中文摘要：

2009-2011年对内蒙古呼和浩特市郊区十字花科蔬菜和武川县油菜上小菜蛾Plutella xylostella（L-1）种群消长动态进行了调查，并比较了呼和浩特地区小菜蛾对11种杀虫剂的抗药性。结果表明，在呼和浩特郊区，小菜蛾成虫于4月上旬开始出现，一年中有4个发生高峰，分别为4月下旬或5月上旬、6月中旬、8月下旬和10月上旬；小菜蛾幼虫在春甘蓝和秋白菜整个生长期间均有发生，大约有4个发生高峰，分别为6月上中旬、6月下旬或7月上旬、9月上旬和10月上旬。在武川县，小菜蛾成虫于4月末或5月初开始发生，春夏季数量高于秋季，共有2个发生高峰，2009年为5月下旬和6月中旬，2010年为6月上旬和8月上中旬；小菜蛾幼虫在6月下旬开始出现，在油菜整个生长期间，小菜蛾幼虫约有3个数量高峰，分别为7月初、7月末和8月下旬，秋季数量高于春夏季。在供试的11种杀虫剂中，溴虫腈对小菜蛾幼虫的毒力最高，Lc。为0．22mg·L-1其次为多杀菌素、氯虫苯甲酰胺、氟虫腈和BT，Lc，。分别为0．82—0．83、1．09、1．36和3．41mg·L-1；再次为茚虫威和阿维菌素，LC50分别为15．74mg·L-1和6．03～23．47mg·L-1；然后为丁醚尿、虫酰肼和啶虫隆，LC5。分别为51．30、52．66和61．9lmg·L-1最低为高效氯氰菊酯，L。为462．66～673．26mg·L-1。抗药性测定表明，呼和浩特地区小菜蛾幼虫未对溴虫腈、虫酰胼、氯虫苯甲酰胺和丁醚尿产生抗性，对多杀菌素和氟虫腈为低抗性，对茚虫威和BT为中抗性，对高效氯氰菊酯、啶虫隆和阿维菌素为极高抗性。

英文摘要：

The population dynamics and insecticide resistance of the diamondback moth, Plutella xylostella （ L. ）, were investigated on cruciferous vegetables in a Hohhot suburb, and on rapeseed in Wuchuan County, Inner Mongolia from 2009 to 2011. In the suburb of Hohhot city, adult moths began to occur in early April and had four peaks of abundance during the year： late April or early May, mid- June, late August and early October. Larvae were continually present during the growing season of cabbage and Chinese cabbage and had four peaks of abundance ： early mid-June, late June or early July, early September and early October. In Wuchuan county, adults first appeared in late April or early May and there were more adults in spring and summer than in autumn. In 2009 two peaks occurred in late May and mid-June but in 2010 peaks occurred in early June and early to mid-August. Larvae began to appear in late June and had three peaks during the rapeseed growing season in early July, late July and late August. There were more larvae in autumn than in spring and summer. The toxicity of eleven insecticides to larvae was tested using the leaf dipping bioassay method. The most toxic was Chlorfenapyr with a LCso value of 0.22 mg. L-1, followed by spinosad, chlorantraniliprole, fipronil and BT- CrvlAc, with LCs0 values of 0.82 - 0. 83,1.09, 1.36 and 3.41 mg. L-1 , respectively, indoxacarb and abamectin with LC50 values of 15.74 mg. L-1 and 6.03 - 23.47 mg L-1 , respectively, diafenthiuron, tebufenozide and chlorfluazuron with LC50 values of 51.30,52.66 and 61.91 mg L -1 , respectively, and finally alpha-cypermethrin with LCs0 values of 462.66 - 673.26 mg. L-1. A resistance bioassay of P. xylostella larvae to 11 insecticides indicated no resistance to chlorfenapyr, tebufenozide, chlorantraniliprole and diafenthiuron, low resistance to spinosad and fipronil, moderate resistance to indoxacarb and BT-CrvlAc and high resistance to alpha-cypermethrin, chlorfluazuron and ahamectin.