小菜蛾在春茬甘蓝上的分布及其防治研究

Distribution of the diamondback moth,Plutella xylostella,at different cabbage growth stages and its control during spring season

系统调查了小菜蛾在春茬甘蓝不同生育期的分布规律。结果表明，在甘蓝莲座期，小菜蛾的卵主要产在甘蓝近地面的茎部、叶柄和叶背等比较隐蔽的部位，包心初期，大量的小菜蛾幼虫集中在甘蓝的心叶进行为害，进入包心后期，小菜蛾主要在甘蓝的内叶为害，进入收获初期，小菜蛾转移到外叶为害。据此，甘蓝的包心初期和后期是对小菜蛾进行防治的两个重点时期，结合科学合理施药，在甘蓝的整个生长季节施药2～3次即可有效控制小菜蛾的为害。

The distribution pattern of the diamondback moth （DBM）, Plutella xylostella, at different cabbage growth stages was investigated during spring season. The DBM laid most of her eggs on relatively cryptic parts of cabbage, such as stems adjacent to the ground, leafstalks and downside leaves at rosette growth stage. At the ini- tial head formation stage, a large number of DBM larvae were concentrated on the heart leaves. At the late head formation stage, larvae of the DBM were present and caused damage to inner leaves. The DBM shifted to outer leaves at the early harvest time. According to the distribution pattern, the two important stages for control of the DBM were initial head formation stage and late head formation stage. Combined with scientifically sprayed insecticides, 2 or 3 sprays were enough for effective control of the DBM during the whole cabbage growth stage in the spring season.