Studies On Control Effect Of Eucryptorrhynchus Brandti And E. Chinensis (Coleoptera:Curculionidae) On Ailanthus Altissima And Genetic Differentiation Of Different Populations And Mitochondrial Genome Of E. Brandti

Eucryptorrhynchus brandti Harold (Coleoptera:Curculionidae), along withi ts closely related species Eucryptorrhynchus chinensis Olivier, are herbivores which mainly feed on Ailanthus altissima (Mill.) Swingle. Larva of both beetles mainly attack on the cambium and xylem of A. altissima, even lead it to die. They spread with the seedling dispatching of A. altissima. E. brandti is considered as important natural enemies of A. altissima. In this study, the control effect of E. brandti and E. chinensis on A. altissima in China was evaluated. The differentiation of different geographic populations of E. brandti was studied and the mitochondrial genome of E. brandti was sequenced and analyzed except for the control region. The results are showed in turn belowe:1、Five treatments were used to stress the trees. Tree health condition, number of E. brandti and E. chinensis adults and emergency holes were recorded on fixed date. The results showed that the greater the degree of stress inflicted on A. altissima, the more successful was the development of Eucryptorrhynchus spp. and the control effectiveness of A. altissima. The overall study showed that E. brandti can contribute to the biological control of A. altissima in North America.2、Geographic differentiation analysis based on mtDNA COⅠ、COⅡ、COⅢ,CYTB genes, and ribosomal rDNA-ITS2gene of E. brandti was conducted with some general outcomes in below.(1) The average content of (A+T)%in the four mtDNA genes was72%, which tallied with the suggestions that mitochondria had a mutation pressure from G+C to A+T and that the base transition rate is higher than the transversion rate.(2) Variation sites were found in both mtDNA and rDNA genes with7variable sites among all four mtDNA genes and only one variable site in the rDNA ITS2gene.(3) AMOVA analysis apparently showed genetic differentiation existing in COI and COIII genes of E. brandti.(4) Haplotype analysis showed that each geographical population had both shared haplotype and sole haplotype. However, the latter is much more obvious than the former. It indicated that both gene flow and genetic differentiation exist among each geographical population.(5) Gene flow analysis demonstrated that the genetic differentiation between Xi’an geographical population (BSXX) and either Beijing (BBJ) or Huludao (BLNH) geographical population was the highest. All the Nm values of each geographical population were less than4, indicating the gene flows were rare.3、Most mitochondrial genomes of E. brandti were successfully sequencedwith the exception of D-loop region in the present study. The results were showed as follows. (1) The length of the E. brandti mtDNA acquired is15534bp which contains13protein coding genes,22tRNA genes and2rRNA coding genes, as well as partial D-loop region. All these genes showed a high bias towards A+T.(2) Most protein-coding genes of the studied E. brandti started with a typical ATN codon while three protein-coding genes (ATP6、ND4and CYTB) started with ATGATA. All the13protein-coding genes ended with TAN. Leucine, isoleucine, serine, phenylalanineare were the most frequently used amino acids in the mitochondrial protein-coding genes.(3) Besides tRNASer(AGN) lacking of dihydrouridine arm, other tRNAs had typical secondary structures of clover leaf. The anticodons of most tRNAs were GNN and UNN, which were similar to those found in other Hexapoda animals. The aminoacyl stems and anticodon loops of tRNAs were conservative while other stems and loops were variable. The problem of mismatching between some tRNA anticodons and high frequent synonymous codons could be repaired by UU pairing.(4) The predicted secondary structure of lsrRNA gene was identical to other insects’ However, the predicted secondary structure of ssrRNA gene was much different from both length and its secondary structure.