Potential of Entomopathogenic Nematode (Steinernema kraussei) against Last Instar Larvae of Different Lepidopteran Insect Pests

ABSTRACT Entomopathogenic nematodes(EPNs) are considered as very effective biological agents against several soil dwelling pests. The following research demonstrates the reproductive potential of EPN specie Steinernema kraussei against last instar larvae of four lepidopteran insects, wax moth(Galleria mellonella), pink bollworm(Pectinophora gossypiella), eggplant fruit borer(Leucinodes orbonalis) and armyworm(Spodoptera litura) at 27±2°C under laboratory conditions. The results indicated that the larvae of G. mellonella and S. litura were better host as compared to P. gossypiella and L. orbonalis for multiplication of infective juveniles(IJs) of the S. kraussei. Four different concentrations(50, 100, 200 and 500 IJs) of tested EPN specie were used against insect's larvae. Reproduction rate of S. kraussei was highest at concentration of 500 IJs as compared to 50, 100 and 200 IJs. Similarly, the effect of different temperatures was also studied to evaluate the efficacy of S. kraussei on insect larvae. At 25°C, S. kraussei showed significantly higher larval mortality of insect larvae followed by 15°C and 10°C. Effect of storage time of EPN culture was studied on insect's larvae and results showed that 2-week-old culture was more efficient as compared to 4-and 6-week-old cultures in reproduction. The larvae weight of 0.5 g was best option in comparison to 0.25 g for the reproduction of S. kraussei. The results conclude that S. kraussei is a potential biological control candidate to suppress the larval populations of a number of Lepidopteran insects in the soil.