1993 Fiscal Year Final Research Report Summary
Studies on origin of diapause, wing polymorphism and photoperiodism in insects
| Project/Area Number |
03660037
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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 |
植物保護
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| Research Institution | Hirosaki University |
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Principal Investigator |
ANDO Yoshikazu Hirosaki University, Faculty of Agriculture, Professor, 農学部, 教授 (20003775)
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| Co-Investigator(Kenkyū-buntansha) |
MASAKI Sinzo Hirosaki University, Professor Emeritus, 名誉教授 (00003418)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Diapause / Wingpolymorphism / Photoperiodism / Biological clock / Cricket / Grasshopper / Noctuid / Selection |
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| Research Abstract |
1. The Dianemobius fascipes-nigrofasciatus species group shows a geographic cline in the incidence and intensity of egg diapause in parallel to the climatic gradient extending from the tropics to the temperate region. A similar clinal variation has been established in the laboratory by isolating several lines from the subtropical Ishigaki population and selecting for different diapause traits.
2. Twenty-four isofemale lines isolated from the Ishigaki population showed a wide range of variation in the critical daylength for the wing-form detemination. We concluded that the liability for macroptery but not the photoperiodic time measurement was responsible for this variation. Selection schems for different critical photoperiods were effective only in shortening but not lengthening the critical photoperiod.
3. The photoperiodic time measurement for the induction of pupal diapause in Mamestra brassicae showed either an oscillator or an hourglass response to various experimental protocols. We infer that the photoperiodic time measurement is performed by an hourglass mechanism and a circadian system is involved in the process of diapause induction.
4. We explored factors causing a large variation in hatching time of overwintered eggs of Oxya jezoensis. We found that eggs laid in late autumn successfully overwintered before the diapause stage. In early spring, they reached the diapause stage and the diapause delayd embryogenesis. Moreover, eggs after overwintering survived a long period of immersion in water, and could hatch after the paddy field was draibed in autumn.
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