| Booklice belong to the genus of Liposcelis Motschulsky 1852 in the family of Liposcelididae in Psocoptera. They are regarded as a worldwide spread storage pest. Booklice can spread a long distance with their infection in goods of import and export trades or passenger belongings. With the international trading increasing, bookilic are posing an increasing threat in quarantine issues in recent years. Booklice are of small body size, so they are difficult in morphological identification. Quarantine departments arouse for rapid and accurate identification techniques in identifying booklice. By studying the evolutionary relationship between different reproduction types (sexual and asexual), it will provide theoretical support for the control of booklice. By sequencing and analyzing mitochondrial genomes booklice species, as well as mitochondrial genomes comparatitive study of among taxons at species, genus, and order level, it will highly enhance the development of insect comparative genome study and the understanding mitochondrial genome evolution.In this study, I carried out molecular study of 10 common stored booklice species, including: sequenced 155 mtDNA COI sequences from 43 geographical localities of 10 common stored booklice species; designed and screened 8 pairs of species-specific primer pairs for specific amplification of 8 common stored booklice species; bulit phylogeentic trees of the Arizona sexual strain and 13 parthenogentic strains of L. bostrychophila (Badonnel) based on sequences of mtDNA 12S rRNA and 16S rRNA; screened endosymbionts of Arizona sexual strain (5 males and 8 females) and 9 parthenogentic strains (21 individulas) of L. bostrychophila; amplified mitochondrial genome of 12 strains of 4 booklice species and carried out comparative mitochondrial genome study among different taxon levels with published mitochondrial genome sequences of Psocoptera species. The main results are as follows:(1) I bulit a morphological taxonomic key and a DNA barcoding library of 10 common stored booklice species. I developed a molecular identification technology system through DNA barcoding. This systerm can be used in molecular identification of 10 common booklice species.(2) I designed and screened 8 pairs of species-specific primers for 8 common booklice based on multiple alignments of DNA barcoding sequences. These species-specific primer pairs form fast diagnosis kits. They can be applied in rapid and accurate identification of booklice with a timesaving, economic and effective advantage.(3) I studied the phylogenetic relationship between the Arizona sexual and parthenogenetic L. bostrychophila geological strains. The results showed that the Arizona sexual L. bostrychophila colony contained two hyplotypes (HI and HⅡ). Besides, the Arizona sexual L. bostrychophila colony is close to a parthenogenetic strain from Illinios. The primary results support the hypotheses that the sexual reproduction mode involved from parthenogenetic reproduction mode in L. bostrychophila.(4) The screening of endosymbionts was tested revealed that Rickettsia showed infection in all tested parthenogenetic individuals, but not in any sexual individuals in L. bostrychophila. Rickettsia might play an important role in parthenogenetic reproduction form in L. bostrychophila.(5) Among all tested Psocoptera species, mitochodrial genome only detected fragmented in L. bostrychophila. Mitochodrial genome of L. bostrychophila fragmented into two middle-size chromosomes. In other Psocoptera species, the mitochodrial genome is of a single circular chromosome.(6) The mitochondrial genome of different strains of L. bostrychophila fragmented in three different styles, among which, one fragmentation style might be a transitional form of other two styles.(7) Various types of extensive gene rearrangement were found in five Liposcelis species. The rearrangement types among booklice speces did not follow sepecific rules.(8) The evolutinary rate of three suborder of Psocptare from high to low is:Troctomorpha> Trogiomorpha> Psocomorpha(9) coxl is the most conserved gene in Psocoptera species. However, the parewise alignment revealed a similarity of 82.5% beween different strains of L. bostrychophila. It’s necessary to redifine intra-specific genetic divergence in molecular identification through DNA barcode of COI fragment. |
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