LONG-TERM ASSOCIATION OF TOMATO YELLOW LEAF CURL VIRUS WITH ITS WHITEFLY VECTOR BEMISIA-TABACI - EFFECT ON THE INSECT TRANSMISSION CAPACITY, LONGEVITY AND FECUNDITY

The association between tomato yellow leaf curl geminivirus (TYLCV, Is raeli isolate) and its insect vector, the whitefly Bemisia tabaci, was investigated. Insects that emerged during a 24 h period were caged wi th TYLCV-infected plants for a 48 h acquisition access period, then wi th egg-plants - a TYLCV non-host - for the rest of their lives. While TYLCV DNA was associated with the whiteflies during their entire adult life, the amount of capsid protein rapidly decreased and was not dete ctable in the insect after approximately 12 days of age. The ability o f the infected whiteflies to transmit TYLCV to tomato test plants stea dily decreased with age but did not disappear completely, Transmission by viruliferous insects decreased from 100% to 10-20% during their ad ult lifetime, compared with a decrease from 100% to 50% for non-viruli ferous insects. The association of TYLCV with adult B. tabaci red to a reduction of 17-23% in their life expectancy compared with insects th at had not acquired the virus, and to a 40-50% decrease in the mean nu mber of eggs laid, These results suggest that TYLCV has some features reminiscent of an insect pathogen.