Monitoring of insecticide resistance in field populations of Tuta absoluta from seven widely used pesticides in major tomato-producing areas of Xinjiang, China

Objective To clarify the current insecticide resistance status of field populations of Tuta absoluta in major tomato-growing regions of Xinjiang, and provide theoretical support for scientific pesticide rotation and precise field pest management.

Methods The leaf-dip bioassay was adopted to determine the resistance levels of Tuta absoluta populations collected from the Ili River Valley, Bayingolin Mongolian Autonomous Prefecture, Hotan Prefecture and Kashgar Prefecture against seven commonly used insecticides.

Results Significant regional differences in resistance were detected among geographical populations, and resistance exhibited rapid evolutionary characteristics from 2022 to 2024. In 2022, resistance ratio (RR) of all tested populations ranged from 0.03 to 102.50, covering susceptible, low, moderate and high resistance grades. Field populations had developed high resistance to spinetoram and 34% spinetoram·methoxyfenozide premix, while most populations remained susceptible to moderately resistant to lambda-cyhalothrin, abamectin and imidacloprid. By 2024, resistance levels of populations in the Ili River Valley increased sharply with obvious inter-population differentiation. The Qapqal population showed extremely high resistance to 20% chlorantraniliprole with RR=795.22. Populations from Qapqal, Huocheng and Yining all possessed extreme resistance to 10% cyantraniliprole, with RR values of 324.21, 1097.13 and 422.53 respectively. Populations from Qapqal and Yining developed moderate resistance to 35% imidacloprid, with RR=13.60 and RR=24.71, reflecting rapid resistance evolution and prominent regional heterogeneity.

Conclusion 2.There are obvious disparities in insecticide resistance among Tuta absoluta populations across Xinjiang. Populations in the Ili River Valley have evolved extreme resistance to diamide insecticides. For field production, the application frequency of chlorantraniliprole and cyantraniliprole should be reduced, pesticide rotation strategies optimized, and insecticide selection pressure alleviated to delay further resistance evolution.