**7. Conclusion**

The research proved the existence of non-local *M. alternatus* in southwestern Yunnan by utilizing the modern molecular techniques. It is the first, yet not only an isolated study on the population phylogeny of the *Monochamus* longhorn beetles in China, but also another exemplar of applying the molecular techniques to the research of biological invasion. Apart from demonstrating the feasibility of detecting non-local populations, it also provided an insight that, unlike the dispersal of other invasive alien species, such as fruit flies, the spread of pine wood nematodes in mainland China was mostly due to human-aided relocation of infested, un-treated wood packaging materials. Therefore, preventing the infested wood materials from circulating or being transported may become the most important checkpoint of preventing the pine wilt disease from expanding.

## **8. Future research and objectives**

In the research discussed here, the modern molecular techniques provided strong evidence which proved the dispersal of the pine wood nematodes in southwestern Yunnan was caused by the casual introduction of non-local Japanese pine sawyer, *Monochamus alternatus*, and even helped to identify the possible origin of those non-local *M. alternatus* by combining both of the molecular data and the historical facts of telecommunication construction in the infested area. The most advanced technology nowadays allows the scientists to identify the pine wood nematodes directly from either the wood sample or the beetles (X.R. Wang et al., 2010; X.R. Wang et al., 2010; Y.Q. Hu et al., 2011). By utilizing such innovative methods, the foresters and plant quarantine staff are able to turn the identification of invasive organisms from sheer speculation to solid evidence. By promoting such concept along with the modern molecular techniques, not only will future law enforcement benefit, but also the regional and international trading embargos surrounding quarantine and/or invasive organisms shall be solved in a proper manner.

Apart from identifying non-local populations, population phylogeny can also be used to study the historical dispersal (including both natural dispersal and human-aided relocation) of insects, as suggested by research mentioned earlier (Kawai et al., 2006; Shoda-Kagaya, 2007; Shi et al., 2010). Since China has a 28-year dispersal history of the pine wilt disease, the dispersal pattern of the pine wood nematode as well as its key vector, *M. alternatus*, should be an interesting field to research. However, to date, there is only one paper on the dispersal pattern of the nematodes in China (Sun et al., 2008). Currently, the senior author and his colleagues are conducting a panoramic research on the population phylogeny of *M. alternatus* sampled from multiple localities in mainland China. The result of this research is to partially answer the long-asked question regarding the dispersal pattern of *M. alternatus* during the spread of the pine wilt disease in China. And as it is now possible to test the genetic profiles of *B. xylophilus* and *M. alternatus* together, future studies on the dispersal pattern and original sources of the pine wood nematodes in China can be revealed more thoroughly.
