North-Westward Expansion of the Invasive Range of Emerald Ash Borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) towards the EU: From Moscow to Saint Petersburg

Abstract

Agrilus planipennis is a devastating invasive pest of ash trees in European Russia, Ukraine, and North America. To monitor the north-western limit of its European invasive range, in June 2018 we established 10 study plots along the federal highway M10 (Russia) that runs between Moscow and Saint Petersburg through Tver’ City (approx. 180 km from Moscow), and lined with ash trees. On each plot, 2–4 Fraxinus pennsylvanica trees with heights ranging 6.1–17.0 m and diameters ranging 7.0–18.0 cm were girdled, i.e., 50 cm of their bark were removed. The study plots were visited and girdled trees were examined in September and November, 2018, and in October, 2019. Observations revealed that the current continuous north-western limit of A. planipennis range in European Russia coincides with the north-western border of Tver’ City and this range limit has not distinctly shifted north-westward during 2015–2019. In spite of the rich food supply (due to abundant F. pennsylvanica and F. excelsior plantings) in Tver’ City and along roads going to and from, the population density of A. planipennis in the area is currently low. Recent (September 2020) sudden detection of a spatially isolated A. planipennis outbreak approx. 520 km far north-westward from Tver’ (in Saint Petersburg) suggested that A. planipennis most likely had arrived at Saint Petersburg not by gradual stepwise (flying tree-to-tree) expansion of its continuous invasive range in Tver’ City, but as a result of its accidental introduction by means of, e.g., “insect-hitchhiked” vehicles, transported plants for planting, and/or other commodities. The proximity of the reported A.planipennis outbreak to the borders of the EU (approx. 130 km to Estonia and Finland) requires urgent measures for its containment and control, and constant monitoring.

Invasive Populations of the Emerald Ash Borer Agrilus planipennis Fairmaire, 1888 (Coleoptera: Buprestidae) in Saint Petersburg, Russia: A Hitchhiker?

“…However, no further consistent territorial expansion of the beetle was detected that could be explained by beetles flying over 520 km from Tver to Saint Petersburg [7]. To establish those enclave populations of EAB, long-distance, humanassisted transportation of the beetle by cars and trains was suggested to be necessary [5,7].…”

“…Furthermore, the pest started to spread from Moscow in all directions, and by 2020 was recorded in 18 provinces of European Russia, towards the west approaching the border of Belarus, and in the southwest invading eastern Ukraine [4,5]. In September 2020, EAB was detected in Saint Petersburg [5][6][7]. This was a notable event for the city, famous for its architecture and historical parks.…”

Invasive Populations of Emerald Ash Borer <em>Agrilus planipennis</em> Fairmaire, 1888 (Coleoptera: Buprestidae) in Saint Petersburg, Russia: a “Hitchhiker”?

“…Furthermore, the pest started spread from Moscow in all directions, and by 2020 the pest was recorded in 18 provinces of European Russia, towards the west approaching the border of Belarus and in the south-west invading eastern Ukraine [4,5]. In September 2020, EAB was detected in Saint Petersburg [5][6][7]. This became a resonant event for the city, famous with its architecture and historical parks.…”

“…However, no further expansion from Tver has been detected few years afterwards, while simultaneously reporting incidence and establishment of EAB in Saint Petersburg, a "jump" of approx. 520 km westwards from Tver [7]. To establish those enclave EAB populations, long-distance human-assisted transportation of EAB by cars and railway has been suggested, or, in other words, those vehicles must have been successfully "hitchhiked" by EAB [5,7].…”

“…520 km westwards from Tver [7]. To establish those enclave EAB populations, long-distance human-assisted transportation of EAB by cars and railway has been suggested, or, in other words, those vehicles must have been successfully "hitchhiked" by EAB [5,7].…”