Annals of Plant Protection Sciences

B-biotype of cotton whitefly, Bemisia tabaci (Bemisia argentifolii) due to its wide spreadibility, high fecundity, polyphagous nature, fast adaptability to insecticides and being vector of many geminiviruses had emerged as a pest of quarantine significance with negative impact on the economy of the agricultural countries. Thus, monitoring of whitefly populations for B-biotype required quick and reliable identification methods. In order to develop B-biotype sequence specific molecular markers, three numbers of polymorphic RAPD-DNA bands were identified in the RAPD-PCR profiles of B-biotype relative to non B-biotype variants of B. tabaci. Based upon the sequence data of these polymorphic RAPD-DNA fragments, three pairs of SCAR (sequence specific amplified region) primers were developed for molecular identification of B-biotype through specific PCR amplification. When used in PCR amplification from different B-biotype and non B-biotype variants, two of these SCAR primer pairs (BbF07–573_FR & BbA01–970_FR) effectively amplified a single fragment of predetermined size (480 bp & 938 bp, respectively) from all the B-biotype variants only (Australia, Israel & three B-biotype variants -1,-2 and -3 identified in India). Though, the third SCAR primer pair (BbF16–269_FR) through amplification of the expected 239 bp fragment similarly showed its specificity for all the other B-biotype, it was not specific for an Indian B-biotype-3 variant. The SCAR primers were equally effective in molecular identification of B-biotype in a multiplex PCR by co-amplification of both the respective SCAR markers in a single PCR reaction. Analysis of a 150 populations of 1351 whitefly individuals collected from nine different states of India with two SCAR primer pairs (BbF07–573_FR & BbA01–970_FR) in a multiplex PCR established whereas B-biotype was predominating type in south Indian states, this biotype has started contaminating native whitefly populations of Gujarat and Maharashtra states. However, all North Indian states were free from this biotype. In view of the fast spreading nature of B-biotype, molecular monitoring of whitefly populations for B-biotype with the SCAR primers through multiplex- PCR developed in this study, will help in studying the migration pattern of B-biotype with respect to season, host crop and region for adopting appropriate control measures which were different from those found for control of non B-biotype of whitefly and in its detection for quarantine checks.