Defining the invasion boundaries of a non-native bark beetle, Ips amitinus

Союзный короед ( Ips amitinus (Eichhoff)) - европейский вид, сравнительно недавно проникший в Сибирь, где образует очаги массового размножения в насаждениях нового для него растения-хозяина - сосны сибирской ( Pinus sibirica Du Tour). В одном из очагов в кедровниках Томской области в июне-августе 2024 г. были вывешены барьерные ловушки с диспенсерами, содержащими аналоги агрегационного феромона союзного короеда производства Российского центра карантина (ВНИИКР) и австрийской фирмы Witasek. В период активного лета короеда диспенсеры отечественного и австрийского производства не привлекли ни одной особи союзного короеда. Диспенсеры ВНИИКР отловили его специализированного энтомофага муравьежука Thanasius femoralis (Zetterstedt) и ряд нецелевых видов короедов и усачей. Видовой состав отловленных насекомых диспенсера австрийского производства был неотличим от такового контрольных ловушек. Подчеркивается необходимость дополнительных исследовательских работ по поиску и наработке феромонных смесей для мониторинга популяций союзного короеда в его вторичном ареале. The small spruce bark beetle ( Ips amitinus (Eichhoff)) is the European species which invaded Siberia providing outbreaks in forests predominated by its new host plant, the Siberian pine ( Pinus sibirica Du Tour). The barrier pheromone traps with dispensers containing synthetic aggregation pheromone of small spruce bark beetle produced by the Russian Quarantine Center (VNIIKR) and the Austrian company Witasek were placed in the pest foci in the Siberian pine forest of the Tomsk Region and regularly checked in June-August 2024. During the period of bark beetle flight, the synthetic pheromones of Russian and Austrian producers attracted no one small spruce bark beetle specimen. Instead, the Russian pheromone attracted specialized entomophagous predator Thanasius femoralis (Zetterstedt) and a number of non-target species of bark beetles and sawyer beetles. The catches on the Austrian pheromone were indistinguishable from control traps in terms of the composition of attracted insect species. The necessity of additional research on the development of efficient pheromone mixtures for monitoring small spruce bark beetle in its secondary range is emphasized.

The list of parasitoids inhabit in the centers of mass reproduction of the allied bark beetle Ips amitinus (Eichh.) in the Tomsk Region is given. Parasitoids were reared from the branches cut in the upper parts of the crowns to the Siberian pine Pinus sibirica Du Tour., inhabited by the allied bark beetle. The branches were collected in the centers of its mass reproduction in the Tomsk region, in the invasive part of the range of this xylophagous allied bark beetle. In addition to Ips amitinus, the branches were inhabited by Pityogenes chalcographus (L.), Pityogenes conjunctus Rtt., Pissodes piniphilus (Hbst), and Monochamus saltuarius Gebler. In total, 11 species of xylophagous parasitoids inhabiting branches were found, including 5 parasitoids of the union bark beetle: Coeloides ungularis (Thomson.), Dinotiscus eupterus (Walker), Tomicobia seitneri (Ruschka), Rhopalicus tutela (Walker), Roptrocerus xylophagoraum (Ratzeburg). Eubazus semirugosus (Nees), Spathius rubidus (Rossi), Eurytoma arctica Thomson, Tomicobia pityophthori (Bouček), Rhopalicus quadratus (Ratzeburg) were bred from the branches that dwelt Ips amitinus и Pityogenes chalcographus. Braconid Coeloides ungularis Thomson as the host of Ips amitinus is indicated for the rst time.

Ips amitinus arrived in Northern Europe at the beginning of 1900s, although its recent expansions to the northernmost conifers have been rapid. Analyses of recent records, MaxEnt models and regional population size estimates are used to discuss its peculiar range shifts and potential as a forest pest in Northern Europe. Ips amitinus was probably absent in northern glacial refugia for Norway spruce in the Russian plain and northward expansions from its glacial refugia in the Central European mountains may have been slowed down by: (i) ecological barriers of post‐glacial dry plains and bogs in Central Europe; (ii) heavy utilization of conifers; and (iii) Allee effects as a result of fragmented forests and an unfavourable climate for a cold‐adapted species in the continental lowlands. MaxEnt models predict that I. amitinus may become widespread in the Northern European forests, whereas its populations in the southernmost mountain ranges of Europe may decline in the future. The population levels of I. amitinus in recently invaded northern areas are still lower than those in core areas of Central Europe, although the population development in Central Europe indicates that future bark beetle outbreak periods may boost the I. amitinus populations in Northern Europe as well.

