Molecular characterization of whitefly,Bemisia tabaci(Hemiptera: Aleyrodidae) populations infesting cassava

Abstract

AbstractBemisia tabaci(Gennadius) populations, collected from cassava and other plants in major cassava-cultivation areas of Sub-saharan Africa and from elsewhere around the world, were studied to determine their biotype status and genetic variation. Random amplified polymorphic DNA–polymerase chain reaction (RAPD–PCR) markers were used to examine the genetic structure of the populations. The dendogram obtained using the neighbour joining method (NJ) split the cassava-associated populations from the non-cassava types with a 100% bootstrap probability. Analysis of molecular variance (AMOVA) of the RAPD fragments revealed that 63.2% of the total variation was attributable to differences among populations, while the differences among groups (host) and within populations accounted for 27.1 and 9.8% respectively. Analysis of the internally transcribed spacer region I (ITS 1) of the ribosomal DNA confirmed that the cassava populations ofB. tabacipopulations were distinct from non-cassava populations. Experiments to establish whitefly populations on various host plants revealed that cassava-associated populations were restricted to cassava only, whereasB. tabacifrom other hosts were polyphagous but did not colonize cassava. Hence, populations ofB. tabacifrom cassava in Africa represent a distinct group.