Cross-sea Migration Monitoring Of Three Species Of Planthoppers And The Phylogenetic Structure Of Laodelphax Striatellus In The Monsoon Region Of China

The suction trap is a plant protection equipment for population system monitoring and ecological research of small migratory pests.It can provide an important basis for forecasting important agricultural pests,comprehensive management and biodiversity research.At the same time,the study on genetic diversity and genetic structure of target pests in different geographical populations can understand the relationship between population genetics and evolution.It provides a theoretical basis for the study of the significance of pest occurrence and the genetic adaptation mechanism of disasters.At present,the dynamics of Laodelphax striatellus,Nilaparvata lugens and Sogatella furcifera moving across the sea,and the genetic structure of the different geographical populations of the L.striatellus in monsoon region of China are still unclear.In this study,the three insects were monitored by the suction trap.At the same time,the genetic diversity and pedigree genetic structure of the L.striatellus were studied by SSR,it is helpful to understand the laws of transoceanic migration of these three insects in northern China,and to study the genetic evolution relationship of different geographical populations of L.striatellus.It provides a theoretical basis for exploring the source of insects,the law of population occurrence and the genetic mechanism of disasters.The study also has important reference for the implementation of specialized system control for the migration of other migratory pests and the implementation of major pests.This study used the suction trap to monitor the population dynamics of three rice planthoppers that migrated across the sea for 7 years（2012–2018）at the Changdao Pest Control Field Research Station（38.2°N,120.5°E）.The different geographical populations of L.striatellus in the eastern monsoon region of China were collected,and then their genetic diversity and genetic structure were studied.The following results were obtained:1.In 2012–2018,the Changdao area attracted a total of 760 rice planthoppers,with the largest number of L.striatellus（605 individals）,the second largest number of Sogatella furcifera（87 individals）,and the least number of Nilaparvata lugens（5 individals）;There are large differences in the dynamics of three rice planthoppers in different years.Usually,the annual fly ash has two peak periods of migration（May-June and August-September）.In 2015-2018,there are two peaks of migration in August and September.In 2012 and 2013,there is only one peak migration period in June.2.The analysis of the number of male and female males in different years,usually the number of females in the peak of the first migration of the L.striatellus and the S.furcifera is higher than that of the males,at the peak of the second migration,there were more males than females.3.Nine microsatellite loci were rich in polymorphic information in 48 populations of the L.striatellus population in the monsoon region of China,and the genetic diversity of 48 populations was relative high（Na = 6.173,Ne = 3.638,Ho = 0.540,He = 0.628）,Shandong Changdao（CDA15）population has the highest average number of alleles 11.556,of which Liaoning Kaiyuan（KY）population has the lowest average allele number of 2.789.The heterozygosity of the L.striatellus population was at a medium level,and Liaoning Donggang（DG14）,Shandong Changsao（CDA15）,Jiangsu Dafeng（DF）and Henan Zhoukou（ZK）populations showed high loss of heterozygosity(F_IS > 0).Liaoning Shenyang SY12 and Liaoning Shenyang SY13 population showed excessive heterozygosity(F_IS < 0).Most of the population points did not deviate from the Hardy-Weinberg balance.In general,the genetic diversity of different geographical population of L.striatellus was compared: Southwest > East China > Central China > North China > Northeast.4.The Jilin（JL）population has an FST > 0.25 and a small gene flow（Nm <1）,as does the Liaoning Kaiyuan（KY）population.This indicates that these two groups have significant genetic differentiation.5.Nei’s genetic distance system tree,Bayesian cluster analysis and PCo A analysis showed that 48 geographical populations were divided into 6 groups,namely SY groups,JL groups,ZK and JX groups,PJ groups,KY groups and other groups.The AMOVA divergence analysis showed that the genetic variation of L.striatellus in the eastern monsoon region of China was mainly from the inside of the population（73%）,and the level of genetic variation among the populations was relatively low（27%）.The results of IBD analysis showed that there was no correlation between genetic differentiation and geographic distance（R² = 0.0397,P = 0.020）.Bottleneck bottleneck analysis showed that,in general,26 of the 48 populations of the L.striatellus population may have experienced bottlenecks in the near future.Except for the DG13,DG15 and DZ populations,the other populations are in line with the normal L-type distribution.