Bark beetles are serious forest pests in Slovakia. Their outbreaks may have significant ecological and economic impacts on spruce forests. There is a variety of natural enemies that activate themselves during population outbreaks of insects and entomopathogenic fungi belong to important antagonists with a potential to regulate populations of their hosts. In 2014–2016, species richness and prevalence of entomopathogenic fungi were evaluated during the bark beetle outbreaks in spruce forests affected by windstorms in the Tatra National Park in Slovakia. Three Beauveria species, B. bassiana, B. caledonica and B. pseudobassiana, with Metapochonia bulbillosa were identified from 271 specimens of three bark beetle species, Ips typographus, Ips amitinus and Pityogenes chalcographus. Beauveria bassiana was the dominant pathogen and infected all three bark beetle species. Phylogenetic analysis identified three phylogenetic groups of B. bassiana in the evaluated host populations. M. bulbillosa was reported for the first time from bark beetle hosts and Slovakia. The prevalence of fungal infection in natural populations of I. typographus was low, varied between 0.07 and 0.72%, and have little influence on the bark beetle abundance.

Today, when somebody is talking about bark beetles management, there are two different approaches. The first one includes bark beetles in the category of pests and the second one includes bark beetles in the category of insects with important ecologic role in forest. From our point of view, up to particular limits, both approaches remain valid. Thus, in our research raise the problem of bark beetles population level into logging debris, which remains in the forest after clear-cutting. In our research, we started with the hypothesis that in logging debris a high number of bark beetles can multiply sufficient to install after that in neighbors standing trees. From our samples resulted seven bark beetles species as follows: Ips typographus , Ips amitinus , Ips acuminatus , Pityogenes chalcographus , Dryocoetes autographus , Hylurgops palliatus , Hylurgops glabratus . The most numerous were I. typographus (43%), P. chalcographus (40%), and H. palliatus (9%). The preferences for the thickness of logging debris had just P. chalcographus and H. palliatus . All the rest of the species preferred in equal mode thick or thin logging debris. Regarding the felling date of trees, we can affirm that cutting of trees early in spring may limit the beetles spreading. About logging debris management, our results show the necessity of their removal from forest and capitalization, because they are hosts for many bark beetles.

Bark beetles are serious pests for forestry in Slovakia. Their outbreaks may have significant ecological and economic impacts on spruce forests. Effective control of bark beetles is difficult due to their cryptic habits, however, microbial control using entomopathogenic fungi is believed to be a promising alternative to traditional control measures. During 2014–2015, diversity and prevalence of entomopathogenic fungi was studied in populations of bark beetles infesting spruce forests affected by windstorms in the Tatra National Park in Slovakia. Three Beauveria species, B. bassiana, B. caledonica and B. pseudobassiana, together with Metapochonia bulbillosa were identified from 271 specimens of three bark beetle species, Ips typographus, Ips amitinus and Pityogenes chalcographus. Beauveria bassiana was the predominant pathogen and infected all three bark beetle species. Phylogenetic analysis identified three phylogenetic groups of B. bassiana in the evaluated host populations. M. bulbillosa was reported for the first time from bark beetle hosts and Slovakia. The prevalence of fungal infection in natural populations of I. typographus was low and varied between 0.07 and 0.72%.

