Rice yellow mottle virus (RYMV) disease, is essentially restricted to the African continent. It is the most important disease on rice in the United Republic of Tanzania (comprising both mainland Tanzania and the islands of Zanzibar). To minimise yield lost to the disease, a thorough knowledge of the epidemiology of the virus and the vector biology/ecology are required. This review therefore puts together the fragment information already available on RYMV epidemiology and vector biology/ecology in Tanzania, with emphasis on progress made and where effort is still required.
The feeding period of the grain aphid, Sitobion avenae, an important vector of barley yellow dwarf virus (BYDV), was studied in six varieties of spring barley (Hordeum vulgare L.) in an attempt to explain the resistance mechanisms in some barley varieties to BYDV. There was no significant difference in aphid feeding period between the resistant and susceptible varieties. The mechanisms underlying BYDV resistance do not seem to involve factors related to alterations in the feeding period. Suggestions for future studies are highlighted.
Intensive surveys conducted at Samaru and its environs in the northern Guinea Savanna of Nigeria between October 2000 and September 2002, indicated that Bemisia tabaci (Genn.) infests forty two (thirty three cultivated and seven wild) species of plants. Twenty nine of the plants were found in upland, two in the lowland and eleven in both upland and lowland (fadama) areas. Heavily infested plants were distorted, chlorotic and stunted. Symptoms of virus infection were associated with some of the infested plants. This is the first comprehensive report of hosts of B. tabaci in Nigeria.
Authors:R. S. Abdallah, O. O. Banwo, R. H. Makundi and J. C. Mbapila
Rice yellow mottle virus (RYMV) is a severe disease of rice in Africa. It is naturally transmitted by several species of beetles. Chaetocnema pulla is widely believed to be an important vector of RYMV in Tanzania. However, the high incidence of RYMV in some rice fields where C. pulla was not seen in large numbers indicated that more vectors of the virus might exist. Transmission studies conducted showed Dactylispa lenta to be a vector of RYMV in Tanzania. This has not been previously known.