The Taxonomic Study On The Tettigonioidea Of Northeast Area (Orthoptera: Ensifera)

Tettigonioidea is the second biggest superfamily in Ensifera of Othoptera. More than 6000 species have been described which belong to 1070 genera in worldwide. Most of them are phytophagous insects and important pests in agriculture and forest; others are predatory insects and are insect enemy and potential resources for biocontrol. Thus katydids are useful material for ethology. The systematics study of them has not only theoretical but also practical value in pests control, plant protection and resources usage.In China, there are more than 330 species of katydids, which distribute widely. There are resourceful abundant in Northeast Area, and also abundant biologic resource, and the biological diversity is complexity. We primarily investigated the katydids of this area, and discovered that the katydids distribute widely.In this paper, the taxonomic studies on katydids are researched detailedly, which distribute in Northeast Area and belong to Tettigonioidea. We collected 21 species of katydids which belong to 3 families, 10 genera, described their configurations separately, and researched them from other four parts; the purpose is to discuss the relationships among them.The research contents and results are as following.1. MorphologyIn this part, the configurations of 21 species of katydids were described using the traditional classification methods. We use the classification system that Liu and Yin brought up in 1999, the results are as follows.(1) The 21 species of katydids belong to 3 families, 10 genera:①Family Phaneropteridae, genus Phaneroptera Audinet-Serville, Ducetia Stal, and Elimaea Stal;②Family Tettigoniidae, genus Gampsocleis Fieber, Uvarovites Tarbinsky, Tettigonia Linnaeus, Metrioptera Wesm. and Atlanticus Scudder;③Family Conocephalidae, genus Conocephalus Thunberg and Ruspolia Schulthess. The results are absolutely in accord with the classification system that Liu and Yin have brought up.(2) Morphological analysis indicates that some species are similar, they are G. sedakovii sedkovii and G. sedakovii obscura, T. ussuriana and T. cantans, R. nitidula and R. jezoensis, C. chinensis and C. fuscus. Therefore, we researched these 21 species of katydids from the following four microcosmic parts.2. AnatomyIn this part, the alimentary canals of 21 species of katydids were analyzed by using the external anatomy and scanning electron microscope, briefly discussing the relation between morphological characters of alimentary canals, and clustering analysis of these 21 species was studied based on their lengths of foregut, midgut and hindgut for the first time, the results are as follows.(1) The alimentary canals include three parts: foregut, midgut and hindgut. The significant differences between different genera exist in the crop, proventriculus and gastric caeca of midgut. The rest are less important in the taxonomy.(2) There are some obviously differences about the morphological characters of alimentary canals between different subfamilies, different genera and different species. And the relation between them coincided with the relation shown in the traditional morphic classification.(3) There is a very close relationship between morphological characters of alimentary canals and feeding habits. The studies can be quite helpful in researches on the relation between the different genera, as well as on the phylogeny. And it might be useful in insect control.(4) The results of clustering analysis are consistent with those of morphological classification. G. sedakovii sedkovii and G. sedakovii obscura, T. ussuriana and T. cantans, R. nitidula and R. jezoensis, C. chinensis and C. fuscus clustered with each other, and then clustered with other species.3. CytologyIn this part, the chromosomal conventional karyotypes of 21 species of katydids were studied, and clustering analysis of these species was studied based on their chromosomal relative lengths, the results are as follows.(1) All the species of katydids have the basic sex determining mechanism XX♀/ X0♂, and most of Orthopteran species have this sex determining mechanism.(2) In the males of katydids, chromosome numbers vary from 2n= 31 (♂) to 2n = 27(♂). The family Tettigoniidae has chromosome numbers of 2n= 31, 29; the family Phaneropteridae is 2n= 31, 29, 27 and the family Conocephalidae is 2n= 31.