This Book provides a detailed account of genomic variations amongst geographic isolates of Helicoverpa armigera Nucleopolyhedrosis Virus which in turn is reflected in their bio-efficacy. The procedural detailing given here will be extremely helpful to the beginners in the field. We have tried our best to cover all the aspects with detailed discussion on each and every aspect.We wish the beneficiaries of this book all the very best in their endeavor to unearth the new vistas of this science.