| The rice stem borer,Chilo suppressalis Walker（Lepidoptera:Pyralidae）is one of the most serious rice pests in China.Genetic diversity and population genetic structure are important research contents of integrated pest management.In order to identify the genetic differentiation and gene flow among different populations of pests,clarify its population demographic history and phylogenetic relationship,inferring their migration pathway and dispersion,it is necessary to investigate its genetic diversity and population genetic structure based on some molecular genetic markers,such as microsatellite loci（SSR）.In view of the fact that the population genetics of C.suppressalis is still research blank in Liaoning Province and the population genetic relationship is not clear,we used microsatellite molecular markers to analyze the genetic variation and population genetic structure of different populations of C.suppressalis.Meanwhile,we used 16S r DNA high-throughput sequencing technology to study the gut bacterial diversity and community structure of different populations of C.suppressalis.The main results are as follows:1.We studied the genetic variation,genetic differentiation and genetic structure of sixteen populations of C.suppressalis in Liaoning Province based on twelve microsatellite loci.In general,twelve microsatellite loci were highly polymorphic.The average number of alleles（Na）and effective allele number（Ne）of each microsatellite locus were 6.646 and5.693.The genetic variation of different geographical populations of C.suppressalis was moderate level.The average observed heterozygosity（Ho=0.468）was similar to the average expected heterozygosity（He=0.595）.There were genetic variations among different geographic populations of C.suppressalis.Qingyuan（QY）population had the highest level of genetic diversity（He=0.611）.In contrast,Beizhen（BZ）and Xinglong（XL）populations had the lowest genetic diversity（He=0.532）.2.There was moderate genetic differentiation among different geographic populations of C.suppressalis in Liaoning Province(0.004<FST<0.193).There was a certain gene flow in the population（1.048<Nm<64.017）.Based on neighbor tree（NJ）,Bayesian clustering analysis and principal coordinate analysis（PCo A）,the populations of C.suppressalis was divided into three genetic groups,western,eastern,and northern¢ral populations in Liaoning.The results of isolation-by-distance（IBD）and spatial autocorrelation analysis showed that there was no correlation between genetic distance and geographical distance.In addition,the analysis of bottleneck effect showed that C.suppressalis has no bottleneck effect in these regions.3.The bacterial diversity and community structure of C.suppressalis collected from five representative rice producing areas were studied by using 16S r DNA high-throughput sequencing technology.A total of 1,084,644 high quality sequences with an average length of 418.44bp were obtained.A total of 1650 OTUs were obtained according to 97%similarity threshold.The gut bacteria of C.suppressalis of different populations were annotated into 30 phyla,61 classes,159 orders,296 families and 697 genera.At the level of phylum,the most dominant bacteria in all populations was Proteobacteria.In addition,the abundance of Firmicutes,Actinobacteria and Bacteroidetes was relatively high.The secondary dominant bacteria in Huanren（HR）population was Actinobacteria,and in the other four populations were Firmicum.The dominant bacteria at the level of genus were Sphingomonas,Halomonas,Curvibacter and Serratia.Halomonas was the most dominant bacteria in Donggang（DG）population.Serratia was the most dominant bacteria in Huanren（HR）population.And the most dominant bacteria in other three populations were Sphingomonas.4.The gut bacterial diversity and community composition of C.suppressalis in different geographical populations were different.The bacterial community diversity of C.suppressalis in Beizhen（BZ）,Liaoyang LY)and Changtu（CT）population was higher than that in Donggang（DG）and Huanren（HR）populations which were in eastern Liaoning.The results of PCA,PCo A and clustering tree were consistent.The bacterial community structure of Liaoyang,Changtu and Beizhen populations were similar,and were significant differences among Donggang and Huanren populations.LDA effect size（LEf Se）analysis identified the microbial groups with significant effect in Beizhen,Changtu and Liaoyang population.Moreover,the composition of gut bacterial community was related to environmental factors such as temperature and humidity.According to the comparison with KEGG database,the functional annotation results of C.suppressalis in different populations were basically consistent,and the abundance of functional genes related to membrane transport,amino acid metabolism,carbohydrate metabolism,replication and repair were relatively high. |
