| Budget Amount *help |
¥4,990,000 (Direct Cost: ¥4,600,000、Indirect Cost: ¥390,000)
Fiscal Year 2007: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
Through the 3-year survey the current faunas for wasps, bees, ants and termites were clarified on the Krakatau Islands. Forty-six species of wasp were collected from the four islands, the number being only 74.2% of that (62)in the previous survey in 1982. In some groups the equilibrium species number was already reached in 1982, and in all the groups the species number decreased in 2005-08. In bees, 24 species were collected in 1982, 23 species in the present survey, showing a slight change. On the other hand, in ants and termites the species number had distinctly increased after 1982 (77 spp. in 1982, 95 spp. in 2005-07). The ant species number has constantly increased during ca. 100 years. Termite species number greatly increased after 1996, when the survey was quite incomplete; during ca. 100 years colonization curve has similar slopes among the survey periods. Since most of wasps and bees prefer open sites, it was expected that the species number should decrease as the forest develops. The results agree with this prediction. On the other hand, large parts of ant and termite species are living in forests. Development of forest may accelerate immigration of more forest species. Our result supports this prediction; species number is still steadily increasing. Not a few cases of turnover due to vegetation change were observed in ants; species of open site decreased and forest species increased. Thus, the time needed for the attainment of equilibrium species number can be different among groups with different habitat preferences. In termites the most cases of migration to the Krakataus may have been done through drifting. Also in ants, one such case was confirmed for Leptogenys sp. which has wingless foundress queen. Emergence of adults from a drifted log was also observed in a Typoxylon species, a spider hunter wasp. However, generally in wasps, bees and ants, migration by flight may be more common.
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