Abstract:

【Objective】 To carry out quantitative evaluation of the control effects of predatory natural enemies on cotton aphids (Aphis gossypii) by using DNA molecular detection techniques in Xinjiang cotton fields in the hope of providing important scientific and technological support for the effectively use of predatory natural enemies in biological control. 【Methods】 In this paper, we firstly carried out the correlation analysis between the population number of cotton aphids and the detection rate of cotton aphids in the midgut of predatory natural enemies by using DNA molecular detection technology, and then the dominant predatory natural enemies in Xinjiang cotton fields was determined based on the detection rate of cotton aphids. Meanwhile, the feeding preference habits of predatory ladybeetles were analyzed based on the detection rate of cotton aphids and Therioaphis trifolii in the midgut of predatory ladybeetles collected from cotton fields and adjacent alfalfa strips, respectively. 【Results】 In 2019 and 2021,the population number of cotton aphids was closely correlated with the detection rate of cotton aphids in the midgut of predatory natural enemies, and the Pearson correlation coefficients was 0.921 and 0.839, respectively. The quantitative analysis of the detection rate of cotton aphids in the midgut of different predatory natural enemies in two years showed that Hippodamia variegata was the dominant predatory natural enemy in Xinjiang cotton fields. In 2019, when predatory ladybeetles were collected from alfalfa strips, the detection rates of T.trifoliiin June, July and August were respectively 52.50％, 73.70％ and 27.95％, and the detection of rates cotton aphids in June, July and August were 0,21.10％ and 38.71％, respectively. When predatory ladybeetles were collected from cotton fields, the detection rates of cotton aphids in June, July and August were respectively 18.11％, 75.52％ and 49.53％, and the detection rates of T.trifoliiin June, July and August were 92.12％, 29.60％ and 5.61％, respectively. These results showed that predatory ladybeetles mainly feed on T. trifoliifrom alfalfa strips when the population number of cotton aphids was fewer, and they mainly feed on aphid species from their habitats when cotton aphids and T. trifolii simultaneously occurred. 【Conclusion】 The control effects of predatory natural enemies on cotton aphids could be quantitatively evaluated by using DNA molecular detection techniques. Alfalfa strips adjacent with cotton fields can provide alternative prey for predatory natural enemies, which play an important role in their conservation.

Key words: DNA molecular detection technology; quantitative analysis; predatory natural enemies; cotton fields; alfalfa strips

摘要：

【目的】利用DNA分子检测技术定量评价新疆棉田重要捕食性天敌对棉蚜的控害作用,为有效发挥捕食性天敌在棉田害虫生物防治中的作用提供支撑。【方法】田间系统调查棉蚜种群数量,运用DNA分子检测技术定量分析的捕食性天敌中肠棉蚜检出率并分析相关性,以棉蚜检出率为依据研究新疆棉田优势捕食性天敌,基于棉田和邻近苜蓿条带采集捕食性瓢虫的中肠对棉蚜和三叶草彩斑蚜的检出率分析捕食性瓢虫的取食偏好习性。【结果】2019~2021年,棉田棉蚜种群数量和捕食性天敌中肠棉蚜检出率均密切相关,Pearson相关系数分别为0.921和0.839;多异瓢虫是新疆棉田优势捕食性天敌。2019年当捕食性瓢虫采自苜蓿条带时,三叶草彩斑蚜在6月、7月和8月的检出率分别为52.50 ％、73.70 ％和27.95 ％,棉蚜在6月、7月和8月的检出率分别为0、21.10 ％和38.71 ％;当捕食性瓢虫采自棉田时,棉蚜在6月、7月和8月的检出率分别为18.11％、75.52 ％和49.53 ％,三叶草彩斑蚜在6月、7月和8月的检出率分别为92.12 ％、29.60 ％和5.61 ％。当棉蚜种群数量较少时,捕食性瓢虫以取食苜蓿条带的三叶草彩斑蚜为主,当棉蚜和三叶草彩斑蚜同时发生时,捕食性瓢虫以取食栖息生境的蚜虫种类为主。【结论】利用DNA分子检测技术可以定量评估捕食性天敌对棉蚜的控害作用。邻近棉田的苜蓿条带可以为捕食性天敌提供替代食物,对其具有重要的保育作用。

关键词: DNA分子检测技术, 定量分析, 捕食性天敌, 检出率, 棉田, 苜蓿条带