Electronic Thesis and Dissertation Repository


Master of Science




Donly, Cam

2nd Supervisor

Smith, David R



Pest management strategies are crucial for reducing insect crop damage, and methods with species-specific effect are particularly desirable. Expressing dsRNA with sequence complementarity to a vital gene of feeding pests is a strategy that has shown potential. I modified the chloroplast genome of cultivated tobacco, Nicotiana tabacum, by adding a sequence encoding a 2222 base pair dsRNA complementary to the vacuolar-type H+-ATPase subunit A mRNA of Manduca sexta and demonstrated expression of the product in leaves of the plants. Although feeding this same dsRNA that was synthesized in vitro to larvae knocked down expression of the target gene and induced lethality, chloroplast-encoded dsRNA had no effect on survival or target gene expression of feeding larvae. The results of this study suggest that a possible limitation for this strategy is the level of expression due to the length of the product, or that this strategy is inefficient for certain insect species.