Abstract Background Culex tritaeniorhynchus is the primary vector of Japanese encephalitis virus (JEV), a disease of global public health significance, and is widely distributed across Africa, Asia, Australia, and Europe. Despite its epidemiological importance as a JEV vector, studies on insecticide resistance in Cx. tritaeniorhynchus populations from the Republic of Korea (ROK) remain extremely limited. This study aimed to investigate the spatial and temporal occurrence of knockdown resistance ( kdr ) mutations in Cx. tritaeniorhynchus populations from the ROK. Additionally, the association between phenotypic resistance to pyrethroid insecticides and kdr alleles was examined. Methods Culex tritaeniorhynchus specimens were collected from eight locations across the ROK to assess the occurrence of kdr mutations. Additionally, WHO tube bioassays were conducted using the pyrethroid insecticide deltamethrin to assess phenotypic resistance and its association with kdr mutations. Results The kdr mutation 1014F was detected in all surveyed populations, and the frequency of the 1014F allele remained relatively stable during the peak abundance period of Cx. tritaeniorhynchus from July to September. Bioassay results further indicated that Cx. tritaeniorhynchus populations in the ROK exhibit resistance to pyrethroid insecticides. However, no clear association was detected between the presence of the 1014F mutation and pyrethroid-resistant phenotypes. Conclusions These findings indicate the need for further investigations into insecticide resistance in Cx. tritaeniorhynchus to support effective vector control and mitigate the risk of JEV transmission. Moreover, the results suggest that pyrethroid resistance in Cx. tritaeniorhynchus may not be driven solely by kdr mutations, indicating the potential involvement of additional resistance mechanisms.
Jeon et al. (Tue,) studied this question.