Determination of Economic Threshold level (ETL) of brown planthopper, Nilaparvata lugens Stal. population in different stages of rice crop at Raipur

Abstract

Determination of Economic Threshold Level (ETL) was carried out at glass house of\rEntomology Dept., Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh during\r2012 and 2013. The five to ten BPH nymphs/hill attacked at seedling, fifteen to twenty\rat tillering and twenty to twenty five at booting stage can cause yellowing in lower\rleaves then wilting and death in the varieties TN-1, Swarna, Karma mahsuri and\rMahamaya. However, the variety Ptb-33 is not affected because of its high level of\rresistance to BPH but Karma mahsuri was moderately susceptible as compared to TN-\r1 but variety Mahamaya and Swarna noticed high level of susceptibility. Descending\rorder of BPH infestations observed with the different varieties can be ranked as TN-1\r< Swarna < Mahamaya < Karma masuri < ptb-33 within seven day after nymph release.