We regularly invite other specialists to talk about biological invasions. The first article is from Sofia Costa, researcher at the Functional Ecology Centre of the Coimbra University and director of Fitolab. She has been working with nematodes since 1997 and tells us about an invading nematode that has attacked the pine trees in Portugal.
The pine wood nematode, Bursaphelenchus xylophilus, was first detected in Portugal in 1999. Due to its complex life cycle, and because it’s always “hidden” or inside the trees or inside an insect that disperses it, it has managed to evade containment and control strategies.
In just over 10 years since its detection, the nematode dispersed throughout the national continental territory and island of Madeira, being responsible for the elimination of many acres of maritime pine (Pinus pinaster).
This microscopic vermin is native to North America, where it feeds preferably on conifers of the genus Pinus, which are resistant to them. In the early 20th century it arrived in Japan and later on reached the Asian continent (Taiwan, Korea, China), becoming devastating to the local Pine forests, which are susceptible to nematodes.
This nematode has typical characteristics of an invader organism, such as a high adaptive capacity and reproduction rate, having a competitive advantage over other nematodes that, in invaded systems, are associated with trees (Cheng et al 2009).
Contrary to what one might think, there are other nematodes that can live within the pine trees without causing significant damage. Some of these are indeed so similar to those of B. xylophilus and can only be distinguished through molecular analysis, carried out by specialists in recognized laboratories. The relationship between genetic diversity and the geographic distribution of these species of Bursaphelenchus, one native, and the other an invasive species, is being evaluated by Portuguese investigators (Pereira et al, 2013).
In the photo: dead pine with symptoms of pine nematode attack, in 2010, Sto António Olivais
This post is also available in: Portuguese (Portugal)