Seasonal migration ofCnaphalocrocis medinalis(Lepidoptera: Crambidae) over the Bohai Sea in northern China

Abstract

AbstractThe rice leaf roller,Cnaphalocrocis medinalis(Guenée), is a serious insect pest of rice with a strong migratory ability. Previous studies on the migration ofC. medinaliswere mostly carried out in tropical or subtropical regions, however, and what the pattern of seasonal movements this species exhibits in temperate regions (i.e. Northern China, where they cannot overwinter) remains unknown. Here we present data from an 11-year study of this species made by searchlight trapping on Beihuang Island (BH, 38°24′N; 120°55′E) in the centre of the Bohai Strait, which provides direct evidence thatC. medinalisregularly migrates across this sea into northeastern agricultural region of China, and to take advantage of the abundant food resources there during the summer season. There was considerable seasonal variation in number ofC. medinalistrapped on BH, and the migration period during 2003–2013 ranged from 72 to 122 days. Some females trapped in June and July showed a relatively higher proportion of mated and a degree of ovarian development suggesting that the migration of this species is not completely bound by the ‘oogenesis-flight syndrome’. These findings revealed a new route forC. medinalismovements to and from Northeastern China, which will help us develop more effective management strategies against this pest.