A Global Perspective of Rice Brown Planthopper Management II- After Green Revolution Era

Rice Brown Plant hopper, Nilaparvata lugens (Stal) (BPH) has started becoming a major pest in tropical rice growing countries only after major areas were covered by dwarf varieties or high yielding varieties (HYVs). Detailed discussion both historical and experimental evidence on several possible causes like Changed architecture of rice plant, Associated change in agricultural practices, change in micro-climate in rice crop ecosystem, Lack of insect resistance in dwarf varieties, Increased use of insecticides, Consequent destruction of natural enemies, Development of insecticide resistance is presented. Among these, microclimatic factors in rice ecosystem, notably optimum temperature, low wind movement, high water vapor pressure and consequent high relative humidity among abiotic factors and nitrogen rich plant sap among biotic factors appeared to be the most important. Lack of BPH resistance in HYVs does not appear to be the primary cause. Higher insecticide usage in HYVs appeared to be responsible for persistence of BPH menace partially due to destruction of natural enemies and more importantly through development of insecticide resistance and resurgence. However this seems to be secondary cause for BPH problem in all tropical rice growing countries of Asia including China and India.