DNA Barcode Of Lygaeoidea (Insecta:Hemiptera:Heteroptera) In Inner Mongolia

Lygaeoidea(Insecta:Hemiptera:Heteroptera)are widely distributed in Inner Mongolia.Most of them are economic pests,which can pose a greater threat to farmland,grassland and forest.Most are dark in color,small in size and similar in morphology,which makes identification difficult.In this study,DNA barcode was used to Lygaeoidea for the first time.96 COI gene sequences were amplified and 31 were downloaded from the GeneBank,totally 127 COI gene sequences,belonging to6 family 27 genera 39 species.The sequence characteristic of COI gene was analysed.The applicability of COI gene of DNA barcode in species identification of Lygaeoidea,the phylogenetic relationship of Lygaeoidea with NJ,MP and BI method,and the genetic relationship of six different geographical populations of Nysius ericae were discussed.Through the combination of similarity comparison in GeneBank and BOLD and morphological identification,we found that Lamproplax picea was a new record species in China,Henestaris halophilus was a new record species in Inner Mongolia,and there may be a synonym of Emblethis vicarius and Emblethis branchynotus.Analysis of sequence charateristic of gen COI of Lygaeoidea showed that the average content of A+T(65.6%)was significantly higher than that of G+C(34.6%),which showed a strong A+T bias;there was also a bias in amino acid composition,UUA(L)with the highest coding frequency(11.4),UGU(C)and UGC(C)with the lowest coding frequency(0);the contents of Trp(2.94),His(1.96)and Cys(0)were identical in 39 species of Lygaeoidea.The transition mainly occured between T and C(80%),and transversion mainly occured between T and A(20%).K2P model was used to calculate the genetic distance of COI gene sequence.The maximum intraspecific genetic distance(4.41%)was smaller than the minimum interspecific genetic distance(6.56%).There was no overlap of genetic distance.The average propotion between interspecific genetic distance and average intraspecific genetic distance was more than 173,far more than the standard.In the NJ tree,the same species all formed a monophyly,consistent with the results of traditional taxonomy.Using the Best match,Best close match and All species barcodes in specifications identifier 1.0,the success rates of accurate identification are 100%,87.61% and 92.03%,Cluster divided the data into 40 groups;jMOTU analysis showed that the success rate of species division was 95.28%,41 groups;ABGD analysis showed that the success rate was 93.70%,38 groups;PTP analysis showed that the success rate was 97.64%,40 groups.Among the above five methods,the results of NJ tree constructed based on K2 P genetic distance model were consistent with the results of traditional taxonomy,and the results of other methods were different from traditional taxonomy.The species division of Lygaeoidea still needs to be improved.The phylogenetic relationship of 39 species of Lygaeoidea with the outgroup Physopelta cincticollis was constructed.The results showed that among 39 species,7 genera with 2 or more species,5 of which were monophyletic;the Ortholomus genus was nested in Nysius genus,and had the closest relationship with Nysius senecionis.It should be further studied to determine its taxonomic status.The position of Plithisus lativentris was varied in NJ,MP and BI trees.It closely related to Kleidocerys resedae of Lygaeidae,Oxycarenus pallens of Oxycarenidae and Dimorphopterus spinolae of Blissidae respectively,while far from other species of the Rhyparochromidae,that supported the view of upgrading the Plinthisinae to Plinthididae.The topological structure of phylogenetic tree was the same in most case at the genus level,but the phylogenetic relationship was confused at the higher level.Therefore,COI gene can be used as a molecular marker to analyze phylogenetic relationship on genera and species level.Genetic analysis of 6 populations of Nysius ercia from Huhhot,Tongliao,Chifeng,Wuhai,Xilinguole and Erdos showed that Tajima's D was-0.7780(P > 0.10),Fst was 0.75,Nm was 0.21,there was certain genetic differentiation;The results of AMOVA showed that the variation mainly existed between populations;TL population had the sigle haplotype H2.