Abstract:In order to evaluate the resistance risk of emamectin-benzoate to Frankliniella occidentalis (Pergande), the cross-resistance and biochemical resistance mechanisms of emamectin benzoate resistant population were investigated using the methods of Munger cell, synergist and enzyme activity assay. The results showed that the resistance population had high level of cross-resistance to abamectin with 31.656-fold, medium level of cross-resistance to acetamiprid with 12.182-fold, low level of cross-resistance to imidacloprid, chlorfenapyr, cyhalothrin, chlorpyrifos and methomyl with 5.517-8.568-fold, yet no cross-resistance to spinosad. The synergists piperonyl butoxide (PBO), diethyl maleate (DEM), s, s, s-tributyl phosphorotrithioate (DEF) and triphenyl phosphate (TPP) all had significant synergism to the emamectin-benzoate resistance- and field populations. Compared with the susceptible population, the emamectin-benzoate resistance population had significantly increased contents of cytochrome P450 and b5, activities of mixed-functional oxidases O-demethylase, glutathione S-transferases and carboxylesterase with 3.89, 3.61, 5.32, 4.42 and 1.30 fold increase, respectively. Therefore, it was inferred that the increased detoxification enzyme activities may play an important role in the resistance of F.occidentalis to emamectin-benzoate.