不同类型棉田棉铃虫天敌功能团的组成及时空动态

比较分析Bt基因棉棉田、常规棉综防棉田棉玲虫天敌功能团的组成、数量、时空和多样性的发生动态。主要结果为：Bt棉田比常规棉综防棉田和化防棉田天敌种类分别增加16.3%和54.1%；百株累计捕食性在敌数量分别增加52.8%和176.3%，棉铃虫幼虫寄生蜂数量分别降低42.9%和52.9%；天敌功能团多样性分别增加10.1%和24.1%。常规棉棉田二代、三代棉铃虫幼虫寄生率分别为11.1%－65.0%和4.1%-66.2%，Bt棉田为0.0%-5.0％。就不同类型天敌功能团来说，Bt棉田瓢虫和草蛉的数量比综防棉田分别减少8.4%和5.8%，比化防棉田分别增加34.1%和206.3%；Bt棉田食虫蝽和蜘蛛的数量比综防棉田分别增加180.6%和71.2%，比化防棉田分别增加329.1%和483.7%。棉铃虫捕食性天敌空间生态位发生动态在各类棉田相似。分析认为：Bt棉田有利于保护瓢虫和草蛉，有利于食虫蝽类和蜘蛛类天敌的增殖；Bt棉田棉铃虫天敌群落依次比常规棉综防棉田和化防棉田稳定。不同时期、不同类型棉田的棉铃虫天敌功能团数量和所起的作用不同。6月下旬棉铃虫捕食性天敌控制作用存在“空缺”，7月下旬化防棉田出现天敌控制“空缺”。不同时期捕食性天敌功能团恢复能力有差异。6月底－7月初天敌恢复能力最强，7月下旬，天敌恢复能力最弱。天敌功能团中，瓢虫恢复能力最强，食虫蝽类和蜘蛛类天敌次之。

Comparison Analyses of the Functional Groups of Natural Enemy in Transgenic Bt-cotton Field and Non-transgenic Cotton Fields With IPM, and Chemical Control

Based on the survey in 1997, a further systematic survey was made in a transgenic Bt cotton field and two non-transgenic cotton fields (one with IPM, one with chemical control) in Nanpi county, Hebei province, in 1998. The main purposes for this research were to understand the time-space dynamics of the different functional groups in different types of cotton fields, and work out a new IPM strategy in transgenic Bt cotton fields. In an area of 0.3 hm 2 for each field, 10 plants in 10 spots were fixed for s...