Allen, Carol DianneABSTRACT Title of Thesis: TRANSMISSION OF <italic>CYMBIDIUM MOSAIC VIRUS</italic> IN ONCIDIUM ORCHIDS BY <italic>PERIPLANETA AUSTRALASIAE</italic> Carol Dianne Allen, Master of Science. 2012 Thesis Directed by: Gary Coleman, Ph.D. Department of Plant Science and Landscape Architecture <italic>Cymbidium mosaic virus</italic> is the most common disease in orchids infecting a large number of cultivated orchids found in all phases of the industry and around the world. Its transmission occurs through contact by contaminated cutting tools, human hands, or water. Although insects known to transmit plant viruses have been exposed to orchid viruses, none have been found to successfully transmit <italic>Cymbidium mosaic virus</italic>. <italic>Periplaneta australasiae</italic>, the Australian cockroach, is a common greenhouse pest that is known to feed on orchid plants. In controlled conditions Australian cockroaches were given inoculation access through feeding activity on known CymMV positive orchid plants and then allowed to feed on virus free plants. The virus free plants were isolated from subsequent insect exposure and after a period of time samples from the feeding damage sites were analyzed for the presence of virus RNA through nested and hemi-nested PCR techniques. A statistically significant number of samples were positive demonstrating that with high population numbers and long term exposure, virus transmission is possible.ThesisVirologyEntomologyPlant pathologyAustralian CockroachCymbidium mosaic virusHemi-nested PCROrchidsPeriplaneta australasiae