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Article

Fungal Diversity Associated with the Sharp-Dentated Bark Beetle Ips acuminatus (Coleoptera: Curculionidae) in Latvia

by
Natalija Burnevica
*,
Elza Gricjus
,
Liva Legzdina
,
Zane Strike
,
Baiba Krivmane
,
Selita Rancane
,
Janis Lekavičs
,
Agnis Smits
and
Darta Klavina
Latvian State Forest Research Institute “Silava”, Rigas 111, LV2121 Salaspils, Latvia
*
Author to whom correspondence should be addressed.
Forests 2026, 17(1), 9; https://doi.org/10.3390/f17010009
Submission received: 27 November 2025 / Revised: 15 December 2025 / Accepted: 18 December 2025 / Published: 20 December 2025
(This article belongs to the Section Forest Health)
Browse Figures
Versions Notes

Abstract

Over the last few decades, the frequency of outbreaks of Ips acuminatus has rapidly increased in Latvia. These beetles are commonly associated with blue-stain fungi, which increase tree mortality and decrease the timber quality of affected trees. The aims of this study were: (i) to identify fungi associated with I. acuminatus in Latvia and (ii) to determine the influence of different factors (such as locality, month of beetle capture, beetle sex) on the diversity of associated fungi. From a total of 590 analysed I. acuminatus beetles, 564 resulted in fungal growth and yielded 1247 fungal isolates, representing 36 fungal taxa. Among the fungi isolated, the most common were Akanthomyces muscarius, followed by Penicillium spp., Mucor spp., Cladosporium cladosporioides, Leptographium cucullatum, Ophiostoma minus, and Graphilbum acuminatum. No significant differences in fungal diversity between different locations and between male and female I. acuminatus were observed. However, significant seasonal differences were observed between months in which I. acuminatus beetles were captured and fungal communities isolated from them. More research is needed on the potential of the entomopathogenic fungi isolated in this study for the biological control of I. acuminatus. Also, the pathogenicity of isolated Ophiostomatoid fungi and their ability to cause blue-stain in Pinus sylvestris timber could be further evaluated.

1. Introduction

The sharp-dentated bark beetle, Ips acuminatus (Gyllenhal), was historically considered a minor pest; however, over the last few decades, outbreaks in Europe have become more frequent, leading to notable tree mortality [1,2]. In Latvia, several localized outbreaks have been recorded, the most extensive of which was initiated by the Stikli Bogs fire in 2018, which affected 1353 ha of forest [3].
Ips acuminatus main hosts are trees from the genus Pinus, and this bark beetle prefers to colonize smooth-barked sections of the pine upper parts of the trunk or branches [4]. It is a polygynous species, with males as the primary colonizers, which subsequently attract females to a male-created mating gallery using aggregation pheromones [5]. One male usually mates with numerous females (from 2 to 12) in a mating chamber, and variation in sex ratio in different localities can be high (from 1:1.4 to 1:20 (male/female)) [6,7].
In Latvia, Scots Pine (Pinus sylvestris) is one of the most widespread and economically significant tree species, occupying 38% of Latvia’s total forest area [8]. Most pine stands in Latvia are between 51 and 110 years old [8], an age range highly susceptible to I. acuminatus attacks, especially when trees are weakened by weather conditions and drought stress [4]. In the last decades, drought periods during springtime and early summer, as well as summer temperature records, have become more frequent, which could increase the impact of pests and pathogens on weather-stressed trees [9]. Ips acuminatus outbreaks have not only a direct impact on pine vitality but also a secondary effect due to beetle-associated pathogenic fungi, mostly from the genus Ophiostoma [4]. These fungi can cause crown thinning, needle yellowing, and tree mortality, affecting various tree species [10,11]. Several studies have also reported an association between I. acuminatus and the Diplodia tip blight and stem canker disease-causing fungus Diplodia sapinea [12,13,14].
Natural enemies are important in controlling the population of I. acuminatus [4,15]; however, timely silvicultural actions are key to managing population growth in an area. Removing infested trees before the new generation of beetles emerges helps prevent the infestation from spreading to nearby trees [16]. Other control methods include mass trapping with pheromone traps [17], sanitation fellings, and removing logging residues from clearcuts [3].
Studies conducted in other countries have shown regional differences in the fungi associated with I. acuminatus [12,18,19], indicating a knowledge gap in the Baltic region, including Latvia, where no such studies have previously been conducted. The main aims of this study were (i) to identify fungi associated with I. acuminatus in Latvia and (ii) to determine the influence of different variables (such as locality, month of beetle capture, and beetle sex) on the diversity of associated fungi.

