Susceptibility of Different Developmental Stages of the Tobacco Cutworm, Spodoptera litura (Fabricius) to Entomopathogenic Nematode, Steinernema abbasi PN-1

The tobacco cutworm, Spodoptera litura Fabricius is a widely distributed polyphagous pest that is causing economic damage to different crop plants. Many pesticides have been used extensively to control S. litura, but they are currently ineffective because of the development of pesticide resistance and their detrimental effects on the environment and human health. Although entomopathogenic nematodes (EPNs) have been employed as biological control agents against S. litura, little is known about the pathogenicity of these EPNs. Here we studied the virulence of Steinernema abbasi PN-1 against different stages of S. litura. The results reveled that all tested larval stages and pupae of S. litura were found susceptible to S. abbasi. There was a positive correlation between insect mortality and the nematode concentration. The S. abbasi caused 100 per cent larval mortality at 48-60 h of post treatment in all tested doses in laboratory. There was a positive correlation between insect mortality and the nematode concentration while the time to cause complete mortality was negatively correlated with the increase in larval days and nematode concentration. However, further field studies are required use S. abbasi as efficient biological control agents against S. litura.