Invasion genomics uncover complex introduction patterns of the globally invasive whitefly, Bemisia tabaci MED

Aim The sweet potato whitefly, Bemisia tabaci MED is a globally invasive species that causes serious economic damage to agroecosystems. Despite the significant threat it poses to agricultural and economic crops worldwide, the global perspective of the invasion patterns and genetic mechanisms contributing to the success of this notorious pest is still poorly understood. The objective of this research was to enhance genome and population genetic analyses to better understand the intricate invasion patterns of B. tabaci MED. Location Samples were collected in native (Spain, Croatia, Bosnia and Herzegovina, Cyprus, and Israel) and invaded regions (China, South Korea and North America). Methods We first assembled a chromosome‐scale reference genome of B. tabaci MED and then employed the restriction site‐associated 2b‐RAD method to genotype over 20,000 high‐quality single‐nucleotide polymorphisms from 29 geographical populations. Results A reference genome of B. tabaci MED, with a size of 637.47 Mb, was available. The majority of the assembled sequences (99%) were anchored onto 10 linkage groups, with an N50 size of 58.76 Mb, representing a significant improvement over previous whitefly genome assemblies. We identified rapidly expanded gene families and positively selected genes, probably contributing to successful invasion and rapid adaptation to the new environment. Population genomics analysis showed that three highly differentiated genetic groups were formed, and complex and extensive gene flow occurred across the Mediterranean populations. The genetic admixture patterns in East Asia populations were distinct from those in North America, indicating that they had different source populations. Conclusions The high‐quality, chromosome‐scale genome of B. tabaci MED offered opportunities for more comprehensive genome‐wide studies and provided solid foundation to the complex introduction events and the differential invasiveness of B. tabaci MED worldwide.