| Budget Amount *help |
¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000)
Fiscal Year 2015: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2014: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2013: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
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| Outline of Final Research Achievements |
We investigated the factors in the expansion of the distribution range and population size of the socially parasitic hornet Vespa dybowskii in Japan. The haplotype analyses suggested that artificial transfer of the overwintered queens from Honshu to Hokkaido (or vice versa) has not occurred. The recent expansion of its distribution range either in Hokkaido and Honshu would be of the host-species switch from V. crabro to V. simillima. While the recorded hosts at about 60 years ago were nearly always V. crabro, recent host records show that more than 60% of the host hornet species are V. simillima. The population sizes of V. simillima have recently increased in urban areas, whereas those of V. crabro have decreased in various regions in Japan. These findings suggest that a possible switch in the principal host from V. crabro to V. simillima is one of the factors underlying the rapid range expansion and increase in the population size of V. dybowskii.
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