| Chilo suppressalis (Walker)(Lepidoptera:Pyralididae) is one of the major pests of rice. Because of its widespread and large number of host plants, the complex interactions between the borer and the diverse environments may bring to its high genetic variation, which makes it difficult to manage. It is reasonable to find out the population genetic structure of the C. suppressalis, analyze its phylogeography and infer the demographic history of this species as well as its differentiation mechanism. In this study, we build life table of C. suppressalis between Jiangxi Province and Jiangsu Province, and we use molecular techniques to examine the intraspecific variation based on mitochondrial COII and ribosomal ITS sequences among the populations of C. suppressalis collected from different geographical areas in China respectively. Additionally, we discuss the genetic structure and the molecular diversity among the different populations of C. suppressalis based on the two molecular markers.1. To build life table of C. suppressalis between shangrao and funingFrom the life table we can see that there was a significant difference on the pupal stage of female pupae of Chilo suppressalis between funing and shangrao, respectively,6.32d and7.15d, the pupal stage of female pupae about Id longer than Funing, but the pupal stage of male pupae between the two geographic populations have no significant differences. Pupa weight of the two populations also exist significant differences, the weight of female pupae was58.6mg of Funing populations, and Shangrao populations was44.0mg, much lower than Funing populations. In other biological indicators, the two geographic populations of Chilo suppressalis have no significant differences.2. The intraspecies phylogenetic analyses of C. suppressalis based on mtDNA-COII sequences.There were a certain degree of genetic differentiation of C. suppressalis among14geographic populations, and some have a grater differentiation based on mtDNA-COII sequences. The COII sequences among different geographical populations of C. suppressalis have eight variable positions, and all these variations occurred in the third codon sites, C. suppressalis intraspecific variation analysis between these populations from0to1.3percent and the Ningdu sample differed from the others obviously. Different geographic populations of C. suppressalis togethered for a large clade by Bootstrap consensus tree, the populations of Ganyu, Tongcheng and Xinfeng were in the same samples by bootstrap consensus tree, and the populations of Nanjing, Longnan, Wuyuan, Wan-an, Lujiang, Yizheng, Hengfeng and Shanghang were in the same samples. The phylogenetic trees showed that Ningdu population had the most diversity among the14populations based on COII sequence.3. The intraspecies phylogenetic analyses of C. suppressalis based on rDNA-ITS sequences.To investigate the phylogenetic relationships of C. suppressalis, we comparied the sequences based on ribosomal DNA (rDNA). The results showed that the length of ITS was from545to585bp with variation of40bp and the average length was576bp. The phylogenetic trees showed that Ningdu population (ND) had the most diversity among the14populations based on COII sequence, as well as Xingguo population (XG) had the most diversity based on ITS sequence. In both trees, we found that Longnan (LN), Wuyuan (WY), Lujiang (LJ), and Shanghang (SH) populations were in one clade, other populations were slightly different. Next we should select more molecular markers to find out the genetic structure of C. suppressalis. |
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