Observations of the autumn migration of the rice leaf roller Cnaphalocrocis medinalis (Lepidoptera: Pyralidae) and other moths in eastern China

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Abstract
The autumn migration of the rice leaf roller moth, Cnaphalocrocis medinalis Guenée, in eastern China was studied at two sites (one in southern Jiangsu Province and one in northern Jiangxi Province), using radar and aerial netting. It was confirmed that C. medinalis is a high-altitude nocturnal windborne migrant, with large numbers of moths taking-off at dusk and flying continuously for several hours. Migration was post-teneral and the females had immature ovaries. Maximum densities of the moths typically occurred between 250 and 550 m above ground, and layering was intense on some nights. Moth layers often occurred at an altitude where there was a wind-speed maximum. In early September, migrant C. medinalis from southern Jiangsu Province were carried on the winds in an approximately westward direction. However, the winds prevailing in late September and October took migrants from both sites towards the south-west or south. Forward trajectories for C. medinalis and other insects emigrating from northern Jiangxi during October indicated that they were able to reach the tropical rice-growing areas near the south China coast, where year-round breeding would be possible. Incidental observations on the migratory flight of other lepidopteran pests, including Mythimna separata (Walker), Spodoptera litura (Fabricius), Ctenoplusia agnata (Staudinger) and Agrotis ipsilon (Hufnagel) (all Nocturidae), Spoladea recurvalis (Fabricius) and particularly Omiodes indicata (Fabricius) (both Pyralidae) are presented.