2. Materials and Methods

2.1. Study Sites

Between May and September 2025, a total of 14 pheromone-baited traps were installed across three study areas: five traps in Daugavpils, five traps in the Garkalne study area, and four traps in the Kalsnava study area (Table 1). All study areas consisted of Scots pine-dominated mature (85 to 120 years old) stands situated on dry, nutrient-poor soils, but they differed in their disturbance regimes.
The Garkalne sites have been subject to recurrent forest fires since 2021; the Kalsnava sites are in clearcuts of pine stands harvested the previous year, with adjacent pine stands; and the Daugavpils sites are areas with a historical presence of I. acuminatus but no recent disturbance events.

2.2. Collecting Ips acuminatus Beetles

The presence of the species in the areas was monitored using slit traps (WitaTrap) produced by the Witasek Company (Feldkirchen, Austria) and the Acumudor Micro lure from Chemipan (Warsaw, Poland). They are previously described as the most attractive to I. acuminatus [20]. The traps were placed in early May and monitored until the end of September. Traps were examined weekly for beetle captures, with the inspection frequency increased to twice a week during the peak flight period in July due to a high presence of natural enemies (e.g., Thanasimus formicarius L.) in the traps. Because fungal dispersal is mostly carried out by the adult beetles [4], the other development stages were not tested in this research.
In total, 886 I. acuminatus (31 male to 855 female) were collected, and 1 to 20 beetles from each trap weekly capture were subjected to fungal isolation (590 beetles in total: 31 male and 559 female). The beetle sex was determined using a microscope by the shape of the third elytral spine, which is the distinctive feature of the sexes for I. acuminatus [4]. Additionally, due to the activity of natural enemies, numerous detached beetle wings were collected in Garkalne sites. Assuming two wings represented one individual, this corresponded to an estimated total of 1033 beetles (1010 female to 23 male).

2.3. Isolation and Identification of Fungi Associated with Ips acuminatus

In laboratory, each no surface-sterilized I. acuminatus beetle was dissected into two pieces using flame-sterilised forceps, placed on separate Petri dish (one beetle per dish) contained modified Hagem agar media (5 g glucose, 0.5 g NH4NO3, 0.5 g KH2PO4, 0.5 g MgSO4·7H2O, 5 g malt extract, 0.1 g chloramphenicol, 20 g agar, 1000 mL H2O with addition of 0.05 g cycloheximide and 0.01 g streptomycin after media was autoclaved and when cooled down to 55 °C) and incubated in the dark at 21 °C. Every 5–6 days, Petri dishes were evaluated, and all emerging fungal mycelia were subcultured on Hagem agar media (5 g glucose, 0.5 g NH4NO3, 0.5 g KH2PO4, 0.5 g MgSO4·7H2O, 5 g malt extract, 20 g agar, 1000 mL H2O at pH 5.5). All obtained fungal pure cultures were examined under a microscope and grouped into morphotypes based on mycelial-specific features (e.g., hyphae, conidia). In total, 70 morphological groups were allocated. From those, six species/genera were identified only microscopically: Penicillium spp., Aspergillus spp., Mucor spp., Absidia spp., Trichoderma spp., and Aureobasidium pullulans [21]. The remaining mycelial morphotypes were subjected to molecular identification. For DNA extraction, fungal mycelia were collected from the surface of Hagem agar media using a flame-sterilised scalpel, placed in 2 μL Eppendorf tubes, and stored in the freezer until DNA extraction.
Molecular analyses were performed at the LSFRI “Silava” Genetic Resource Centre. DNA was extracted using a modified CTAB method [22] followed by PCR amplification with fungi–specific primers ITS1F (5′-CTTGGTCATTTAGAGGAAGTAA-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) [23,24]. PCR reactions were performed in a volume of 10 µL containing approximately 50 ng DNA, 5× HOT FIREPol Blend Master Mix Ready to Load (Solis BioDyne, Tartu, Estonia) (containing 10 mM MgCl2), and 0.3 µM of each forward and reverse primer. PCR was carried out in a thermocycler (Eppendorf Mastercycler Epgradient; Eppendorf, Hamburg, Germany) using the following protocol: initial pre-denaturation step at 95 °C for 15 min, followed by 35 cycles of 95 °C for 30 s, annealing at 55 °C for 30 s, and 72 °C for 45 s, and a final extension step of 72 °C for 10 min. PCR fragments were analyzed via gel electrophoresis on 1.5% agarose gels stained with ethidium bromide, and Sanger sequenced [25] in two directions using ITS1F and ITS4 primers.
The nucleotide sequences obtained were analyzed using the NCBI BLAST function (https://blast.ncbi.nlm.nih.gov/Blast.cgi (accessed on 1 November 2025)) for identification of fungal species. The ITS sequence homology was set at 98%–100% for fungal taxa and 94%–97% for genus level. The sequence data are placed in the Zenodo Open repository for EU-funded research (doi: 10.5281/zenodo.17854999).

