| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2003: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2002: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
I studied the two aspects of ecological impact, reproductive disturbance and introduction of alien parasites, caused by the naturalization of the European bumblebee Bomb us terrestris. In order to clarify the impact of inter-species crosses between the introduced and native bumblebees on reproduction of the native species, I investigated the following 4 process ; 1)mating behavior of males and queens, 2)dynamics of spermatozoa in a male through ageing, 3)dynamics of spermatozoa in a male through multiple mating, and 4)the availability of spermatozoa for fertilization in inter-species crosses. I found that males could mate plural times and a queens could be inseminated by plural males. This results, associated with the high sex ratio, suggest the keen sperm competition in bumblebees. Inter species crosses showed that males of B.terrestris could mate with the two native species, B.hypocrita and B.ignitus, and then fertilized eggs could be produced. However, the eggs could not hatch, which indicates post-zygotic isolation. So, if many males of the European bumblebee mate with the native queens in the field, reproductive disturbance will occur, Secondly, I investigated the status of infection of the endoparasitic mites in the natural population of the native species. I detected the mites exhibiting the European DNA haplotypes from the native bees in the field. And the infestation rate of the European mite seemed to be increasing in the native species populations.
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