Field screening of common jute (Corchorus olitorius) varieties against major pests in Eastern Terai region of Nepal

Field screening of eleven most popular jute varieties belonging to Corchorus olitorius species was done against the major pests in the farm of Jute Research Programm, Itahari, Sunsari, Nepal during 2017 and 2018. Different species of pests belonging to insects, mites and nematodes were found feeding on jute. Among them, jute Semilooper (Anomis sabulifera Guen.), Bihar hairy caterpillar (Spilarctia obliqua Wlk.), yellow mite (Polyphagotarson emuslatus Banks), are causing economic damage to the jute crop. Eleven jute varieties were selected to conduct varietal preference and tested against major pest of jute in field condition. Among the eleven varieties JRO-524 was found to be moderately resistant against the Semilooper (A. sabulifera) and Bihar hairy caterpillar (S. oblique) but least susceptible to yellow mites. Likewise, the variety KEN-DS-058, KEN-DS-066, BJRI-1965 and BJRI-1968 showed highly susceptible to major pest Semilooper (A. sabulifera), Bihar hairy caterpillar (S. oblique) and yellow mites. The variety BRD-SRB-061, YA-41, O-4, KEN-BL-130, Itahari-2 showed moderate resistance to Semilooper (A. sabulifera), Bihar hairy caterpillar (S. oblique) but moderately susceptible to yellow mites. Further, the fibre production capacity of the varieties under different pest’s pressure was found relatively higher in variety JRO-524 followed by YA-41, BRD-SRB-061, KEN-BL-130 and O-4 respectively. The relatively higher yield recorded under varying pest levels over two consecutive seasons is an indicative of greater field tolerance of olitorius jute varieties.

Detrimental effect and GC-MS analysis of some plant oils against Polyphagous pests Spodoptera litura and Spilarctia obliqua

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.