author(s)
Ramandeep Kour, RK Gupta, Hafeez Ahmad, Suheel Ahmad Ganai, Nadeya Khaliq and Simranjeet Kour

abstract
To determine the biological characteristics of different isolates of Pieris brassicae Granulosis virus, bioassays were carried out against the third instar larvae of Pieris brassicae under laboratory conditions. The four different GV isolates of P. brassicae isolated from different geographical regions, exhibited differential degree of pathogenicity in terms of both LD₅₀ and ST₅₀. The LD₅₀ values of different GV isolates of P. brassicae against 3^rd instar larvae of P. brassicae varied from 6.31 x 10³ to 1.22 x 10⁴ OBs/larvae with non significant differences between the isolates. However, significant differences were observed in the ST₅₀ estimates of four different isolates of PibrGV against 3^rd instar larvae of P. brassicae which varied from 5.90 to 7.43 days. The Sudhmahadev isolate exhibited 11.01- 20.59% reduction in ST₅₀ as compared to Poonch, Chatha and Himachal Pradesh isolates. Among all these isolates, Sudhmahadev isolate of PibrGV was found to be most effective.