MSpace

MSpace is the University of Manitoba’s Institutional Repository. The purpose of MSpace is to acquire, preserve and provide access to the scholarly works of University faculty and students within an open access environment.

 

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Open Access
Impacts of a flea beetle double-stranded RNA-based insecticide on the ground beetle Pterostichus melanarius
(2025-04) Lampimaki, Silas; Belmonte, Mark (Biological Sciences); Lee, Jae-Hyeok (Biological Sciences); Whyard, Steve
Flea beetles (Phyllotreta cruciferae and P. striolata) are the most damaging insect pests of canola, one of Canada’s most economically valuable crops. Chemical insecticides are currently the primary method of flea beetle control, but concerns about their impact on non-target organisms highlight the need for safer alternatives. RNA interference (RNAi) has been recognized for its ability to selectively kill insect pests by silencing target genes through sequence-specific exogenous double-stranded RNA (dsRNA). However, sequence similarity between pest and beneficial insects continue to pose risks about potential off-target effects. In this study, two dsRNAs targeting the UBE2L3 and Snf7 gene in P. cruciferae were evaluated for off-target effects in the predatory ground beetle Pterostichus melanarius. A bioinformatic analysis was used to identify the similarity between the dsRNA sequences and their respective orthologs in P. melanarius. Beetles were then injected with the dsRNAs, and relative gene expression and mortality were measured. Following injection of the UBE2L3 dsRNA, which shares 83.4% similarity and a 29 bp matching segment with P. melanarius, target gene expression was reduced by 69.9%. Conversely, injection of the Snf7 dsRNA, which only shares 62.6% similarity, did not induce gene knockdown. Despite the knockdown of UBE2L3, no significant mortality was observed in any treatment group, including the positive control, suggesting that an insufficient dose of dsRNA was used. These findings demonstrate that sequence similarity influences the off-target effects of dsRNA, which can be predicted using a bioinformatic assessment. Continued sequencing of beneficial insects is required so that dsRNA can be designed to have minimal similarity with other species to reduce off-target effects.
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Open Access
Investigating the impact of helminths on mercury in Arctic foxes
(2025-04) Whiteside, Kayla; Detwiler, Jillian (Biological Sciences); Davoren, Gail (Biological Sciences); Roth, Jim
Mercury (Hg) pollution in the Arctic poses a growing threat to the health of local wildlife, yet many factors behind Hg bioaccumulation remain poorly understood. Primarily ingested through diet, Hg bioaccumulates in animal tissues and can impair neurological and reproductive functions. Intestinal helminths have demonstrated the ability to take up Hg while residing in their hosts and have consequently been suggested to benefit their hosts through mitigating toxin exposure. In this study, I used Arctic foxes harvested over five years from Churchill, MB to analyze fox muscle total mercury concentrations ([THg]) (ng/g), intestinal helminth [THg], and helminth biomasses to determine if (i) helminth group (taxa and size) influences helminth Hg uptake, and (ii) helminths benefit their host by decreasing host Hg uptake. Results showed that [THg] did not significantly vary with fox sex, age, or harvest year. Cestodes demonstrated higher [THg] than nematodes, though size did not influence [THg] for either taxon. Both cestodes and nematodes demonstrated [THg] increases relative to host [THg], though only the cestodes had significantly higher [THg] than their hosts, and no significant effect was seen for either cestode or nematode biomass on fox [THg]. Overall, this study provides valuable insight into host-helminth-Hg dynamics. Further research is needed to elucidate the mechanisms and significance of helminth Hg uptake to help understand their potential applications in mitigating toxin exposure in wildlife.
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Open Access
The effects of topically-applied double-stranded RNA pesticides on Myzus persicae
(2025-03) Joseph, Kelvin Tom; Wilkins, Olivia (Biological Sciences); Lee, Jae-Hyeok (Biological Sciences); Whyard, Steve
The green peach aphid (Myzus persicae) is a major agricultural pest, causing billions in crop losses and contributing to global food insecurity. Increasing incidences of insecticide resistance and off-target effects highlight the need for alternative control methods. RNA interference (RNAi), a gene-silencing mechanism triggered by exogenous double-stranded RNA (dsRNA), has emerged as a promising approach to species-specific pest control. Topically applied dsRNA offers a non-GMO alternative to traditional pesticides, selectively inducing mortality in pests by targeting essential genes. One such gene, Chitin Synthase (CHS), is crucial for the insect exoskeleton, tracheae, and gut. However, dsRNA penetration through the aphid’s hydrophobic exoskeleton remains a challenge, necessitating delivery enhancements like surfactants. This study tested two dsRNA structures—long linear dsRNA (210 bp) and short paperclip RNA (pcRNA, 25 bp)—targeting CHS, with and without the surfactant Silwet. Third-instar aphids were topically treated with a dsRNA droplet, and their survival and fecundity were monitored over eight days. Several bioassay optimizations were implemented, including stretching diet packets, treating third instars instead of adults, filter-sterilizing diets, and chilling aphids before treatment. Bioassays demonstrated that dsRNA + Silwet significantly increased aphid mortality, whereas dsRNA alone and all pcRNA treatments had no significant effects. No significant fecundity reduction or CHS gene knockdown was observed. While only a single gene target was assessed, findings suggest RNAi-based pesticides hold potential for aphid control, and Silwet improves dsRNA efficacy. Further research on optimizing dsRNA formulations could enhance their application as next-generation pesticides.
