Monitoring of resistance to chlorantraniliprole and analysis of fitness costs in field populations of Tuta absoluta

Objective This study aimed to investigate the resistance status of five field populations of Tuta absoluta collected in Xinjiang, and clarify their fitness costs.

Methods Leaf-dipping bioassays were used to assess resistance to chlorantraniliprole, and age-stage two-sex life tables were constructed for resistant and susceptible populations to analyze fitness costs.

Results Bioassay results showed that all five field populations exhibited moderate to extremely high resistance to chlorantraniliprole, particularly in the Yili River Valley, where resistance was highly prevalent. Compared with the laboratory-susceptible population, the field population collected from Huocheng County had longer developmental duration and lower fecundity. Calculated based on the net reproductive rate (R₀), the relative fitness (R_f) of the resistant field population was 0.76.

Conclusion Tuta absoluta populations in the Yili River Valley of Xinjiang have developed widespread resistance to chlorantraniliprole, likely driven by high selection pressure from field insecticide use. In the absence of pesticide selection pressure, the survival and reproductive capacity of resistant populations are significantly weaker than those of susceptible populations. Attention should be paid to controlling the application frequency of chlorantraniliprole and other diamide insecticides in this region to slow resistance evolution.