Biodiversity And Molecular Identification Of The Scolytinae Reinvestigation In Chongqing Area

Bark beetles are one of the most important forest pests in the world,which can have a great impact on local forest resources,wood processing and exportation industry.In China,many species of bark beetles have been listed as quarantine objects.However,there are only sporadic reports on the study of the beetles in Chongqing area.In order to systematically understand the diversity of Scolytinae in Chongqing,and to provide a classification basis for the control of forest diseases and insect pests,the main counties,natural reserves and forest parks of Chongqing were collected in 2015 to 2017.More than 150 specimens of Scolytinae were collected,belonging to 41 species of 24 genera of 11 tribes.There are 3 new species records in China and 26 new species records in Chongqing.The collection results indicate that Xyleborinus saxesenii,Xylosandrus crassiusculus,Phloeosinus sinensis and Cryphalus lipingensis are the dominant species in Chongqing area.Pengshui,and Chengkou County have higher species diversity,with 13 and 11 species,respectively.The whole genome DNA was extracted from the collected beetle and the partial sequences of the 28 S rDNA,COI and CAD labeled genes were amplified for analysis.The partial sequences of the corresponding genes in the GenBank database were used for analysis.Among the sequences obtained,the proportions of variation site,conserved site,parsimony-information site and singleton site of self-descendant locus were analyzed.We calculated the values of T,C,A,G,A+T,G+C,Transition,Transversion,the ratio of Transition and Transversion and drew the map of substitution saturation and genetic distance of each species.A phylogenetic tree was constructed by using Neighbor-Joinning(NJ)and Maximum Likelihood(ML).The results showed that Ambrosiodmus and Ambrosiophilus have a close relationship;Dryocoetini and Xyleborini have a close relationship,Dryocoetiops moestus accumulation in Xyleborini;the genetic relationship among the genera in the Xyleborini was confused,Euwalacea,Xylosandrus and Cnestus may have different origins.The species of the Scolytoplatypodini,Cryphalini and Xyloterini can be distinguished well.This study has enriched the data of the insects in Chongqing and provided the basic data for the study of biology and control techniques of the beetle in Chongqing.