| The resistance of Helicoverpa armigera (Hübner) that came from Taian, Xiajin in Shandong Province and Tianmen in Hubei Province of China to 4 insecticides fenvalerate,phoxim,methomyl and endosulfan were measured. The resistance mechanism was studied by means of synergist and enzyme dynamics.8 insectsides were filtered by topical application method.The effect of transgenic Bt cotton to the resistance of H.armigera was examed and the mechanism was studied by means of enzyme dynamics.1. The resistance of H.armigera that came from 3 different cotton regions of Taian, Xiajin in Shandong Province and Tianmen in Hubei Province to four insecticides was measured by topical application method.The results showed that the resistance of Taian, Xiajin and Tianmen populations to fenvalerate reached the highest level,the LD50 was 115.22μg·g-1,367.01μg·g-1 and 495.23μg·g-1,which reached 315.8 folds ,1005.8 folds and 1357.2 folds respectively.The resistance of Taian, Xiajin and Tianmen populations to phoxim was the low level to sensitive level.the LD50 was 11.929μg·g-1, 14.413μg·g-1 and 27.079μg·g-1,which reached 1.8 folds,2.2 folds and 4.1 folds respectively. The resistance of Taian, Xiajin and Tianmen populations to methomyl was the low level.the LD50 was 33.696μg·g-1, 44.982μg·g-1 and 27.547μg·g-1,which reached4.7 folds, 6.2 folds and 3.8 folds respectively.The resistance of Taian, Xiajin and Tianmen populations to endosulfan was sensitive.the LD50 was 103.69μg·g-1, 57.455μg·g-1 and 25.903μg·g-1,which reached 1.9 folds, 1.1 folds and 0.5 folds respectively.Compare with the results of 2001,the resistance of three populations to 4 insecticides were declined.The declined rates was related to the resistance level and the growing of transgenic Bt cotton.2. Synergism to 4 pesticides by 5 synergist were measured,the results showed that: The resistance to fenvalerate was mainly related to the improving of the activity of detoxifcation enzyme and subsidiarily related to the improving of the activity of isozyme and the reducing of the cuticle penetration. The resistance to phoxim and methomyl was mainly related to the improving of the activity of CarE and subsidiarily related to the improving of the GST and the reducing of the cuticle penetration.The synergism to endosulfan by 5 synergist was unvisible because of the sensitivity of the H.armigera to endosulfan.3. The results of the biochemistry measure showed that: Protein content, P450 content, CarE activity, AChE activity, GST activity, GSH content of three field populations were higher than the sensitive population.This indicate that the resistant mechanism was complex, the detoxification of MFO,CarE,GST and the passivation of drone enzyme were the main cause of the resistance of H.armigera to pesticides.The resistance level of three resistant populations were related to which resistant mechanism.4.Transgenic Bt cotton had remarkable effects to the larva Survival,pupa weight, immaturity periods of H.armigera.Third day and sixth day larva Survival,sixth day larva weight,pupa weight were remarkable reduced. While immaturity periods protracted remarkably.Larva Survival, sixth day larva weight,pupa weight,immaturity periods were resumed,but still lower than Xiajin populations.The diversity probably was an important reason for the effect of transgenic Bt cotton to resistance.5.Without any exposure to the pesticide pressure in the lab, using common artificial diet to breed the resistant H.armigera population,which resistant declined rates were 78.16%,28.26%,27.95% and 23.94% respectively. Using artificial diet mixed with transgenic Bt cotton leaves to breed the resistant H.armigera population,which resistant decline rate were78.16%,28.26%,27.95% and 23.94% respectively.This showed that the resistant decline of H.armigera field resistant populations to pesticides was not only related to the reduce of pesticide quantity but also related to the growing of transgenic Bt cotton.6. The results of the biochemistry measure showed that:The main mechanism that transgenic Bt cotton affected the resistance of H.armigera to pesticides was the function diversity of MFO.Besides,the diversity of CarE activity,AChE activities,GST activity, GSH content were also the factors of the effect.7. Screening for 8 pesticides showed that the virulence of emamectin B1 Benzoate was the highest and it's the best pesticide to manage the H.armigera.The virulence of cyhalothrin, indoxacarb, chlorfenapyr were also high,which can be used for H.armigera management. The virulence of profenofos,chlorphrifos were low,which can be only used for exchanging pesticides.The virulence of deltamelthrin, triazophos were too low, which had been useless for H.armigera management.
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