Effective Management of Scirpophaga incertulas Walker on Rice Crop During Kharif Season in West Bengal, India

摘要

Scirpophaga incertulas Walker (Pyralidae: Lepidoptera) is a cosmopolitan pest to rice crop (also known as yellow stem borer or YSB) rendering extensive damage to growing stems at pre-harvest condition. Effective control of S. incertulas population by broadly defined insecticide based management strategy is found less prudent due the regional variability of the pest life cycle. An amalgamation of some selected cultural practices as a part of phyto-sanitation together with the adoption the judicious application of least toxic insecticide formulation was found effective to check borer menace and side by side also to restore field natural enemy population. Experiment for three consecutive years (2008-2010) at the upper Gangetic plains of West Bengal (India) was done to assess the relative efficacy of some selected insecticide formulations on both S.incertulas and its natural enemies in field condition. Efficacy of each treatment was estimated in consideration of yield, extent of suppression of pest induced damage and the retention of natural enemy population. In consideration of yield, need-based application of new generation pesticide like flubendiamide (480 SC) together with the conventional application of neem seed kernel extract [NSKE] (5%), neem leaf extract[NLE] (5%), deltamethrin (1%) +triazophos (35%) gave best result. This result was followed by the application of new molecule of rynaxypyr(0.4%G) and the usual use of NLE (5%), NSKE (5%), clorpyriphos (50%). Formulation of NSKE (5%), emamectin benzoate, NLE (5%), clorpyriphos (50%) neem and oil is the third best application protocol. This was followed by the application of neem oil mix formulation, clorpyriphos (50%)+ cypermethrin(5%) and NLE(5%). Application of NSKE (5%), neem oil (5%), carbofuran (35 G) ranked sixth. Least was noted in only NSKE (5%) application. Though yield was comparatively low in treatment of NSKE (5%), but it has supported second highest number of natural enemies. Application of NLE (5%) + flubendiamide (480 SC)+ NSKE (5%)+[ (deltamethrin 1% +triazophos 35%)] was relatively more lethal to the natural enemies and the incidence of all the natural enemies were lowest. The control plot registered maximum number of natural enemies though the yield was minimum against all treatments.