Filamentous Fungi and Yeasts Associated with Mites Phoretic on Ips typographus in Eastern Finland

Abstract

The European spruce bark beetle (Ips typographus) has become a major forest pest in Finland in recent years. The beetle is a well-known vector of mainly ophiostomatoid fungi causing blue-stain of timber and pathogens that have the ability to amplify the insect damage. It also vectors other associated organisms, such as phoretic mites. The ecology of these mites remains poorly understood, including their associations with fungi. In this study, we considered filamentous fungi and yeasts associated with mites phoretic on I. typographus. Fungal identifications were based on DNA sequences and phylogenetic analyses of the ITS and/or partial β-tubulin gene regions. Fifteen fungal species were detected, including eight yeasts and seven filamentous fungi. Eleven percent of the beetles carried mites and of these 74% carried at least one fungal species. An average of two fungal species were carried per mite. The most commonly found filamentous fungi were Grosmannia penicillata (25%), Ophiostoma bicolor (19%), O. ainoae (12%) and O. brunneolum (12%). Of the yeast species, the most commonly found was Wickerhamomyces bisporus (47%). This study is the first to report yeasts associated with I. typographus and its phoretic mites in Finland. Majority of the filamentous fungal species found are those previously reported in association with I. typographus. The results also confirmed that many of the fungal species commonly found on I. typographus are also associated with its phoretic mites. However, the nature of the symbiosis between the mites, beetles and fungal associates remains to be understood.

The core gut microbiome changes throughout life cycle and season of bark beetle Ips typographus

“…Meyerozyma guilliermondii was captured by us only from cultivation and it was also recorded in the microbiome of ambrosia beetle Platypus koryoensis (Yun et al 2015), where also its enzymatic capability of plant tissue degradation was detected.Wickerhamomyces bisporus was previously found in association withI. typographus (Giordano et al 2012) and is also the dominant yeast species found on phoretic mites of the same beetle species (Linnakoski et al, 2021). Species of Wickerhamomyces have been also reported from galleries and guts of wood-boring insects (Hui et al 2013;Ninomiya et al 2013), indicating their common association with beetles.…”

Fungal Communities Associated with Siricid Wood Wasps: Focus on Sirex juvencus, Urocerus gigas, and Tremex fuscicornis

“…Several species of yeasts (e.g., Kuraishia molischiana (0.42%), Wickerhamomyces bisporus (0.22%)) were also detected, which were previously shown to be associated with different bark beetles such as Ips typographus or Dendroctonus sp. [53][54][55][56].…”

Ophiostomatoid fungi synergize attraction of the Eurasian spruce bark beetle, Ips typographus to its aggregation pheromone in field traps

“…We acknowledge the limitations of testing pure single-species cultures under field conditions. In the breeding galleries constructed by the beetles, several closely related species of ophiostomatoid fungi and yeasts co-inhabit the phloem of the bark ( Giordano et al, 2013 ; Linnakoski et al, 2021 ). Therefore, one approach would be to analyze mixed microbial cultures in their natural growth substrates together with pheromones in field traps.…”