Survey of Bemisia tabaci (Gennadius) (Hemiptera : Aleyrodidae) biotypes inBrazil using RAPD markers

In 1991, the poinsettia strain. silverleaf whitefly or B biotype of Bemisia tabaci was detected in Brazil. This variant is afar more serious agricultu ral pest than the previously prevalent non-B (BR) biotype. The correct iden tification of B. tabaci is problematic since it is highly polymorphic with extreme plasticity in key morphological characters that vary according to t he host. RAPD-PCR was used to survey the B biotype and other biotypes of B. tabaci in Brazil. Whiteflies were collected from cultivated plants and wee ds from 57 different localities and on 27 distinct crops, RAPD analyses usi ng two selected 10-mer primers reliably identified the BR biotype and the B biotype of B. tabaci and also differentiated other whitefly species. The p resence of the B biotype was confirmed in 20 Brazilian states. The BR and B biotypes of B. tabaci were found to coexist in the whitefly populations of three different localities: Jaboticabal, SP; Rondonopolis and Cuiaba, MT, and Goiania, GO.