Biological Control of Cabbage Butterfly, Pieris brassicae, by a Locally Isolated Entomopathogenic Nematode, Heterorhabditis bacteriophora SKUASTK-EPN-Hr-1 in Kashmir

In vitro assay method was used to assess the bio-efficacy of a new isolateof entomopathogenic nematode (EPN), Heterorhabditis bacteriophora SKUASTK-EPN-Hr 1 against 3^rd, 4^th and 5^th larval instars of cabbage butterfly, Pieris brassicae, collected from Anantnag (J&K). The results revealed an indirect relationship between larval instars and their susceptibility to H. bacteriophora SKUASTK-EPN-Hr 1, and a positive correlation between EPN concentration and insect mortality. After 48 h exposure, there was 100.0, 96.7, 90.0 and 66.7%; 80.0, 76.7, 60.0 and 46.7%, and 73.3, 66.7, 53.3 and 43.3% mortality of 3^rd, 4^th and 5^th larval instars at 50, 40, 30 and 20 IJs/larva, respectively. After 96 h exposure 100% mortality of pest was observed upto the dosages of 20 IJs/larva while 66.7, 53.3 and 43.3% mortality of 3^rd, 4^th and 5^th larval instars of P. brassicae was recorded at 10 IJs/larva, respectively. The LC₅₀ values of H. bacteriophora SKUASTK-EPN-Hr 1 against 3^rd, 4^th and 5^th larval instars ranged from 46.72–9.41, 75.44–9.93 and 88.22–10.86 IJs/larva at 24–96 h and LT₅₀ values varied from 65.18–23.27, 84.37–30.15 and 107.36–33.71 h at 10–60 IJs/larva, respectively. The LC₅₀ and LT₅₀ values for the EPN considering 48 h time and 20 IJs/larva as standards against 3^rd, 4^th and 5^th larval instars, were 13.58, 22.15 and 27.38 IJs/larva and 38.17, 50.23 and 52.73 h after exposure, respectively.