Effects Of Transgenic Bt Cotton On Population Dynamic Of The Main Pests And Their Natural Enemies

The paper studied the population dynamic of the main pests and their natural enemies in no-control pest transgenic Bt cotton field no-control pest normal cotton fields pest-control normal cotton field. The results are outlined as follows:1. Bt cotton was highly resistant to cotton bollworm and anomis flava. The fallen eggs of second generation decreased by33.3% and that of third ,fourth generation increased by 35 % 32.5%than that of no-control pest field; but than that of pest-control field, the second generation decreased by 10.1%,the third and fourth increased by 42.8% 56%.The second third fourth generation bollworm decreased by90% 84.9% 74.9% respectively than that of no-control pest field ;and the second decreased by 53%, the third and fourth increased by 26.5% 55.1% than that of pest-control field .Anomis decreased by 87.7% than that of no-control field and 54.3% than that of pest-control field.2. Bt cotton had an indirect effect on non-lepidopteran pests. Compared with that of no-control pest field ,the seedling aphids decreased by 14.3% , the summer aphids increased by 8.0% ,the red spider mite and stinkbug decreased by 33.1% 3.1%, the thiailrides vaporariorumand Empoasca biguttula shiraki increased by 58.8% 15.3% ;But compared with that of pest-control field, the seedling aphids , summer aphids red spider mite stinkbug thiailrides vaporarionim empoasca biguttula shiaki increased by 82.7% 67.5% 88.1% 40.2%. 70.6% 62.3% respectively.3. Bt cotton had no obvious effect on the total number of natural enemy .In no-control pest field, preying natural enemies increased by 27.2%, parasitic natural enemies decreased by 11.9%, the total number had no significant difference ; In pest-control field , preying and parasitic natural enemies increased by 83.8% 60.8%, and the total number raised significantly.