Bio-Efficacy of Some Newer Insecticides Against Yellow Stem Borer, Scirpophaga Incertulas (Walker) and Leaf Folder, Cnaphalocrocis medinalis (Guenee) in Aromatic Rice

Abstract

An investigation was carried out to study the "Bioefficacy of some newer insecticides against yellow stem borer, SciqJophaga incertulas .(Walker) and leaf folder, Cnaphalocrocis medina lis (Guenee) in aromatic rice" in randomized block design with three replications at Crop Research Centre of Sardar Vallabh Bhai Patel University of Agri. & Tech., Meerut. During the crop season, twelve insect species were found attacking the aromatic rice at different crop growth stages. Of these, yeJlow stem borer, S. incertulas Walker and leaf folder, C. medinalis Guenee were recorded as major pests. The incidence of S. incertulas was recorded first on third week of July and reached to its peak (8.66 per cent dead heart) during middle of October when average temperature and relative humidity were 27.75°C and 59.47 per cent, respectively. The inci<dence of C. medinalis was first recorded on second fortnight of July and reached a maximum level at the end of August to start of September when mean • temperature and relative humidity were 26.75°C and 72.79 per cent, respectively. The incidence of S. incertulas and C. medina/is were negatively correlated with all the weather parameters. Efficacy of different insecticides viz., imidacloprid, triazophos, B. thuringiensis, indoxacarb, endosulfan, spinosad, thiamethoxam, monocrotophos and lambda cyhalothrin tested against S. incertulas and C. medina/is revealed that lambda cyhalothrin @ 25 m1 a.i./ha was found most effective treatment in reducing the infestation of both the insects followed by indoxacarb @ 36 ml a.i./ha. The endosulfan @ 700 tnl a.i./ha was recorded less effective. Among biopesticides, a new molecule spinosad @ 200 m1 a.i./ha was found more effective. The higher yield ( 44.10 q/ha) and higher cost benefit ratio ( 14.04) were also obtained frOJn lambda cyhalothrin. Bacillus thuringiensis was found most safer to spider population followed by spinosad at all observational interval.