Genetic mutations and insecticide resistance in Diaphorina citri: a comparative study across Chinese citrus regions

Abstract

Background: Diaphorina citri, a serious pest of citrus, causes significant economic losses due to its role in spreading Huanglongbing. Chemical treatment is the primary method for controlling D. citri. In recent years, D. citri has demonstrated varying resistance levels to a number of pesticides. Combination bioassay and amplicon sequencing approaches can provide a more accurate assessment of resistance in D. citri.

Results: Field populations of D. citri exhibited significant variability in pesticide susceptibility depending on geographic location. The Guilin population showed the highest imidacloprid sensitivity, with a median lethal concentration (LC₅₀) of 1.14 mg L^-1, indicating a comparatively high susceptibility to this pesticide. In contrast, the Chongzuo population exhibited the lowest sensitivity, with an LC₅₀ exceeding 2000 mg L^-1, reflecting a significant resistance level. Molecular analysis showed that resistance levels were associated with specific genetic mutations in two key areas: VGSC_L925M, VGSC_M918T, and the acetylcholine receptor α (nAChRα_N88S). Furthermore, there was a correlation between the rate of these mutations and the resistance level. Interestingly, the VGSC_L925M mutation was prevalent in the Chongzuo population, exhibiting a significant frequency of 42.08%. The nAChRα_N88S mutation, found at a low frequency of 0.24%, was unique to the Chongzuo population.

Conclusion: The frequency of VGSC_L925M mutations linked to pyrethroid resistance and nAChRα_N88S mutations associated with neonicotinoid resistance has been revealed in D. citri from major citrus-producing regions in China. We recommend region-specific resistance management strategies, immediate reduction of pyrethroid use in Chongzuo area with high L925M mutation frequencies. This research also provides fundamental data to manage resistance in D. citri. © 2025 Society of Chemical Industry.

Keywords: Diaphorina citri; amplicon sequencing; molecular detection; resistance monitoring.