Genetic diversity and differentiation of <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> nuclear polyhedrosis virus isolates from India

India has a rich biodiversity of microbes. Soil is the major source for isolation of entomopathogens, after the infected insects themselves. Four isolates of Helicoverpa armigera nuclear polyhedrosis virus (HearNPV) were obtained from the samples collected one each from Anand, Surat and Junagadh of Gujarat and Patancheru of Andhra Pradesh. All the HearNPV isolates appeared as clear, irregular six-sided objects with rounded edges, phase-bright under phase contrast. Junagadh, Surat, Patancheru and Anand isolates gave 27.47–42.80%, 36.83–51.32%, 26.05–43.76% and 42.99–54.85% mortality, respectively, when the percent mortality was pooled over period. The least number of HearNPV polyhedral inclusion bodies (PIBs) (5.1 × 10⁷) of the Anand isolate were required to kill 50% of the H. armigera population within 120 h. The Anand isolate was fastest (90.30 h), followed by Surat (120.26 h), Junagadh (139.53 h) and Patancheru (143.10 h) in killing 50% of the H. armigera population at a dose of 10⁹ PIBs ml⁻¹. RAPD analysis of all 15 arbitrary oligonucleotide primers generated 353 scorable bands with 201 loci. A total of 181 polymorphic bands were obtained, ranging in size from 141 to 1,873 base pairs. The percentage of polymorphic loci was 90.19%. The mean polymorphism information content (PIC) value for 15 primers was found to be 0.99. The similarity coefficient values based on 15 RAPD markers ranged from 0.235 to 0.407. The four isolates were grouped into two clusters: one cluster consisted of Junagadh and Anand and the second cluster consisted of Surat and Patancheru.