Population structure inferred from COI data analyses for Bactrocera dorsalis (Diptera: Tephritidae) in the Karnataka region of India

Abstract

ABSTRACTThe Oriental fruit fly, Bactrocera dorsalis (Hendel) causes tremendous losses in mango (Mangifera indica L.), its high level of polyphagy coupled with the ability to complete overlapping generations and mobility made this insect pest a unique example to study its population genetic diversity at both spatial and temporal levels. However, the genetic diversity and phylogeographic structure of B. dorsalis at regional level remain to be unexplored. We analysed the genetic diversity and population structure of B. dorsalis throughout the Karnataka region. Results revealed the existence of abundant haplotypes as well as nucleotide diversity in Tumkur and Kolar populations that showed high similarity to the neighbouring states viz., Vellore of Tamil Nadu and Chittoor of Andhra Pradesh. Genetic diversity indices [number of Haplotypes, haplotype diversity (Hd), nucleotide diversity (π), polymorphic sites (S) and the average number of pairwise nucleotide differences (k)] across Karnataka maintain high levels of genetic diversity at different geographic locations. All haplotypes were monophyletic and have a significant phylogeographic structure (Nst>Gst; P < 0.05). The star-like median-joining network of haplotypes distribution implied that most of the fruit flies derived from relicts and subsequently fragmented. Further, the neutrality tests and mismatch distribution analysis confirmed that B. dorsalis underwent a recent demographic expansion.