Isolation and characterization of Ha NPV associated with Helicoverpa armigera insect pest

Abstract

Dead larvae of Helicoverpa armigera were collected from different parts of Bengaluru. Some larvae were diseased and the cuticles were ruptured, discharging of white body fluid on plant parts. Nucleopoly hedroviruses were isolated from the diseased larvae of various populations of pod borer Helicoverpa armigera. Observation of discharged body fluid under light microscope revealed that the large number of spherical particles resembling as viral occlusion bodies (OBs). The virus was characterized as Helicoverpa armigera nucleopoly hedrovirus (Hear NPV) based on morphological and biological characterization. Scanning electron microscopy of OBs purified from diseased larvae revealed polyhedral particles of size approximately 0.460-1.030 µm, The transmission electron microscope (TEM) images of the OBs revealed the tetrahedral shape with dimensions of 0.831-0.­­­­­­­­­­990 µm, The semisynthetic diet bioassay showed LC50 values of NPV against 2nd instar larvae of Helicoverpa armigera indicated 1x104 OBs/ml. Hear NPV was further mass multiplied and stored for further studies.