Planting trap corn could not only increase the quantity of native predators in the cotton fields, but also concentrate them on the trap corn. The distribution of ladybirds, green lacewings and spiders during cotton growth period was: the trap corn>the treatment cotton field>the contrast cotton field. There were 89.89% ladybirds, 2.24% green lacewings and 7.86% spiders in the native predators. Coccinella undecimpunctata Linnaeus was the dominant species among them in the cotton fields, whose rate being 82.66%. Its quantity in the treatment cotton field was 1.8 times compared to that in the contrast cotton field. |