The Application Of Mitochondrial DNA Seqences For The Assoiation Of Larval And Adults Stages Of Ecologically Important Caddisfly (Insecta: Trichoptera)

Identification of the larval stage of aquatic insects is one of most important factors in biomonitoring water quality. The morphological diagnostic characters for many mature and early instar larvae are still lacking in China. Partial sequences of the mitochondrial cytochrome oxydase I and II and a transfor RNA ( CO I CO II and tRNA ) gene of the adults and larvae from caddisflies were. Lepidostomaflavum, L.fui, L. arcuatum, Paraphlegopteryx morsei, Apsilochorema unculatum and Apsilochorema hwangi, and the larval and adult stages of these species were sequenced and associated. The DNA-based identification of ecologically important hydropsychids larvae was primarily studied. The role of CO I gene and its fragments on phylogenetic reconstruction of four lepidostomatids were discussed. Larvae of all reared species and Goera ramose were described for the first time except for Apsilochorema hwangi.The association of larval and adult stages of ecologically important Caddisfly (Insecta: Trichoptera) using mitochondrial DNA sequencesLarval and adult amplification fragments were cloned and sequenced. DNA sequences were aligned using Clustal X software (Gene Codes Corporation). Analysis of genetic and phylogenetic relationship was performed using MEGA2.1. Genetic relationships among haplogenotypes were estimated based on the pair-wise matrix of sequence divergences by Kimura's Two-parameter method. Phylogenetic trees were constructed by the Neighbor-Joining (NJ) method. Confidence levels for NJ tree were assessed by bootstrapping from 1000 pseudo-replications.The partial sequences of the mitochondrial CO I , CO II and tRNA gene of theadults and larvae of 4 species from Lepidostomatidae and the adults and larvae ofApsilochorema unculatum and A. hwangi were sequenced and compared in this study. In the sequences obtained (1718~2239bp), A % + T% was about 69.2 %, 267 nucleotide sites were substituted in Apsilochorema and 266 nucleotide sites were substituted in Lepidostomatidae. AT bias in the third codon position site was much higher than the other two sites, reaching about 81.9%.The results of sequence analysis showed that intraspecific divergence is <1% between the adult and the larva and interspecific divergence is 14-24% in Lepidostomatidae, and that intraspecific divergence is <1% between the adult and the larva of Apsilochorema unculatum, and interspecific divergence is 13% between the larva of Apsilochorema unculatum and the adult of A. hwangi, which identified the association of larval and adult stages of 4 species from Lepidostomatidae and larval and adult stages of A. unculatum.The study indicates that mitochondrial DNA sequence analysis is a useful tool to associate the larval and adult stages of Trichoptera, in turn, it will be valuable for health assessment of stream ecosystems.The role of cytochrome oxidase I gene and its fragments on phylogenetic reconstruction of 4 lepidostomadonIt is well known that the phylogenetic trees reconstructed from different genes forthe same set of organisms are often different. The differences between phylogenetic trees reconstructed may be due to insufficient sampling of nucleotides or codons, different assumptions used in the analysis of patterns of nucleotide or amino acid substitutions, different sorting of genes, etc., but in most cases it is difficult to know which of the reconstructed trees is the correct one because the true tree is unknown. This paper reported some initial results of studying about the role of a fragment of the CO I gene on phylogenetic reconstruction of 4 lepidostomatids.The CO I sequence is subdivided into 3 fragments according to its base position: Pos. # 430-779, Pos. #780-1179 and Pos. #1180-1569. Complete CO I sequence, CO II sequence and CO I + II sequence were used for comparison. Nucleotide composition and variation of each sequence fragment were analyzed using MEGA2.1.Geneticrelationships among haplogenotypes were estimated based on the pair-wise matrix of sequence divergences by Kimura's Two-parameter...