A Chinese wasp affects 100% of chestnut trees in Galicia
The plant protection authorities of Galicia, the first chestnut producing region in Spain, have declared that this Asian wasp already affects 100% of its chestnut trees, so this year its production will be greatly reduced.
Spain has about 300,000 hectares of chestnut trees, although many of them have wood as a productive objective. Galicia, with some 40,000 hectares, is the first producer of chestnuts (15,000-25,000 tons per year) and the first exporter; it’s followed by Castilla y León and Andalucía. In Galicia, this sector generates about €40 million a year.
The Dryocosmus kuriphilus entered Spain through Cataluña in 2012, and arrived in Galicia in 2014. In Europe it first appeared in Italy, in 2002, due to the import of trees for genetic improvements; from there, it spread to many other countries. The bad situation in Italy and France favored the Galician sector but now this advantage is over.
It seems that an effective control method is another Chinese wasp, Torymus sinensis, which is its natural predator, for whose use the Spanish Ministry of Agriculture hasn’t given its authorization yet.
In Spain there’re at least four autochthonous species of Torymus, so the researchers in charge of the evaluation want to clear all potential risk before the generalized release of the exotic species.