Comparative bio-efficacy of nuclear polyhedrosis virus (NPV) and Spinosad against American bollwormm, Helicoverpa armigera (Hubner) oleh Ahmad Nawaz, Habib Ali, Muhammad Sufyan, Muhammad Dildar Gogi, Muhammad Jalal Arif, Mazhar Hussain Ranjha, Muhammad Arshid, Muhammad Waseem, Tariq Mustafa, Muhammad Qasim, Muhammad Rizwan, Madiha Zaynab, Khalid Ali Khan, Hamed A. Ghramh