Abstract: The Pyemotes is one of the most important natural enemies of the bark pests, and spreads widely in China. It is difficult to identify the relationships among the Pyemotes populations on different hosts because of their belonging to closely related species undistinguishable by morphological characters. The RAPD analysis of 9 populations of Pyemotes on different hosts collected from Changli County, Hebei Province and Jixian County, Tianjin City were carried out to explore the relationships among these Pyemotes populations. Thirty-two primers with high polymorphic and steady bands were obtained after selecting in 100 primers repeatedly. The results of phylogeny analysis based on the genetic distances of the tested 9 populations indicated that the they could be divided into three groups (A, B and C). Group A contains Pyemotes dryas only; Group B contains P. scolyti and the Pyemotes parasitizing Scolytidae spp.; Group C are divided further into two subgroups, one is the Pyemotes parasitizing Pteromalidae spp., and another contains the Pyemotes parasitizing Phloeosinus aubei Perris, Dermestidae sp., Sinoxylon japonicum Lesne, and Cryphalus exignus, respectively. Reproductive isolation was found between the population of Pyemotes parasitizing Pteromalidae spp. and others, which suggests that the former should be a different new species.

Key words: Pyemotes, host, diversification, RAPD, phylogeny