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本文应用种群数量发展趋势指数和干扰作用控制指数，研究不同菜场的小菜蛾Ｐｌｕｔ－ｅｌｌａｘｙｌｏｓｔｅｌｌａ（Ｌ．）种群动态。在大量而频繁施用广谱性杀虫剂的菜场，小菜蛾的种群数量发展趋势指数高达２９．３。在应用苏云金杆菌制剂代替广谱性杀虫剂的菜场，经过若干世代以后，小菜蛾的种群数量发展趋势指数下降为４．８８，接近于不使用化学杀虫剂的小区的水平（３．４０）。在试验中，散放赤眼蜂Ｔｒｉｃｈｏｇｒａｍｍａ（Ｔ．ｃｏｎｆｕｓｕｍＶｉｇｇｉａｎｉ，＝Ｔ．ｃｈｉｌｏｎｉｓ，Ｎａｇａｒａｊａ，ｎｅｃ．Ｉｓｈｕ）使小菜蛾种群干扰作用控制指数下降为０．２４。施用苏云金杆菌制剂使小菜蛾的种群数量发展趋势指数下降为０．２９，这两种措施在种群数量发展趋势指数比较低的情况下可以防治小菜蛾。散放赤眼蜂和施用苏云金杆菌制剂的处理，种群数量发展趋势指数下降为０．０６，表达了两者相辅相成的作用。即使在种群数量发展趋势指数高达２９．３，也可能受到良好的效果。
In this paper, population dynamics of Plut-ellaxylostella (L.) Populations in the diamondback moth (Plutella xylostella) were studied by using population trend index and disturbance control index. In a large and frequent application of broad-spectrum insecticides in the farms, the diamondback moth population trend index up to 29.3. After a few generations of applying the Bacillus thuringiensis preparation instead of a broad-spectrum insecticide, the population trend of Plutella xylostella dropped to 4.88 and was close to the level of a community without chemical pesticides (3.40 ). Trichogramma (T. confusum Viggiani, = T. chilonis, Nagaraja, nec. Ishu) was used to reduce the control index of the disturbance of diamondback moth populations to 0.24. Application of Bacillus thuringiensis to the Plutella xylostella population trend index down to 0.29, both measures in the case of population trends in the number of relatively low resistance to the diamondback moth. Trichogramma spread and application of Bacillus thuringiensis preparation treatment, population trends index decreased to 0.06, expressed the role of the two complement each other. Even with a population trend index of up to 29.3, good results may be achieved.