Influence of ecological habitat on the occurrence and dynamics of Lygus lucorum Mayr and its natural predator

The population dynamics of Lygus lucorum Mayr and its main native predator in cotton fields with different ecological habitats were systemically investigated for the period 2005 ~ 2007 to determine an economic and effective method of controlling L. lucorum damage on cotton. Ten treatments were grouped into five experimental sets (cotton fields close to and far from orchard fields; cotton fields planted with 54 000 plants per hectare and at even spacing, and with 45 000 plants per hectare and at uneven spacing; rationally chemical controlled and non-chemical controlled cotton fields; mono-crop cotton field and sunflower-intercropping cotton field; and transgenic cry1A cotton field and transgenic Bt plus CpTI cotton field). The results indicate similar native predator species composition in the cotton fields irrespective of the ecological habitat. The identified predators include Propylaea japonica Thunberg, Coccinella septempunctata Linnaeus, Chrysoperla sinica Tjeder, C. septempunctata Wesmael, Nabis sinoferus Hsiao, Orius minutus Linnaeus, Pardosa T-insignita Boes. et Str., Misumenops tricuspidatus Frab., and Erigondium gramincola Sundevall. Significant difference of L. lucorum and its natural predator population exists among in different ecological habitats. L. lucorum is effectively controlled in cotton fields far from orchard field, planted at 45 000 plants per hectare with uneven plant spacing and under rationally chemical controlled. Plantations of transgenic Bt plus CpTI cotton reduce L. lucorum, but have no effect on native predators. Intercropping with sunflower increases native predator number and reduces L. lucorum in cotton fields. The study suggests that planting transgenic Bt plus CpTI cotton in field far from orchard at rational density and uneven spacing with rationally chemical control can effectively control L. lucorum in transgenic cotton fields.