|Budget Amount *help
¥19,630,000 (Direct Cost: ¥15,100,000、Indirect Cost: ¥4,530,000)
Fiscal Year 2014: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2013: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2012: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2011: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000)
|Outline of Final Research Achievements
We aim at comprehensively testing all existing hypotheses of biological invasion in ants by focusing on Brachyponera （Pachycondyla）chinensis that has been invaded from East Asia to North America. Our polulation genetic, chemical and behavioral study revealed that their population and social structure was polygyny-polydomy and multicolonial that was qualitatively the same between the introduced (USA) and the native (Japan) ranges. However, in the USA their density was higher than in Japan. The stable isotope analysis suggested a shift in the trophic level or food niche, i.e. this ant is a specialist hunter of termites in Japan but has become a generalist predator in the USA. The pupal mortality presumably correlated to the infection lord was higher in Japan. Those results suggest that as the mechanism of biological invasion of this ant the ecological release is more important than social insect-specific mechanisms such as genetic bottleneck.