Genetic Diversity Of Myzus Persicae (Homoptera:Aphididae)Populations On Peach Trees From Different Geographic Regions In China

The green peach aphid (Myzus persicae Sulzer) is a primary pest of fruit trees, particularly peach trees in China. Despite the economic importance of this pest, little is known about its genetic structure or its patterns of dispersal at local and regional scales; however, knowledge of these characteristics is important for establishing effective control strategies for this pest.The genetic variability of460individuals from23populations on peach trees in China was investigated using7polymorphic microsatellite loci,2mtDNA loci and EF-la loci. Main results were summarized as follows:Microsatellite:(1)7microsatellite loci in23populations showed high polymorphism (PIC=0.874), that loci and sample are reasonable. Observed heterozygosity was significantly lower than expected heterozygosity, exhibited H-W equilibrium and dislinkage of balance, this phenomenon caused by heterozygous loss.(2) Observed heterozygosity is mostly lower than expected heterozygosity and most of populations were in Hardy-Weinberg equilibrium after corrected by Boferroni.(3) From the AMOVA, we found that12.15%(P<0.05) of genetic variation was among populations, and the remaining79.46%(P<0.05) of the genetic variation was between individuals, indicating that the main source of genetic variation exists within individuals. Genetic differentiation estimates reached an Fst=0.1215, suggesting middle genetic differentiation (0.05<Fst<0.15).(4) Population genetic analysis showed:the NJ tree of all populations had divided into two branches. This indicated that Myzus persicae population differentiation of two areas was significantly, the reason may be caused by climatic and geographical factors.(5) The Mantel test also identified a significant correlation between genetic and geographic distance (γ=0.2864, β<0.05). We can infer that geographic isolation is a major factor contributing to genetic differentiation. Low R value indicating that gene exchange among Myzus persicae (Sulzer) population is affected by other factors besides the geographical distance. mtDNA and EF-1α:(1) Three loci showed polymorphism in general, averaged Pi=1.080%, averaged h=0.402, A+T bias existed obviously in mitochondrial loci base content (COI:76.99%; COII:80.89%).(2)11haplotypes and22haplotypes were found seperatedly in COI, COII and EF-la. In3loci, H3for the original haplotypes was the most widely distributed.(3) Analysis of molecular variance AMOVA showed extreme differentiation, the average Fst=0.72.(4) A phylogenetic tree from three gene revealed that southern and northern populations, populations appeared significant genetic differentiation, similar to SSR.