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Background: Soybean, Glycine max (L.) Merr.) is an important kharif growing crop and affected by a number of insect pests which are directly or indirectly decrease the yield. To increase the yield, the infestation by insect pest should be managed. Spodoptera litura is considered as the major pest of soybean crop and damages soybean to a very extent. Cultivation of insect resistant soybean can be the best technique for pest management program. Insect resistance is usually conferred by antixenosis i.e. the set of plant characteristics and insect responses that lead to undesirability of host. Thus, to find out the antixenosis resistance among 16 germplasm this study was performed. Methods: Seasonal incidence of S. litura was recorded with the abiotic parameter. Antixenosis resistance was determined through non-choice and free-choice feeding assay likewise MLAC (cm2) and C-value were calculated to find out the preference or non-preference of soybean germplasm. Trichome density and length were also examined which aids in the resistance mechanism. Result: Incidence of pest show positive correlation with temperature and morning humidity. The data on area consumption and C-value of soybean signified the resistant germplasm (BAUS 102, DSB34, MACS 1493 and RSC 11-03) and highly susceptible germplasm (NRC 131 and RSC 11-07) against S. litura which also conferred indirect relationship with trichome density and length.

Four plant oils at the concentrations of 2.5, 5 and 10% viz.; Jatropha, (Jatropha curcas) Ocimum, (Ocimum grattisimum) Kapoor, (Cinnamomum camphora) Lantana, (Lantana camara) were tested for the growth regulatory activities against 8 day old larvae of S. litura and S. obliqua larvae and plant oil composition testing by GC-MS analysis for selected oils. Among four oils J. curcas (10%) showed better results for both the insects while least effective were L. camara (2.5%) and C. camphora (2.5%) for S. litua and S. obliqua larvae respectively. J. curcas (10%) also showed highest terminal larval mortality followed by C. camphora > O. grattisimum > L camara for mentioned insects. The analysis of plant oils revealed the presence of over 43 compounds, contributed to 99.16, 92.78 and 94.97 % of the total tested oils (J. curcas, O. grattisimum and C. camphora) respectively. In tested oils by GC-MS analysis among other compounds in highest quantity terpenoids were found. These plant secondary metabolites can be the responsible factor for effect of plant oils against insect-pest growth and development or as plant based insecticides.