Abstract: 【Aim】 The objective of this study is to detect the genotype of ace-1, the target gene of organophosphorus and carbamate insecticides, in field populations of Spodoptera frugiperda in China, and to identify the frequency of resistance genes, so as to provide guidance for the scientific use of insecticides in the field. 【Methods】 Samples of S. frugiperda larvae were collected from maize fields in 12 provinces in China, and the genomic DNA was extracted individually. Then the ace-1 gene fragment was cloned using gene specific primers, and the genotype and resistance gene frequency of three amino acid mutation sites, A201S, G227A and F290V, were analyzed through base and amino acid sequence alignment, DNA sequencing and peakTrace Basecaller analysis. 【Results】 The genotype and mutation frequency of the ace-1 gene of 589 individuals of field populations of S. frugiperda from 12 provinces in China analyzed through DNA detection method revealed that 137 individuals exhibited resistant heterozygous genotype at locus A201S, and the resistance gene frequency reached 11.6%. Meanwhile, no resistant homozygous genotype was found. At locus G227A, all the 589 individuals displayed susceptible homozygous genotypes. The resistance gene frequency at locus F290V was the highest (57.1%), and there were 523 individuals carrying homozygous or heterozygous resistance genes, accounting for 88.8% of the total samples. 【Conclusion】 The results indicate that S. frugiperda invading in China carries a high-level frequency of resistance genes to organophosphorus and carbamate insecticides. Organophosphorus and carbamate insecticides should not or less be used in the field control of S. frugiperda, and resistance monitoring in fields should be strengthened.

Key words: Spodoptera frugiperda; ace-1, genotype, resistance gene frequency, organophosphorus insecticides, carbamate insecticides, insecticides resistance