Problematic migration to cultivated field of cabbage looper Trichoplusia ni as a pest ; Their ecological aspects and how they control.

卷心菜环纹夜蛾是美国长期危害的农作物害虫。但2000年在日本西部地区(鹿儿岛和兵库县)的甘蓝田中发现了大量的卷心菜幼虫，其分布范围从日本西南部向东北部蔓延。例如，千叶县没有发现幼虫，该项目于2003年首次确认了T.ni的出现。利用信息素诱捕器捕获的成虫和田间采集的幼虫监测了T.ni在甘蓝田里的年发生情况。从春季到秋季，日本血吸虫幼虫数量呈增加趋势。兵库县甘蓝田的优势种在春季以黑心莲为主，秋季以黑腹拟球藻为主。但黑星天牛幼虫的抗寒性比T.ni更强。因此，春季甘蓝田的优势种又变成了黑斑潜蝇。在这个项目中，日本黑斑潜蝇的来源尚不清楚。但在日本黄粉虫上的寄生率低于美国黄粉虫。这些数据表明，日本卷心菜卷叶蛾与美国卷心菜卷叶蛾有很大的不同。

The cabbage looper Trichoplusia ni (Lepidoptera, Noctuidae) is notorious crop pest in the USA for long time. However, there was no report about T.ni as a crop pest in Japan.But there were many larvae of T.ni in cabbage field of west parts of Japan (Kagoshima and Hyogo prefectures) in 2000.Distribution of Japanese cabbage looper is spreading from south-western to north-eastern parts of Japan. For example, there was no larvae in Chiba prefecture, and first appearance of T.ni was confirmed by this project in 2003.Annual occurrence of T.ni in cabbage field was monitored by adults captured by pheromone trap and larvae by field collecting. The number of larvae of T.ni is increasing from spring to fall. The dominant species of cabbage fields in Hyogo prefecture is Autographa nigrisigna in spring, then changing to Trichoplusia ni in fall. But cold resistance of larva of A.nigrisigna is stronger than T.ni. So, the dominant species of cabbage field changing to A.nigrisigna in spring again.Origin of Japanese T.ni could not clarify in this project. But parasitism rate of Copidosoma floridamum on Japanese T.ni is lower than T.ni of the USA. These data suggested that Japanese cabbage looper is quite different from American strain.