Genetic Diversity, Population Sturucture And Gene Flow Of Helicoverpa Armigera (H(?)bner) In China

To study genetic structure of Helicoverpa armigera (Hiibner) in a major cotton cropping regions of China and identify genetic structure, migration events, we did research on 10 indigenous H. armigera populations, two of which came from lab and the others came from yield. We estimated H. armigera populations' genetic structure using 5 microsatellite markers, including the genetic differentiation among populations, gene flow, the relationship between geographical distance and genetic differentiation constructed phylogenetic trees.1) All H. armigera populations had high level allelies diversityWe got 149 alleles with 29.8 alleles/loci as mean value on five microsatellite loci, just. obtained one allele on each lab populations. All of the microsatellite loci were polymorphic. We also got 62 alleles with a mean value of 31 alleles/loci on two E-cadherin gene loci, while E-cadherin gene loci were polymorphic too. The microsatellite loci and E-cadherin gene markers were heterozygote deficiencies. In other word, in each H.armigera population, individuals did not match randomly. The result infered that there may have something we unknow now exist, inflience H.armigera populations' genetic structure.2) H. armigera populations had low or mediate level genetic differentiationGenetic distance between two lab populations and 8 yield populations was quite high. To assess the populations' bottleneck effect, mode-shift evidence for bottleneck was observed in the lab populations, but not observed in the yield population. A low level of genetic divergence was observed in most paired comparisons among samples within all yield populations, with FST ranged from 0.018 (Q06-2 versus Q06-4) to 0.103 (Q8-2 versus WD). Compared with others yield populations from eastern of China, XJ population had a mid-level of genetic differentiation, excepting Q07-2 (FST=0.028). A low level of genetic differentiation was observed in most paired comparisons among all Hebei populations, ranged from 0.018 to 0.063. Two populations of Shandong (FST=0.048) showed a low level of genetic differentiation. Geographical distance between Shandong populations and Hebei populations was shortest in all four region distances, but Shandong populations and Hebei populations was got a mid-level of genetic divergence, with FST values ranging from 0.058 to 0.103. NJ population had a low level genetic differentiation with Hebei and Shandong populations, respectively. In a nested AMOVA analysis referring to five regions, we demonstrated genetic differentiation in a mid-level, with the global FST of 0.06484 and 3.63% of the total variation among the regions. In the analysis among regions,93.52% of total variance was figured out in the regions. In the AMOVA among populations in 8 yield populations, we got the global FST of 0.6848 and population divergence attributing to the total molecular variance was in the ratio of 6.85%.There was a positive correlation between geographic distance (Log10(D)) and genetic differentiation FST/(1-FST) (r=0.11306,p=0.5668). The regression of genetic differentiation FSR/(1-FST) to geographic distance (Log10(D)) showed the regression coefficient was great (b=0.07) but not significant(p>0.1). It inferred that geographic distance block took a positive but not significant effect on H. armigera populations' differentiation among regions.3) Gene flow, assignment test detection of first generation migrantsThe average number of migrants exchanged per generation (Nm) between yield H. armigera populations ranged from 2.172 (Q08-2 versus WD) to 13.955 (Q06-2 versus Q06-4). Nm<0.3 among two populations and eight yield populations, and Nm=0 between two lab populations.In Bt plant region, Hebei populations, H. armigera genetic structure kept stable along time. Nm among Bt-cotton plant regions was less than among Bt-cotton plant region with other regions or among other regions. The nearer the regions were, the more stable Nm values showed. In exclusive test, H. armigera populations showed that there was not even a region be the origins of other regions. In assignment test, XJ population's immigrant was much more than emigrant (p<0.05), while population's immigrant and emigrant was not significant (p>0.05) on other regions' populations, so XJ population might have one direction gene-flow way.4) Bt-cotton Plant's effect on genetic structureOn individual level,Bt-cotton plant had not obvious effect on H. armigera. We used two E-cadherin gene primers to research the 10 populations, compared them with the five microsatellite markers. The results showed there had not evidence to support H. armigera populations' gene diversity decrease because Bt-cotton was plant.But on region population level, Bt-cotton plant might have a positive effect on H. armigera. Two Bt-cotton plant regions, Hebei and ShanDong, with a near geographic distance, showed a bigger genetic difference. This meant Bt-cotton plant may have effect on H. armigera populations, and have risk on H. armigera management.