Phylogeography of Sesamia cretica Lederer (Lepidoptera: Noctuidae)

The greater sugarcane borer, Sesamia cretica Lederer (Lepidoptera: Noctuidae) is an important pest of maize, sorghum and sugarcane in Africa, the Middle East, and Mediterranean Europe. However, the population genetics and phylogeography of this pest are unknown. Some insect pests exhibit genetic differentiation congruent with their geographical location and ecological conditions. To evaluate this, a molecular analysis was conducted on populations of S. cretica collected from Ethiopia, Eritrea, Kenya, Cameroon and Iran, using the cytochrome c oxidase subunit I (COI) region of the mitochondrial genome. Phylogenetic analyses based on neighbor joining tree separated the 22 specimens into two clades, the Ethiopian and Afro-Asian. The clades diverged long before the domestication of sorghum and the introduction of sugarcane in Africa. Analysis of molecular variance (AMOVA) indicated significant genetic differentiation among the clades. The observed genetic variation between the clades was further accompanied by restricted gene flow. The results of mismatch distribution analyses were consistent with the demographic expansion of the clades.