Abstract

B-biotype Bemisia tabaci has developed high levels of resistance to many insecticides. To investigate the risks and explore possible mechanisms of resistance to the diafenthiuron in B. tabaci, a 24.7-fold diafenthiuron resistant strain (TH-R) was established after selection for 20 generations compared with the susceptible strain (TH-S). Biochemical assays showed that the activity of cytochrome P450 towards P-NA was significantly higher (3.6-fold higher) in the TH-R strain than in the TH-S strain. Similarly, the carboxylesterase (COE) activity and Glutathione S-transferase (GST) activity were also significantly higher (2.55- and 1.65-fold higher, respectively) in the TH-R strain than in the TH-S strain. The expression of 5 of 7 P450 genes was significantly higher (>2.3-fold) in the TH-R strain than in the TH-S strain. The expression of COE1 was significantly higher (>2.3-fold) in the TH-R strain than in the TH-S strain. Cytochrome P450, COE and GST appear to be responsible for the resistance to diafenthiuron in B. tabaci. It is also valuable for usage of insecticides for resistance management and control of this species.

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