2.4. Data Analysis

The incidence of fungi isolated from bark beetles and the Sørensen similarity index were calculated using Excel. Diversity t-test and Shannon diversity index, as well as PCA (Principal components), were calculated using software PAST 5.3 [26]. To analyze the variables influencing the number of Ophiostomatoid taxa and the presence of some dominant taxa (genus Ophiostoma and Graphilbum with focus on species Ophiostoma minus and Leptographium cucullatum), generalized linear mixed-effects models (GLMM) were analyzed with the lme4 R v.4.4.3 package (function glmer with a Poisson distribution (binomial in case of species) were implemented. Models used in this study incorporated both fixed effects (beetle sex and sampling month) and random effects (specific location and trap ID). The significance of fixed effects was evaluated using variance analysis (ANOVA). Data analysis was performed in R v.4.4.3 [27]. Graphs created using Excel and PAST 5.3. Variation in beetle sex ratio among locations was assessed using Pearson’s Chi-squared test of independence in R [28].

3. Results

3.1. Seasonal Flight Activity of Bark Beetle Ips acuminatus

Ips acuminatus flight activity occurred between weeks 21 and 36 (Figure 1), with a distinct peak in July (week 28) and a smaller secondary peak at the start of August (week 32), when new generation beetles were observed in the traps. The highest beetle abundance in one week was recorded in Garkalne (≈300 beetles), while Kalsnava and Daugavpils showed considerably lower activity (<100 beetles). Wing pair counts from Garkalne followed a similar temporal pattern, and flight activity declined to baseline levels by week 35. The highest beetle activity was recorded in traps placed in 1- to 2-year-old post-fire forest stands.
The sex ratio of I. acuminatus differed significantly among the three study locations (Pearson’s Chi-squared test: χ2 = 7.28, df = 2, p = 0.026). Overall, males accounted for a small proportion of beetle captures across all sites. The highest male-to-female ratio was observed in Kalsnava (1:17), followed by Daugavpils (1:30) and Garkalne (1:41).

