The population dynamics of the vegetable whitefly, B. tabaci, was investigated in spring and autumn of 2009, and its resistance to 3 neonicotinoid insecticides was investigated during 2009-011 to provide the basic information and scientific guidance. The results showed that the population of whiteflies increased quickly in the mid-May until harvest time in spring. It rose up in early September in the plastic shed in autumn, which occurred later in the open field, then decreased in mid-October. The population of B. tabaci was obviously higher in the plastic shed than in the open field. The resistance of B. tabaci to imidacloprid and thiamethoxam was very high in 2009, and significantly decreased in 2010 and 2011, with LC50 values from 133. 94mg/L to 251. 16mg/L, which were moderate resistance. In contrast, its resistance to nitenpyram increased consistently from 2009 to 2011, having the resistance ratio from 6. 68-fold to 83. 62-fold. It's proper to grasp the periods before mid-May in spring and mid-September in autumn with lower population densities for control of B. tabaci in Beijing area. The resistance of B. tabaci to nitenpyram has increased rapidly in recent 3 years and attention should be paid to the insecticide rotations.%为了明确北京地区蔬菜烟粉虱的种群发展动态及对常用烟碱类杀虫剂的抗药性,为烟粉虱防治适期的确定及高效杀虫剂的选择提供基础资料及科学指导,2009年调查了北京地区春茬和秋茬蔬菜烟粉虱的种群动态,并监测了该地区2009-2011年度烟粉虱种群对3种烟碱类杀虫剂的抗药性.结果表明,春茬蔬菜烟粉虱在5月中旬种群快速上升,持续到春茬拉秧；秋茬蔬菜烟粉虱在塑料棚内9月上旬种群数量即开始上升,露地出现时间较晚,10月中旬后种群数量下降；塑料棚内种群数量明显高于露地蔬菜烟粉虱数量.烟粉虱2009年对吡虫啉和噻虫嗪的抗药性很高,2010年和2011年抗性程度显著下降,LC50处于133.94～251.16 mg/L,属中等抗性水平；而对新型杀虫剂烯啶虫胺的抗药性在近3年内持续升高,抗性倍数由6.68倍升至83.62倍,即由低抗性水平升至高抗性水平.上述调查结果表明,北京地区蔬菜烟粉虱的防治应掌握春季5月中旬前、秋季9月中旬前种群处于低密度时进行.烟粉虱对新型杀虫剂烯啶虫胺的抗药性在近三年内快速上升,生产中应注意药剂的轮换使用.
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