Cheng's nematode

Systematic position: Bursaphelenchus chengi belongs to the phylum Nematoda, class Chromadorea, order Aphelenchida, and family Aphelenchoididae. It is a recognized plant-parasitic nematode that maintains a complex biological relationship with both its host trees and specific insect vectors.

Host plants: The primary hosts of this nematode are coniferous trees, specifically species within the Pinus genus. Bursaphelenchus chengi is often associated with declining pine forests, where it exploits the physiological stress of the trees to facilitate its own colonization and rapid population growth.

Biology and life cycle: The life cycle involves a migratory stage where the nematodes are transported by wood-boring beetles of the genus Monochamus. Once the beetle feeds on the host tree, the nematodes migrate into the xylem, where they feed on parenchymal cells and epithelial tissues surrounding the resin ducts. The population multiplies rapidly within the tree's vascular system.

Damage and economic impact: Infestation leads to a drastic reduction in oleoresin flow, resulting in rapid needle chlorosis and wilting. The internal damage to the wood structures causes systemic vascular failure, typically leading to the death of the tree within a single season. The pest poses a significant threat to timber quality and ecosystem stability in pine-dominated regions.

Control measures: Management strategies primarily focus on quarantine and phytosanitary regulations to prevent the movement of infested wood.

• Sanitation logging: removal and destruction of infested trees.
• Vector control: targeting wood-boring beetles with systemic insecticides.
• Wood treatment: heat treatment or fumigation of timber intended for export to ensure the elimination of the nematode.