Pines Under Attack

Sunday, October 28, 2018
By Vivienne Hughes

A micro-organism, native of North America and Japan is wiping out the pine forests across the country. From the moment of being attacked by this tiny invader, the tree doesn’t even last a month.

The plague started in neighbouring Portugal in 1999 and at present has affected half the country, whereas in Spain in the last ten years there have been six critical focal points: two in Castilla-León, two in Extremadura and two in Galicia, all of which border on Portugal.

Researcher Begoña de la Fuente at the Universidad Politécnica de Madrid (UPM) said that the probable areas of entry have been identified using a computer model that predicts propagation development. The computer model can predict entry points basing its calculations on infected areas across the border.

What they are dealing with is Bursaphelenchus xylophilus, more commonly known as pine wood nematode or pine wilt nematode (PWN) which is a pathogen that needs a vector (an infected insect).

Its life cycle takes place in already dead or dying wood, where the nematodes live and feed upon fungi, rather than the wood itself. The nematode cannot travel outside of the wood independently; it must be transported by an insect vector; i.e., the pine beetle.

The micro-organism is a 2mm worm whose life cycle is perfectly synchronised with its host who both profit from the relationship: the beetle provides the transport to healthy trees and the worms kill them of so that the beetle can feed off them.

With a healthy pine the pressure with which it exudes resin stops the beetles life cycle, but as the worm debilitates the tree by stopping the flow of water in the trees’ cells, the resin pressure drops and the beetle can advance.

With global warming producing more days with temperatures above 25ºC and longer drought periods, the inroads that this dynamic duo are making are gathering momentum.

But it is also affecting the export of timber because the EU has a quarantine period on pine for this reason, which is causing economic problems in that sector.

The only effective countermeasure is the early identification of infected pines and their elimination, as well as the massive use of traps in the trees for the beetles, especially during spring when they reach adulthood and can fly.

(News: Spain)

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