Evaluation of entomopathogenic nematode (EPN) isolate, Heterorhabditis indica of Vidarbha region, against the tobacco cutworm, Spodoptera litura

Abstract

The present study on pathogenicity of entomopathogenic nematodes against Spodoptera litura in laboratory conditions was undertaken during 2020-21, with the aim to ascertain the effectiveness of entomopathogenic nematodes, against an obnoxious cosmopolitan pest S. litura. Experiments were conducted by using entomopathogenic nematode (EPN) isolate Heterorhabditis indica (CICR-Guava), on filter paper, against Galleria mellonella and S. litura at the treatment dose of 10, 20, 30, 40, 60, 80 and 100 IJs/100µl along with control (Sterile distilled water). The results of our study revealed that, EPN isolate H. indica (CICR-Guava) caused 100% mortality at the treatment dose of 40 IJs/100µl within 72 h of infection in 5th instar larvae of G. mellonella and in case of S. litura, 100% mortality was recorded within 72 h of infection at the treatment dose of 100 IJs/100µl in 3rd instar larvae, which was found more susceptible. The median lethal concentration of H. indica (CICR-Guava) for 5th instar larvae was 2.29 IJs/100µl. The result of reproductive potential of isolates of entomopathogenic nematodes revealed that the highest yield was obtained from 5th instar larvae of G. mellonella at treatment dose of 100 IJs/100µl 278667 IJs per larva. In case of S. litura, the highest yield obtained was 152533 IJs. It could be concluded that, there was a positive correlation between nematode treatment concentration, time of exposure and the insect mortality of the tobacco cut worm and multiplication rate of IJs increased with increase of exposure time and size of larvae. This EPN isolate, H. indica (CICR-Guava) can be suggested as biocontrol agents for the control of S. litura in the Vidarbha region.