| Budget Amount *help |
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1998: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1997: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
The results of the investigation showed that the British subspecies of cabbage butterfly, Pieris rapae rapae is different from Japanese subspecies in some visual features of the wings. British males have only one spot instead of two on the dorsal surface of the forewing, both male and female are more yellowish, and they both lack ultra-violet color which is the essential element of the Japanese female wing color for the mate recognition by the Japanese male. This indicates little visual sexual dimorphism in the wings of the British. It follows that may suffer some difficulties in discriminating females, if they do it visually.
It was shown that the British subspecies is basically similar to the Japanese subspecies in the mating behaviors. As in Japanese subspecies, British males fly about for a mate, approach her immediately when they find her visually and attempt to mate her. No essential roles of the olfaction in the mate recognition was suggested. British males were, however, observed to mistakenly approach other resting males and in some case to attempt to mate, probably due to the little visual sexual dimorphism. This maladaptive copulatory attempt is not successful, because the approached males reject copulatory attempt mechanically by the flutter response.
The British males were shown to approach the British subspecies of female wing model when presented it with the whitish form of the Japanese female wing model. They were, however, observed to show mating response to the yellowish form of the Japanese female wing model when presented it with the cospecific female wing model. Japanese males, on the other hand, showed very rare mating response to the British female wing model when it was presented with the Japanese female wing model 20cm apart. They were, however, observed to show the mating response to the British female wing model when it was presented 1.5cm apart. The results suggest that two subspecies may be partly isolated through mating behaviors.
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