| The Tianshan Mountains divide Xinjiang into two parts: the north and the south.The rainfall in Northern Xinjiang is relatively humid,and the content of organic matter is relatively higher than that in the south.It is one of the main region of agricultural production in Xinjiang.North of Xinjiang is rich in crops such as wheat,rice and corn,as well as various economic warm crops such as cotton.Trichogrammatidae and Mymaridae which belong to the order Hymenoptera,suborder Apocrits,superfamily Chalcidoidea,are two common and important egg parasitic wasps,which are rich in resources,widely distributed,and have significant effects on pest control in various crops such as corn,rice,sugar cane,cotton and vegetables.Therefore,the accurate identification of them and studies on their biological characteristics have important reference value and significance for the biological control of agricultural pests in northern Xinjiang.However,due to their small size,rich variaton species,wide geographical distribution and different growth stage of host,cryptic and allied species,it is difficult to accurately identify them only based on traditional morphological characteristics.DNA barcode technology can use short specific gene fragments as barcodes to quickly identify species.It has the advantages of objectivity,simplicity,accuracy,and easy to operation,effectively supplementing the shortcomings of traditional morphological identification.Therefore,the technique can be used to solve the difficulties and problems of the morphological identification of Trichogrammatidae and Mymaridae parasitoids.In this study,DNA barcode based on genes COI and ITS2 were studied on the trichogrammatids and mymarids collecting from main farmlands in northern Xinjiang.The genomic DNA was obtained by the non-damage DNA extraction method,and the DNA barcode molecular labeling experiment was performed on the template through the COI and ITS2 genes.The obtained gene sequence was used to construct the phylogenetic tree of Trichogrammatidae and Mymaridae to compare their genetic distances.Combined with morphological characteristics,it can be accurately classified and identified.The main results are as follows:1.The application of DNA barcode in identification of Trichogrammaidae from the fields in northern Xinjiang(1)More than 350 specimens and 122 slide-made specimens were checked,as a result,they were separated into 6 genera and 16 species through the preliminary morphological identification,as follows:Ufens Girault,1911U.foersteri Kryger,1918U.simillis Kryger,1932Oligosita Walker,1851O.shibuyae Ishii,1938O.japonica Yashiro,1979O.brevicornis Lin,1994Aphelinoidea Girault,1911A.anatolica Nowicki,1936A.shawanica Hu & Lin,2005Pseudoligosita Girault,1913P.krygeri Girault,1929P.elongata Lin,1994P.curvata Lin,1994Trichogramma Westwood,1833T.evanescens Westwood,1833T.dendrolimi Matsumura,1926T.chilonis Ishii,1941T.pintoi Voegelé,1982T.sp.Mirufens GiraultM.longitubatus Lin,1994(2)The characteristics of COI and ITS2 genes of Trichogrammaidae were studied,and 70 COI and 95 ITS2 genes of 6 genera and 15 species were obtained.The length of the obtained COI gene fragments was 518 bp,and the A+T content(74.0%)was significantly higher than the C+G content(26.0%),showing obvious base bias.The lengths of ITS2 gene fragments obtained were 625 bp.The A+T content is 49.6%,and the C+G content is 50.4%.(3)Analysis of the genetic distances of COI and ITS2 sequences of above 6 genera and 15 species showed that these two genes could solve the problems such as difficulty to identifying the female specimens of Trichogramma,and the damaged specimens,also the problems of allied species such as T.evanescens Westwood and T.pintoi Voegelé.The diffirence between morphological identification and DNA barcode of Oligosita Walker,Trichogramma Westwood were analyzed combined with two kinds of data,and get the final definition of the species,which 6 genera and 17 Trichogrammaidae species from farmland in Northern Xinjiang were definition.2.The application of DNA barcode in the classification and identification of Mymaridae from fields in northern Xinjiang(1)More than 500 specimens and 155 slide-made specimens were checked,as a result,they were separated into 6 genera and 11 species through the preliminary morphological identification,as follows:Anagrus Haliday,1833A.dmitrievi Triapitsyn and Hu,2018A.nigriceps(Smits van Burgst,1914)A.atomus(Linnaeus,1767)A.sp.Stethynium Enock,1909S.triclavatum Enock,1909Anaphes Haliday,1833A.longicornis Walker,1846Erythmelus Enock,1909E.rex(Girault,1911)Lymaenon Walker,1846L.karlik(Triapitsyn,2013)L.litoralis(Haliday,1833)L.sp.Stephanodes Enock,1909S.reduvioli(Perkins,1905)(2)The characteristics of COI and ITS2 genes of Mymaridae were studied,and 96 COI and 102 ITS2 of 6 genera and 9 species were obtained.The lengths of the COI gene fragments obtained were 500 bp,and the A+T content(76.7%)was significantly higher than the C+G content(23.3%),showing obvious base bias.The lengths of ITS2 gene fragments obtained were 630 bp.A+T content is 52.8%,C+G content is 47.2%.(3)Analysis of the genetic distances of COI and ITS2 sequences of above 5 genera and 8 species were analyzed.The results showed that these two genes could solve the problems such as difficulty to identifying the female specimens of Mymaridae,and the the damaged specimens,also the problems of allied species such as A.nigriceps and A.dmitrievi.The difference between morphological identification and DNA barcode of Lymaenon and other divergent species were analyzed for morphological identification and Combining the two kinds of data to get the final definition of the species,which 6genera and 11 Mymaridae species from farmland in Northern Xinjiang were definition.(4)New 5 genera and 7 species of DNA barcode,including Anagrus.dmitrievi Triapitsyn and Hu,2018,A.nigriceps(Smits van Burgst,1914),S.triclavatum Enock,1909,Anaphes.longicornis Walker,1846,E.rex(Girault,1911),L.karlik(Triapitsyn,2013)and L.litoralis(Haliday,1833),the results of the research enriched the NCBI data of Mymaridae.3.The phylogenetic analysis of Trichogrammatidae and Mymaridae from Northern Xinjiang based on the COI and ITS2 sequence is analyzed.Trichogrammatidae: From the phylogenetic tree based on COI gene,it obviously divided into Trichogramma Westwood,Oligosita Walker and Ufens Girault.From the phylogenetic tree based on ITS2 gene,it obviously divided into Trichogramma Westwood,Aphelinoidea Girault,Oligosita Walker,Pseudoligosita Girault,Mirufens Girault,Ufens Girault,which is similar with the morphological identification results,and indicated that the taxonomy of it is supported by molecular levels.Through comparative analysis,the COI gene is more suitable for molecular identification in the genus Trichogramma Westwood and Oligosita Walker than the ITS2 gene.Mymaridae: From the phylogenetic tree based on COI gene,it obviously divided into Anagrus Haliday、Anaphes Haliday、Erythmelus Enock and Lymaenon walker.From the phylogenetic tree based on ITS2 gene,it obviously divided into Anaphes Haliday、Stethynium Enock,Erythmelus Enock,Anagrus Haliday,Lymaenon Walker,which is similar with the morphological identification results,and indicated that the taxonomy of it is supported by molecular levels.Through comparative analysis,the COI gene is more suitable for molecular identification in the genus Anagrus Haliday and Lymaenon Walker than the ITS2 gene.In conclusion,this study can provide a new method for the rapid and accurate identification of Trichogrammatidae and Mymaridae parasitoid in Northern Xinjiang.A large number of COI and ITS2 gene fragments obtained in this article can be used as a reference bar code for identification,and provide an important reference basis for the future use of two kinds of parasitoids to prevent farmland pests in Northern Xinjiang. |
PDF Full Text Request