Isolation, identification, bioassay of native entomopathogenic nematodes, Steinernema siamkayai stock, somsook & reid, 1998 (Rhabditida: Steinernematidae) and Heterorhabditis indica Poinar, Karunakar and David, 1992 (Rhabditida: Heterorhabditidae) and their bio-efficacy against banana stem weevil, Odoiporus longicollis (olivier) (coleoptera:curculionidae)

Three native isolates of entomopathogenic nematode (EPN) were isolated from soil samples collected from Tiruchirappalli, Tamil Nadu. Based on sequence annotation of ITS region of rDNA, the EPN species were identified as Steinernema siamkayai (NCBI accession nos. MH091332 and MH091330) and Heterorhabditis indica (MH 299879).Virulence of these two EPN species showed that S. siamkayai was more virulent than H. indica, as the maximum insect mortality caused by S. siamkayai and H. indica, at 200 infective juveniles per insect was 74.6% and 69.2% respectively, at 72 hours of exposure. LD₅₀ values of S. siamkayai and H. indica were 1.09 and 2.74, at 96 hours of incubation. H. indica was found to be more effective than S. siamkayai against adults of banana pseudostem weevil, Odoiporus longicollis, as the former causes 100% weevil mortality, at an inoculum of 20, 000 at 120 hours of exposure, compared to 80% of S. siamkayai. The results of this study revealed the potential and scope of EPNs for the management of O. longicollis in banana.