Bioefficacy and mass culturing of Heterorhabditis bacteriophora (Nematoda:Heterorhabditidae) on cabbage butterfly, Pieris brassicae (Lepidoptera:Pieridae) in temperate region of Kashmir, Indi

Abstract

A laboratory investigation was carried out to assess the bioefficacy and mass culturing of Kashmir isolate of entomopathogenic nematode (EPN), Heterorhabditis bacteriophora on cabbage butterfly, Pieris brassicae in Srinagar. The pathogenicity of H. bacteriophora against 3^rd, 4^th and 5^th larval instars of P. brassicae showed cent per cent mortality of the pest in all the three larval instars at the dosages of 20 IJs/larva and above. The LC₅₀ values of H. bacteriophora against 3^rd, 4^th and 5^th larval instars of P. brassicae ranged from 46.61 to 9.32, 76.33 to 9.82 and 91.36 to 10.08 IJs/larva at 24 to 96 h and that the LT₅₀ values from 65.15 to 23.12, 84.54 to 29.20 and 105.36 to 33.52 h at 10 to 60 IJs/larva, respectively. The average production of nematode infective juveniles per larvae was found to be 7.02 x 10³, 25.74 x 10³ and 58.45 x 10³ and that from per gram of host body weight was 91.49 x 10³, 151.30 x 10³ and 233.78 x 10³ in 3^rd, 4^th and 5^th larval instars of P. brassicae, respectively. The total time period between the larval mortality and the initiation of emergence of the infective juveniles from the cadavers ranged from 7-8, 9-10 and 10-11 days and the peak period of emergence of infective juveniles ranged from 10-13, 14-19, 16-21 days after mortality from the cadavers of 3^rd, 4^th and 5^th larval instars of P. brassicae, respectively. The total duration of nematode emergence recorded during the period between larval mortality and cessation of emergence of infective juveniles from the cadavers ranged 17-19, 23-25 and 26-29 days after mortality in case of 3^rd, 4^th and 5^th larval instars of P. brassicae, respectively.