3.2. Fungi Associated with Ips acuminatus

From a total of 590 analysed I. acuminatus beetles, 564 (95.6%) resulted in fungal growth and yielded 1247 fungal isolates, representing 36 fungal taxa (Table 2). Among the fungi isolated from I. acuminatus, the most common was the entomopathogenic fungus Akanthomyces muscarius (isolated from 44% of all analysed beetles), followed by molds Penicillium spp. (34%), Mucor spp. (21%), Cladosporium cladosporioides (19%), and Ophiostomatoid fungi Leptographium cucullatum (19%), Ophiostoma minus (17%) and Graphilbum acuminatum (9%). The most frequently found fungi in Daugavpils were Mucor spp. (found in 43% of beetles), followed by Penicillium spp. (20% of beetles). Among the Ophiostomatoid fungi, the most abundant were L. cucullatum and O. minus (both isolated from 13% of beetles). In locality Garkalne, the most abundant were A. muscarius (59% of beetles), followed by Penicillium spp. (35% of beetles), among Ophiostomatoid fungi—L. cucullatum (25% of beetles) and O. minus (23% of beetles). In Kalsnava, the most abundant were Penicillium sp. (37% of beetles) and A. muscarius (18% of beetles) among Ophiostomatoid fungi, followed by L. cucullatum (8% of beetles) and G. acuminatum (7% of beetles). Significant differences in fungal diversity between locations were not observed (p > 0.05). The Sorensen similarity index ranged from 0.51 to 0.65, whereas the Shannon diversity index ranged from 2.39 to 2.49.
The most abundant fungal species isolated from male I. acuminatus was entomopathogenic A. muscarius (48% of male beetles), followed by O. minus (32% of male beetles). Among other Ophiostomatoid fungi, seven species were isolated from male I. acuminatus: L. cucullatum (13% of all male beetles), G. acuminatum (10%), L. olivaceum (10%), O. macrosporum (6%), O. piceae (6%), G. furuicola (3%), and O. ips (3%). Among female beetles, most frequently isolated were A. muscarius (44% of all female beetles), followed by Penicillium spp. (35%). In addition, 10 species of Ophiostomatoid fungi were isolated: L. cucullatum (19% of all female beetles), O. minus (16%), G. acuminatum (9%), O. piceae (7%), O. ips (7%), L. olivaceum (4%), O. macrosporum (4%), G. furuicola (0.1%), Sporothrix pseudoabietina (0.1%), and Sporothrix sp. LV27 (0.1%). Regarding fungal diversity between male and female beetles, no significant differences were found (p = 0.12). The Sørensen similarity index between fungal communities was 0.6, while the Shannon diversity index was 2.37 for males and 2.55 for females. However, blue-stain fungus O. minus was isolated twice more frequently from male I. acuminatus than from female (32% vs. 16%) (Figure 2), and beetle sex was indicated as a significant factor for this species by GLMM modelling (p < 0.05) (Table 3).

3.3. Seasonal Differences in Fungal Communities Isolated from Ips acuminatus

Significant differences were observed between months in which I. acuminatus beetles were captured and fungal communities isolated from them (Figure 3). Significant differences were observed between July and August and between July and September (p = 0.002 and p = 0.01, respectively). Between July and May, the difference was nearly significant (p = 0.06). Shannon diversity indexes were: 1.48 in May, 2.36 in June, 2.52 in July, 2.31 in August, and 2.02 in September. In May, very few fungal species were isolated: from 51 I. acuminatus beetles, only 13 fungal isolates were obtained, representing six fungal species, the most abundant being Penicillium spp. (62% of all isolates). The only Ophiostomatoid fungal species isolated in May was L. cucullatum (8% of all isolates). In June, fungal diversity was higher: from 28 beetles, 69 fungal isolates were obtained, representing 16 fungal species. The most abundant fungus was Penicillium spp. (64%), followed by A. muscarius (46.4%). Among Ophiostomatoid fungi, the most abundant were O. minus and O. piceae (respectively, isolated from 18% and 14% of beetles). In July, when the peak of I. acuminatus activity was observed, fungal diversity was also the highest: from 379 beetles, 862 fungal isolates were obtained, representing 31 fungal taxa. The most isolated fungus was A. muscarius (45%), followed by Penicillium spp. (38%). Among Ophiostomatoid fungi, the most abundant were L. cucullatum and O. minus (both 24%). In August, from 103 beetles, 229 fungal isolates were obtained, representing 21 fungal species. The most abundant was Mucor spp. (56%), followed by A. muscarius (52%). Among Ophiostomatoid fungi, the most frequently isolated was L. cucullatum (11%), followed by G. acuminatum (9%). In September, when I. acuminatus activity decreased, 66 fungal isolates were obtained from 29 I. acuminatus beetles, resulting in 11 fungal species. The most abundant fungus was A. muscarius, isolated from 76% of beetles. Among Ophiostomatoid fungi, the most frequently isolated were L. cucullatum and O. ips (both isolated from 24% of beetles).
The proportion of isolations of Ophiostomatoid fungi among other isolated fungi increased in July (from 8% in May to 38% in July), when peak activity of bark beetles was also observed. There was a significant decrease in August (13%), followed by another peak in September (23%). Incidence of entomopathogenic fungi increased slightly after the peak activity (from 20% in July to 36% in September) (Figure 4).
The lowest Sørensen similarity index was between May and June, July, and August (respectively, 0.27, 0.22, and 0.30). Between May and September, the Sørensen similarity index was 0.47; between June and September, 0.44; and between July and September, 0.38. The Sørensen similarity index for other months ranged from 0.50 to 0.58.

