稻螟染色体C带核型研究

Studies on Karyotypes and C-banded Chromosome Profiles of Chilo suppressalts,Tryporyza incertulas and Cnaphalocrocis medinalis

应用C带技术分析二化螟Chilo suppressalis(Walker)、三化螟Tryporyza incertulas (Walker)和纵卷叶螟Cnaphalocrocis medinalis (Guenée)[Lepi-dotera:Pyralidea]细胞有丝分裂中期核型及染色体C带特征。结果表明:①三种稻螟均由XX/XY型性别决定,K染色体为近中着丝点,Y染色体具端着丝点;②二化螟和三化螟的Y染色体均与X染色体长臂部分同源区配对,纵卷叶螟的Y染色体则与X染色体短臂全长配对;③二化螟核型2n=12:5AA+XX(♀)/XY(♂),5对常染色体(5AA)中,有一对中着丝点染色体,其余为端着丝点;④三化螟核型2n=14:6AA+XX(♀)/XY(♂),常染色体均为端着丝点;⑤纵卷叶螟核型2n=10:4AA+XX(♀)/XY(♂),常染色体具端着丝点。从而初步建立了3种稻螟染色体组C带带型。

The karyotypes and somatic chromosome C-banding patterns in mitotic metaphases of rice stemborer (Chilo suppressalis Walker), yellow stemborer (Tryporyza incertulas Walker) and leaf folder (Cnaphalocrocis medinalis Guenee) were analyzed by C-banding technique. It was found that 1 the sex determination of both the stemborers and the leaf folder were all of XY type, the X sexual chromosomes being submetacentromeric and the Y telo-centromer-ic ; the Y chromosome of both the stemborers homogenously paired with partial long-arm of the X chromosome next to its centromeres, while the Y chromosome of the leaf folder paired with the whole short-arm of its X chromosome in spermatocyte meiosis(Fig. 2 a and b) ; (3) the 2n karyotype of Chilo suppressalis consisted of 5 pairs of autosomes (AA) plus the sexual chromosomes XX (female) or XY (male), one pair of the autosomes (No. Dhaving metacentro-meres and the others having telocentromeres (Fig. 1 I a and I a)j (4) the 2n karyotype of T. incertulas consisted of 6 pairs of AA plus the XX in female or the XY in male, all the A A having telocentromeres (Fig. 1Ib and I b) (5) the 2n karyotype of C. medinalis consisted of 4 pairs of AA plus the XX in female or the XY in male, where all the A A had telocentromeres (Fig.1Ie and I c). The chromosome C-ibanding profiles of the three insect pests were established and the interspecific relationships between the pests and the evolution of their chromosomes discussed (Fig. 3).