Ophiostomatoid fungi can severely affect the health and economic value of Norway spruce trees (Picea abies). Although the diversity of ophiostomatoid species and their associations with insects have been well-investigated in central and northern Europe, little is known about the conditions in south-eastern Europe. This study aims to study the assemblages of ophiostomatoid fungi associated with three bark beetle species (Ips typographus, Ips amitinus, and Pityogenes chalcographus) that infect Norway spruce in Slovenia. Bark beetles were sampled in four phytogeographic regions in Slovenia. The fungi found on the bark beetles were identified based on morphology, DNA sequence comparisons of ITS regions and phylogenetic analysis. The species compositions of the fungal associates of the three insect species were compared and the pairwise associations of the occurrence of the fungal species were analysed. Thirteen different species were found. The most commonly encountered fungal associates of the beetles were Ophiostoma bicolor, Ophiostoma brunneo-ciliatum, Grosmannia piceiperda, Ophiostoma ainoae, Ceratocystiopsis minuta, and Grosmannia penicillata. The composition of the fungal associates differed among the bark beetle species, but not among the phytogeographic regions. This study confirms that ophiostomatoid species are common associates of the investigated bark beetle species. Many ophiostomatoid species have strong host associations. I. typographus and P. chalcographus can act as effective vectors for O. bicolor, O. ainoae, G. piceiperda and O. brunneo-ciliatum, whereas I. amitinus often carries G. piceiperda and C. minuta in Slovenian forests.

In the upper montane zone of coniferous forests in the norther part of the Karkonosze (Giant) Mts. analyses were conducted on the colonisation of spruce trees by bark beetles (Scolytinae, Coleoptera), providing data on the species composition of the assemblages and the frequency of individual species. The study was conducted in 2020–2021. Twenty-four trees (144 sections) were inspected. Thus, the frequency of Ips typographus, I. amitinus and Pityogenes chalcographus was determined in trees colonised in the spring and summer periods. Preferences of these spruce bark beetle species were specified in relation to the colonisation of individual stem sections of specific thickness. It was found that the share of Ips amitinus in the assemblage of bark beetles in spruce coniferous forests in the upper montane zone of the Karkonosze Mts. observed in the stand margins is over 26% and it is by 10% higher than the frequency of Ips typographus. An increased frequency of Ips amitinus was recorded in stems and rollers in the diameter size classes of 9–20 cm. When assessing the competitiveness for breeding sites between I. typographus and I. amitinus in areas of their joint occurrence, it may be stipulated that Ips typographus colonises first the assortments most preferred by that species, thus becoming the dominant species in those areas, while at the same time retreating in the other sections before Ips amitinus, which at a very strong population (as e.g. the one found in the analysed area) colonises them in such numbers that it limits the space for colonisation and development by Ips typographus.

С использованием традиционных и современных методов картографии изучены биологические инвазии в темнохвойные леса Западной Сибири опасных чужеродных стволовых насекомых-дендрофагов - уссурийского полиграфа (Polygraphus proximus Blandf.) и союзного короеда (Ips amitinus (Eichh.)). Наряду с мониторингом инвазионных процессов, проводимым в Томской области и включавшим широкое обследование ее территории для получения фактографических данных о степени деградации поврежденных лесов, особое внимание при картографировании уделялось применению средств ГИС-технологий. На примере некоторых аспектов данных инвазий представлены особенности и возможности составления, а также использования картографического материала в научных и прикладных целях. Показана высокая результативность пространственно-временной оценки наблюдаемых процессов и явлений на локальном уровне методами современного картографирования с привлечением материалов наземного мониторинга и ортофотоснимков с беспилотных летательных аппаратов. С помощью ГИС дана наглядная пространственная оценка степени деградации поврежденных вредителями лесов, лесопатологического состояния насаждений и размера ущерба от воздействия инвазивных дендрофагов на модельных территориях. Выявлено, что для Томской области наибольшая степень риска от экспансии уссурийского полиграфа и союзного короеда наблюдается в южных и юго-восточных районах. Использование функционала ГИС позволило создать серию оригинальных тематических карт, отражающих различные аспекты пространственных особенностей инвазий, что позволяет делать краткосрочные прогнозы зарождения и распространения очагов вредителя, проводить мониторинг и контроль их развития, а также выявлять направленность процесса распространения вредителей на разных уровнях территориальной иерархии. Biological invasions into dark coniferous forests of Western Siberia by dangerous alien stem pests: four eyed fir bark beetle (Polygraphus proximus Blandf.) and small spruce bark beetle (Ips amitinus Eichh.) were studied using traditional and modern methods of mapping. Along with the monitoring of invasion carried out in Tomsk oblast, which included a wide survey of its territory to obtain factual data on the degree of degradation of damaged forests, special attention was paid to the use of GIS technologies. Using an example of some aspects of these invasions, the features and possibilities of compiling as well as using map material for scientific and applied purposes are presented. The high efficiency of spatiotemporal assessment of observed processes and phenomena at the local level by using modern mapping methods with the involvement of ground monitoring material and orthophotos from unmanned aerial vehicles is shown. A spatial assessment of the degree of degradation, vital state, and the amount of damage caused by invasive bark beetles in model areas using GIS is made. The highest degree of risk from the expansion of P. proximus and I. amitinus was revealed for the southern and southeastern parts of Tomsk oblast. The use of the GIS functionality made it possible to create a series of original thematic maps that reflect various aspects of the spatial features of invasions, which permits short-term forecasts of the origin and spread of pest foci, monitoring and control of their development, as well as identifying the direction of the pest spread process at different levels of the territorial hierarchy.

