The Resistant Mechanism Of Different Strains Bemisia Tabaci To Phoxin And Thiamethoxam Insecticides

Bemisia tabaci Gennadius(Homoptera:Aleyrodidae) is one of the most devastating agricultural pests. Which damage vegetables, ornamental crops, and other economic crops. The tobacco whitefly Bemisia tabaci Gennidius emerged all over the world recent years, which is closely related with the resistance of B. tabaci to chemical pesticides .This thesis had done some research to the resistance to the insect pesticides from the activity of metabolizable enzymes and target gene clone.A 40 fold phoxin-resistant strain of Bemisia tabaci was achieved after 19 generations under the pressure of killing about 75% population. This resitant strain showed some tolerance to imidacloprid and acetamiprid. We researched some activity of metabolic enzymes in the body. The formerly reports approved that the metabolic enzymes in the body of resistant whitefly strain are not sensitive to insect pesticides. We achieved some results about the metabolic enzymes activity. There are some differents between susceptible strain and resistant strain indeed. The AchE of phoxin-resistant strain and Thiamethoxam-resistant strain are not sensitive to insect pesticides. The AchE is the most different between susceptible strain and resistant strain among AchE, MFO,GST and CarE. There are not remarkable differents among the strains that eggplan, tomato, cotton as host in the AchE, CarE, GST activity. And there are not remarkable differents between the B-biotype strains and non-B-biotype strain in the AchE, CarE, GST activity. In a word, We found the AchE activity of the two resistant Bemisia tabaci strains is obvious higher than the sensitive Bmisia tabaci.Recently a series metabolic enzymes gene were cloned and the molecular mechanism of B. tabaci was explored primarily. So we only need clone AchE gene of resistant strains. Then we cloned the cDNA fragment encoding AchE of the susceptible and resistant Bemisia tabaci by RT-PCR. We found 4 differents in DNA level and 3 differents in protein level between susceptible strain and phoxin-resistant strain and 5 differents in DNA level and 4 differents in protein level between susceptible strain and thiamethoxam-resistant resistent strain and 1 different in DNA level and 1 different in protein level between thiamethoxam resistent strain and OP resistent strain by DNAMAN softwear. There are some relations between phoxin-resistant strain and thiamethoxam-resistant resistent strain.