Potential Geographical Distribution And Genetic Diversity Of Dendroctonus Valens In China

The red turpentine beetle(Dendroctonus valens),native to North America,is an important forestry invasive insect.It was introduced to China in 1998 and then spread rapidly to surrounding provinces.The red turpentine beetle whose host is mainly Chinese pine in China has caused a large number of Chinese pine deaths since the invasion and brought significant economic losses to China.In order to clarify the genetic diversity and genetic structure of red turpentine beetle,find the diffusion mechanism and provide theoretical basis for the prevention and control,we analyzed the potential geographical distribution based on the maximum entropy theory with the latest distribution data,and studyed the genetic diversities and structures based on mitochondrial COI and microsatellite sequences.The main research results are as follows:(1)Update the latest distribution range of red turpentine beetle in China:Shanxi,Shaanxi,Henan,Hebei,Liaoning,Inner Mongolia and Beijing.Geographical coordinates range:N35.31°-41.42°,E108.84°-118.94°,altitude 388 m-1824 m.(2)We used the distribution data from field investigation and literature,based on the current and future climate conditions,to predict the potential geographical distribution area of red turpentine beetle in China.The AUC of both training data and test data were 0.997.The results showed:the potential geographical distribution of red turpentine beetle was from N3° to 45°,from E100° to 125°.Most of the range of the distribution fell in semi-arid and semi-humid areas under the current climate conditions.The highly adaptable areas were mainly in Shanxi,Shaanxi,Beijing,Liaoning and Hebei.The next diffusion trend of red turpentine beetle was the northeast and southwest directions,which included Jilin,Heilongjiang,Sichuan and other provinces.Under the future climate conditions,geographical distribution shrank except for the northeast region.Both results were consistent with the field investigation,so a variety of quarantine measures are needed to prevent the further spread of D.valens to the northeast and to reduce the risk of further proliferation.(3)An analysis of mitochondria COI sequence was conducted using 82 samples from eight geographical populations,including Inner Mongolia?Chifeng?Liaoning?Beijing.The results showed that the number of haplotypes from Chinese population was high,a total of 23,the largest number was from northern populations.There was a shared haplotype H4,which could be inferred as an original haplotype.The genetic diversity indexes such as haplotype number and haplotype diversity of the northern population and Qinshui population were higher.The average value of haplotype diversity and nucleotide diversity were 0.82 and 0.0104,indicating that the red turpentine beetle from China had a high genetic diversity,might be the reason of big population quantity,or multiple invasion.The Chinese population of red turpentine beetle was clustered into three branches in the bayes cladogram.Yan 'an,Beijing and Chifeng was in the first cluster,Qinshui,LingYuan was in the second cluster,Baoding was in the third cluster.All red turpentine beetle populations from China was in one cluster with the populations from United States western region.It showed that,in recent years,no more populations outside of the western America was settled down in China.(4)Nine microsatellite loca were used to analyze the genetic diversity of red turpentine beetle in China.All the sites except A2 were polymorphic locus,and the PIC value of all loca were higher than 0.25 except A6.Among different populations,the genetic diversity parameters of Jixian were highest.All the populations in this study accorded with Hardy-Weinberg equilibrium test,but some loca were deviated from it.The Fst value of Qinshui and Lingyuan was the lowest,Chifeng and Baoding was the highest.According to the Neighbor-Joining tree of different populations of red turpentine beetle,the results showed that there was similarity in the north populations,but no obvious clustering rules.All red turpentine beetle populations from China were in a same cluster with the populations from United States western region,which was consistent with the result based on COI sequence.