Abstract: Tomato virus disease has become one of the most important diseases in tomato production，resulting in a large reduction in tomato yield or even a failure of the harvest. Tomato chlorosis virus（ToCV） and tomato yellow leaf curl virus（TYLCV）cause severe losses in the field，and co-infection of ToCV and YLCV will also have a series of effects on the B. tabaci feeding，virus acquisition，and virus transmission，causing great difficulties in the prevention of tomato virus diseases. The changes of detoxification enzymes and gene related to physiological defense responses，after B. tabaci feeding on tomatoes co-infected with ToCV and TYLCV was clarified，to control B. tabaci effectively. In this study，the changes of detoxification enzymes in co-infected B. tabaci were studied by enzyme activity determination and real-time fluorescence quantitative PCR technology，and healthy tomatoes were used as the control. The results showed that expect the enzyme activity of glutathione S-transferase（GST）and UDP-glucuro- nosyltransferase（UDPGT）of B. tabaci fed on ToCV infected tomatoes were lower than those fed on healthy B. tabaci，viruliferous B. tabaci’s GST，carboxylesterase（CarE），acetylcholinesterase（AchE），cytochrome P450（CYP450）and UDP enzyme activities and gene expression levels were higher than those of healthy B. tabaci，and there were significant differences in CarE，AchE，P450，UDP enzyme activities and gene expression levels after B. tabaci feeding and infection. The results showed that the detoxification defense of B. tabaci was induced to different degrees after feeding on the co-infected tomato and TYLCV-infected tomato plant，thus helping B. tabaci to transmitt the virus.

Key words: tomato, Bemisia tabaci, ToCV, TYLCV, co-infection, detoxification enzymes