Tomato yellow leaf curl virus (TYLCV) is a major threat to tomato production in the tropical and subtropical regions as well as in the greenhouses of the temperate zone. Development of TYLCV epidemics in the recent years was largely affected by the changes in the interaction of virus strain, vector population and the host genotype. Persistence and infectivity of a newly reported TYLCV isolate, TYLCV-Ir2, from Iran were studied. Virus free whiteflies reared on cauliflower plants were fed on the TYLCV infected tomato plants for 48 hours and were then put back on the none host cauliflower plants to examine the persistence of the virus in its insect vector. TYLCV infected whiteflies were tested for the presence of viral DNA using PCR and for its infectivity by testing their ability to infect healthy tomato plants. A 670 bp fragment of viral DNA was detected from whiteflies until 12th day of living on cauliflower plants, while their ability to infect tomato plants was just four days as tested after three, four and seven weeks post inoculation. These observations were further confirmed by back inoculation tests. Results of this study suggested that although viral DNA can persist in the life span of an infected adult whitefly, however, the infectivity can be retained only less than 6 days post acquisition.
