| Bactrocera dorsalis（Hendel）（Diptera:Trypetidae）,is widely distributed in tropical and subtropical areas,mostly in the southern regions of China.It is an important invasive pest worldwide.As a large province abundant with fruits and vegetables,Guangxi was one of the earliest regions invaded by B.dorsalis which had been causing serious losses in fruit in some areas.After long-term interaction with host and environment,B.dorsalis may have a strong genetic structure,which makes it hard to the control.Given this,B.dorsalis of 24 areas in Guangxi were widely collected.The dissertation deals with a variety of bioinformatics research methods such as the phylogenetic relationships,pedigree biogeography and genetic variation parameter analysis among B.dorsalis populations,examines geographical pattern and diversity based on 8 microsatellites and mitochondrial COI fragments.The main results were as follows:1.The full-length transcriptome Library of B.dorsalis was constructed.Bioinformatics analysis of sequencing data showed that 40,319,890 subreads,535,241 Circular consensus sequences（CCS）and 386,916 full-length non-concatemer（FLNC）sequences were produced by Pac Bio Sequel system.A total of 12,274 of 22,780 high-quality（HQ）isomers were identified and mapped with99%accuracy,corresponding to 5,365 known isoforms and 226 unannotated new isoforms.Of the 12,274 sequences analyzed,2,412 sequences were shared across four databases.Among them,11,150（90.84%）,8,675（70.68%）,6,102（49.71%）and 3,169（25.82%）sequences were annotated in Nr,Swiss-Port,GO and KEGG databases,respectively.2.Microsatellite analysis and screening based on full-length transcriptome database showed that there were 1,978 SSRs loci were detected from 12,274 non-redundant transcripts.8 pairs of primers were selected from 80 to analyze the genetic diversity of 179 individuals from 24 populations in different areas.The average number of alleles Na,effective alleles Ne,expected heterozygote He and Shannon index I were 3.98,2.78,0.54 and 1.03,respectively,indicating there was a good loci polymorphism.3.Studies on microsatellite molecular markers showed that 118 alleles were detected by 8 pairs of microsatellite primers.The average number of different alleles（Na）,the average number of effective alleles（Ne）,average observed heterozygosity（Ho）,average expected heterozygosity（He）and average Shannon information index（I）among 179 samples from 23 geographical populations ranged from 2.25 to 5.75,1.69 to 3.61,0.31 to 0.69 and 0.34,to 0.66,and 0.56 to1.32.AMOVA analysis of molecular variance showed that the variation was mainly from individuals.The mean values of Fis,Fit and FST were 0.086,0.224and 0.154,respectively,showing a high level of genetic differentiation.The mean values of Nm 1.542 showed high level gene exchange.Matel test indicated that there was no significant correlation between geographical distance and genetic distance among different populations.4.The results of mitochondrial DNA COI fragment showed that 98haplotypes were observed from 337 B.dorsalis samples,of which 39 shared haplotypes.The average haplotype diversity and nucleotide diversity of the 24geographical populations were 0.941 and 0.00658,exhibiting a high level of genetic diversity.The results of F-statistical method to measure the degree of genetic differentiation indicating that high genetic differentiation among most populations.AMOVA results showed that the main factor causing variation of the population was the individual variation.The overall value of neutral test was p<0.01,and the mismatch analysis diagram showed obvious bimodal pattern,indicating that the stable population of B.dorsalis had experienced population expansion.In conlusion,B.dorsalis of these 24 areas of Guangxi presented high population genetic diversity with high-level genetic differentiation.The insect flight and airflow cause individuals mixed among different geographic populations.Simutaneously,the geographic isolation has little influence on B.dorsalis because of human activies making them achieve long-distence diffusion and finally presented the high-level gene flow among populations. |
