**2.3 Economic importance of** *M. alternatus*

There are basically four aspects of economic importance of *M. alternatus*. As a stem-boring coleopteran of the conifers, the direct feeding and ovipositing of the adults damages the tender shoots, needles, and bark of the host, which may weaken the host when a sizable population occurs in a stand. The tunnels inside the host built by the larvae often cause more damage which eventually kills the host and substantially reduces the economic value of the timber (L.P. Wang, 2004). *M. alternatus* spends the entire immature stage in the host, which makes it very difficult to be detected from timber and/or wood packaging materials and can be easily relocated to new habitats via transportation in trading (Haack, 2006). As timber and/or wood packaging materials with *B. xylophilus* can also be relocated (Braasch et al., 2001; Gu et al., 2006), the concealed *M. alternatus* would subsequently introduce the nematodes into new habitats via its dispersal. Hence, *M. alternatus* has been recognized as a dangerous forest pest by forestry authorities worldwide.
