Distribution, impact and rate of spread of emerald ash borer Agrilus planipennis (Coleoptera: Buprestidae) in the Moscow region of Russia

Surveys of ash trees along the major motorway routes leading away from the city of Moscow during July 2013 indicated that emerald ash borer (Agrilus planipennis) was well established up to 235 km west of the city and 220 km to the south. Over the last 4 years, the beetle has spread in these directions at an average rate of 30–41 km year, which cannot be explained by natural dispersal alone and implies that human-assisted transport is contributing significantly to the spread of the pest, probably via the hitchhiking of adult beetles on vehicles. The European common ash (Fraxinus excelsior) is uncommon in Moscow and in the boreal forests to the west and north, but those trees that are present suggest that this species is not killed as rapidly by A. planipennis as North American ash species and that it may need to suffer a degree of stress before it succumbs rapidly to infestation. Nevertheless, A. planipennis is a major threat to F. excelsior, and south of Moscow, where the beetle has become established in natural broadleaved woodlands in which F. excelsior is a major component, many of the ash trees are suffering severe dieback and mortality. The abundance and almost continuous distribution of F. excelsior in these woodlands means that A. planipennis now has the opportunity to spread unhindered on a broad front to other countries in Europe.