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Open Access
Comparing the boldness and exploration of co-occurring invasive marine crabs (Hemigrapsus sanguineus and Carcinus maenas)
(2024-03) DeJaegher, Emily; Detwiler, Jillian (Biological Sciences); Davoren, Gail (Biological Sciences); Ramey-Balci, Patricia
Boldness (i.e., the propensity to take risks) and exploratory behaviours can influence an animal’s ability to acquire resources, thus affecting competitive success. The Asian shore crab, Hemigrapsus sanguineus, and European green crab, Carcinus maenas, co-occur as highly invasive species in coastal areas of the United States, and more recently, in Atlantic Canada. Both crabs use structurally complex rocky intertidal habitat and consume similar macroalgal and invertebrate prey, such that they likely compete for resources. Competitive interactions between co-invaders could influence the success of either species, affecting their impacts on the ecosystem. Yet, there is a gap in research comparing behaviours, such as boldness or exploration, between co-invaders such as these crabs. Here, the boldness of H. sanguineus and C. maenas are compared by investigating their tendencies to exit preferred rocky habitat with shelter to explore an open and brightly lit area. The crabs’ exploratory tendencies are also compared, by evaluating if the species spontaneously alternate (i.e., preferentially explore regions that they have least recently explored), an indicator of efficient exploration. The two species had similar latencies when exiting the sheltered habitat, but C. maenas spent more time in the open area overall. Both crabs also tended to spontaneously alternate, but H. sanguineus had a greater tendency to do so than C. maenas, revealing for the first time the existence of significant differences in spontaneous alternation behaviour between invasive species. If the strong exploration ability of H. sanguineus can improve the species’ ability to find resources, it may have a competitive advantage over C. maenas in regions where the crabs co-occur.
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Open Access
In search of Net Positive Carbon Grain Farming in the Northern Great Plains: innovation in policy and practice
(0025-05-20) Rourke, David; Entz, Martin (Plant Science); Haque, Emdad (Natural Resources Management); Orr, Mary-Jane (Natural Resources Management); Glenn, Aaron (Natural Resources Management); Chowdhury, Atahural (University of Guelph); Davidson-Hunt, Iain
This thesis addresses the opportunities that exist for grain farms to help mitigate anthropogenic global warming. The thesis developed Rourke’s General Farm Practice Change Theory, then uses that theory to develop a Net Positive Carbon Grain Farming Framework along with a Global Warming Mitigation Credit Framework. In-depth semi-structured interviews were conducted for sixteen cases involving participants from Manitoba, Saskatchewan, Alberta, North Dakota, and South Dakota. The research is a qualitative exploratory participatory narrative case study. The data was transcribed via UM Zoom and uploaded to NVivo where it was coded and queried for emerging themes. Data was also collected to calculate estimates of emissions, CO2 sequestration, contribution margins, and production output. From this data I was able to determine a Net Positive carbon grain farming score as well as a Sustainable Farm Index rating. During the interview, each participant was asked 10 questions on each of 12 Beneficial Management Practices, BMPs. A 1 to 5 scale was used to record their response and then fed into a tool developed for the study labelled as BERT /E. The BERT/E tool considers the following variables: beliefs (B), economics (E), regulatory (R), technology (T), and the farmer’s physical and mental energy (E) to make a change. BERT/E scores are an indicator of the farmers BMP adoption score. This study yielded both theoretical advancement as well as practical outcomes. The practical outcomes included identifying two participants whose farms are currently Net Positive. This included identifying the BMPs they used to become Net Positive and how their approach differed from the overall group. I was also able to assemble 50 recommendations that would improve the ability of the twelve BMPs to assist farmers in becoming Net Positive. Ultimately, the findings of this work demonstrate that grain farms can be instrumental in tackling anthropogenic global warming.
