Genetic Diversity and Geographic Distribution of Bemisia tabaci Species Complex Infecting Soybean in Northern Hills and North Western Plains of India

Background: The Silverleaf whitefly, Bemisia tabaci (Gennadius), is a pest of global significance causing huge economic loss to a wide range of agricultural crops. The pest is regarded as a cryptic species complex which differs in its adaptability to host, fecundity and resistance to insecticides. The expected outcome of the investigation is updated information on prevalence of cryptic species of B. tabaci in the major soybean growing areas in the region. Methods: A roving survey was carried out to assess the occurrence of B. tabaci in the major soybean growing areas of Northern Hills and North Western Plain zones during three consecutive crop seasons from 2018 to 2020. The survey locations were divided in to two broad groups viz., Hills and Plains (Tarai region) and a total of 76 villages were visited during the survey. Cryptic species composition was analyzed using the mtCOI sequence through PCR amplification. Result: The mean whitefly population per plant for the three years in hills and plains were 0.53 and 3.55, respectively. The highest whitefly population was observed in 2019 (1.79 per plant) followed by 2018 (1.50 per plant) and 2020 (1.11 per plant). There was significant (p<0.0001) negative correlation (r = -0.749) with altitude. Phylogenetic relationships indicated the existence of two cryptic species Asia -1 and Asia -II -1. Of these, Asia -II -1 was found to be prominent especially in the North Western Plain Zone. In the Northern Hill Zone both Asia 1 and Asia -II -1 were detected.