Studies on biological control potential of Steinernema abbasi CS-39 against Helicoverpa armigera (Hub.) (Lepidoptera: Noctuidae) by adopting the regression probit model

Background In India, application of entomopathogenic nematodes (EPNs) as a bio-agent against insect pests was known since 5–6 decades with the application of the exotic species Steinernema carpocapsae (DD-136 Strain). EPNs have a strong potential to control the soil-borne insect pests. In the present study isolated strain was identified as Steinernema abbasi and docketed as CS-39. The efficacy of the isolated strain was tested against the American bollworm, Helicoverpa armigera (Hub.) (Lepidoptera: Noctuidae). Results Laboratory bioassay revealed that the median lethal concentration (LC 50 = 83.21 IJs) of the S. abbasi isolate CS-39 was quite sufficient to achieve 100% mortality after 24 h of exposure. Mean mortality percentage was estimated > 75% at all concentrations, i.e., 25, 50, 100 and 200 IJs/larva, and 100% mortality was achieved at 200 IJs/larva after 24 h of concentration exposure. Positive relationship was found at every concentration of exposure and % mortality of the insect pest ( H. armigera ) after 36 ( p