Spatiotemporal dynamics and migration pathways of the transboundary Beet Webworm Loxostege sticticalis (Linnaeus) between Northern China and Mongolia in 2022

Clarifying the population dynamics, source-landing relationships, and migration pathways of the beet webworm Loxostege sticticalis (Linnaeus) both domestically and internationally, as well as understanding the meteorological mechanisms shaping these patterns, is pivotal for remote, accurate, and location-specific pest forecasting. Based on light trap data from northern China and field survey data from Mongolia in 2022, we simulated the migration trajectories, source regions, and primary landing areas of L. sticticalis, and analyzed the synoptic systems and processes during its migration. The results indicate frequent exchange of L. sticticalis populations between China and Mongolia in 2022. The L. sticticalis migrants initiating their flights from Mongolia primarily undertook a southeastward migration pathway, supplemented by eastward cyclonic and southwestward paths. The main landing areas were located in North China and Northeast China, with migration events potentially extending to Shandong, Heilongjiang, and Xinjiang provinces. Populations originating from North China exhibited a capacity for migrating into Northeast China and Mongolia through 1 to 5 consecutive nights of flight. During this period, the Northeast China Cold Vortex (NCCV) and the Mongolian Cyclone alternately regulated the synoptic circulation pattern governing the migration of L. sticticalis. The spatiotemporal distributions and intensities of these systems were key determinants of the transboundary migration routes and distances of L. sticticalis. The NCCV dominated, and the precipitation and downdrafts it induced were crucial for the massive landing of L. sticticalis in northern China.