Transmission of tomato yellow leaf curl geminivirus to imidacloprid treated tomato plants by the whitefly Bemisia tabaci (Homoptera: Aleyrodidae)

The ability of whiteflies [Bemisia tabaci (Gennadius), B biotype] to transmit tomato yellow leaf curl geminivirus (TYLCV, Israeli isolate) to imidacloprid-treated and untreated tomato plants was investigated. Viruliferous whiteflies were caged with treated tomato plants held in a nethouse. Insect mortality and tomato infection was assessed during the summer and the winter seasons, after insecticide application. In summer, insects that were given access to tomato plants 3 and 11 d after insecticide treatment died within 80 min. This period increased to 150 min 18 d after treatment. The insecticide lost its potency 25 d after application. In winter the lethal effect of the insecticide lasted longer than in summer. In summer as well as in winter, 70% of the tomato plants caged with viruliferous whiteflies 3 d after insecticide treatment became infected. These figures increased to 80% 11 d after treatment and to nearly 100% 18 d after treatment. Insecticide-treated plants were as prone to infection as nontreated plants. Approximately 48 min of access to a treated tomato plant was sufficient for a single viruliferous insect to inoculate the virus with an efficiency rate of 20% or more. Transmission efficiency was similar to that achieved on nontreated plants. Therefore, viruliferous insects had enough time to inoculate TYLCV to imidacloprid-treated plants before they died.