| The thesis studied thoroughly the morphological structure by optical microscope and scanning electronic microscope and the mitochondrial cytochrome oxidase I (COI) gene sequence of larvae and adult of Cephenemyia trompe in reindeer for evolution by the molecular biology techniques.The results of the optical microscope observation showed that the first stage larvae are 2.45±0.03 × 0.74±0.01mm, yellowish-white, spindle-shaped. Each segment has the dense denticles ventrally aligned in rows and only the rudiments of denticles dorsally, which is characterized by the long tassel-like denticles on the last row and lateral parts of each segment. The end of the larvae has a row of comb-shaped denticles. The second stage larvae are 11.32±0.08 × 6.10± 0.05mm, cylinder-shaped with two ends slightly narrowed. Each segment is surrounded with six to eight rows of denticles dorsally and ventrally which are long and dark. The comb-like denticles on the ends are more and bigger than L1. The third stage larvae are 33.20±0.006 × 10.22±0.03mm and brownish -yellow. Each segment is surrounded with denticles which are denser and bigger on segments Ⅴ-Ⅷ, especially on dorsum. There is a region of shuttle-shaped denticles at the central anterior part between segments Ⅳ-Ⅷ dorsally. Denticles on lateral parts of each segment ventrally are much bigger. There is a bigger denticles part on the posterior margin of each segment ventrally. Denticles are long and sharp on it. The Adults are like a bumble bee and measure 14-16mm in length. There is a clear convexity on the central of the antennal groove. Its abdomen has yellowish-black hairs. Wing is characterized by 2R5 wing-cell which is narrowly opened and m2 vein which is slightly long and bends down to the posterior.The results of the scanning electron microscope observation showed that The denticles shape of larvae is distinct on the different position, which are cone-shaped, mushroom-cone shaped or aquiline beak shaped, generally having bigger base. The pore of posterior spiracle of L3 under optical microscope, is a membrane structure with a suture centrally.The results of DNA nucleotide sequence confirmed that the size of mitochondrial cytochrome oxidase I gene (partial cds.) of larvae and adult of C. trompe from the reindeer of Inner Mongolia in China is 672 ~ 676 bp. The analysis of phylogenic evolution tree showed that there are a few differences for the nucleotide sequence between adults (C. trompe NA.) and L3 (C trompe NL.) larvae whose homology is near to C. trompe of Norway isolate (C. trompe L.)and slightly far from C stimulutor and C. ulrichii belonging to the same genus but different species. However, they are far from Oestrus ovis of being different genus on homology. This confirmed that the isolates of C. trompe NL. and C. trompe L. belong to the same species. Furthermore, they belong to the same genus of Cephenemyia with C. stimulator and C. ultrachic. The genus of Cephenemyia and the genus of Oestrus belong to the same family of Oestridae.Comparing the nucleotide sequence of the mitochondrial cytochrome oxidase I gene (partial cds.) between the isolate of C. trompe NL. and other related larvae isolates showed that there are obvious differences between different genus of Oestridae and variation within each genus ranged from 18.6% to 23%. Different species pairwise divergences of Cephenemyia ranged from 1.9% to 9.9% and intraspecific variation of C. trompe was 0.9%. This study indicated that the nucleotide sequence of the mitochondrial cytochrome oxidase I (COI) gene could reflect the phylogenetic relationships among genera, species and strains to some extent.
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