Host Parasite Relationship
In “primary transmission” when the beetle feeds on susceptible host pines, the PWN will enter the tree and feed on the epithelial cells which line the resin ducts. This is referred to as the “phytophagous” phase of the PWN, and will result in pine wilt. When the host is infected, the transmission of water within the plant is restraining; under peak conditions, pine wilt can become apparent within a few weeks after infection, the needles turn brown, and the leaves turn yellow, and eventual death of the tree. From the time of infection to the death of the plant/tree/host, it only takes two to three months. Though the susceptibility of many species of pine is still a matter of contention, susceptibility has been proven (using Koch’s postulates) in a few species, which includes Scotch, Slash, Japanese red, and Japanese black pines. The Slash pine is the only susceptible species native to North America, and its susceptibility has been shown to be relatively weak compared to foreign pines. Because of this the direct economic impact due to pine wilt, in this part of the world, is limited to predominantly landscaping settings.
Read more about this topic: Bursaphelenchus Xylophilus
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