Aceria ilicis, a gall mite found in the Netherlands
In March 2009, a population of Aceria ilicis (Acari: Eriophyidae) was detected in a nursery located at St. Oedenrode in the Netherlands on an imported Quercus ilex tree. A. ilicis is a gall mite which feeds on Q. ilex, and possibly on other oak species such as Q. macrolepis, Q. coccifera, Q. ithaburensis and Q. robur. A. ilicis occurs mainly around the Mediterranean Basin and its presence has been recorded at least in the following EPPO countries: Cyprus, France, Italy, Portugal, Spain, Turkey, and United Kingdom. It is likely that A. ilicis occurs in most countries where its major host, Q. ilex, is present. A. ilicis feeds and reproduces in erinea galls formed by expanded leaf hairs at the underside of leaves. Galls on inflorescences are less commonly reported. Affected trees are not severely damaged by A. ilicis, but their aesthetical value may be reduced.
In the Netherlands, Q. ilex is not widely cultivated because of its sensitivity to frost. The Dutch NPPO stated that no phytosanitary measures will be taken because of the low economic impact of A. ilicis.
Sources
NPPO of the Netherlands (2009-06)
Pest report. Aceria ilicis (Canestrini, 1890) – on Quercus ilex at a nursery in the Netherlands. http://www.minlnv.nl/cdlpub/servlet/CDLServlet?p_file_id=38763
Denizhan E, Çobanoglu S (2008) Eriophyoid mites of Quercus robur L. Tarim Bilimleri Dergisi 18(2), 79-82. http://tarimdergisi.yyu.edu.tr/say18(2)pdfler/79-82.pdf
Stork AL, Wüest J (1996) Galles à Aceria ilicis (Acari: Eriophyoidea) sur inflorescences de Quercus ilex (Fagaceae) en Bretagne (France). Annalen des Naturhistorischen Museums in Wien 98B Suppl., 25-34. http://www.biologiezentrum.at/pdf_frei_remote/ANNA_98BS_0025-0034.pdf