Alien pests can spread quickly: wooly ash aphid Prociphilus fraxinifolii (Hemiptera: Eriosomatidae) has occupied Europe in 18 years.
Prociphilus fraxinifolii (woolly ash aphid) is a pest of ash trees (Fraxinus spp.). This species, which is native to North America, was first recorded in Europe in 2003, in Budapest, and then began to spread quickly. In 2019-2021, we first detected P. fraxinifolii in Belarus (Brest) and eight regions of European Russia, namely Astrakhan, Nizhny Novgorod, Samara, Saratov, Smolensk, Tambov, Volgograd and Voronezh regions. By 2021, P. fraxinifolii has spread over a vast territory in Europe: from Spain in the west to the Volga River in the east. The distance between the westernmost and easternmost localities is 4180 km. The known range is disjunctive: Armenia, Belarus, Bulgaria, Germany, Great Britain, Hungary, Poland, Romania, Spain and 16 regions of European Russia. This case indicates that some alien pests are able to occupy the whole of Europe in less than two decades after the first record in the continent. It is known that P. fraxinifolii can infest native ash species F. excelsior, but all our findings, as well as most findings indicated in the literature, were on F. pennsylvanica introduced from North America. We never found P. fraxinifolii on F. excelsior even near infested F. pennsylvanica trees.