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本文系统调查研究化防与非化防两类棉田中棉蚜和天敌种群动态。结果表明:化防与非化防两类棉田中,棉蚜有非常相近的种群动态结构。均于6月5日—15日出现第一次发生高峰,6月20—25日出现第一次发生低谷;7月5日—15日出现第二次发生高峰。以后相继出现数个小的种群数量变化波动。棉蚜于6月5日—10日出现第一次迁飞高峰,6月25日—30日出现第二次迁飞高峰。棉田天敌种群数量来源在6月10日之前主要为外境天敌向棉田迁入,且尾随蚜量紧密。无时间差。6月10日之后主要是棉田自身天敌的繁衍增殖,开始有尾随时间差。当蚜量与天敌单位之比大于150时,蚜量将继续增加,天敌尾随;当蚜量与天敌单位之比小于或等于150时,蚜量将逐渐减少;瓢虫在我地区年发生4—5代。棉田天敌在6月25日之前以瓢虫为主,占棉田天敌单位总量的81,4%。草蛉占15,8%,食蚜蝇、蜘蛛、寄生蜂等占2.8%。6月25日之后,以草蛉为田间优势天敌种群,占田间天敌单位总量的61.5%,瓢虫占31.7%;化防对棉蚜种群影响不大(甚至会激发棉蚜虫的大发生),而对天敌种群数量影响较大。棉蚜在棉株现蕾前数量较大,危害明显,而在现蕾后,数量较少,危害较少。
This paper systematically investigates the population dynamics of cotton aphids and their natural enemies in two types of cotton fields. The results showed that cotton aphid had a very similar dynamic population structure in two types of cotton fields. The first peak occurred on June 5 and June 15, the first trough occurred on June 20 and June 25, and the second peak occurred on July 5 and July 15. Since then there have been several small changes in population fluctuations. Cotton aphid appeared on June 5 -10, the first peak of migration, June 25 -30 appeared the second peak of migration. Natural enemies of cotton population sources before June 10 mainly for the natural enemies of cotton moved into the field, and the amount of trailing aphids close. No time difference. After June 10, the main multiplication and multiplication of its own natural enemies in cotton fields began to have a trailing time difference. When the ratio of aphids and natural enemy units is greater than 150, the amount of aphids will continue to increase and the natural enemies trailing. When the ratio of aphids and natural enemy units is less than or equal to 150, the amount of aphids will gradually decrease; 5 generations. Cotton field natural enemies before June 25 ladybugs, cotton natural enemies accounted for 81.4% of the total units. Scallops accounted for 15,8%, hoverflies, spiders, parasitic wasps, etc. accounted for 2.8%. After June 25, the dominant species of natural enemies in the field were grass weeds, accounting for 61.5% of the total natural enemies in the field and 31.7% in ladybugs. The chemical defense has little effect on the populations of cotton aphids (even triggering a large occurrence of cotton aphids) , While the number of natural enemies has a greater impact on the population. Cotton aphid large number of buds before the bud, the damage was obvious, but after the budding, the smaller the number, less harmful.