Seasonal Migration of Apolygus lucorum (Hemiptera: Miridae) Over the Bohai Sea in Northern China

During the past decade, Apolygus lucorum (Meyer-Dur) has become a key pest on cotton in northern China. Whether or not this species is a migrant, and if so, what pattern of seasonal migration this species exhibits remains unknown. The combination of searchlight trapping and radar observation on an isolated island in the center of Bohai Gulf during the past 11 yr provided direct evidence that both male and female A. lucorum adults migrate at least 40-60 km (and probably much greater distances) across the Bohai Gulf waters. There were considerable yearly and monthly variation in the number of A. lucorum trapped on BH, and the migration period during 2009-2013 ranged from 102 to 154 d. A. lucorum adults had downwind displacement rather than randomly by heading toward their seasonally favorable directions, which toward the east-northeast in summer, but south-southwest (SSW) in early autumn. The vast majority of adults flying at airspeeds 0.5-2.5 m/s and at altitudes <150 m above ground level. Most of trapped females were virgins with little or no ovarian development, as suggests that the onset of migration is initiated mainly by sexually immature individuals, which is termed the oogenesis-flight syndrome. Such findings reveal a new route for A. lucorum movements northward to and southward from the northeastern agricultural region of China, which will help us develop more effective management strategies against this pest species.