CHARACTERIZATION OF 5 INDIAN ISOLATES OF THE NUCLEAR POLYHEDROSIS-VIRUS OF HELICOVERPA-ARMIGERA

Five Indian geographical isolates of the nuclear polyhedrosis virus of Helicoverpa (Heliothis) armigera were studied for the variation in th eir size, virulence, and the restriction and electrophoretic patterns of the polyhedrin. The diameter of the polyhedra varied from 1.6 to 2. 4 mu m (mean 1.933 mu m), with no significant differences among the fi ve isolates. The most virulent isolate was that from Ooty (GOT), with the lowest LC(50) value of 2.538 x 10(3) purified occlusion bodies (PO B)/ml, followed by the isolate from Coimbatore (CBE). Genomic variabil ity as determined by the HindIII digestion pattern of the DNA, showed that isolates OOT and CBE were similar and that the three other isolat es, viz., APK, GUJ, and RAJ represented another group which had a simi lar restriction pattern. The SDS-PAGE electrophoretic pattern of the p olyhedrin of all the isolates was the same.