Detoxification Enzyme Activity and Gene Expression in Diafenthiuron Resistant Whitefly, Bemisia tabaci

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 (CarE) 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, CarE 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.