Bio-efficacy of entomopathogenic nematodes, Steinernema feltiae and Heterorhabditis bacteriophora against the Cabbage butterfly (Pieris brassicae [L.]) under laboratory conditions

Abstract Background Entomopathogenic nematodes (EPNs) have the potential to supersede larvicidal activity for the management of various insect pests. Result Lab experiments were conducted to test the pathogenicity of 2 EPNs local species; Steinernema feltiae and Heterorhabditis bacteriophora at different (IJs/cm2) concentrations against the cabbage butterfly, Pieris brassicae (L.). The native isolate was obtained from soil samples, collected from Rajgarh, Hamachi Pradesh, India. Petri dish bioassay used the EPNs species (S. feltiae HR1 and H. bacteriophora HR2) at the concentrations (0, 10, 20, 40, 80, 160 IJs/cm2). Based on the pathogenicity of the strains, only 2 isolates effectively showed larvicidal activity. The highest (%) (72.08 and 67.42%), at the 2nd instar larval mortality was recorded in the treatments with H. bacteriophora and S. feltiae at160 IJs/cm2, respectively. At the 4th instar larvae, respective larval mortality (85.38, 69.50%) was recorded in treatment with H. bacteriophora, and S. feltiae, respectively, at160 IJs/cm2. In case of pupae, the mortality rates were (62.12, 58.58%) for H. bacteriophora and S. feltiae, respectively, at 160 IJs/cm2; (74 and 12%) for both the tested EPNs, respectively, at 80 IJs/cm2. Percent of P. brassicae larval mortality treated with the tested EPN isolates was significantly higher than the untreated control. Results revealed that the percent of larval mortality significantly increased with the increase in time periods, being maximum at 72 h. S. feltiae and H. bacteriophora, strains showed potent larvicidal activity at low concentration even at 48 and 72 h of exposure. Conclusion This study revealed that the local strains of EPNs (S. feltiae HR1 and H. bacteriophora HR2) were found as a biocontrol agent against P. brassicae.