Genetic Structure Of Colorado Potato Beetle Populations Based On SSR Marker

The Colorado potato beetle is a world-famous invasive pest that seriously harms the Solanaceae crops such as potatoes.It was discovered in 1993 in the Tacheng area and the Yili area of Xinjiang,China,and appeared in Jilin Province in northeastern China in 2013.By 2018,this beetle has invaded 46 counties and cities in China's three provinces and regions,posing a serious threat to potato production nationwide.In order to reveal the genetic variation and diffusion path of the beetle in the process of invasion and spread,this study used 9 pairs of microsatellite markers to analyze the genetic diversity,genetic structure and evolution history 11 beetle geographical populations in Northeast China,Xinjiang,China and neighboring countries Kyrgyzstan and Kazakhstan.Genetic diversity,genetic structure and demographic history.The main findings are as follows:1)The average H_E of the all-inclusive A_R and the expected heterozygosity of all Chinese populations were 3.23 and 0.55,which was significantly lower than the average genetic diversity of European and American populations obtained by Grapputo(2006)(A_R and H_E were 6.4 and 0.68,respectively).In China,the average values of various groups in Xinjiang are 3.18 and 0.54,and the average values of various groups in Northeast China are 3.44 and 0.60.The genetic diversity of potato beetle population in Northeast China is slightly higher than that in Xinjiang.The A_R and H_E of the Kyrgyz population were 2.96 and 0.43,respectively,and the genetic diversity was significantly lower than that of all Chinese populations.The A_R and H_E of the Kazakhstan population were 3.12 and 0.56,respectively,which was close to the average level of genetic diversity of Xinjiang population in China.The genetic diversity of all populations in this study showed a significant negative correlation with altitude,and altitude may be an important factor affecting the genetic diversity of potato beetle populations.2)During the invasion of Colorodo potato beetles,all populations experienced significant bottlenecks,and geographical isolation blocked gene flow between populations expect from Kazakhstan and Tacheng to the inland populations,and made the Colorodo potato beetle population in Xinjiang,China differentiates into two distinct branches.The first branch consisted of all the populations on the northern slope of the Tianshan Mountains(from Tacheng to Mulei);while the second branch consisting populations from the Ili Valley,Altay and the Northeast China.The two branches in Xinjiang were isolated by the Tianshan and Gurban Bangut Desert,indicating that geographical barriers are an important factor in the formation of population patterns and the restriction of the spread of Colorodo potato beetles.3)The approximate Bayesian Computation(ABC)results show that the populations of the Northeast China and Yili Valleys are originate from Europe.The other populations outside the Ili Valley are the side branches during the diffusion process from Europe to the Ili Valley.Among them,the inland populations in Xinjiang(Muile County and Urumqi County)belong to the youngest one and originated from Tacheng.4)According to the genetic structure analysis,the three populations in Northeast China showed a relatively distant phylogenetic relationship with each other,suggesting that there may be multiple sources of populations in the Northeast China,including the Khabarovsk Krai and Primorsky Krai in Russia.The gene flow among the three populations in Northeast China is very weak,indicating that the populations in Northeast China are still in the early stage of invasion and the population is not stable enough.