Genetic differentiation among cotton bollworm, Helicoverpa armigera (Hübner) populations of south Indian cotton ecosystems using mitochondrial DNA markers

Genetic diversity among 12 cotton bollworm, Helicoverpa armigera (Hübner) populations from different geographic regions of South India was done using mitochondrial DNA-specific markers. Thirteen selected mtDNA universal markers/primers generated a total of 167 PCR amplicons, of which 162 were polymorphic across all 12 populations. An average of 12.85 amplicons per primer was noted. All populations could be differentiated from one another using specific primers; specific band(s) could be potentially used to differentiate individual populations. Genetic relationships between the populations were evaluated by generating a similarity matrix based on Jaccard's index and a phenetic dendrogram was generated by UPGMA method. Principal component analysis separated the 12 populations into different groups based on band-sharing data. Populations showed varied degrees of genetic similarity within a range of 0.04-0.52. Also, the populations appeared to be more dispersed on the principal component plot indicating a wide genetic base. On a larger scale, genetic differences among populations appear to result from low dispersal rates between populations. The level of genetic variation detected between the H. armigera populations with mtDNA-PCR analysis suggests that it is an efficient marker technology for delineating genetic relationships amongst populations and estimating genetic diversity, thereby gaining insight into genetic structure of populations and its further use in formulation of appropriate area wide management strategies for this pest.