Effects Of The Endosymbionts,Wolbachia And Cardinium,on The Population Differentiations Of Oligonychus Ununguis

The mite,known as Oligonychus ununguis,collected from the timber tree,Cunninghamia lanceolata,is always considered to be the same as that collected from the economic tree,Castanea mollissima.But differences in feeding habits,morphology and some gene sequences were found between the C.mollissima population from Shandong Province(TSBL)and the C.lanceolata population from Zhejiang Province(ZJSM)of O.ununguis.Reproductive incompatibility was also found between these two populations and the incompatibility was not resulted from the geographical isolation.The insect's endosymbionts,Wolbachia and Cardinium,have the ability to manipulate the reproduction of their hosts,for example,causing cytoplasmic incompatibility.The incompatibility,in particular bidirectional incompatibility,mediated by microorganisms is likely to play an important role in the differentiation of species.In order to define whether the reproductive incompatibility between the C.mollissima population from Shandong Province(TSBL)and the C.lanceolata population from Zhejiang Province(ZJSM)of O.ununguis is related to the endosymbionts,the infection rates of Wolbachia and Cardinium in the C.mollissima population from Shandong Province(TSBL),the C.lanceolata population from Zhejiang Province(ZJSM)and other populations of O.ununguis were detected by PCR.This research can lay the foundation for further exploring the differentiation mechanism between the chestnut population and the Chinese fir population and the reproductive regulation of the endosymbionts to O.ununguis.The main results are as follows:1.Neither the C.mollissima population from Shandong Province(TSBL)nor the C.lanceolata population from Zhejiang Province(ZJSM)was infected with Wolbachia.The reproductive incompatibility between the C.mollissima population from Shandong Province(TSBL)and the C.lanceolata population from Zhejiang Province(ZJSM)of O.ununguis was independent of Wolbachia and Cardinium.2.In all the detected 12 populations(the C.mollissima population from Shandong Province(TSBL),the C.lanceolata population from Zhejiang Province(ZJSM),the C.mollissima population from Mount Culai(CLSBL),The Quercus acutissima population from Mount Tai(TSML),the Quercus variabilis population from Mount Tai(TSSPL),the C.mollissima population from Yantai(YTBL),the C.mollissima population from Hebei Province(HBBL),the Q.variabilis population from Hebei Province(HBSPL),the Q.acutissima population from Hebei Province(HBML),the Q.acutissima population from Henan Province(HNML),the Q.variabilis population from Henan Province(HNSPL)and the C.mollissima population from Beijing(BJBL))of O.ununguis,the infection rates of Wolbachia and Cardinium were zero and 8.3% respectively.Cardinium was detected only in the Q.acutissima population from Hebei Province,but the intrapopulation infection rate was higher with 66.7%.3.The Cardinium infecting O.ununguis was closest to that from Teranychus urticae,but was more distant to that from T.cinnabarinus in the phylogenetic tree based on Cardinium 16 S r RNA gene sequences.The Cardinium infecting O.ununguis and that infecting T.cinnabarinus were in two different branches of the phylogenetic tree.We consider that the C.mollissima population from Shandong Province(TSBL)and the C.lanceolata population from Zhejiang Province(ZJSM)of O.ununguis probably have differentiated into two different species according to the above results and previous findings about the population differentiation researches of O.Ununguis.In order to define the reasons of differentiation or the classification status of these two populations,we also sequenced 28 S r RNA gene of the two populations and carried out the phylogenetic analysis based on the sequences of 28 S r RNA gene.Results showed that the genetic relationship between the two populations was very close because the two populations were clustered in one branch with very high bootstrap value.The two populations are likely to differentiate into two different species because of their long-term adaptation to different host plants.