北疆棉田捕食性天敌昆虫应对棉蚜的数量反应

Behavioral responses of predatory insects to Aphis gossypii in cotton fields in north Xinjiang

【目的】棉蚜Aphis gossypii是新疆棉田的主要害虫,近来的研究多集中于南疆棉区,较少关注北疆棉田在新种植模式下的天敌种群数量发生规律。本文研究了北疆棉田棉蚜的优势种捕食性昆虫数量发生规律。【方法】对五家渠地区棉田中棉蚜及其4种主要捕食性天敌昆虫(2种瓢虫和2种草蛉)的种群数量进行了持续2年的跟踪调查。【结果】不同种捕食性天敌昆虫对棉蚜种群数量变化具有不同的响应,具体表现为:七星瓢虫Cocinella septempunctata数量随蚜虫数量增大而显著增大,多异瓢虫Hippodamia verigata和普通草蛉Chrysopa carnea随蚜虫数量增大而逐渐增大,而大草蛉Ch.septempunctata种群数量与棉蚜数量无关;连续2年的大田调查均发现,这4种捕食性昆虫种群数量在7月底有一高峰,而且七星瓢虫和大草蛉数量大于多异瓢虫和普通草蛉。【结论】七星瓢虫和大草龄是北疆五家渠地区棉田棉蚜的优势天敌。

[Objectives] To understand the behavioral responses of the main predators of aphids in cotton fields in north Xinjiang. [Methods] We undertook a two-year survey of Aphis gossypii and four of its insect predators, two ladybird beetles, Cocinella septempunctata and Hippodamia verigata, and two lacewings, Chrysopa carnea and Ch. septempunctata, in cotton fields in the Wujiaqu region of northern Xinjiang. [Results] The survey showed differential numerical responses to cotton aphids and varying seasonal patterns among the four predatory insects. Co. septempunctata increased strongly in abundance in response to aphid abundance; H. verigata and Ch. carnea increased gradually but Ch. septempunctata did not increase in abundance, in response to aphid abundances. The four predatory insects showed similar seasonal trends in abundance, all peaking at the end of July. Co. septempunctata and Ch. carnea were more abundant than H. verigata and Ch. septempunctata across the entire cotton-growing season. [Conclusion] The results of this study indicate that Co. septempunctata and Ch. carnea are the dominant natural enemies ofA. gossypii in cotton fields in the Wujiaqu region of northern Xinjiang.