Population Genomics of Pesticide Resistance in the Mediterranean Fruit Fly

The Mediterranean fruit fly Ceratitis capitata (Wiedemann) commonly known as medfly is considered a model organism for the tephritid fruit fly group. It is one of the most invasive and economically important insect pests occurring on more than 250 host plants worldwide. It is also an interesting model for evolutionary studies. In our study, we are investigating the evolutionary biology of natural medfly populations and their pathway of invasion worldwide using ecological traits such as insecticide resistance, as a useful indicator of evolutionary change. We compared gene sequences of resistant and non-resistant strains collected from various geographical localities where the medfly is well established, i.e. the Mediterranean basin, Sub-Saharan Africa, Latin America, Australia and the Pacific region. This comparison revealed portions of the locus for Acetylcholin Esterase that are in linkage disequilibrium with a SNP conferring insecticide resistance. We extended this analysis across the entire genome, to test for other parts of the genome affected by control measures using Restriction-site Associated DNA (RAD) tags. This genome scan allowed us to estimate the genetic divergence and age of local populations, based on their total genetic variation at each locality, as a measure of population age and drift effects and the degree of interconnectedness among our sampling sites.