POLYMERASE CHAIN-REACTION DETECTION OF VIRULIFEROUS BEMISIA-TABACI (HOMOPTERA, ALEYRODIDAE) WITH 2 TOMATO-INFECTING GEMINIVIRUSES

The sweetpotato whitefly, Bemisia tabaci (Gennadius), is an important pest worldwide. A new biotype of sweetpotato whitefly, biotype B, caus es damage by direct feeding and by the transmission of plant viruses, such as geminiviruses. In the Mediterranean area, tomato yellow leaf c url geminivirus (TYLCV) is the most serious disease of tomatoes. Anoth er whitefly-transmitted geminivirus, tomato mottle geminivirus (ToMoV) , is presently a serious problem in tomato production in west-central and southwestern Florida. Because of the increasing incidence of white fly-transmitted geminiviruses, it is necessary to develop rapid and si mple diagnostic methods for the detection of viruliferous whiteflies. The polymerase chain reaction is a sensitive and specific technique fo r the detection and identification of plant pathogens. Polymerase chai n reaction methods were used successfully to amplify 1.1-kb DNA fragme nts from individual viruliferous B. tabaci carrying either TYLCV or To MoV, and no amplified DNA fragments were obtained when nonviruliferous B. tabaci adults were processed similarly. Southern hybridization ana lysis proved that fragments amplified from viruliferous B. tabaci adul ts were viral DNA. This polymerase chain reaction-based detection meth od is sensitive enough to detect TYLCV and ToMoV in individual virulif erous B. tabaci in mixed samples of up to 25 (1 viruliferous: 24 nonvi ruliferous) and 10 (1 viruliferous: 9 nonviruliferous) individuals, re spectively. The potential uses of this polymerase chain reaction-based detection method in epidemiological studies of geminiviruses are disc ussed.