Abstract
The citrus red mite, Panonychus citri (McGregor) (Acari: Tetranychidae), has a worldwide distribution and is the most important citrus pest in many countries, including Japan, Spain and China. Apart from citrus, P. citri also feeds on other woody plants such as pear, peach and holly. To characterize the population genetic structure of citrus red mite in association with their host plants, the gene flow (Nm) and genetic differentiation among sympatric populations of P. citri (F ST estimates) on different host plants were estimated using the ribosomal internal transcribed spacer 1 (ITS1) sequence. The results indicated that there were high levels of gene flow (Nm = infinite) among the populations from the same host genera and the same host family. Populations of P. citri displayed genetic differentiation and low levels of gene flow (Nm < 1) between the populations collected from Rutaceae and Oleaceae host plants. While the haplotype network presented a parallel pattern, there was no one central common haplotype. Pairwise F ST indicated that in China, P. citri has differentiated into two groups, one of which was associated with sweet olive and the other with other host plants. The result of cytochrome oxidase subunit I analysis also supported this result, suggesting the possibility of sympatric host race formation in this species.
Acknowledgements
This study was supported in part by a Special Fund for Agro-scientific Research in the Public Interest (201103020), the Program for Changjiang Scholars and Innovative Research Team in the University (IRT0976), the Natural Science Foundation of Chongqing (CSTC, 2009BA1042) and the earmarked fund for Modern Agro-industry (Citrus) Technology Research System of China to J-J W.