4. Discussion

In the present study, we collected Ips acuminatus beetles from three different localities with different site histories. This is the first study focused on fungi associated with I. acuminatus in Latvia.
Ips acuminatus exhibited a clear, seasonally structured flight period, with a major peak in late July and a smaller emergence-related peak in early August, most prominently in the high-abundance Garkalne locality (Figure 1). Beetle activity was highest in young (1–2-year-old) post-fire stands, and the notably high activity of natural enemies in Garkalne may further reflect the suitability of these habitats for bark beetle–associated communities. Although overall captures were female-based, the sex ratio varied significantly among locations, indicating site-specific differences in population structure.
The most frequently isolated fungus was the entomopathogenic fungus A. muscarius (formerly known as Lecanicillium muscarium). This fungus mainly infects insects from Hemiptera; however, it has also been reported from other groups of insects [28]. All entomopathogenic fungi are of great interest as potential biocontrol agents for numerous forest pests [30,31,32]. More research is needed on the potential of A. muscarius and other entomopathogenic fungi (Beauveria bassiana and B. pseudobassiana) identified during this study for the control of I. acuminatus. The only fungus tested against I. acuminatus in a Bulgarian study was Cordyceps farinosa (formerly known as Paecilomyces farinosus), which was ineffective [33].
In total, 10 species of Ophiostomatoid fungi were found associated with the I. acuminatus beetle in Latvia. The most frequently isolated was O. minus, which was commonly isolated from I. acuminatus in various previous studies from several countries [12,18]. In Ukrainian [12] and Swedish [34] studies, O. minus was identified as the fungus causing dieback of artificially inoculated pine seedlings, highlighting its role in increased tree mortality. Besides I. acuminatus, this fungus is associated with other bark beetle species, Tomicus piniperda [34] and T. minor [35]. In our study, O. minus was isolated twice as frequently from male I. acuminatus as from female I. acuminatus, suggesting that O. minus may be the primary agent in overcoming tree resistance and making trees more susceptible to further mass insect attack.
The other most isolated species of Ophiostomatoid fungi was Leptographium cucullatum. This fungus belongs to the L. olivaceum species complex [36] and is mainly associated with the spruce bark beetle Ips typographus [36,37,38]. The other species in this complex, isolated less frequently, was L. olivaceum, which is mainly associated with I. typographus [39] and I. sexdentatus [40] but has also been isolated from I. acuminatus [12].
Graphilbum acuminatum was the third-most-frequently isolated species of Ophiostomatoid fungi. This fungus is mainly associated with I. acuminatus, though its pathogenicity has not been tested. Graphilbum acuminatum and Sporothrix pseudoabietina were the most common fungi associated with I. acuminatus in Poland [18]. In our study, S. pseudoabietina was found at only one location and was uncommon.
Ophiostoma ips, O. macrosporum, and O. piceae were found in all localities. All these Ophiostoma species were frequently isolated from I. acuminatus in other studies, but their pathogenicity is low [4]. Interestingly, O. macrosporum is regarded as a nutritionally important ambrosia fungus for I. acuminatus [4], but it was not found in recent studies conducted in Ukraine [12], Poland [18], and Slovakia [19].
Diplodia sapinea was isolated from only one beetle in the locality of Garkalne, where most I. acuminatus beetles were captured. In some studies, I. acuminatus is considered a potential vector of D. sapinea [4,13,14]; however, this has not yet been proven.
Seasonal differences in fungal communities observed in this study may be influenced by beetle activity, as very few I. acuminatus were captured in May and September. However, the proportion of isolated Ophiostomatoid fungi among other fungal isolates increased following maximal activity peaks of I. acuminatus. Further studies regarding seasonal differences of fungal diversity associated with bark beetle I. acuminatus, as well as their role in tree decline in Latvia, are needed. In addition, the pathogenicity of isolated Ophiostomatoid fungi and their ability to cause blue-stain in P. sylvestris timber could be evaluated in future studies.

5. Conclusions

The most frequently isolated fungi from I. acuminatus were the entomopathogenic fungus Akanthomyces muscarius, followed by molds from genus Penicillium, Mucor, Cladosporium, and Ophiostomatoid fungi Leptographium cucullatum, Ophiostoma minus, and Graphilbum acuminatum. There were significant seasonal differences (p < 0.05) observed between months; when I. acuminatus beetles were captured and fungal communities isolated from them, but no significant differences found between different locations and between male and female I. acuminatus (p > 0.05).

