Saproxylic beetles play a crucial role in key processes occurring in forest ecosystems, and together with fungi contribute to the decomposition and mineralization of wood. Among this group are mycetophilic beetles which associate with wood-decaying fungi and use the fruiting body for nourishment and development. Therefore, their feeding strategy (especially in the case of fungivorous species) requires special digestive capabilities to take advantage of the nutritional value of fungal tissue. Although polypore-beetle associations have been investigated in numerous studies, detailed studies focusing on the microbiome associated with species feeding on fruiting bodies of polypores remain limited. Here we investigated the bacterial communities associated with larvae and adults ofBolitophagus reticulatuscollected fromFomes fomentariusgrowing on two different host tree: beech (Fagussp.) and birch (Betulasp.), respectively. Among 24 identified bacterial phyla, three were the most relatively abundant (Proteobacteria, Actinobacteria and Bacteroidetes). Moreover, we tried to find unique patterns of bacteria abundances which could be correlated with the long-term field observation showing that the fruiting bodies ofF. fomentarius,growing on birch are more inhabited by beetles than fruiting bodies of the same fungus species growing on beech. Biochemical analyses showed that the level of protease inhibitors and secondary metabolites inF. fomentariusis higher in healthy fruiting bodies than in the inhabited ones. However, tested microbiome samples primarily clustered by developmental stage ofB. reticulatusand host tree did not appear to impact the taxonomic distribution of the communities. This observation was supported by statistical analyses.

Detailed external structures of mature larvae of two subcortical species, Nudobius lentus (Gravenhorst) and Gabrius splendidulus (Gravenhorst), are re-described and illustrated based on light and scanning electron microscopy. A combination of characters to distinguish the mature larvae from those of other genera within the tribe Xantholinini for N. lentus, and the subtribe Philonthina for G. splendidulus is presented. Diagnostic larval characters to identify species and genera are given.

Formica polyctena belongs to the red wood ant species group. Its nests provide a stable, food rich, and temperature and humidity controlled environment, utilized by a wide range of species, called myrmecophiles. Here, we used the high-throughput sequencing of the 16S rRNA gene on the Illumina platform for identification of the microbiome profiles of six selected myrmecophilous beetles (Dendrophilus pygmaeus, Leptacinus formicetorum, Monotoma angusticollis, Myrmechixenus subterraneus, Ptenidium formicetorum and Thiasophila angulata) and their host F. polyctena. Analyzed bacterial communities consisted of a total of 23 phyla, among which Proteobacteria, Actinobacteria, and Firmicutes were the most abundant. Two known endosymbionts—Wolbachia and Rickettsia—were found in the analyzed microbiome profiles and Wolbachia was dominant in bacterial communities associated with F. polyctena, M. subterraneus, L. formicetorum and P. formicetorum (>90% of reads). In turn, M. angusticollis was co-infected with both Wolbachia and Rickettsia, while in the microbiome of T. angulata, the dominance of Rickettsia has been observed. The relationships among the microbiome profiles were complex, and no relative abundance pattern common to all myrmecophilous beetles tested was observed. However, some subtle, species-specific patterns have been observed for bacterial communities associated with D. pygmaeus, M. angusticollis, and T. angulata.

Recent years have witnessed a fall in the numbers of bee colonies worldwide. To a large extent, this is due to diseases affecting honeybees. One such disease is nosemosis, which is caused by fungi from the genus Nosema. The antibiotic fumagallin used to be administered to treat nosemosis, but as it was found capable of being transferred to bee products, this practice has ceased. We therefore focused on natural substances for treating this disease, among them, aqueous extracts of the nest carton produced by the jet-black ant (Lasius fuliginosus). We tested the influence of 0.1% and 1% concentrations of such extracts on the incidence of nosemosis in honeybees. The “birch carton 2” extract turned out to be the most effective inhibitor of this disease. The incidence of nosemosis following the administration of this extract, as manifested by the number of spores, fell ca 18-fold in comparison with the control. Moreover, the “birch carton 2” extract was not found to be toxic towards bees. GA

The mature larva and pupa of Neomida haemorrhoidalis are described and illustrated for the first time. The mature larva of Bolitophagus reticulatus is completely redescribed and illustrated, and its pupa is described for the first time. The differential diagnosis of the two species is presented. Information about their biology and life history is also given.

This study summarises information on the occurrence of Myrmecophilus acervorum in Poland in the years 1851–2022. We collected information about 143 localities: 40 from literature and 103 unpublished. Myrmecophilus acervorum is reported from seven new regions: the Baltic Coast, Białowieża Primeval Forest, Eastern Sudety Mts, Kraków-Wieluń Upland, Podlasie Lowland, Sandomierska Lowland and Trzebnickie Hills. While until 2010 observations were rare (35 localities), in the years 2011–2022 the species was found in 108 new localities. A total of 443 individuals of M. acervorum were observed in Poland, but the sex was identified only for 138, of which 135 were mature females or female nymphs. Males were recorded only historically in the Pomeranian Lakeland. At present, these records should be treated with caution, as they are uncertain.