Molecular Phylogenetic Research Of Partial Species Of Coreidae (Hemiptera: Heteroptera) Inferred From COⅡ Gene

Coreidae is a big family of Heteroptera. There are 250 genera, 1800 species known in the world, and about 63 genera, 200 species known in China. Coreidae which is a kind of phytophagous insects and important pests of agriculture and forest have been studied widely in many fields such as taxonomy, molecular phylogeny, biogeography and etc. However, there are still lots of debates on the phylogenetic relationships among tribes and genera levels. Phylogenetic relationships of Coreidae have been studied by external morphological characters, molecular characters, Isoenzymes and etc. And more molecular markers should be used for the study of the taxonomy and phylogenetic relationships within this family.The mitochondrial cytochrome oxidase subunit II (COII) gene is the most widely used genetic marker for molecular systematics of animals, especially in insects. In this research, The COII gene sequences were amplified by PCR, and then sequenced directly through cycling sequencing method. 585 bp sequences of 18 species of Coreidae and 1 species of Alydidae were obtained. Based on the analyses of COII gene sequences, we reconstructed the phylogenetic relationships of these species by using Neighbor-Joining (NJ), Maximum Parsimony (MP), Maximum Likelihood (ML) and Bayesian Inference (BI) methods. The conclusions are showed as follows:1) The average contents of T, C, A and G to COII gene of 19 species in Coreidae are 33.6%, 16.4%, 36.3% and 13.7%, respectively. A+T content is 69.9%, while G+C content is 30.1 %, which shows a strong A+T bias. These sequences code 195 amino acids and contain 19 kinds of amino acids, respectively. The contents of Leu and Ile are very high.2) To these 18 species of Coreidae, ratio of transition to transversion(R) of COII gene sequence is 1.1;Transitions are slightly higher than transversions;most transitions occur between T and C, while most transversions occur between A and T;substitutions of the third position of codons are the highest: transitions are 56.1 % of all transitions, while transversions are 75%;The relationship between P distance and Ratio(R) is consistent with the typical distance-dependent character of mtDNA in Insecta;Theresult of substitution saturation analysis shows that substitutions are saturated. Ratio(R) of 6 species of Mictini s. str is 2.1;transitions are 63.5% of all transitions, while transversions are 86.2%;The relationship of P distance and Ratio(R) to 6 species of Mictini s. str is very unclear;The result of substitution saturation analysis shows that its substitutions are not saturated.3) The phylogenetic relationships among 18 species of Coreidae and the outgroups which include Oncopeltus fasciatus (Hemiptera: Lygaeoidea) and Triatoma dimidiate (Hemiptera: Reduviidae) had been reconstructed. The results show that: Mictini s. str is a monophyleny;two genera of Cloresmini is a monophyletic;Sinotagus has a high relative relationship with Homoeocerus, Hygia touchei (Colpurinae) has a high relative relationship with Cloresmini, Trematocoris tragus has a high relative relationship with Cordysceles turpis.4) One of the purposes of this research is to testify the primitive characters on molecular level of Pseudophloeinae and Colpurinae. And then decide whether put these two subfamilies into Coreidae or raise them to higher rank. The results of phylogenetic trees could not solve the problems because of insufficient taxon samplings.5) Phylogenetic trees of 6 species of Mictini s. str had been reconstructed with the outgroups of Coriomeris nigridens Jakovlev (Coreidae) and Riptortus pedestris Fabricius (Alydidae). The results which show that Anoplocnemis, first separate from lineage, is most primitive in Mictini s. str explain the reason why Anoplocnemis which is mainly distributed in Africa differs from other genera in morphology charactors in Asia.6) The results of phylogeney to 6 species of Mictini s. str show that Derepterini, named by Hsiao Tsaiyu, is a paraphyleny and synonymized to Mictini.7) The phylogenetic relationships of 6 genera in Mictini s. str is {{{{Ochrochira + Mictis) + Paramictis) + (Derepteryx + Rhamnomia)) + Anoplocnemis), which is consistent with the result of phylogenetic relationships based on morphologic characteristics founded by Li Xinzheng.8) This study solves some relationships well among genera in Mictini s. str and proves again that COII gene is very suitable to solve phylogenetic relayionships of species or genera between and within family.