Detection of insecticide susceptibility and target-site mutations in field populations of Spodoptera frugiperda (Lepidoptera: Noctuidae)

Abstract

Fall armyworm, Spodoptera frugiperda (J. E. Smith), is an economically important pest throughout the world. At present, the control of S. frugiperda in China largely relies on the application of chemical insecticides. In this study, the susceptibility of nine field populations of S. frugiperda to eight recommended insecticides was evaluated by using the diet-overlay method. The results indicated that spinetoram, lufenuron, and emamectin benzoate exhibited high acute toxicity to S. frugiperda, whereas chlorantraniliprole, indoxacarb, tetrachlorantraniliprole, chlorfenapyr, and lambda-cyhalothrin exhibited relatively low toxicity. Two site mutations (A201S and F290V) of the Ace-1 gene were identified from the field populations, the R allele frequencies of A201S and F290V ranged from 5.0% to 29.6% and 21.2% to 67.3%, respectively. In addition, the resistant homozygote F290V was detected in the field, with the highest genotype frequency of 40.0% in the JZ population. However, no site mutation in VGSC was detected in any tested field population of S. frugiperda. These results provide valuable information for the selection of insecticides and are helpful for insecticide resistance management of S. frugiperda.