Microsatellites reveal a strong subdivision of genetic structure in Chinese populations of the mite Tetranychus urticae Koch (Acari: Tetranychidae)

We identified 109 alleles. We found a highly significant genetic differentiation among the 25 populations (global FST = 0.506, global FST {ENA} = 0.473) and a low genetic diversity in each population. In addition, genetic diversity of the red form mites was found to be higher than the green form. Pearson correlations between statistics of variation (AR and HE) and geographic coordinates (latitude and longitude) showed that the genetic diversity of the red form was correlated with latitude. Using Bayesian clustering, we divided the Chinese mite populations into five clades which were well congruent with their geographic distributions.Spider mites possess low levels of genetic diversity, limit gene flow between populations and significant and IBD (isolation by distance) effect. These factors in turn contribute to the strong subdivision of genetic structure. In addition, population genetic structure results don't support the separation of the two forms of spider mite into two species. The morphological differences between the two forms of mites may be a result of epigenetic effects.The phytophagous two-spotted spider mite Tetranychus urticae Koch is a serious pest of various agricultural plants including fruit trees, vegetables, ornamentals and agricultural crops. Owing to its rapid development and high reproductive capacities, and ability to feed on more than 900 plants [1], T. urticae has spread worldwide. Despite the importance of this pest, the population genetic structure of this mite has been unclear in China. A better understanding of population genetic structure could help to manage mite populations by providing more reliable estimates of population dynamics and the risk of spreading acaricide resistance genes. The population genetic structure of an organism is determined by various factors, such as geographical barriers, ecological difference, and historical processes, as well as the dispersal ability of the species. T. urticae has multiple dispersal mechanism