Life Cycle/ Reproduction
The basic propagative lifecycle of the PWN is typical of most nematode species, having four vermiform juvenile stages (J1-J4), followed by an amphimictic (male and female) adult stage.This basic life cycle takes place in dead or dying wood when the nematodes are said to be in their “mycophagous” phase, feeding on fungus within the wood and NOT on the wood itself. The PWN is unable to travel outside of the wood by itself, and in order to reach another host tree (living or dead) it must be carried by an insect vector. B xylophilus has the shortest life cycle compared to any parasitic nematode. One generation is completed within four days after the nematode is cultured on fungi at its optimum. During the summer, the parasite reproduces very rapidly to very high numbers resulting in the spread throughout the resin canal system of susceptible pines, into the trunk and therefore all of its branches (even into the roots). If living tree cells are no longer available the parasite feeds and reproduces on the fungal hyphae that is growing through the resin canals. In the fall and winter the parasite becomes inactive but then resumes activity in the spring.
Read more about this topic: Bursaphelenchus Xylophilus
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