Rice yellow mottle virus (RYMV) is the only known viral disease of rice in Africa and it is endemic to the continent. It is now the most important disease of rice in Tanzania and is commonly found in lowland rice, which accounts for 80% of the country's rice production. The disease was first observed in Tanzania and Zanzibar in the early 1980s but has only lately drawn research attention. Ali (1999) and Luzi-Kihupi et al (2000) reported that RYMV has been observed in most of the major rice-growing regions in Tanzania and that the disease is spreading at an alarming rate between and within these regions. RYMV is transmitted efficiently by chrysomelid beetles (Bakker 1974). The important vectors in Tanzania are Chaetocnema sp. (a yet to be described species), C. pulla Chapuis, and Dactylispa sp. (not Dactylispa bayoni Gestro) (Banwo et al 2000). However, Dactylispa sp. is believed to be a potentially important vector since it is not found in all RYMV fields.