| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2001: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
The fall webworm, Hyphantria cunea Drury (Lepidoptera: Arctiidae) was introduced from North America into Japan in 1945. For the first three decades after the introduction, the life cycle of this species was bivoltine. Thereafter, the life cycle shifted to a trivoltine one in southwestern areas of Japan. There are two scenarios for the process that led to the voltinism shift, one based on a single and the other on multiple independent colonizations. To test them, mitochondrial DNA sequences were analyzed in the black-headed type of fourteen Japanese, one Korean and two North American populations of H. cunea. In addition, the red-headed type of two North American populations of H. cunea were analyzed in the same regions of mitochondrial DNA for comparison. In the black-headed type, the sequences were similar in all Japanese populations and the Korean population. However, those of the North American populations differed from those of the other populations and each other. The present results suggest that the process of the shift in voltinism occurred originally in Japan, and that the Japanese and the Korean population of H. cunea originated from a relatively small area in North America.
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