Characterization of cassava whitefly (Bemisia tabaci (Gennadius)) from diverse agro-ecological zones of Kerala, India, reveals the presence of different biotypes as pests in cassava.

Mosaic disease spread by the whitefly, Bemisia tabaci, is the major threat to cassava cultivation. This study reveals the variations in cassava whitefly populations across 13 agro-ecological zones of Kerala State, India, and their virulence. Discriminant analysis of morphometric measurements of whitefly pupa from different agro-ecological zones showed more evident distinction compared to adult, and analysis of the whitefly genome using 10 selected ISSR primers has revealed two major clusters within the Sulthan Bathery population, as out group. Sequence analysis of the mitochondrial cytochrome oxidase1 gene showed the presence of two whitefly biotypes, Asia I and Asia II 5. This is the first report of whitefly biotype Asia I infesting cassava. The genetic variation could be the result of isolated speciation under highly diverse elevations and agro-ecological conditions. Cassava plants infested with the Asia I biotype had very low cassava mosaic disease severity compared to those infested with the Asia II 5 biotype. The present study, for the first time, provides molecular evidence of the possibility of more than one biotype of B. tabaci infesting cassava in India. [ABSTRACT FROM AUTHOR]