Molecular Phylogenetic Relationships Of Dryocosmus Kuriphilus Yasumatsu Of Different Host Populations Based On Partial Sequences Of COâ…  And COâ…¡ Gene

The chestnut gall wasp, Dryocosmus kuriphilus Yasumatsu, is one of the most serious pests of forests which damages the chestnut trees in China. Therefor the researches on controlling the chestnut gall wasps were of great significance on forests. However, studies on molecular phylogeny of D. kuriphilus are very few in China, and a comprehensive phylogeny is lacking.The genealogical relationship among 11 populations of D. kuriphilus attacking different Castanea species from different areas were analyzed based on partial CO I and CO II gene sequences in this paper. The results based on CO I gene revealed a total of 80 variation sites for the 660 bp DNA fragment, including 15 parsimony-informative sites and 65 singletons. The average content of T, A, C and G were 30.6%, 43.3%,13.7% and 12.4%, respectively. The average content of A+T (73.9%) was much higher than that of G+C (26.1%), displaying a distinct A+T bias. The sequences of individuals sampled from Castanea henryi in two populations in Fujian, Shuiyuan (Jianou, Fujian) and Chunchi (Zhouning, Fujian), were quite different from that of the other samples, with a genetic distances higher than 2%. Overall, the sequenced COI gene region showed very limited variation among the other 8 populations on C. mollissima, C. seguinii, or C. henryi hosts from China and one population on C. sativa hosts from Italy, with among population genetic distances less than 0.3%. Phylogenetic reconstruction using Neighbor-joining and UPGMA methods supported a monophyletic clade comprising the two Fujian populations associated with C. henryi hosts in Shuiyuan and Chunchi. Whether these populations represent a distinct host race or a cryptic species deserves further investigation. The results based on COâ…¡gene revealed a total of 7 variation sites for the 257 bp DNA fragment, including 6 parsimony-informative sites and 1 singletons. The average content of T, A, C and G were 42.4%,34.4%,9.8% and 13.4%, respectively. The average content of A+T (76.8%) was much higher than that of G+C (23.2%), displaying a distinct A+T bias. The result of genetic differentiation of these chestnut gall wasp was consistent with the result of CO I gene, the evolutionary trees also differentiated into two major branches and the composition of the various branches are of the same. It is probably that these populations represent a distinct host race or a cryptic species based on these results.