Abstract: To understand the probability and direction of long-distance dispersal of the wheat midge, Sitodiplosis mosellana (Géhin), populations with air current, we analyzed the profile of S. mosellana density that was determined with a series of balloon-supported yellow traps located vertically at altitudes from 5-75 m above ground level, and the internet-based HYSPLIT-4 (HYbrid Single-Particle Lagrangian Integrated Trajectory) model was used to simulate the dispersal trajectory of S. mosellana at various altitudes in Luoning (34.35°N, 111.52°E), Henan province in 2010 and in north China in 2007. The results indicated that the aerial densities of S. mosellana (number of individuals per trap) at altitudes of 5, 45, 50 and 65 m were higher than those at other altitudes, showing stratification according to altitude above ground. The immigration populations came from Nanyang, Henan province, and the emigration populations moved with airflow to Yiyang, Henan province in 2010. The wheat midge populations dispersed step by step from southwest to northeast with southwest air current in 2007. The dispersal with air current was an important way of long-distance dispersal of S. mosellana. The results may help realize the population expansion and provide a reference value for monitoring population dynamics and optimizing integrated management of S. mosellana in China.

Key words: Sitodiplosis mosellana; wheat, population dispersal, air current, HYSPLIT-4 model, dispersal trajectory, altitude stratification