Through recent two years' systematical investigations on two spotted spider mite, it was clear that the plants with mite,plants with red leaf, the number of red leaf, leaves with mite and the number of adult and nymphal mite in the transgenic Bt cotton fields were always higher than those in the conventional cotton fields, but there were no significant differences.In the whole growth and developmental period of cotton, two spotted spider mite occurred mainly in the first twenty days of June and from the end of July to beginning of August, and this mite had the similar population dynamics in two types of cotton fields.In addition, when the previous crop of cotton was different, the occurrence and damage of two spotted spider mite in cotton field were also different, the population density of the mite and the number of damaged plants in the cotton field without previous crop were always obviously lower than those in the cotton field with previous crop horsebean.%通过近2年的系统调查,明确了Bt棉处理棉叶螨的有螨株、红叶株、红叶数、有螨叶和成若螨数量始终高于常规棉对照,但差异均不显著;棉叶螨在在棉花全生育期的发生为害主要有2个时段,1个是在6月上中旬前茬夏熟作物成熟离田期,另1个是在7月底8月初秋熟玉米成熟离田期,两类棉田处理所表现的消长动态也基本相似.另外,棉花前茬茬口不同,棉叶螨的发生为害也有差异,空白茬口棉田的螨量与被害株始终低于蚕豆茬,趋势十分明显.
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