Characterisation of indigenous entomopathogenic nematode, Steinernema abbasi PN-1 Elawad and its biocontrol potential against major lepidopteran pests

Soil samples were collected from different crop research center(s) from G B Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India to isolate & identify the occurrence of entomopathogenic nematodes (EPNs). The isolated EPN from soil samples was identified as Steinernema abbasi (PN-1) based on morpho-taxometric and molecular studies. Phylogenetic analysis of the present isolate S. abbasi PN-1 based on D2/D3 regions showed no variation among populations of S. abbasi. This is the first report of the existence of an indigenous isolate of EPN (Steinernema abbasi) in Pantnagar, Uttarakhand, India. To understand the host range of S. abbasi, PN-1, insects of different orders: Lepidoptera, Coleoptera, and Hemiptera were selected and exposed to PN-1 at the concentration of 200 IJ (Infective Juvenile)/1000 µl. PN-1 was found to be effective against insects of all the order used in present study. However, the insects from order Lepidoptera were highly susceptible to PN-1 as 100 per cent mortality was recorded at 48 h after treatment. To study time concentration mortality response of PN-1, five different doses were used and tested against 2nd, 3rd, 4th instar larvae of Galleria mellonella, Helicoverpa armigera, Spodoptera frugiperda, and Spodotera litura in laboratory condition. From this study it was concluded that late instars were more susceptible to younger instars. There was a positive correlation between nematode concentration and insect mortality, while the median lethal time (LT50) was negatively correlated with increased nematode concentration and larval instar stages.