Morpho-taxometrical and molecular characterization of Steinernema abbasi (Nematoda: Steinernematidae) and its pathogenicity and generative potential against lepidopteran pests

Abstract

BackgroundAn entomopathogenic nematode (EPN) was recovered by using Galleria baiting technique from the soils of marigold fields of Noida, Uttar Pradesh, India. Based on morphological, morphometrical and molecular characterizations, the isolated strain was identified as Steinernema abbasi and tagged as CS38. The isolated strain was conspecific to original description with minor deviations. Infective juveniles (IJs) of present strain were longer than original description.ResultsMolecular analysis was done using ITS1-5.8S-ITS2 and D2D3 regions. Pathogenicity and generative potential of the present strain CS38 were tested against larvae of 3 lepidopteran insect pests, namely, Galleria mellonella L., Helicoverpa armigera (Hb.) and Spodoptera litura (Fab.). Different concentrations of IJs/larva, viz. 25, 50, 100, and 200 IJs/larva, were used for bioassay trails. All experiments were repeated thrice to reach the optimum authenticity. Results of bioassays revealed that isolate CS38 was highly virulent against the 3 insect pests and caused (100%) mortality within 48 h under laboratory conditions. Generative potential of the studied S. abbasi CS38 was recorded high in G. mellonella (19 × 104 IJs/larva) at 100 IJs/larva concentration, followed by H. armigera (63.4 × 103 IJs/larva) and S. litura (60.5 × 103 IJs/larva).ConclusionsIsolate CS38 is an indigenous, dominant and highly virulent strain that can be utilized as a biological control agent against the three studied insects. Moreover, it can be used for commercialization of the production of EPN-based biopesticide to be added under Integrated Pest Management in Indian agriculture system.