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我县随着栽培制度的改革,褐稻虱逐步上升为水稻穗期的大害虫。近年来对水稻生产威胁极大。褐稻虱在我县一般于7月中、下旬由外地大量迁入,以后在本地繁殖3—4代。8月下旬—9月上旬发生的第四代,为害单季晚稻;9月下旬—10月上旬发生的第五代,为害单季稻、后季稻。四、五代的虫量很大,一般年份,四代虫口每亩12—30万头,大发生年高达100万头以上;五代虫口单季晚稻50—200万头,后季稻10—80万头;大发生年单、后季稻的虫量分别每亩达220万头和170万头左右。而三代虫量则很少,主要发生
With the reform of the cultivation system in our county, brown planthopper gradually rose to a large pest in rice heading stage. In recent years, the threat to rice production is enormous. Brown planthopper in my county generally in mid-July, late from a large number of immigrants from the field, after breeding 3-4 generations in the local. In late August - early September occurred in the fourth generation, damaging single-season late rice; late September-early October occurred in the fifth generation, damage single-season rice, the latter part of rice. Four or five generations of large quantities of insects, the general year, four generations of insect population of 123,000 acres per acre, the annual occurrence of up to 1 million more than five generations of insects single-season late rice 50-200 million, 10-80 million after the season rice Head; the annual occurrence of large single, the amount of late rice crop up to 2.2 million acres and 1.7 million heads each. The three generations of insects is very small, the main occurrence