The four-eyed fir bark beetle Polygraphus proximus Blandford (Coleoptera, Curculionidae, Scolytinae) has become an aggressive invader in Siberia’s fir forests in recent decades. However, its spread in the invaded area is not yet complete; this species is absent so far in most of the Siberian fir Abies sibirica Ledeb. range. To predict this process, appropriate models are needed, including at the local level. One of the essential parameters for modeling is the flight characteristics of imago. To evaluate its flight potential, we placed slabs (sections of the bark with a thin sapwood layer) in an area without forests or with forests with an absence of fir at the end of May. The beetles overwintered under the bark in these slabs. We also placed short fir trap logs at distances ranging from 50 to 1500 m in the four cardinal directions from the release point to attract migrating beetles. After the beetles from the slabs had completed their migration, we evaluated the number of parental pairs (male and female) of the four-eyed fir bark beetle on the trap logs (p) and their number per dm² (p_S). The sole factor that affected the colonization of host objects in our experiment was the distance from the release point. The relationship between p and p_S and the distance to the release point can be accurately represented by a negative exponential curve. This experiment established a flight distance of 1500 m, with calculated values of 4919 m for p and 2965 m for p_S. However, an analysis of similar experiments and studies using flight mills suggests that these values may not be extreme in an environment with few and sparse host objects. In conditions of abundant food supply, the actual flight distance of P. proximus beetles is significantly less than the theoretically possible maximum.

The trans-Palearctic moth Phyllonorycter populifoliella (Lepidoptera: Gracillariidae) is a major pest of the North American Populus balsamifera and its hybrids widely planted as ornamentals in North Asia (i.e., the Asian part of Russia). We DNA barcoded Ph. populifoliella from distant geographical populations in Russia and analyzed them together with the data from eight European countries and India to estimate intraspecific variability and the haplotype richness in the Palearctic, and specifically in North Asia. Furthermore, using next-generation sequencing (NGS, Sequel platform, PacBio), we investigated larval and pupal remnants found in an old herbarium from the Nearctic, where P. balsamifera occurs naturally, to verify if any events of the moth introduction to this biogeographic zone happened in the past. Relatively high intraspecific variability in the COI gene of mtDNA, reaching 3.73%, was recorded in Ph. populifoliella. Overall, 30 COI haplotypes were defined in 83 specimens from the Palearctic, with a noticeable richness in North Asia (21 haplotypes). Using NGS, the remnants of 14 Phyllonorycter specimens dissected from up to 174-year-old herbaria from the Palearctic and Nearctic were sequenced, and four moth species were identified. Among them, there were three Palearctic species, Ph. populifoliella, Ph. pastorella (Zeller), and Ph. apparella (Herrich-Schäffer), and one Nearctic, Ph. nipigon (Freeman). No evidence of Ph. populifoliella introduction to North America was documented based on the examination of the herbarium dated 1850–1974. Three specimens of Ph. populifoliella identified from herbaria from Austria and Poland (dated 1879–1931) represented one haplotype (H7) known from the recent time. Overall, our study clarifies the modern range, provides insights into phylogeography, and defines the haplotype richness of the native leafminer outbreaking on the alien host. Furthermore, it underlines the use of old herbaria to explore the historical distribution of endophagous insect species.

В ходе лабораторного эксперимента определяли время вымачивания бревна пихты, необходимое для полного уничтожения жуков уссурийского полиграфа Polygraphus proximus Blandf. (Coleoptera: Curculionidae: Scolytinae) – дальневосточного инвайдера. Одновременно в обрабатываемых отрубках проследили судьбу комплекса паразитоидов полиграфа – двух видов паразитических хальцид Dinotiscus eupterus Walker и Raptrocerus mirus Walker (Hymenoptera: Pteromalidae). При комнатной температуре 100 % смертность жуков полиграфа наступила через 3 недели вымачивания, а паразитоидов – через 4 недели. В природных условиях, весной, время вымачивания нужно увеличить, так как при низких температурах метаболизм насекомых может быть понижен и их гибель в анаэробных условиях наступит позднее. Мы рекомендуем весной выдерживать зараженные бревна под водой не менее 6 недель. The laboratory experiment was used to determine the time of fir log submersion necessary for complete mortality of the beetles of the four-eyed fir bark beetle Polygraphus proximus Blandf. (Coleoptera: Curculionidae: Scolytinae), a Far Eastern invader. Simultaneously, the fate of a complex of Polygraphus parasitoids: two species of parasitic chalcids Dinotiscus eupterus Walker and Raptrocerus mirus Walker (Hymenoptera: Pteromalidae) – was traced in the processed cuts. At room temperature, 100% mortality of four-eyed fir bark beetle occurred after 3 weeks of submersion and of parasitoids after 4 weeks. In natural conditions, in spring, the submersion time should be increased, because at low temperatures the metabolism of insects may be reduced and their death in anaerobic conditions will occur later. We recommend keeping infested logs under water for at least 6 weeks in spring.

