Population Genetic Diversity And Structure Analysis Of Rhynchophorus Ferrugineus(Olivier)in China Based On Microsatellite Markers

Rhynchophorus ferrugineus is an entry plant quarantine pest(a list of the 2017 version).It is also a national forestry quarantine pest(The Announcement of State Forestry Administration:2013 No.4).The pest was first recorded in Guangdong palm nursery in 1997,China.And it has caused serious damage to palm plants in southern China over recent decades.Population genetic diversity also is an important factor which can affect the survival and adaptability of invasive species.Based on this,in order to understand the genetic diversity of the R.ferrugineus in China as well as its diffusion history and transmission way,the purpose of this paper was to study the genetic diversity and differentiation rules of R.ferrugineus in China by using the technology of microsatellite molecular marker on the basis of extensive sampling in the distribution area of R.ferrugineus in China.It can provide a theoretical basis for analyzing the spread and control of R.ferrugineus according to the above content.The main results are as follows:(2)The Hardy-Weinberg equilibrium exact of R.ferrugineus populations in six provinces(Hainan,Yunnan,Guangxi,Sichuan,Jiangxi and Fujian)was tested and the results show that the except that most loci of Guangxi and Jiangxi populations conform to Hardy-Weinberg equilibrium,other populations deviate from this equilibrium in 9 microsatellite loci.Particularly,there was a significant deviation from Hardy-Weinberg equilibrium in Hainan,Fujian as well as Yunnan provinces.The analysis results indicate:observed heterozygosity of Hainan,Yunnan,Xinyu and Fujian populations was lower than the expected heterozygosity,the reason of Hardy-Weinberg equilibrium deviation in these four provinces might be mainly caused by frequent inbreeding within the population.(2)Genetic diversity of the population in 12 sampling areas from six provinces was further analyzed,it is found that among the 12 geographical populations studied in this paper,the populations of Mengzi,Wuzhishan,Wanning,Fuqing,Mengla,Chongzhou,Yulin,Xinyu and Xiamen have higher genetic diversity(the value of Nei's mean>0.5).The bottleneck effect of the detection results are shown:only the Mengzi population suffered from the bottleneck effect recently.It is speculated that the Mengzi population may have frequent gene exchanges with the origin countries of R.ferrugineus and other area of China,which enables the population to have high genetic diversity even after experiencing the bottleneck effect.The genetic diversity level of R.ferrugineus populations in chongzhou and xinyu of the new invaded areas also keeps high.One hand,the populations in these two populations may have multiple invasions from different sources.On the other hand,due to the need of urban construction,the host plants continuously planted in the invaded areas provide a good living and feeding space so that the two populations have a high level of genetic diversity and are free from the effects of the bottleneck effect.(3)The study on the genetic differentiation of twelve populations of the R.ferrugineus shows that the main genetic variation among populations occurs within the population and the variation among populations is not obvious(the value of Fst mean=0.1769).Gene flow between the R.ferrugineus populations showed that most populations had frequent gene exchange.However,Fuqing population and other 7 populations in Hainan and Yunnan(Changjiang,Qionghai,Wuzhishan,Sanya,Wanning,Mengla and Mengzi)did not obtain high level gene flow.Considering the long genetic distance between Fuqing population and 7 populations in province of Hainan and Yunnan(Nei's>0.5),this result indicates that there might be multiple invasion sources and invasion paths in population of R.ferrugineus.(4)Neighbour-Joining phylogenetic trees,STRUCTURE and principal coordinate analysis(PcoA)were used to analyze R.ferrugineus of 12 geographic populations.The results showed that all 12 populations were divided into three groups.Based on the comprehensive analysis of the above three methods:five populations(Changjiang,Qionghai,Wuzhishan,Sanya and Wanning)in Hainan province are grouped together for a cluster;Mengzi,Mengla and Yulin population are grouped together for a cluster;Fuqing,Xiamen Chongzhou,Xinyu population are grouped together for a cluster.The results of STRUCTURE and PcoA analysis on the population of R.ferrugineus in Xinyu,Jiangxi and Chongzhou,Sichuan showed that this invasive weevils were mainly introduced to the above two areas from Fujian.