Objective  To clarify the effects of thiamethoxam on resistance and detoxification metabolic enzyme activity of Nilaparvata lugens.

Method  The resistance levels of N. lugens population in greenhouse against four insecticides (imidacloprid, thiamethoxam, buprofezin, chlopyrifos) and the sensitivities to two new types of insecticides (sulfoxaflor, triflumezopyrim) were measured using rice seedling immersion method. The synergistic effect of three synergists piperonyl butoxide (PBO), diethyl maleate (DEM), triphenyl phosphate (TPP) on thiamethoxazine, and three detoxification enzymes (carboxylesterase, qlutathioneS-transferase, cytochrome P450s) activities were analyzed.

Result  N. lugens population showed high resistance to thiamethoxam with the resistance ratio of 277.92 folds, sensitive to sulfoxaflor and triflumezopyrim, and no cross resistance to triflumezopyrim. PBO had the strongest synergistic effect on thiamethoxam with the synergistic ratio of 1.99. Cytochrome P450s activity of greenhouse population reached 4.70×10⁻³ IU/ mg, which was 2.13 folds to that of susceptible strain.

Conclusion  The increased activity of cytochrome P450s could be the main factor resulting in the metabolic resistance of N. lugens to thiamethoxam. The alternate use of sulfoxaflor and triflumezopyrim can effectively control the occurrence of N. lugens.