Author Contributions

Conceptualization, A.S.; methodology, N.B.; software, N.B. and L.L.; validation, Z.S.; formal analysis, E.G. and B.K.; investigation, S.R. and L.L.; data curation, N.B. and L.L.; writing—original draft preparation, N.B.; writing—review and editing, L.L. and D.K.; visualization, J.L.; supervision, D.K.; project administration, D.K.; funding acquisition, D.K. and A.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research was supported by the National Research Programme “Innovation in Forest Management and Value Chain for Latvia’s Growth: New Forest Services, Products and Technologies (Forest4LV)” (project No. VPP-ZM-VRIIILA-2024/2-0002).

Data Availability Statement

Data are available upon personal request to the corresponding author—sequence data placed in Zenodo Open repository for EU-funded research (https://zenodo.org/communities/eu/, accessed on 26 November 2025).

Acknowledgments

The authors are grateful to Roberts Matisons, Zane Saule, and Luize Elizabete Cerusa for their assistance in the laboratory, field work, and data analysis.

Conflicts of Interest

The authors declare no conflicts of interest.

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Forests 17 00009 g001
Figure 1. Weekly capture of Ips acuminatus per study area, and the number of beetle wing pairs in Garkalne. Week numbers are according to the ISO week date standard (ISO-8601-1:2019) [29].
Figure 1. Weekly capture of Ips acuminatus per study area, and the number of beetle wing pairs in Garkalne. Week numbers are according to the ISO week date standard (ISO-8601-1:2019) [29].
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Figure 2. Ordination diagram based on PCA of fungal communities in male and female Ips acuminatus.
Figure 2. Ordination diagram based on PCA of fungal communities in male and female Ips acuminatus.
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Figure 3. Ordination diagram based on PCA of fungal communities in Ips acuminatus beetles captured in different months.
Figure 3. Ordination diagram based on PCA of fungal communities in Ips acuminatus beetles captured in different months.
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Figure 4. Changes in the composition of different fungal ecological groups during the beetle flying period.
Figure 4. Changes in the composition of different fungal ecological groups during the beetle flying period.
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Table 1. Geographical coordinates of study sites.
Table 1. Geographical coordinates of study sites.
Study AreaTrap SiteLongitudeLatitude
Daugavpils155.9121626.46869
255.9147126.46188
355.9195426.46586
455.9291826.47763
555.9368026.46891
Garkalne157.0353624.42798
257.0456224.49557
357.0607124.42741
457.0484424.40907
557.0032224.32353
Kalsnava156.6787525.84702
256.6715325.84529
356.6725225.86201
456.6779025.89302
Table 2. Fungi isolated from bark beetle Ips acuminatus in Latvia.
Table 2. Fungi isolated from bark beetle Ips acuminatus in Latvia.
Fungal TaxaLocality (% of Beetles Colonized/% Among Isolates)Total (% of All Beetles/% Among All Isolates)
Daugavpils Garkalne Kalsnava
Absidia spp.-2.6/1.01.9/1.42.2/1.0
Akanthomyces muscarius15.0/9.058.5/23.417.9/13.744.4/21.0
Alternaria alternata7.5/4.514.2/5.78.0/6.211.9/5.6
Alternaria infectoria2.5/1.50.3/0.1-0.3/0.2
Armillaria cepistipes--0.6/0.50.2/0.1
Aspergillus spp.2.5/1.50.3/0.11.9/1.40.8/0.4
Aureobasidium pullulans-0.8/0.30.6/0.50.7/0.3
Beauveria bassiana12.5/7.52.3/0.92.5/1.93.1/1.4
Beauveria pseudobassiana-1.5/0.61.2/0.91.4/0.6
Blastobotrys sp. LV59-0.3/0.1-0.2/0.1
Botrytis cinerea-0.3/0.10.6/0.50.3/0.2
