Ecological mechanisms underlying the impact of temperate cyclones on the late-season occurrence of Nilaparvata lugens in the lower reaches of the Yangtze River

The rice-growing region in the lower reaches of the Yangtze River is a serious perennial outbreak area of the brown planthopper (BPH, Nilaparvata lugens) in China. As a typical mobile frontal system, temperate cyclones traverse over ten degrees of longitude, frequently causing extensive wind and rainfall that inevitably influence the migratory behavior of BPH. However, the impact mechanism of temperate cyclones on the migration of BPH remains unclear.

This study investigated the impact of temperate cyclones on August migration patterns in the region by analyzing light-trap data (June to September during 2004-2019) from 20 monitoring stations in the lower reaches of the Yangtze River and temperate cyclone parameters, employing correlation analysis and generalized linear models (GLMs).

The results demonstrated significant effects of August temperate cyclones on BPH migration peaks in the area. The frequency of Jianghuai cyclones showed a significant positive correlation with population abundance (r = 0.684, P < 0.001), whereas the intensity of East China Sea cyclones exhibited a significant negative correlation (r = -0.627, P < 0.001). High-frequency Jianghuai cyclones promoted population growth and northward migration of BPH to the lower reaches of the Yangtze River through the eastern sector's warm temperatures, reduced precipitation, and southerly winds. Conversely, intense East China Sea cyclones hindered migration via the western sector's cool temperatures, heavy rainfall, and easterly winds, resulting in lower population levels.

This study establishes that spatio-temporal characteristics of specific temperate cyclone types (Jianghuai/East China Sea cyclones) significantly modulate BPH migration. These findings not only enhance early warning systems in the lower reaches of the Yangtze River but also provide novel insights into meteorological drivers of migratory insects.