Origin, selection, and spread of diamide insecticide resistance allele in field populations of diamondback moth in east and southeastAsia

BACKGROUND The investigation of molecular mechanisms and evolution of resistance to insecticides is an ongoing challenge, as researchers must provide guidance to manage the resistance to achieve sustainable production in agriculture. Predicting, monitoring, and managing insecticide resistance requires information on the origins, selection, and spread of resistance genes. The resistance ofPlutella xylostella(L.) against diamide insecticides is becoming an increasingly severe problem in east and southeast Asia. In this study, the evolution of resistance was investigated using a resistance allele [ryanodine receptor (RyR); G4946E mutation] and its flanking regions, as well as mitochondrial cytochromecoxidase subunit I (mtCOI). RESULTS The sequences of the flanking region of the G4946E andmtCOI suggested that the G4946E mutation has a key role in resistance. Furthermore, the G4946E mutation has multiple origins, and congenic resistant mutations have spread across east and southeast Asia, despite substantial geographical barriers. In addition, the susceptibility of field populations partially recovered during winter, based on the observed decrease in the G4946E (resistant allele) frequency. Finally, the resistance level indexed by the frequency of the E4946 allele was significantly lower in non-overwintering regions than in overwintering regions. CONCLUSION The information of the present study is useful to monitor resistance using molecular markers and to develop strategies to delay the evolution of diamide resistance.

Automated summary

The study revealed that the G4946E mutation plays a key role in resistance and has multiple origins across east and southeast Asia, despite geographical barriers. Field populations showed partial recovery in resistance levels during winter, with the frequency of the resistant allele decreasing. Regions that do not experience overwintering have significantly lower frequencies of the E4946 allele compared to overwintering regions.