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Open Access
Seabird personality and individual behavioural consistency in the Canadian North Atlantic
(2025-04-25) Legard, Matthew; Fraser, Kevin (Biological Sciences); Kelly, Debbie (Psychology); Daunt, Francis (UK Centre for Ecology and Hydrology); Davoren, Gail
Animal personality (i.e., consistent individual behaviour over time/across contexts) is made up of distinct trait continuums (e.g., docile-aggressive; docility) that can play an important role in shaping the behavioural responses of animals, and therefore, can influence fitness. Understanding personality in animal populations can be a useful tool to aid conservation decisions. To date, limited research on personality has been carried out in seabirds, especially species from the family Alcidae. This family, which includes the razorbill (Alca torda), is characterised by a stout body which facilitates diving but results in high energetic costs of flight. In comparison to personality, individual consistency in seabird behaviour (e.g., migratory route) is well studied, but studies rarely compare across species. If individuals within a population behave consistently (e.g., migratory site fidelity), but differences are present among individuals (i.e., behavioural diversity), this variation may expose components of populations to varying threats (e.g., offshore wind development). Therefore, understanding this behavioural variation across and within species will aid in the protection of populations with lower diversity, which are more likely to experience population declines. The aims of this thesis were to: 1. Determine the best method for quantifying the docile-aggressive trait in razorbills (Ch.1). 2. Investigate relationships between docility and razorbill behaviour during the breeding (Ch.2) and non-breeding (Ch.3) periods. 4. Explore behavioural diversity in migratory routes of seabird species that breed in Atlantic Canada (Ch.4). In Chapter 1, I found that different behavioural tests had varying suitability for identifying docility in razorbills. Of the tests, standardized observer ratings were the best test for quantifying docility in razorbills and potentially other hard to observe species. In Chapter 2, I found that razorbills exhibit consistent behaviour during the breeding period, but this consistency is context dependent (i.e., varying prey availability periods) and not related to docility. Additionally, I found no relationship between fledging success and docility. In Chapter 3, I found individual consistency in razorbill non-breeding behaviours but no relationships between any observed non-breeding behaviours and docility. Finally, in Chapter 4, I found varying levels of behavioural diversity both within and across seabird families (Alcidae, Laridae and Sulidae).
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Open Access
Conservation of genetic diversity using life history predictors of adaptive potential
(2025-04) Goertz, Alyssa; Fraser, Kevin (Biological Sciences); Detwiler, Jillian (Biological Sciences); Garroway, Colin
Biodiversity loss is reducing population sizes globally, leading to a decline in genetic diversity. This is concerning, as genetic diversity is vital for species' survival and adaptation to future environmental change. Conservation frameworks, such as the International Union for Conservation of Nature (IUCN) Red List, assess extinction risk but overlook genetic diversity and adaptive potential. This is primarily because genetic data is not available for most species. My project directly addresses the lack of consideration of genetic diversity conservation framework by examining the relationship between adaptive potential and easy-to-measure life history traits. If easy-to-measure traits reflect adaptive potential, they can be used to guide conservation where direct estimates of adaptive potential are lacking. Adaptive potential reflects the additive genetic variance (VA) underlying fitness. VA reflects genetic diversity and capacity for adaptation and is used in calculating heritability. I hypothesized that life history traits (e.g., body mass, longevity, fecundity, and age of maturity) predict adaptive potential, measured by heritability. The data for heritability were derived from studies by Mittel et al. (2015), Holstad et al. (2024), and life history trait data from Myhrvold et al. (2016). Data inclusion consisted of heritability measured for morphological, life history, behavioural, and physiological traits, for terrestrial vertebrate species and from wild populations. The relationship between heritability and life history traits was measured using generalized linear mixed models. My results revealed significant relationships between heritability and life history traits. Larger body mass and longer lifespan were associated with low heritability, while larger litter/clutch sizes and earlier ages of maturity were associated with high adaptive potential. Morphological heritability estimates exhibited stronger correlations with life history traits compared to other heritability estimates, suggesting they may be a more reliable proxy for predicting adaptive potential. These findings highlight the potential of using life history traits to infer species’ genetic diversity and adaptive potential, offering a valuable tool to improve conservation prioritization.