In laboratory and field experiments, the role of the fungus Grosmannia aoshimae—the specific fungal symbionts of the four-eyed fir bark beetle Polygraphus proximus—in chemical communication of beetles within vector populations was investigated. Evidence of the attractiveness of volatiles produced by the G. aoshimae mycelium was obtained that affected adult vector beetles both at the stage of choosing trees for colonization and at the stage of determining the boring site during a direct contact with plant tissues. In addition, it was found that terpenes of Siberian fir (Abies sibirica) and volatiles produced by Leptographium mycoassociates of the black fir longhorn beetle (Monochamus urussovii) also demonstrated attractiveness during tree colonization by bark beetles. However, the influence of these substances on P. proximus beetles was less effective. It was supposed that semiochemicals produced by G. aoshimae may be subdivided into two groups: (1) host monoterpenes chemically modified by the fungus; (2) volatiles produced de novo by mature mycelium that has reached the secondary biosynthesis phase. Volatiles of the first type may play a predominant role at the stage of primary selection and colonization of new trees during the mass flight of P. proximus beetles. Semiochemicals of the second type are important for the vector offspring, especially for young beetles to attract them for maturation feeding to the phloem areas colonized by the fungus, where the nitrogen content has increased and the concentration of host defensive substances has been reduced. The importance of studying chemical communications between bark beetles, their fungal symbionts, and the host plant is noted, since this is necessary for developing methods for monitoring and control of xylophagous pest populations.

Первые находки инвайдера на Урале, в Приуралье и Поволжье отмечены с конца 2010-х гг. В республике Удмуртия P. proximus был впервые обнаружен в 2019 г., в Пермском крае и Челябинской области – в 2022 г., а в Свердловской области – в 2023 г. По последним данным, в результате маршрутного обследования в июле 2024 г. уссурийский полиграф был обнаружен в лесных насаждениях вдоль автомобильных трасс «Екатеринбург–Серов» и «Екатеринбург–Пермь». В Челябинской области инвайдер выявлен на территории всех лесничеств, имеющих в составе древостоев пихту сибирскую, а также в ряде городских лесов и парков, региональных и федеральных ООПТ. Инвазия в эти регионы почти наверняка произошла значительно раньше. В рамках данной работы нами выполнено датирование инвазии полиграфа уссурийского в сравнительно близко расположенных регионах Урала и Приуралья. В сумме объем материала был получен от 253 максимально давно отмерших из-за короеда деревьев и 90 живых деревьев, необходимых для построения мастер-хронологии. Датировка отпада первых заселенных инвайдером деревьев дала представление о времени, когда произошло внедрение уссурийского полиграфа на обследованную территорию. Скорее всего, инвазия P. proximus началась в Удмуртии в 2000-х гг. Самая ранняя гибель деревьев отмечена в Челябинской и Свердловской областях в 2007 г. В Пермском крае гибель деревьев ранее всего отмечена на двух участках Добрянского лесничества (2011 и 2014 гг.). В Пермь инвайдер пришел существенно позднее: в городских лесах отмирания пихт начались в 2018, 2021 и 2022 гг. Так как от года появления полиграфа на новой территории до гибели от него первого дерева пихты проходит минимум 2-3 года, то следует учитывать этот срок при определении времени инвазии. The first discoveries of the invader in the Urals, the Cis-Urals, and the Volga region were made in the late 2010s. In the Udmurt Republic, P. proximus was first detected in 2019, in Perm Krai and Chelyabinsk Oblast in 2022, and in Sverdlovsk Oblast in 2023. According to the latest data, during a route survey in July 2024, P. proximus was discovered in forest stands along the Yekaterinburg-Serov and Yekaterinburg-Perm highways. In the Chelyabinsk Oblast, the invader was detected in all forestry sites with Siberian fir stands, as well as in a number of urban forests and parks, and regional and federal protected areas. These regions were almost certainly invided much earlier. As part of this study, we dated the invasion of P. proximus the Urals and Cis-Urals. In earliest total, data were obtained for 253 trees killed by the bark beetle, and 90 living trees, which were necessary for constructing a master chronology. Dating the mortality of the first trees colonized by the invader provided an idea of the time when P. proximus entered the surveyed area. The invasion of P. proximus most likely began in Udmurtia in the 2000s. The earliest tree mortality was recorded in the Chelyabinsk and Sverdlovsk Oblast in 2007. In Perm Krai, tree mortality was earliest recorded in two sites of the Dobryanskoye forestry (2011 and 2014). The invader arrived in Perm significantly later: fir dieback in urban forests began in 2018, 2021, and 2022. Since at least 2-3 years usually passe between the Polygraphus proximus arrival in a new area and the death of the first fir tree, this period should be taken into account when determining the date of invasion.