The Phylogeny Of Aphidiodea Based On ISSrDNA

Aphidinea are group of famous insects. They are harmful to agricultural plant. In the taxonomic study of Aphidiodea insects, there are some questions about them. In order to clarify the arguments for the phylogenetic relationships of Aphidinea insects, we determined a partial (HOObp) sequence of the 18S ribosomal DNA for 13 aphid species (4 subfamilies , 6 families) at the first time. They distributed mostly in China. In this study we studied the phylogenetic relationships of the two groups: Cervaphidinae and Pterocommatinae using the PCR product direct sequencing method. The respective outgroups Acyrthosium pisum and Lygus heperus Knight are the new gene informations for the International Biology Gene Bank.Here we got the ISSrDNA sequence data of the Aphidiodea, which were firstly aligned by Clustal W and then used to construct phylogenetic tree by MEGA 2.1. The result of Cervaphinae revealed that:㏕he sequence included 797bp in length. The average transition: transversion ratio was 1.0 which indicated the genetic differentiation was great. The ration was 2 in nuclear DNA gene. As a rule the ts:tv ratio decreased with the increasing genetic distance. ㏕he average A+T content is 56.6%. Among Thelaxiade .. Cervaphididinea and Greenideidae ,the A+T contained is 52.5?cK 66.6% and 51.9%,the length of the partial ISSrDNA was 1100bp> 760bp and llOObp respectively. It was found that a decreased in A+T content may has been accompanied by an increasing in length of the whole ISSrDNA gene sequence. (3)The phylogenetic tree by the method of UPGMAN MP> NJ and ME shows Thelaxiade is similar to Greenideidae and Cervaphidinae is a independent group.The studies on Pterocommatinae revealed that: The content of A+T in Aphididae is very variable. It was from 39.6% of A.pisum to 60.4% of Thxoptera odinae. It is clear that Pterocommatinae is closer to A.pisum. But there is ambiguously taxonomic position between Chaitophoridae and Aphidinae. The genetic distance of Aphididae and Macrosiphinae in Aphididae is more diverged than that of between Chaitophoridae and Aphididae. The 600bp-1700bp region of ISSrDNA gene maybe unsuitable to Aphididae, it includes a helix E21. The rate of evolution of in the region is a bit fast. It is necessary for the phylogenetic analysis that selecting suitable gene region, increasing the number of taxon and comparing more molecular markers.