Abstract: 【Aim】 The common cutworm, Spodoptera litura (Fabricius), is one of major agricultural pests all over the world. In this study we evaluated the resistance level of S. litura to insecticides in five major vegetable growing areas of Hunan province and determined the relationship between the resistance to indoxacarb and the activities of detoxification enzymes in S. litura, aiming to offer the theoretical basis for the control of this pest. 【Methods】 The resistance to 10 insecticides in S. litura populations from five districts of Hunan Province from 2014 to 2016 was assayed using a standard leaf dip bioassay method. Indoxacarb was used to select a resistant strain under 40%-70% selection pressure. The activities of CarE, GST and PNOD in the 3rd instar larvae of the susceptible and indoxacarb-resistant strains were tested. 【Results】 Compared with the susceptible strain, the resistant strain of S. litura obtained 26.9-220.2-fold resistance to organophosphates, 68.3-890.8-fold resistance to carbamates, 21.0-267. 2-fold resistance to pyrethroids and 5.2-53.4-fold resistance to relatively novel insecticides including emamectin, abamectin, indoxacarb and chlorfenapyr. After 14 continuous generations of selection with indoxacarb, the selected population obtained 26.43-fold resistance compared with its unselected population. The activities of CarE, GST and PNOD in the selected strain were 2.86, 1.01 and 1.83-fold higher than those in the unselected strain, respectively. 【Conclusion】 S. litura has developed different levels of resistance to the tested insecticides, and the enhancement in the activities of CarE and PNOD is an important mechanism for the increased resistance of S. litura to indoxacarb.

Key words: Spodoptera litura, insecticide resistance, indoxacarb, detoxification enzymes, metabolic resistance