1998 Fiscal Year Final Research Report Summary
SEX ALLOCATION MECHANISMS IN HAPLODIPLOID HYMENOPTERANS
| Project/Area Number |
08456027
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
植物保護
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| Research Institution | KOBE UNIVERSITY |
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Principal Investigator |
NAITO Tikahiko Kobe University, Faculty of Agriculture, Professor, 農学部, 教授 (70031226)
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| Co-Investigator(Kenkyū-buntansha) |
TAKASU Keishi Kobe University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (50212006)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Turnip sawfly / rose sawfly / ichneumonfly / haplodiploidy / sex determination / primary sex ratio / sperm displacement / sex allocation |
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| Research Abstract |
Sex determination and sex allocation in the haplodiploid sawflies and ichneumonfly were investigated.
1. The primary sex allocation of the turnip sawfly Athalia rosae was studied by our embryo chromosome technique. Females usually lay about 50 eggs over a 10 day period. Once-mated females laid many female eggs (100-70% female ratio) within the first three days. The female ratio remarkably decreased after the fourth day, and after the seventh day, all the eggs laid were males. During an oviposition event, the females exhibit a distinct pause in abdominal contractions just before the actual egg deposition act. Unmated females showed a longer pause (11.3 s on average) than mated females (4.4 s on overall average). Sperm displacement was demonstrated in Athalia rosae. When a virgin female was mated successively with two virgin males, the second male removed the sperm of the first male stored in the spermatheca using the conical projection on the penis before ejaculation.
2. Cytological evidence of brother-sister single-pair matings demonstrated two-locus CSD in the rose sawfly Arge nigrinodosa. Two sex loci are independent each other, and individuals hemizygous and homozygous for both loci develop into males and those heterozygous at least for one locus develop into females. Females of this sawfly lay egg mass in a young shoot of wild roses. They showed sex allocation rhythm such as female-female-male, when ovipositing at 25"*"C.
3. Mother-son single-pair matings revealed that the ichneumonfly Coccygomimus luctuosus had single-locus CSD.The diploid males were normal in morphology and survival.
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