(3) The differences of these 21 species are also very remarkable, such as genome formula, the size of chromosomes and their chromosomal relative lengths. G. sedakovii sedkovii and G. sedakovii obscura are different in chromosomal relative lengths and chromosomal length ratio; T. ussuriana and T. cantans are obviously different in genome formula and chromosomal relative lengths; the differences R. nitidula and R. jezoensis are remarkable in chromosomal karyotypes; C. chinensis and C. fuscus are obviously different in genome formula. Therefore, the chromosomal karyotype could use in katydids and other insects taxonomy.(4) The results of clustering analysis are consistent with those of anatomy. The clustering analysis indicated that, the results of karyotypes are in line with those of morphological classification, the evolution of karyotypes is parallel with that of morphology. Cytological characters are different among genera or species and can offer some materials for cytotaxonomy.4. BiochemistryIn this part, the EST isoenzyme of 16 species of katydids were analyzed by using the technique of vertical slab poly-acrylamidae gel electrophoresis, and clustering analysis of these species was researched based on their relative mobilities, the results are as follows.(1) The results showed that there exist certain differences of esterase isoenzyme among segments of the same individuals.(2) There are also some obviously differences about the EST isoenzyme electrophoretogram between different genera and different species. But every different species possess its own isoenzyme bands.(3) The results concluded through the EST isoenzyme coincided with the results concluded through morphic classification. We can conclude that EST isoenzyme possess important and reliable taxonomic value at lower categories.(4) The results also show that the technique of EST isoenzyme which was used in identification of Tettigonioidea and the relative of different species and classific leval is feasible.The results of clustering analysis are consistent with those of morphological classification. The results of clustering analysis are consistent with those of anatomy and cytology.5. Molecular BiologyIn this part, the genomic DNA was extracted from 21 species of katydids. 21 sequences of Cytb (510bp) and 16SrDNA (454bp) have been acquired by PCR amplification and sequenced using specific two pair primers. The base frequency, amino acid frequency, base substitution and genetic distance of DNA sequence have been analyzed by using some biosoftware such as ClustalX1.81, MEGA 3.0. We adopted Cytb and 16SrDNA gene sequences data set as molecular marker and reconstructed the phylogenetic relationships through NJ, ME and MP in MEGA 3.0, the results are as follows.(1) In Cytb gene sequences, the conserved sites are 259bp (50.2%) and the variable sites are 251bp (49.2%); In 16SrDNA gene sequences, the percent of the conserved and variable sites are 60.1% and 39.9% respectively.(2) The average content of T, C, A, G of Cytb gene sequence are 37.3%,22.1%,29.5% and 11.2% respectively, and A+T content is 66.8%, G+C content is 33.3%, which shows a strong A+T bias.The average content of T, C, A, G of 16S rDNA gene sequence are 35.4 %,11.2%,32.8% and 20.3% respectively, and A+T content is 68.5%, G+C content is 31.5%, A+T content is higher than G+C content obviously, which shows a strong A+T bias.(3) The average transition and transversion ratio of Cytb gene sequence is 1.3. Transition is lightly more than transversion. Substitution saturation mainly takes place on the third position of codon. Transition frequently occurs between T and C (49) and transversion usually occurs between T and A (28) in total data set. Substitution on the third position is the most frequent (70%).The average transition and transvertion ratio of 16SrDNA gene sequence is 1.1; transition is lightly more than transversion. Transition frequently occurs between A and G and transversion usually occurs between T and A.(4) The Cytb gene sequence of all katydids codes 170 amino acids. 21 species contain 20 amino acids. Among them, the conserved amino acids are 115 (67.6%) and the variable is 55 (32.4%).(5) The phylogenetic trees of these 21 species in different methods are same in general, and the relationships among them coincided with those in the traditional morphic classification. The relationships of the related species are as follows: Gampsocleis: (((G. sedakovii obscura, G. sedakovii sedkovii), G. ussuriensis), G. gratiosa); Tettigonia: ((T. caudata, T. cantans), T. ussuriana); Conocephalidae: ((R. nitidula, R. jezoensis), (C. fuscus, C. chinensis)).In this study, the results of the above four parts are accordant and consistent with those of morphological classification. The results indicated that, the classification system that Liu and Yin brought up is absolutely right and reliable; and also showed that, the modern classification methods are absolutely used in identification of Tettigonioidea and the other insects.