Characterization of differences between whiteflies using RAPD-PCR.

The B biotype of the sweetpotato whitefly, Bemisia tabaci (Gennadius) has caused over $200 million in crop damage in the US during 1992. The taxonomic classification of the A and B biotypes of B. tabaci is unclear. We used RAPD-PCR to demonstrate DNA differences between the A and B biotypes of this insect. All twenty of the RAPD primers tested distinguished readily between the biotypes. DNA extracted from individual eggs and nymphs showed identical differences. RAPD-based genetic similarity statistics indicate that these two biotypes of B. tabaci were no more similar to each other than to two other whitefly species: bayberry whitefly (Parabemisia myricae) or bandedwinged whitefly (Trialeurodes abutilonea). These results indicate that RAPD-PCR may be useful in distinguishing closely related organisms, but may not be useful in determining higher classification of insects. Before the taxonomic status of B. tabaci biotypes A and B can be determined, results from other genetic, morphological and physiological examinations will have to be compared.