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Open Access
Canopy-dependent environmental factors impact on nitrogen fixation in Shepherdia canadensis in the boreal forest and tundra
(2025-03) Tydings, Jason; Renault, Sylvie (Biological Sciences); Fraser, Kevin (Biological Sciences); Markham, John
Actinorhizal shrubs, plants that symbiotically associate with nitrogen-fixing bacteria and do not depend on soil nitrogen, can increase productivity and facilitate successional changes. High-latitude environments are characterized by harsh abiotic climatic conditions that limit nitrogen availability to plants. However, actinorhizal shrubs are less prevalent at higher latitudes, even though those environments are generally nitrogen-limited. Reduced year-round temperatures, water availability, and light availability are all thought to limit nitrogen fixation due to its energetic costs, making nitrogen fixation unfavourable at higher latitudes. Shepherdia canadensis (buffalo berry) is an actinorhizal shrub that is found in higher-latitude environments across Canada. We wanted to determine, within the northern edge of the boreal forest and tundra, how much nitrogen fixation is occurring in buffalo berry, and how it varies across naturally occurring habitat and canopy-dependent environmental factors. The natural abundance stable isotope technique was used to quantify nitrogen fixation, while canopy-dependent variables were measured using hemispherical image analysis. We found that buffalo berry shrubs were getting a majority of their nitrogen content through nitrogen fixation (55.32% - 94.74%) and that on average, fixation occurred at a higher rate in the forest (74.67%) compared to the tundra (68.00%). Notably, foliar δ13C values varied with canopy openness. Specifically, shrubs in more open areas and the tundra had higher δ13C values, which were interpreted to be a result of stomatal closure in response to reduced water availability. Nitrogen fixation was found to be sensitive to water availability, decreasing with canopy openness (17.99% – 99.79%). This limitation could reduce the productivity of nitrogen-fixing plants in response to warmer climate conditions.
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Open Access
The Role of Physical Movement in Spinal Cord Repair Using an Adult Zebrafish Model
(2025-03) David, Gabrielle; Xing, Lei (Biological Sciences); Stacey, Joy (Biological Sciences); Lindsey, Ben; Jeffries, Ken
Spinal cord injury (SCI) is a debilitating medical condition that can lead to lifelong paralysis. Failure to regain mobility and restore neurons can be attributed to the non-permissive microenvironment within the mammalian spinal cord that is characterized by prolonged inflammation and glial scarring. Unlike mammals, the zebrafish has a remarkable ability to regenerate neurons in the spinal cord following a complete transection. Aside from the activation of chemical pathways that promote growth, zebrafish also have ependymoglial (stem) cells surrounding the central canal that can proliferate and differentiate into all cell types of the spinal cord. Previous studies have investigated factors that promote neuronal regeneration, yet the contribution of locomotion remains unevaluated. Thus, we aimed to explore the role of physical movement in spinal cord repair by developing a swim column that elicited swimming activity (exercise treatment) from injured fish. This apparatus was developed using an aquarium pump to direct flow into a PVC tube placed within an acrylic tank. Adult male zebrafish from motor neuron reporter line, Tg(hb9:eGFP), were used. Results showed that the exercise treatment slowed the rate of recovery and diminished normal swimming behaviour. Downstream analysis of distance travelled, mean velocity, and mobility state duration revealed that SCI fish treated with exercise had delayed recovery compared to SCI fish that were untreated. Contrary to previous studies using mammalian models, we found that functional mobility was hindered, and swim restoration was limited. Furthermore, our findings contrast other zebrafish exercise studies that demonstrated increased neurogenesis in larvae, and attenuation of age-related diseases such as sarcopenia and cardiac failure. These contradictions may be attributed to sample size, experimental timeline, treatment duration, and stress levels. Although the current study did not yield statistically significant results, these preliminary findings lay the groundwork for deeper exploration of movement in regenerative models
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Open Access
Protecting plants against the fungal pathogen Sclerotinia sclerotiorum using host-induced gene silencing
(2025-04) Caners, Rhey; Whyard, Steve (Biological Sciences); Lee, Jae-Hyeok (Biological Sciences); Belmonte, Mark
Sclerotinia sclerotiorum is a fungal pathogen that affects Canadian crops every year. Brassica napus (canola) is particularly vulnerable. Chemical fungicides are widely used to control S. sclerotiorum. However, with increasing concerns about resistance and ecological effects, it is necessary to develop new and improved control methods. Host-induced gene silencing (HIGS) is an RNA interference technology that has the potential to be harnessed to create transgenic, pathogen-resistant crops. In this study, I analyzed the effectiveness of four independently transformed lines of Arabidopsis thaliana expressing RNA to silence the NOB1 gene (SS1G_07873) in S. sclerotiorum. Three of the lines expressed double-stranded (ds)RNA while the fourth line expressed paperclip (pc)RNA, a novel RNA structure which folds over itself on both ends to protect it from nucleases. The analysis was done through detached-leaf lesion assays and transcript knockdown analysis of the NOB1 target gene as well as three known interacting genes. Though improvements are required, the lesion assays show significant decreases in lesion size. Transcript knockdown analysis revealed insignificant changes in NOB1 expression. The interacting genes analyzed showed a significant reduction in transcript abundance, indicating that further experiments are required to understand the processing of foreign RNA in the plant. With further testing to optimize HIGS using SS1G_07873, this technology has the potential to be replicated in crop plants as a means of protection against S. sclerotiorum.