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

[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 of A. gossypii in cotton fields in the Wujiaqu region of northern Xinjiang.