to chemical controls. This research contributes to the understanding aphid interactions with cannabis plants and promotes eco-friendly pest management practices within the burgeoning cannabis industry.
- ItemApplication of antimicrobial peptides to control leaf rust (Puccinia triticina) infection in bread wheat (Triticum aestivum L.)(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2024) Panthi, Urbashi; University of Lethbridge. Faculty of Arts and Science; Kovalchuk, Igor; Bilichak, AndriyScreening and developing novel antifungal agents with minimal environmental impact are needed to maintain and increase crop production constantly threatened by various pathogens. Small peptides with antimicrobial and antifungal activities have been known to play an important role in plant defense both at the pathogen level by suppressing its growth and proliferation as well as at the host’s level through activation or priming of the plant’s immune system for faster, more robust response against fungi. Rust fungi (Pucciniales) are plant pathogens that can infect key crops, threaten global food security and are capable of overcoming the resistance genes introduced in elite wheat cultivars. We performed an in vitro screening of 19 peptides predominantly of plant origin with antifungal or antimicrobial activity for their ability to inhibit leaf rust (Puccinia triticina, CCDS isolate) urediniospores germination. Nine peptides demonstrated significant fungicidal properties compared to the control. Foliar application of the top three candidates, β-purothionin, Purothionin-α2 and Defensin-2, decreased the severity of the leaf rust infection in wheat (Triticum aestivum L.) seedlings. Additionally, increased pathogen resistance was paralleled by elevated expression of the defense-related genes.
- ItemMultigenerational UV stress effects in Arabidopsis thaliana offspring(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2024) Lopez Virgen, Andres Guadalupe; University of Lethbridge. Faculty of Arts and Science; Kovalchuk, IgorContinuous exposure to environmental stress contributes to species diversity and drives microevolutionary processes. However, whether epigenetic alterations, such as differential DNA methylation, are prerequisites for speciation events remains unclear. We hypothesized that prolonged stress exposure would increase epigenetic diversity more than genetic diversity. In this study, we analysed the effects of 25 consecutive generations of UV-C stress on the genome and epigenome of Arabidopsis thaliana. Our results showed that multigenerational UV-C exposure led to significant genetic and epigenetic changes in the progeny. Genomic analysis of the UV-stressed progeny (F25UV) revealed a higher frequency of genetic variations compared to controls (F25C, F2C), with deletions being more prevalent than insertions, probably due to the mechanisms of DNA damage and repair processes triggered by UV radiation. F25UV also exhibited a significantly higher proportion of nonsense mutations, with C-to-T transitions being the most common, likely due to deamination of methylated cytosines. Epigenomic analysis showed that F25UV plants had more differentially methylated cytosines (DMCs) across all contexts than the F2C group. F25UV also had more DMCs than the F25C group in the CHG and CHH contexts, with the most striking difference in the CHH context, where F25UV had over 10-fold more DMCs than the F25C group. Despite these genetic and epigenetic changes, no differences in progeny resilience under stress were observed, based on root analysis, reactive oxygen species levels, and overall growth at both the seedling and mature stages. Our findings suggest that UV radiation stress can induce genetic and epigenetic changes that are capable of being inherited in transgenerational manner. Although these changes did not result in more resilient plants, their non-random nature suggests an evolutionary and adaptive direction.