| Project/Area Number |
61540468
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
生態学
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| Research Institution | Hokkaido University |
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Principal Investigator |
SAITO Yutaka Instructor, Faculty of Agriculture, Hokkaido University, 農学部, 助手 (20142698)
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| Co-Investigator(Kenkyū-buntansha) |
MORI Hans Professor, Faculty of Agriculture, Hokkaido University, 農学部, 教授 (10001398)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1987: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1986: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Sub-sociality / Schizotetranychus celarius / Phytoseiidae / Natural enemy / Experimental method / Kin-selection / Population / 個体群 / 行動 / シミュレーション / ハダニ / 個体群動態 / 近親交配 / 捕食者 / 変異 |
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| Research Abstract |
Data on 4-year population dynamics of 6 species of spider mites and their natural enemies were inputed into the computer files. Based on these files, spatial and temporal dynamics of the prey and predators were analysed. In addition to these, behavioural observations and life history experiments were made with the spider mites and their predators. The results obtained are as follows: The sub-social spider mites, Schizotetranychus celarius, shows an extraordinary pattern of reproduction when left unfertilized state. The reproductive pattern as well as the facts observed in the field surveys strongly suggest a possibility of mother-son matings in S. celarius in nature. Mother-son mating inevitably increases the relatedness between nest members. The possibility that kin-selection in the S. celarius led to sub-sociality is suggested.
A phytoseiid predator, Typhlodromus bambusae preferably fed S. celarius, while it could feed the other species of spider mites occurring syntopically on Sasa leaves. This fact shows that studies on multi-species population dynamics are of importance to a single species population problem.
As a by-product of this project, we discovered that the commonly-used method for experimental study of spider mite and phytoseiid life histories caused temperature variations in the layer where the mites live. A preliminary observation was made to clarify this phenomenon and the result was published.
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