Comparative efficacy of insecticides against rice planthopper by unmanned aerial vehicle across different rice-growing regions

Rice planthoppers are among the most destructive pests, posing a significant threat to both rice yield and quality. Long-term reliance on chemical control has led to resistance against multiple classes of insecticides, and these resistances exhibit regional variability and spatiotemporal dynamics across rice-growing areas. To evaluate the feasibility of using unmanned aerial vehicles (UAVs) for rice planthopper control and to screen for highly effective pesticides under varying initial pest densities across different rice-growing regions, thereby promoting the synergistic application of pesticides, agricultural machinery, and agronomic practices, field trials were conducted in the rice-producing areas, including Jiangsu, Hunan, and Guangdong provinces. This study comparatively analyzed the control efficacy against rice planthoppers among UAVs at different spray volumes (30 L/hm² and 37.5 L/hm²) and knapsack electric sprayers (675 L/hm²). Furthermore, it compared the efficacy of the same insecticide across different rice-growing regions and that of different insecticides within the same region. The results showed no significant difference in control efficacy between the two UAV spray volumes, and both were comparable to the knapsack electric sprayers. Control efficacy varied significantly for the same insecticide across different regions and among different insecticides within the same region. Under the UAV spray volume of 30 L/hm² and 37.5 L/hm², in Jiangsu, nitenpyram 50% SG at 240 g/hm² and triflumezopyrim 20% WG at 135 g/hm² provided the best control, with control efficacy reaching 94.88%-95.18% at 14 days after application. In Hunan, triflumezopyrim 20% WG at 135 g/hm² demonstrated the best performance, achieving 90.30%-93.57% control efficacy from 3 to 14 days after application. In Guangdong, dinotefuran 20% WG at 600 g/hm², nitenpyram 50% SG at 240 g/hm², and triflumezopyrim 20% WG at 135 g/hm² resulted in control efficacies of 95.70%-97.17% at 14 days after application. In summary, UAV application with a spray volume of 30 L/hm² proved effective control of rice planthoppers. Optimizing pesticide selection requires a tailored approach that accounts for initial pest population density and pesticide characteristics across different rice-growing regions. This study provides new insights for the sustainable and efficient management of rice planthoppers and offers a scientific basis for developing region-specific UAV control strategies.