Study On Genetic Structure And Diversity Of Gypsy Moth Based On Microsatellite Markers And Morphological Features

Lymantria dispar Linnaeus,as a holarctic leaf-eating pest,is divided into Asian gypsy moth and European gypsy moth according to whether the female’s flight ability,host species and other factors.The European gypsy moth includes Lymantria dispardispar;Asian gypsy moth includes Lymantria dispar asiatica,and Lymantria dispar japonica.The female adult of Asian gypsy moth has flight capability,and hosts are more abundant,so Asian gypsy moth has been listed as quarantine object in many countries and received more attention.As the distribution of L.d.asiatica in China,the genetic differentiation and subspecies distribution of different geographical populations are not clear.In order to further study of gypsy moth in the differentiation between different localities,find out if other subspecies have been introduced in China,this experiment used nine microsatellite loci of nuclear genes to study the genetic structure and genetic diversity of gypsy moths from 23 regions.The genitals of male adult gypsy moth were dissected and observed,nine morphological characters were determined for quantitative analysis to explore the morphological differentiation of gypsy moth.The main results are as follows:(1)The genetic diversity of gypsy moth showed that the number of alleles in different populations varied greatly,and the number of alleles in gypsy moth in China was mostly higher than that in other foreign geographical populations.The most private alleles were detected in samples from Yunnan and Chengdu in China,private alleles were detected only in Russian and Chinese populations.Gypsy moths showed high genetic diversity.According to Fst and Mantel test,Heilongjiang and Liaoning populations,Tongliao and Charizu populations in northern China were undifferentiated;Yunnan population was relatively special,and it had a large genetic differentiation with other populations;the populations in Xifeng and Kuduer in China showed lower genetic differentiation with the populations in France and Lithuania;the degree of differentiation between different geographical populations in China was lower than thatwith foreign populations;The correlation test of the genetic distance and geographic distance matrix showed that the two matrices are significantly positively correlated with correlation coefficient of 0.501.Geographical isolation might be one of the important reasons for genetic differentiation of Lymantria dispar.(2)According to the UPGMA phylogenetic tree of genetic distance and the results of principal coordinate analysis(PCo A),gypsy moths could be divided into two groups,KG(Greece),JL(Lithuania),FR(France),Kdr(Kuduer),XJ(Xinjiang),XF(Xifeng),MA(Massachusetts),NC(North Carolina),CT(Connecticut),RBI(Shira)gathered into the first group,BJ(Beijing),LN(Liaoning),TL(Tongliao),HB(Hebei),CRS(Charisu),HLJ(Heilongjiang),SX(Shanxi),AH(Anhui),ZY(Zunyi),CD(Chengdu),YN(Yunnan),Hu(Honshu),RM(Primorsky Krai)gather into thesecond group,the geographical distribution of the population corresponded to Asian gypsy moth and European gypsy moth,the contribution rate of the two main coordinates was about 53.24%.(3)Further study of the gypsy moth’s genetic structure revealed that cluster analysis of gypsy moth samples based on microsatellite loci,on the basis of distinguishing Asian gypsy moth and European gypsy moth,gypsy moth could also be divided into northern China and Russian Far East cluster,southern China cluster,Japanese cluster,European cluster,North American and Russian Shira cluster.Among them,some samples from Kuduer and Xifengwere grouped into the same cluster as those from France,Greece,and Lithuania,and other samples from Kuduer were grouped into northern China,other samples of Xifeng were grouped into the southern China cluster.Some samples of Xifeng and Kuduer showed aclose relationship with European gypsy moth.Some loci in gypsy moth from Russian Far East were grouped with gypsy moth from Honshu,Japan,we speculated that some individuals distinct from L.d.asiatica may have been secretly introduced into the Russian far east through the port.(4)Observation of glass slide specimens of the genitalia,samples from localities where Asian gypsy moths are found,in addition to samples from Yunnan and Zunyiinsouthern China,valve’sfinger-like protrusionwaselongate,narrow;sacculus was mostly V-shaped,wide at base,sharp at apex;samples from the distribution areas of European gypsy moth and from China where European gypsy moth might have been introduced,its valve’s finger-like protrusions was short and wide,sacculus was mostly U-shaped,the width of the base was nearly the same as the apex,apex was narrowly rounded.Although the difference between different subspecies was not significant,it could be seen that the single subspecies in Japan was significantly different from other subspecies in genitalia.The characteristics of male genitalia in Yunnan and Zunyi were separated from gypsy moth populations in high latitudes of China.