& Key message The emerald ash borer (Agrilus planipennis Fairmaire), an alien pest native to Asia, has spread to Ukraine and 16 regions of European Russia. It severely damages Fraxinus pennsylvanica Marsh. introduced from North America, but serious damage to European ash (Fraxinus excelsior L.) has not been detected in forests. & Context The first detection of A. planipennis in European Russia was in Moscow in 2003, when it began to spread. & Aims To determine the range of A. planipennis as of 2020. & Methods In 2017-2020, our Russian-Ukrainian research team examined > 7000 F. pennsylvanica trees and > 2500 F. excelsior trees in 84 localities of European Russia, Ukraine, and Belarus. & Results The current range exceeds the area of Spain and includes the Luhansk region of Ukraine and 16 regions of ER:

1 Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), native to Asia, is a destructive invasive pest of ash Fraxinus spp. in U.S.A., Canada and European Russia. It is spreading quickly and will probably soon be detected in other European countries. 2 Information about the life cycle of the pest is needed for detection and survey efforts, development of control options and predicting the potential range in Europe. The life cycle has been studied in North America and Asia, although it has not previously been studied in European Russia. 3 The number of larval instars and the duration of development of A. planipennis in European Russia were determined. Distributions of width of epistome and length of urogomphi indicated four larval instars. The number of excretory ducts and the presence of ledges did not provide a clear differentiation between instars. Development in most of the specimens took 2 years. 4 Generation time is flexible. In warmer regions (Tianjin), most individuals finish development in 1 year, whereas, in colder regions (Moscow, Changchun, Harbin), it takes 2 years. In intermediate climatic regions (Michigan), the ratio of 1 : 2-year life cycles depends on additional factors. The flexibility of the life cycle allows A. planipennis to establish in regions with different climates.

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Emerald ash borer (EAB), Agrilus planipennis, native to East Asia, is an invasive pest of ash in North America and European Russia. This quarantine species is a threat to ash trees all over Europe. Survey in ten provinces of European Russia in 2019–2020 showed that EAB had spread faster and farther than was previously thought. The new infested sites were first detected in St. Petersburg (110–120 km from the EU border: Estonia, Finland) and Astrakhan Province (50 km from the Kazakhstan border). The current range of EAB in Europe includes Luhansk Province of Ukraine and 18 provinces of Russia: Astrakhan, Belgorod, Bryansk, Kaluga, Kursk, Lipetsk, Moscow, Orel, Ryazan, Smolensk, St. Petersburg, Tambov, Tula, Tver, Vladimir, Volgograd, Voronezh, and Yaroslavl. Within these, only seven quarantine phytosanitary zones in five provinces are declared by the National Plant Protection Organization of Russia. EAB was not found in the regions along the Middle Volga: Mari El, Chuvash and Tatarstan republics, Nizhny Novgorod, Samara and Saratov provinces. The infested sites in St. Petersburg and in the Lower Volga basin are range enclaves separated from the core invasion range by 470 and 370 km, correspondingly. It is possible that new enclaves can appear in the cities of Eastern Europe and Kazakhstan far from the current known range. All previously known infestations in European Russia were in green ash (Fraxinus pennsylvanica), which was introduced from North America, and individual trees of European ash (F. excelsior). A first confirmed case of mass decline of several thousand of EAB-infested European ash trees in Moscow province is provided. Therefore, there is no more doubt that under certain conditions EAB can seriously damage native ash trees in European forests.

AimTo develop an approach to model the spatial dynamics of emerald ash borer Agrilus planipennis (Coleoptera: Buprestidae) in European Russia. This tree‐killing pest was detected in Moscow 15 years ago and began to spread, posing a threat to ashes all over Europe. The aim was to determine its probable current range and to evaluate the probability of its dispersal to neighboring countries within the next 5 years.LocationCities and transport hubs of European Russia and neighboring countries. Ash trees in this region occur mainly in urban plantations and along highways.MethodsPairwise distances between all locations were used as the main parameter determining the probability of pest spread. For each location, the probability of detection of A. planipennis was calculated using three simulation recurrent models of long‐distance dispersal. Parametrization was made by comparison with results of surveys in 2003–2015. Field data on the range of A. planipennis in 2016‐2017 were mapped and used for model verification. A prognosis of spread of the pest by 2022 was made.ResultsA model based on fat‐tailed kernel corresponds to both negative and positive results of surveys. According to the model, the current range is likely to be restricted to Russia, but probability of detection of the pest in the east of Belarus, Ukraine, Estonia, Latvia, and Lithuania by 2022 is 15%–40%.Main conclusionsThe forestry services of neighboring countries probably have about 5 years to prepare for the invasion of this pest, but regular surveys are necessary, since the pest can appear at any time. The case considered shows that the simple approach based on a fat‐tailed kernel and just one parameter—pairwise distance between cities—can be used for modeling long‐distance dispersal of alien pests of urban plantations.