Characterization of Heterorhabditis indica (Nematoda: Rhabditida) and their efficacy against insect pests by using regression probit analysis model: Implication on biological control of pest management

Abstract

The potential of Entomopathogenic nematodes (EPN) under laboratory conditions against insect pests has been known worldwide. In the present investigation, the isolates were recovered from the Indian soils and the susceptibility of Galleria mellonella and Spodoptera litura to the infection of EPN was examined. Among all the collected 360 soil samples, four soil samples were found to be positive for the EPN strains and docketed as CH22, CH23, CH25 and CH26.The isolated strains were identified as Heterorhabditis indica based on the morphology, morphometry and phylogenetic analysis. Only one species of Heterorhabditis has been recovered from the Indian soils which could be inferred as one of the dominant species of EPN in Uttar Pradesh, India. The principal component analysis (PCA) values showed large intraspecific differences between the isolated strains and interspecific differences between the species of the Indica group. The laboratory bioassays against the G.mellonella and S.litura revealed the highest virulent strain in CH23 and the least virulence were observed in CH26. The median lethal concentration of CH23 isolate obtained from the bioassays showed high virulence against G. mellonella (LC50 =22.688) and S. litura (LC50 =76.454) within 36 hrs. The CH23 and CH26 isolates showed a positive correlation between the dose and % mortality against both pests.The CH23 strain of H. indica showed high virulence and can be exploited as a new bio-control agent against the insect pest in the integrated pest management programmes (IPM).