Population Genetic Structure Analysis Of Rhynchophorus Ferrugineus (Olivier) Based On Microsatellite Loci And Mitochondrial COI Sequences

The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier)(Coleoptera: Curculionidae, Rhynchophorus), is one of the most serious invasive pests of palm plants. Adults rely on flight for their short-distance dispersal, but also can be carried for long distance by human activities, which may result in a complex population structure and genetic diversity. In this study, we used both microsatellites and cytochrome oxidase subunit I (COI) to describe the genetic structure and probable relationship among different geographic populations of RPW in Fujian Province, in order to better understand its invasion and range expansion. These data will provide fundamental and valuable information for studying invasion pathways and subsequently developing a control strategy for RPW. The main results and conclusions are as follows:1. Two hundred and fifty-three individuals from12geographical populations were analyzed based on13polymorphism microsatellites. The results of alletic richness (AR), observed heterozygosity (Ho) and expected heterozygosity (He), which compared with the results of previous studies of RPW used the same mothed, showed all populations generally exhibited low genetic diversity. All the populations showed a significant deviation from the Hardy-Weinberg equilibrium (P<0.05), and positive inbreeding coefficient FIS values across loci with a deficiency of heterozygosity were presented in most of populations. This is probably contributed by inbreeding effect resulted from gregarious life habits and generation overlap, the Wahlund Effect or a relatively recent introduction, which decrease the genetic diversity in populations. With the exclusion of the primers, the final alignment showed the COI sequences were530bp in length. Eleven haplotypes of RPW populations were observed with high level of haplotype diversity and nucleotide diversity (Hd=0.811,π=0.019, respectively), which might relate to the adaption and selection pressure of new environment of RPW. Multiple introductions might be the direct cause of high level of haplotype diversity.2. Genetic structure based on microsatellite showed that12populations could be divided into four clusters with a low gene flow. No correlation was found between genetic and geographical distance. The results showed an irregular dispersal of RPW in Fujian Province. The analysis of haplotype network tree based on mitochondria COI showed that populations in Fujian were divided into four different clusters, H7, FJ1, and FJ2haplotypes were the dominant haplotypes. Analysis of moleculal variance (AMOVA) based on the two methods revealed genetic differentiations mainly came within populations. A phylogenetic tree together with the sequences from previous studies was constructed. We hypothesize that the genetic relationship of RPW in Fujian populations were closer to those from westnorth of native range (India, Bangladesh or Myanmar) and Southeast Asia (Thailand, Malaysia, Vietnam, and Philippines). Multiple introductions, which caused by high exchange rate of date and ornamental palms by human activities, play a very important role in the expansion of RPW in Fujian Province.