Nematodes as Pinewood Nematode can colonize wood, making their way in the tracheids and ray cells. I wander if they can also dig through the tracheid wall.
In other words are some nematods abble to tunnel tracheid wall in wood ?
This question as i often observe in fossil wood round holes about 70µ in diameter which can hardly be attributed to arthropods.
With best wishes for good health to all
marc
Pine Wilt, which is caused by the pine wood nematode, Bursaphelenchus xylophilus. This nematode is unusual, compared to other plant-parasitic nematodes, because it lives entirely in the above ground parts of the tree and never enters the soil. The pine wood nematode is a microscopic, worm-like animal that feeds on the living plant cells surrounding the water-conducting tissues of pine trees. Once inside a susceptible pine tree the nematodes reproduce rapidly, and move throughout the tree. The tree then begins to display wilt symptoms and soon dies. This wilt typically kills Scots pine within a few weeks to a few months.
Symptoms Resin flow from the wood ceases and the wood is dry when cut, compared to wood from healthy pine trees which will quickly ooze resin and become sticky after cutting. Needles can remain on a dead tree for a year or longer.
Once the pine sawyer beetle introduces the nematode, the infected tree typically dies within a few weeks or months.
Transmission Pinewood nematodes are transmitted from tree to tree by an insect, the pine sawyer beetle, Monochamus spp. Also known as longhorn beetles, pine sawyers are attracted to the dying trees and the females lay their eggs under the bark. When the beetle larva pupates into an adult and begins to emerge from the tree it is infected with thousands of the nematodes that enter its breathing holes. As the adult beetle flies to a new tree it carries the nematodes with it. Nematodes enter the new tree through feeding site wounds made by the adult beetle.
Hosts Scotch pine is the main host of pine wilt, but the disease also occurs in Austrian, Jack, Mugo and Red pine. In the Midwest more than 90 percent of the trees killed by this condition have been Scots pine. The disease does not affect other conifers, such as spruces, firs, and red cedars or junipers.
Monitoring In fall homeowners should check their yards and windbreaks for trees showing signs of pine wilt. Nematodes are not visible to the eye, but can easily be spread by the pine sawyer beetle to entire windbreaks or plantings in a few years. To determine cut a piece of wood from the lower trunk or the base of the lower limbs. A disk of wood, 1 inch in thickness and 3-4 inches across, makes an adequate sample. Place the sample in an air-tight, plastic bag and take it to your local Extension Office. They will send it to a diagnostic lab for positive identification.
Control Sanitation can prevent or slow the spread of pine wilt. Cut down infected trees and burn, bury or chip them. The stump should be removed down to the ground, if possible. This should be done as soon as the infection is discovered to prevent pine sawyer beetles from emerging from the tree the following spring and carrying the disease to other healthy trees. Do not hold the wood for firewood. Dead trees must be removed and destroyed by May 1.
A new protective treatment for pine wilt became available in 2006. Greyhound (abamectin) an insecticide/ nematicide product can be trunk-injected into uninfected trees, and when injected into healthy trees will give about 95% protection from the disease for about three years.
Thanks a lot dear Sir
All this biological data about Bursaphelenchus are interesting.
Do you know if it can actually dig throug tracheid wall ?
All I have seen up to now is that it follows tracheid lumens or ray cells, passing from tracheid into ray cells through window cross-field pitting.
yours sincerely
marc
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