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Evaluating Calmodulin-Targeting dsRNA as a Novel Control Strategy for Varroa destructor: Effects on Reproduction, Survival, and Locomotion Bailey Koller Schmidt (25137537) Other biological sciences not elsewhere classified Varroa destructor Calmodulin-Targeting dsRNA Reproduction Locomotion School: School of Biological Sciences 319999 Other biological sciences not elsewhere classified 280102 Expanding knowledge in the biological sciences Degree Discipline: Biological Sciences Degree Name: Master of Science Degree Level: Masters <p><strong>Varroa destructor (Varroa) is one of the major threats to honey bee (Apis mellifera) health worldwide and is a major contributor to colony losses. Current Varroa management relies heavily on chemical miticides such as flumethrin, but increasing concerns regarding resistance and chemical residues within hives have highlighted the need for alternative or complementary control strategies. RNA interference (RNAi) has appeared as a promising species-specific pest management tool, with calmodulin-targeting double-stranded RNA (dsRNA), previously shown to suppress Varroa reproduction. However, the physiological and behavioural effects of calmodulin suppression in Varroa remain poorly understood.</strong></p><p>This thesis investigated the lethal and sublethal effects of calmodulin-targeting dsRNA on Varroa, with a focus on locomotor behaviour, reproduction, gene expression, and interactions with the pyrethroid miticide flumethrin. Chapter 1 is my General Introduction for my Thesis as a whole. In Chapter 2, laboratory dunking assays and semi-field mini-hive experiments examined the effects of dsRNA exposure on mite locomotion, survival, calmodulin gene expression, and reproductive capacity. Calmodulin-targeting dsRNA significantly reduced calmodulin gene expression and strongly suppressed mite reproduction, while having limited effects on exposed foundress mite survival. Locomotion assays showed a reduction in movement speed following dsRNA exposure, although similar behavioural changes were also observed in the GFP dsRNA controls; suggesting that some effects may reflect general treatment-associated stress responses.</p><p>Chapter 3 investigated whether prior exposure to calmodulin-targeting dsRNA altered mite responses to flumethrin exposure. Flumethrin caused strong dose-dependent mortality and significantly affected locomotor behaviour, but no significant interaction between dsRNA treatment and flumethrin concentration was detected for either survival or locomotion outcomes. More replication and experiments might help better define the interaction between pesticides and dsRNA treatments. These results suggest that calmodulin-targeting dsRNA does not substantially elevate susceptibility to flumethrin-induced mortality under the conditions tested.</p><p>Chapter 4 is my General Discussion for my Thesis as a whole, which looks at both Chapter 2 and Chapter 3’s results. Overall, this thesis demonstrates that calmodulin-targeting dsRNA significantly impairs Varroa reproduction and may also influence locomotor behaviour, while flumethrin remains a strong driver of mite mortality. Although no synergistic interaction between dsRNA and flumethrin was identified, the differing physiological effects of these treatments suggest that they may still function as complementary tools within integrated pest management (IPM) programs. The results support the continued development of RNAi-based technologies such as “vadescana” as potential additions to sustainable Varroa management strategies intended to diminish reliance on conventional chemical miticides.</p> 2026-09-30T00:00:00Z Text Thesis 10.26686/p2mb-z15q https://figshare.com/articles/thesis/Evaluating_Calmodulin-Targeting_dsRNA_as_a_Novel_Control_Strategy_for_Varroa_destructor_Effects_on_Reproduction_Survival_and_Locomotion/34024656 Author Retains Copyright