Detection of intra-snacific variations and analysis of nonulation structure in spider mites, using genetic markers

二斑叶螨和神泽叶螨是两种广泛分布于日本的多食性螨。本研究比较了二斑叶螨和二斑叶螨滞育特征的差异，并确定了二斑叶螨和二斑叶螨的系统发育关系（绿色和红色）之间的滞育，也介于神泽赤眼蜂（K和T）之间。日本赤眼蜂的滞育是高度可变的，滞育百分比从北部的100%到本州西南部和九州的几乎为零，不同寄主类型的群体间差异不显著。另一方面，神泽赤眼蜂具有很强的滞育能力，在日本4个主要岛屿的种群滞育率接近100%。而冲绳种群的滞育率则显著下降。茶树上的神泽木蠹蛾种群滞育能力弱于草本和落叶寄主。COI基因分析线粒体细胞色素氧化酶亚基I的DNA序列分析表明，二斑叶螨的两种形态在一个簇中被识别，且存在遗传学上的差异，提示该螨在日本曾发生过多次偶然迁移。（COI和ITS1）未能明确区分神泽锥虫的T型和K型。结果表明，T型是由K型演化而来的。

Two species of spider mites, Tetranychus urticae and T.kanzawai, are both highly polyphagous and occur widely in Japan. This study compared the variation in diapause characteristics of the two species and determined the phylogenetic relationship between the two forms of T.urticae (green and red) and also between those of T.kanzawai (K and T).The diapause of Japanese T.uticae is highly variable and diapause percentage ranged from 100% in the north to nearly zero in southwestern Honshu and Kyushu, but no difference was detected among populations from different host types. On the other hand, T.kanzawai had a strong diapause capacity and populations in the 4 main islands of Japan exhibited nearly 100% diapause. However, diapause percentage drastically decreased in populations from Okinawa Islands. T.kanzawai populations derived from tea had weaker diapause capacity than those derived from herbaceous and deciduous hosts.Analysis of COI gene (mitochondrial cytochrome oxidase subunit I) showed that the two forms of T.urticae were recognized in a single cluster and the existence of haplotypes with phylogenetical divergence suggested that multiple accidental immigrations of the mite had occurred in Japan.The phylogenetic trees constructed using the DNA sequences (COI and ITS1) failed to clearly distinguish between the two types T and K of T.kanzawai. The results suggested that the T types were derived from the K type.