Chaetomium madrasense2.5/1.50.3/0.10.6/0.50.5/0.2
Chaetomium subaffine--0.6/0.50.2/0.1
Cladosporium cladosporioides15.0/9.022.2/8.98.0/6.218.8/8.4
Diplodia sapinea-0.3/0.1-0.2/0.1
Epicoccum nigrum-0.8/0.3-0.5/0.2
Fusarium avenaceum-0.5/0.21.2/0.90.7/0.3
Graphilbum acuminatum10.0/6.010.1/4.06.8/5.29.2/4.3
Graphilbum furuicola-0.3/0.10.6/0.50.3/0.2
Leptographium cucullatum12.5/7.524.5/9.88.0/6.219.2/9.1
Leptographium olivaceum-6.4/2.60.6/0.54.4/2.1
Mucor spp.42.5/25.419.3/7.717.9/13.720.5/9.7
Ophiostoma ips10.0/6.09.3/3.70.6/0.56.9/2.3
Ophiostoma macrosporum2.5/1.53.4/1.33.1/2.43.6/1.7
Ophiostoma minus12.5/7.522.9/9.24.9/3.817.3/8.2
Ophiostoma piceae-9.5/3.81.2/0.96.6/3.1
Penicillium spp.20.0/11.934.8/13.937.0/28.434.4/16.3
Pestalotiopsis sp. LV47-0.3/0.1-0.2/0.1
Petriella guttulata-0.5/0.2-0.3/0.2
Pleosporales sp. LV24-0.5/0.2-0.3/0.2
Pyrenophora tetrarrhenae-0.3/0.1-0.2/0.1
Sporothrix pseudoabietina-0.8/0.3-0.5/0.2
Sporothrix sp. LV27--0.6/0.50.2/0.1
Sydowia polyspora-0.3/0.1-0.2/0.1
Trichoderma spp.-1.5/0.63.7/2.82.0/1.0
Cylindromonium lichenicola-0.3/0.1-0.2/0.1
Other information
Bacteria90.090.580.287.6
Number of Ips acuminatus beetles analysed40388162590
Number of traps55414
Number of fungal isolates679692111247
Table 3. The summary statistics of the generalized linear mixed-effects model (GLMM). The estimated Chi-square values and p-values (* >0.05, ** > 0.01, *** > 0.001) for the Ips acuminatus beetle sex and sampling month on the presence of dominant Ophiostomatoid fungi (Ophiostoma minus and Leptographium cucullatum), the variance of the random effects, and the marginal R2 values for the refined model are shown.
Table 3. The summary statistics of the generalized linear mixed-effects model (GLMM). The estimated Chi-square values and p-values (* >0.05, ** > 0.01, *** > 0.001) for the Ips acuminatus beetle sex and sampling month on the presence of dominant Ophiostomatoid fungi (Ophiostoma minus and Leptographium cucullatum), the variance of the random effects, and the marginal R2 values for the refined model are shown.
VariableOphiostoma minusLeptographium cucullatum
Sex of Ips acuminatus4.5 *1.0
Sampling month17.6 **19.6 ***
Random effectsvariance
Trap × Sampling area0.5590.467
Sampling area0.0000.000
Model performance, marginal R20.9080.182
Model performance, conditional R20.92110.284
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Burnevica, N.; Gricjus, E.; Legzdina, L.; Strike, Z.; Krivmane, B.; Rancane, S.; Lekavičs, J.; Smits, A.; Klavina, D. Fungal Diversity Associated with the Sharp-Dentated Bark Beetle Ips acuminatus (Coleoptera: Curculionidae) in Latvia. Forests 2026, 17, 9. https://doi.org/10.3390/f17010009

AMA Style

Burnevica N, Gricjus E, Legzdina L, Strike Z, Krivmane B, Rancane S, Lekavičs J, Smits A, Klavina D. Fungal Diversity Associated with the Sharp-Dentated Bark Beetle Ips acuminatus (Coleoptera: Curculionidae) in Latvia. Forests. 2026; 17(1):9. https://doi.org/10.3390/f17010009

Chicago/Turabian Style

Burnevica, Natalija, Elza Gricjus, Liva Legzdina, Zane Strike, Baiba Krivmane, Selita Rancane, Janis Lekavičs, Agnis Smits, and Darta Klavina. 2026. "Fungal Diversity Associated with the Sharp-Dentated Bark Beetle Ips acuminatus (Coleoptera: Curculionidae) in Latvia" Forests 17, no. 1: 9. https://doi.org/10.3390/f17010009

APA Style

Burnevica, N., Gricjus, E., Legzdina, L., Strike, Z., Krivmane, B., Rancane, S., Lekavičs, J., Smits, A., & Klavina, D. (2026). Fungal Diversity Associated with the Sharp-Dentated Bark Beetle Ips acuminatus (Coleoptera: Curculionidae) in Latvia. Forests, 17(1), 9. https://doi.org/10.3390/f17010009

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