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Abstract
Genome stability refers to the ability of an organism’s DNA to maintain its structure and function over time. DNA methylation is an epigenetic mechanism that is important for genome stability despite its primary function being unknown. DNA methyltransferases, specifically DNA methyltransferase 1 (DNMT1), is vital for reproduction and development across living organisms. Bemisia tabaci (Order: Hemiptera), also known as the silverleaf whitefly, has become a top global pest owing to its incredible reproductive potential and genetic machinery. Their recalcitrant nature has necessitated exploration of control methods other than insecticides. The following work explores the relationship between DNMT1 and insect reproduction in hopes to inform future whitefly management strategies and begin to disentangle the complex relationship between DNMT1, DNA methylation, reproduction, and genome stability. The first half of this dissertation reviews the current state of knowledge for both Dnmt1 and whiteflies and lays the foundation for Dnmt1 as an ideal candidate gene for targeting whitefly management based on specificity and sustainability considerations. The latter half investigates the role of Dnmt1 in whitefly oocyte and embryo development. We found that the reduction of DNMT1 resulted in reduced egg production and loss of egg viability without reduced survival or a significant reduction in methylation levels. This suggests that DNMT1 plays a specific role in normal oocyte production and oocyte health outside of its canonical role as a methyltransferase. When we investigated the phenotypic effects of Dnmt1 knockdown on embryogenesis, we found that loss of DNMT1 disrupts blastoderm formation and nuclei morphology, suggesting that DNMT1 likely plays a role in cell cycle regulation during early embryogenesis. These results conclude that targeting whitefly DNMT1 results in significant population reduction through loss of reproductive capabilities while relaxing selective pressures, making it a viable option for further development as a pest management product. The results of this dissertation also shed light on DNMT1’s role as a key player in genome stability.