Update on the situation of Agrilus planipennis in Russia
In Russia prior to 2003, Agrilus planipennis (Coleoptera: Buprestidae - EPPO A1 List) was only known to occur in the Far East, in the Southern part of Primorskye Krai. In this part of Russia, it was considered to be a rare species, exclusively associated with weakened or dying Mandchurian and Chinese ash trees (Fraxinus mandshurica and F. chinensis, respectively). However, damage was first noticed in 2004 when A. planipennis appeared to be the main cause of dieback of F. pennsylvanica (green ash - North American species) planted along the streets of Vladivostok. These infested trees had stem diameters of 20-40 cm. In 2004, the insect was also found near the city of Khabarovsk. Detailed studies carried out in 2010 in the arboretum and city parks of Khabarovsk on dead F. pennsylvanica trees showed that they had been killed by A. planipennis during the preceding 5 to 10 years at the age of 28-35 years.
In European Russia, the first beetles were collected in June 2003 on the streets of Moscow. The identity of the pest was confirmed in 2005. Within the following years, the pest rapidly spread from Moscow in all directions (EPPO RS 2007/067, 2014/062). In the Moscow region, it seems that the insect population has been diminishing since 2015, but the reasons for this decline remain to be elucidaded. In summer 2016, the Northwestern limit of A. planipennis was close to Tver city. In this Northern direction, it is noted that the expansion of the pest has slowed down, possibly because of some limiting factors which remain to be identified (e.g. climate, activity of parasitoids). At the same time, A. planipennis continues to expand its range Southward. In the currently infested regions of European Russia, it is noted that ash trees are mainly planted in cities, along roads and highways, as well as in field-protecting tree belts. Native forest stands of F. excelsior are very rare and of limited size. In the European part of Russia, A. planipennis has been found in the following regions:
Southern European Russia: Voronezh.
Central European Russia: Kaluga, Moscow, Orel, Ryazan, Smolensk, Tambov, Tula, Tver, Vladimir, Yaroslavl.
In the Russian Far East, A. planipennis is naturally controlled by egg parasitoids belonging to the genus Oobius (Hymenoptera; Encyrtidae) and by 3 species of larval ectoparasitoids: Tetrastichus planipennisi (Hymenoptera: Eulophidae), Atanycolus nigriventris (Hymenoptera: Braconidae) and Spathius galinae (Hymenoptera: Braconidae). In the European part, it is noted that local parasitoids have recently started to infest A. planipennis, in particular Spathius polonicus which is causing 50% mortality in A. planipennis larvae in the Moscow region. Two other Spathius species, S. exarator and S. rubidus, have also been recorded as potentially useful parasitoids. So far, among these parasitoids, the most effective species seems to be S. galinae.
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