Scientists have found the emerald ash borer in Barnaul, the capital of the Altai region, simultaneously with the publication of a climate model predicting this event. The borer threatens ash plantations and has already destroyed almost a third of them in Barnaul. Specialists believe that climate change and the greening of cities with Pennsylvania ash can lead to the spread of the pest to other regions of Russia, including southern Siberia. The results of the study are published in the Russian Journal of Biological Invasions.

In the era of globalization, with the highly increased intensity of transportation within and between continents, invasive species are becoming one of the main threats to biodiversity and functioning of ecosystems. Introduced species often lead to serious environmental and economic problems related to the country's food security. Thus, the invasion of alien insects can cause significant damage to agriculture, forestry and gardening. An example of such an invasive species is the East Asian emerald ash beetle Agrilus planipennis Fairmaire. This is a dangerous pest that feeds on many species of ash trees. The emerald ash borer is included in the quarantine lists of most countries in the Northern Hemisphere, and it has conquered almost a third of the North American continent, being  classified as one of the 20 most dangerous quarantine pests for the EU countries. Economic losses from this insect in Moscow and St. Petersburg alone have already amounted to hundreds of millions of rubles. At the same time, the emerald ash borer has been found in 21 other subjects of the Russian Federation.

The most important factors for the capture of new territories by the pest are suitable climatic conditions and the presence of food plants. Climate change can significantly expand the area of the pest's advance. Scientists from the Krasnoyarsk Science Center of the Siberian Branch of the Russian Academy of Sciences, together with colleagues from the State Hydrometeorological Service, have developed a model describing climatically favorable zones for the spread of the ash borer under different climate change scenarios. The calculations were carried out for a scenario with a fairly moderate anthropogenic impact on the climate. The results show that with further climate change, the habitat of the ash borer will shift to the north and east. According to the forecast, it was expected that in Russia the pest would also spread to Siberia, and by 2030-2039 it would reach the Krasnoyarsk Region.

However, in the summer of 2024, it turned out that this forecast had already come true. Specialists discovered the ash borer in the south of Siberia - in the city of Barnaul, the administrative center of the Altai Region. Here, as throughout Siberia, a plant favorable for the development of the borer, Pennsylvania ash Fraxinus pennsylvanica Marsh, is planted. This species is used in landscaping in many Siberian cities: Tyumen, Novosibirsk, Barnaul, Abakan, Krasnoyarsk etc.

Scientists examined all five districts of Barnaul with drying ash plantations and found many beetles and pest larvae under the bark of trees. However, they were unable to find ash borer larvae infected with parasitoids, the main natural enemies of insect pests that keep their population from overreproducing.

"The situation with ash trees in Barnaul must be recognized as disastrous. On average, 60 percent of trees in the city are dying or dried out. All of them have ash borer exit holes and characteristic larval passages under the bark. Only 8% of ash trees can be characterized as healthy, the rest are at different stages of weakening. We managed to reconstruct the condition of ash trees dried out by 2024 in five habitats. In all the cases, their condition could be considered healthy back in 2020. This indicates the recent arrival of the ash borer in Barnaul and partially explains the rapid increase in the number of dried-out ash trees. It has not yet been possible to stop the spread of the pest either in North America, where it was also brought in, or in Europe. Parasitoids could reduce its numbers. Perhaps they came to Siberia together with the ash borer. But it will take time to increase their numbers to a level capable of reducing the density of the ash borer population. At least in Europe, parasitoids began to control the ash borer only 20-25 years after its appearance there. The relevant organizations should consider using a classical biological control scheme - the introduction of the most effective parasitoid of the ash borer from its homeland - the Russian Far East. It is also necessary to use other more resistant ash species instead of Pennsylvania ash in landscaping Russian cities to slow the advance of the ash borer. For example, the Manchurian ash F. mandshurica Rupr is resistant both to this pest and frost,” said one of the co-authors of the study, candidate of biological sciences, head of the laboratory of the V.N. Sukachev Institute of Forest of SB RAS, Yuri Baranchikov.

The study involved specialists from the V.N. Sukachev Institute of Forest, the Yu. A. Izrael Institute of Global Climate and Ecology, the Altai State University, Zoological Institute of RAS, Altai branch of the Center for Grain Quality Assessment, Krasnoyarsk branch of the Federal State Budgetary Institution “All-Russian Plant Quarantine Center”. The work was partially supported by the Russian Science Foundation (No. 22-16-00075).