Using next generation sequencing to uncover population structure and species boundaries in Bactrocera dorsalis and its sister species

Fruit flies in the genus Bactrocera (Diptera: Tephritidae) are among of the most economically damaging crop pests in the world. One group, the B. dorsalis complex, is especially destructive. Four pest species (B. dorsalis, B. carambolae, B. invadens and B. papayae) within this group are morphologically similar and together infest over 200 different tropical fruits and vegetables. These pests have invaded countries throughout the world and cause harm to agriculture not only through crop damage but also trade restrictions. It is therefore of great importance that reliable identification tools be available for growers and inspectors to maximize control efforts. Recent studies suggest that some of these species may not be distinct, due to high morphological and genetic similarity. To explore the species boundaries further, we conducted a population genomic analysis using restriction site associated DNA sequencing on individuals from all four species across their native (Bangladesh, Cambodia, China, Laos, Malaysia, Philippines and Thailand) and invasive (Burkina Faso, Hawaii, Kenya and Tanzania) ranges. We used restriction enzymes to reduce the size of the genome into fragments and selected for fragments shared among individuals for sequencing. Using this approach, we examined thousands of SNPs across the genome revealing genetic diversity and population structure among and within populations. We also used these data to test species boundaries by comparing intra- and interspecific genetic diversity and structure. Relationships between taxa will be reported and their significance discussed.