Influence of atmospheric quasi-biweekly oscillation on immigration of Sogatella furcifera (Horváth) in southern China

This study aims to investigate the influence of quasi-biweekly oscillations on the immigration of the white-backed planthopper (Sogatella furcifera) into southern China, with a focus on the characteristic low-frequency atmospheric circulation fields and their mechanisms during different immigration phases (population peak and trough periods).

Light-trap data from 20 stations across South China (2011-2016) were analyzed. The Morlet wavelet analysis was employed to extract the dominant low-frequency oscillation period of the immigration population during March-May. Key low-frequency atmospheric circulation elements significantly associated with immigration volume were then identified through correlation analysis, and their phase-dependent influences were examined using phase composite analysis, and the climatological characteristics of low-frequency circulation fields during specific phases were summarized.

The analysis revealed a dominant low-frequency oscillation period of 10~20 days in the immigration volume of white-backed planthopper in South China, consistent with the period of atmospheric quasi-biweekly oscillations. The low-frequency wind and geopotential height fields were identified as the primary circulation backgrounds influencing immigration. A regime shift from southwesterly to northeasterly winds-driven by the strengthening of cyclonic circulation over the western Pacific/Sea of Japan and the weakening of anticyclonic circulation over the South China Sea/Bay of Bengal-was found to suppress immigration from source areas to South China. In contrast, positive low-frequency height anomalies and a northward shift of the subtropical high facilitated immigration.

Therefore, atmospheric quasi-biweekly oscillations dynamically modulate immigration through the configuration and evolution of wind and geopotential height fields, indicating that quasi-biweekly signals, such as the activity phase of zonal wind, can support medium-term forecasting of white-backed planthopper immigration.