The study presents new data on spatial distribution of bark beetle pathogens, on changes in frequency over several years and on their prevalence during different time periods within a year from several locations within the wilderness reserve Durrenstein (Lower Austria). The occurrence of pathogens was investigated in Ips typographus (during five years), in Pityogenes chalcographus (during two years) and in Ips amitinus (in one year). In total, seven pathogen species could be detected in I. typographus. The most dominant pathogen species were the Ips typographus-Entomopoxvirus (ItEPV), the sporozoan species Gregarina typographi and the microsporidium Chytridiopsis typographi; the latter two pathogen species were recorded every year and at about similar high (G. typographi) or low (C. typographi) rates, the ItEPV in strongly varying rates. The neogregarine Mattesia cf. schwenkei and the two microsporidia Nosema typographi and Unikaryon montanum were found in I. typographus only sporadically and the rhizopodan species Malamoeba scolyti was found once. The number of infected males and females was relatively similar with almost all pathogen species in most of the years except U. montanum, which occurred exclusively in females. Three pathogen species were recorded in P. chalcographus which were Gregarina typographi, Mattesia cf. schwenkei and Chytridiopsis typographi. Two pathogen species were observed in I. amitinus, Gregarina typographi and Chytridiopsis typographi.

Abstr A ct The results of the study on entomofauna infesting young (25– 45 years) Norway spruces (Picea abies [L.] Karst.) in the area formerly affected by forest decline in the Izerskie Mountains (Western Sudetes), are presented in the paper. Entomological analyses were carried out on tree sections (0.5 m long) obtained from 50 trees (3 sections each) as well as during photoeclector rearing of tree samples (28 sections 0.5 m long). Bark- and wood-boring insects of 21 species and 1 genus were found. The dominant species was Pityogenes chalcographus L. (88% frequency in field analyses) usually accompanied by Ips amitinus (68%). Both species frequently infested whole stems (found in all 3 sections in 62% of analyzed trees). In the group of predators and commensals, 13 species were found, with most frequent Corticeus linearis (Fabr.), Crypturgus spp. and Medetera signaticornis (Loew.). Among the parasitoids belonging to 7 species and 4 genera, Braconids and Pteromalids known as parasites of Scolytid bark beetles, were most common. Taking into consideration reccurence of natural processes such as insect outbreaks, probability of the scenario described in the paper, i.e. shifting bark beetle attack from old into young spruce stands after Ips typographus L. outbreak, is very high in the area of current decline of the Norway spruce in the Western Carpathians.

