Looking at the big picture: worldwide population structure and range expansion of the cosmopolitan pest Ceratitis capitata (Diptera, Tephritidae)

The Mediterranean fruit fly, Ceratitis capitata (Weidemann), is considered one of the most significant tephritid pest species worldwide and is an exotic species in most of its range. Here, we investigated polymorphism at 14 microsatellite loci for a total of 126 populations of C. capitata from six geographical regions, applying network theory and cluster analyses. Analyses revealed nine distinct modules for the Central American region and one in each of the remaining five regions. Bayesian cluster analysis revealed that the highest level of genetic partitioning corresponds with the presence of 3 well-defined genetic clusters. Our results confirm the African origin for Mediterranean populations based on genetic diversity and suggest a direct invasion of C. capitata from the Mediterranean to Central-America. South American populations show links with Central-America, but also exhibit indications of direct admixture with the European cluster. Additionally, the network analysis proposes a South American origin for the Madeiran and Hawaiian flies. Cluster analysis corroborates the hypothesis of a Mediterranean origin for Australian samples. Our work provides novel insights regarding the migration history of Medfly worldwide.