Susceptibility of Red Weevil, Rhynchophorus ferrugineus Oliv to Entomopathogenic Nematodes

The effect of two native isolates of entomopathogenic nematodes viz. Heterorhabditis indica Steinernema sp and an exotic species S glasen were studied against the grub and weevils of Rhynchophorus ferrugineus under laboratory conditions All the three entomopathogenic nematodes were found to be pathogenic to both grubs and weevil of R ferrugineus at varying levels. Insect mortality was increased with increase in dosage of nematodes used LC₅₀ value for R ferrugineus adult weevil was 478.9, 293.2 and 733.1 IJ/weevil for H mdica, Sieinernema sp and S glasen, respectively whereas it was 32 1, 24 9 and 82 2 IJ/grub for H indica, Steinernema sp and S glasen, respectively All the three entomopathogenic nematodes were found to be multiplied well on the adults The highest nematode multiplication was noticed in Sieinernema sp (12 01 x 10³/weevil) which was followed by H indica (8 99 x 10³/weevil) at an initial inoculum of 120 IJ/weevil whereas nematode multiplication was recorded on only few grubs