Interactions of tomato yellow leaf curl virus with its whitefly vector

Whiteflies cause damages to many economically important agricultural crops because of their feeding habits and their begomovirus transmissions. The whitefly Bemisia tabaci is a genetically diverse group, which includes a large number of different biotypes (see Part I, Chapter 3). It is extremely prolific; a single female may lay approximately 400 eggs during her lifetime. Unfertilized eggs give rise to haploid males, whereas fertilized eggs develop into diploid females (arrhenotoky). The male/female ratio naturally changes throughout the course of the year, in fields and in insectaries (Horowitz & Gerling, 1992). B. tabaci develops into a flying adult from an egg, through four instars. Although B. tabaci nymphs are able to ingest and transmit begomoviruses, flying adults are those who spread the disease in the field (Gerling & Mayers, 1996). In this chapter we discuss the characteristics of acquisition, transmission, and retention of Tomato yellow leaf curl virus (TYLCV) and related begomoviruses by the whitefly vector B. tabaci.