Bemisia tabaci populations belonging to Middle East-Asia Minor one (MEAM1) and Mediterranean (MED) groups (formerly biotype B and Q, respectively) have spread throughout the world. Although the introduction of MEAM1 is documented from several Caribbean islands, it is generally not known whether MED has also been introduced; whether indigenous populations have survived; and if in the afÞrmative, to which group(s) they belonged. Whiteßies were collected from seven islands on various plant species. The prevalence of MEAM1 and non-MEAM1 individuals was assessed using a microsatellite approach validated with sequences of the mitochondrial cytochrome oxidase I (mtCOI) gene. Of the 262 samples tested, 247 exhibited the MEAM1 pattern, whereas none showed the MED pattern. The mtCOI gene was partially sequenced from a sample of individuals exhibiting MEAM1 (n _ 15) and non-MEAM1 patterns (n _ 8) and compared with type sequences. The 15 individuals exhibiting the MEAM1 pattern were conÞrmed to belong to MEAM1. Of the eight individuals representative of the sixnon-MEAM1patterns, two belonged to the indigenousNewWorld (NW) group of B. tabaci (NW), one belonged to a distinct species of Bemisia, and Þve belonged to MEAM1. One individual belonging to NW exhibited 99.9% nucleotide identity with a NWindividual from Puerto Rico. The other was identiÞed as the most divergent individual of the North and Central American genetic cluster.Weconclude that a highly homogenousMEAM1population has extensively settled in the Caribbean and that heterogeneous NW populations were still detectable although severely displaced.