Biocontrol Potential of the Entomopathogenic Nematodes, Heterorhabditis bacteriophora and Steinernema feltiaefrom North Western Himalayan Region on Fruit Fly, Bacterocera zahadi Mahmood (Diptera: Tephritidae)

The two indigenous Entomopathogenic Nematodes (EPNs) strains, Heterorhabditis bacteriophora HR2 and Steinernema feltiae HR1, have been evaluated against distinct developmental stages of the fruit fly, Bacterocera zahadi Mahmood i.e. larvae and pupae. Native EPNs strains were isolated and laboratory bioassay studies were done to determine their infectivity against pumpkin fruit fly (Diptera: Tephritidae). The maggots and pupae of B. zahadi Mahmood were exposed to EPNs in Petri plates (9.0 cm diameter) lined with Whatman No.1 filter paper and in plastic cups (4.0 cm diameter) filled with a substrate consisting of a 1:1 mixture of 30-mesh sieved sand and potting soil, respectively, and their susceptibility to nematode infection was determined at various concentrations of 10, 20, 40, 80, and 160 IJs/cm². The 10 larvae and pupae of the test insect were added and allowed to burrow into the substrate within 1 hour of IJs treatment. Both EPN species induced varying amounts of mortality in petri plates containing 10 larval insects, with maximums of 68.66 percent and 54.66 percent caused by H. bacteriophora and S. feltiae, respectively after seven days of exposure at 160 IJs/cm². After seven days of exposure time in plastic jars, various levels of mortality caused by H. bacteriophora and S. feltiae was documented, with maximums of 53.33 percent and 50.00 per cent caused by H. bacteriophora and caused by S. feltiae, respectively. Based on its higher virulence and better ability to penetrate the larval/pupal tissue, the results indicated that H. bacteriophora was found to be the most effective species and may have potential as a biocontrol agent of B. zahadi. Further field testing can be performed for incorporating these indigenous strains of EPNs in an integrated pest management programme for fruit fly management under the mid hills of Himachal Pradesh, India.