Tools and recent progress in studying gene flow and population genetics of the Bemisia tabaci sibling species group

The use of molecular markers in the Bemisia tabaci complex has been a definitive step in identifying the enormous genetic diversity hidden behind the morphological likeness among its members (see Gill and Brown, Chapter 1), and in determining interrelationships. The presence of biologically-based biotypes in B. tabaci was first realized in the 1950s by Bird (Bird 1957; Bird and Maramorosch 1978), who found that morphologically indistinguishable populations of the whitefly differed substantially in biological and ecological traits, including host range, adaptability to different hosts, and plant virus-transmission efficiencies. Later studies used ecological and biological experiments to examine mating compatibilities as well as differences among distinct populations in phytotoxic induction, insecticide resistance, behavior (Brown et al. 1995b).