Abstract

Pine bark beetles are typically associated with complexes of fungi that could reveal different functional interaction. Thus, previously nonaggressive bark beetle Ips acuminatus is considering now to be among the most serious pests of pine forest in Ukraine and other European countries and vectored fungal community is very important to assess total harm of this bark beetle. The aim of this study was to reveal the vectored fungal community associated with the pine engraver beetle, I. acuminatus with special emphasis on pathogenic fungi for further evaluation of harm bark-beetle - fungi association for Ukrainian forest.
 In total, 288 adult beetles were collected from Scots pine trees at six different sites through Ukraine. DNA sequencing as fungal culturing from all beetles resulted in 1681 isolates and amplicons representing 42 fungal taxa. NCBI BLAST search revealed that the overall fungal community was composed of 94 species, of which 80.85% were Ascomycota, followed by Basidiomycota and unidentified fungal group, which accounted for 10.6% and 8.5 % of the total sequences, respectively. Among these, the most commonly detected fungi for pooling dataset were Sphaeropsis sapinea (23.6%), Cladosporium pini-ponderosae (19.44%), Ophiostoma ips (19.1%), Ophiostoma canum (19.1%) and Cladobotryum mycophilum (18.06%). In the pooled dataset of isolates and amplicons for each site, Shannon diversity indices ranged between 1.9 and 2.9 while Simpson diversity index varied between 0.69 and 0.89 indicating rich species diversity.
 In total twelve ophiostomatoid species were detected. All ophiostomatoid fungi were showing varying degrees of virulence and O. minus was the most aggressive fungus in previous studies. It is concluded that I. acuminatus vectors a species-rich fungal community including pathogens such as ophiostomatoid fungi, Sphaeropsis sapinea, different needle pathogens and wood decay fungi that seems to be very important for the assessment of threat of I. acuminatus to the pine forest in Ukraine.

Highlights

  • Bark beetle species (Coleoptera: Scolytinae) that colonize trees from the Pinaceae family are economically and ecologically important forest insects, and high-density outbreaks can devastate1, both managed and natural forests

  • General conclusions that can be taken from our study range different topics which go from the widely discussed role of associated fungi in bark beetles host establishment (Six, 2012, Villari, 2012), to the attempts in understanding ecology and population dynamics of a forest-damaging species as Ips acuminatus

  • I. acuminatus is vector for species-rich fungal community, which was generally dominated by tree pathogens

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Summary

Introduction

Bark beetle species (Coleoptera: Scolytinae) that colonize trees from the Pinaceae family are economically and ecologically important forest insects, and high-density outbreaks can devastate1, both managed and natural forests. Bark beetles are often divided into notional clusters: aggressive and nonaggressive beetles (Krokene & Solheim, 1998), both climate changes and humans have been. Proceedings of the forestry academy of sciences of Ukraine, 2019, vol 18 bringing about unprecedented changes to environments worldwide result in the shift in classical aggressive interactions among certain pests and tree species to less or nonaggressive and vice versa. Nonaggressive beetles occupy weakened, dying-up, or dead trees, but under certain conditions, populations of these nonaggressive beetles can cause massive outbreaks, killing healthy trees (Alamouti et al, 2007). Aggressive beetles are well-known to attack, and even kill healthy trees, the majority of bark beetles occupy only dying or very weakened trees (Krokene & Solheim, 1998)

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