The results of studying the mass reproduction outbreak of a new invasive pest of the Siberian pine (Pinus s-ibirica Du Tour), the small spruce bark beetle (Ips amitinus (Eichh.)), observed in Siberia for the first time, are presented in this paper. The studies were carried out in the south-eastern part of Western Siberia, within the Tomsk region, in pine forests damaged by an invasive bark beetle. It is shown that the occurrence of the outbreak was provoked by favourable weather conditions of recent decades and the abundance of trees, weakened for various reasons, in the recipient ecosystems of the invasion, among which the outbreak of the Siberian moth in 2016–2018 was of great importance. The small spruce bark beetle population dynamics in new habitats was compared with the native area in Europe, and certain peculiarities were revealed: an increase in the populations’ numbers level, a narrowing of trophic specialisation up to a regional monophagy, a decrease in the role of an interspecific competition due to the displacement of local stem dendrophagous species by the invader, the simultaneous existence of outbreak foci in different development stages and the correlation between their characteristics, the species composition of the forest stands and the weakening factors. An original method for assessing the spreading risk for an outbreak of the small spruce bark beetle breeding in the Tomsk region under the influence of a complex of factors that contribute to an increase in its number has been proposed and implemented at the forestries level.

The Panel on Plant Health performed a pest categorisation of the small spruce bark beetle, Ips amitinus (Eichhoff) (Coleoptera: Curculionidae, Scolytinae), for the EU. I. amitinus is a well‐defined and distinguishable species, native to Europe and attacking mainly spruce (Picea spp.) and pine (Pinus spp.) and sporadically fir (Abies spp.) and larch (Larix spp.). It is distributed in 16 EU Member States and is locally spreading in some. The pest is listed in Annex IIB of Council Directive 2000/29/EC. Protected zones are in place in Ireland, Greece and the United Kingdom. Wood, wood products, bark and wood packaging material are considered as pathways for this pest, which is also able to disperse by flight over tens of kilometres. The insects normally establish on fallen or weakened trees (e.g. after a fire or a drought) but can also occasionally mass‐attack healthy trees, when population densities are high. The males produce pheromones that attract conspecifics of both sexes. Each male attracts one to seven females to establish a brood system; each female produces 1–60 offspring. The insects also inoculate their hosts with pathogenic fungi. There are one or two generations per year. The wide current geographic range of I. amitinus suggests that it is able to establish in most areas in the EU, including the protected zones, where its hosts are present. The damage due to I. amitinus is limited and usually does not require control. Sanitary thinning or clear‐felling is the usual control methods, when necessary. Quarantine measures are implemented to prevent entry in protected zones. All criteria for consideration as a potential protected zone quarantine pest are met. The criteria for considering I. amitinus as a potential regulated non‐quarantine pest are not met since plants for planting are not viewed as a pathway.

A new microsporidium is reported from the small spruce bark beetle, Ips amitinus: Microsporidium sp. with uninucleate oval spores measuring 3.5 × 2.5 μm; infecting cells of the midgut epithelium, midgut muscles, the fat body, the Malpighian tubules, and the gonads of adult beetles collected in Austria. Seven other pathogens were found in beetles collected from Austria, the Czech Republic, and Finland. Six of them were already known from I. amitinus. Nosema cf. typographi is recorded for the first time in the overwintering generation of I. amitinus from the Czech Republic.

Two slope profiles covering altidudes from 620 - 1.420 mNN and exposed to N and S, respectively, were investigated during 2 seasons for their thermal conditions regarding the development of spruce bark beetle populations. Temperature of air and cambium in different positions on trap trees were recorded continously, in order to calculate the thermal sums available for the broods under different site and weather conditions. Moreover, flight activity and brood development was observed. In the laboratory the developmental zero and the required thermal sum of Ips typographus (Linnaeus 1758), Ips amitinus (Eichhoff 1871) and Pityogenes chalcographus (Linnaeus 1761) were experimentally determined. Significant differences between the 3 species were found. Since the data from laboratory proved to be valid also in the field, they can be used for calculating the developmental potential of these Scolytidae species under different thermal conditions. The latter differed considerably due to altitude, exposition, shadowing and weather, thus providing a wide range of different thermal sums available to the broods. Taking into account that Ips typographus cannot hibernate in a subadult stage, the effective period of reproduction during season varies between a few weeks in spring and a few months in summer. The implications for population dynamics of Ips typographus and Pityogenes chalcographus are briefly discussed, considering a diapause of adults with Ips typographus and the differences between specific modes of hibernation.