LAUSR

BACKGROUND Laodelphax striatellus is one of the most destructive pests of rice and other cereal crops. Chemical control is still the efficient way for the control of this pest, but insecticide resistance always threatens this approach. RESULTS Monitoring data (2003-2020) showed that Chinese field populations of L. striatellus developed high-level buprofezin resistance within the first four years. This high-level resistance to buprofezin was stable for about ten years and persisted even when buprofezin selection pressure was absent. An established near-isogenic strain (YN-NIS) with 90.8-fold resistance to buprofezin had resistance inheritance of autosomal and incomplete dominance, and the resistance was controlled by multiple genes with no obvious fitness costs (relative fitness of 0.8707). Furthermore, the susceptibility of 29 field populations to other 7 insecticides (2014-2020) showed that: i) low-level resistance to pymetrozine, dinotefuran, sulfoxaflor and thiamethoxam was first detected in 2014 (8 years after introduction), 2016 (3 years after), 2017 (4 years after) and 2019 (19 years after), respectively; ii) moderate resistance levels to chlorpyrifos were found for all populations across multiple years; and iii) no resistance detected for nitenpyram and triflumezopyrim. CONCLUSION The fast buprofezin resistance development in L. striatellus would be caused by incomplete dominant resistance with almost no fitness cost in the resistant strain. Nitenpyram and triflumezopyrim showed no resistance and can be used as the main insecticide for the control of L. striatellus. These findings provide key fundamental information for controlling L. striatellus. This article is protected by copyright. All rights reserved.