Simultaneous Trap Catches of the Oriental Armyworm and the Diamondback Moth during the Early Flight Season at Morioka

Abstract

The Oriental armyworm Pseudaletia separata WALKER and the diamondback moth Plutella xylostella LINNÉ cannot overwinter at Morioka, Iwate Prefecture, and they immigrate annually from warmer areas. Their immigration in spring was monitored using pheromone traps. The first capture of the Oriental armyworm moth in 1982 and in 1983 was recorded on May 13 and on May 7, respectively, and large numbers of diamondback moths were trapped simultaneously. Synoptic charts showed that the fronts concerned were accompanied by depressions which moved northeastward from the lower basin of the Yangze River in China across the Yellow Sea, the Korean Peninsula and the Sea of Japan. These captures coincided with the passage of frontal systems over northern Japan. The weather conditions at the time of trapping also suggested the passage of frontal systems. These facts indicate that the immigrant moths were carried by the same frontal systems along with their movement.