Virulence of Kashmir Isolate of EPN Heterorhabditis bacteriophora (Nematoda: Heterorhabditidae) against Black Cutworm (Agrotis ipsilon)

A laboratory study was conducted to assess the virulence of Kashmir isolate of EPN, Heterorhabditis bacteriophora against black cutworm, Agrotis ipsilon. H. bacteriophora was found pathogenic to A. ipsilon both in Petri-plate bioassay and in sand column bioassay techniques. A positive correlation was observed between the concentration of entomopathogenic nematode and cutworm mortality. The virulence of H. bacteriophora against 3^rd larval instars of A. ipsilon revealed that after 96 hours 100% mortality was seen in all the nematode concentrations tested viz., 25, 50, 100, 150, 200 and 250 IJs/larva in Petri-plate bioassay and upto 100 IJs/larva or above in sand bioassay. The median lethal concentration (LC₅₀) of H. bacteriophora against 3^rd larval instars of cutworm A. ipsilon ranged from 326.9 to 13.1 and 342.3 to 50.7 IJs/larva at 24–72 hour and that the median lethal time (LT₅₀) values from 31.5 to 24.6 hour and 53.3 to 31.1 hour at 100–250 IJs/larva in Petri-plate bioassay and sand column bioassay methods, respectively.