The is insufficient knowledge of arthropod communities occurring in specific microhabitats. In this study, we characterize the arthropod assemblages inhabiting burrows of the common hamster (Cricetus cricetus L.) and factors that determine their diversity and abundance. We tested the following hypotheses: (1) arthropod assemblages are associated with a particular dominant vegetation occurring in the vicinity of burrows; (2) a correlation exists between fine-scale geographic distances among burrows and assemblage dissimilarity; and (3) the type of trap influences the sampling success of captured arthropods. We found 73 morphospecies belonging to 16 families in 109 burrows, most of which were in the families Staphylinidae (Coleoptera) and Parasitidae (Arachnida: Acari: Mesostigmata). The most abundant families were Staphylinidae, Cryptophagidae (Coleoptera), Parasitidae, and Macrochelidae (Mesostigmata) (78.89%). Among the identified species, we found Aleochara irmgardis (Staphylinidae) and Poecilochirus sexclavatus (Parasitidae) which had not yet been reported in Poland, and several other rare species. Meat-baited traps captured 64.34% more individuals, which were more diverse and species-rich than the non-baited control traps, but the former was more selective for saprophages, necrophages, and coprophages. The burrows located in areas overgrown by triticale (a hybrid of wheat and rye) were inhabited by 69.86% of the identified arthropod species, and these also had the highest abundance (64.07%) in comparison with other habitats. However, differences in sample size biased our results toward and overestimate arthropods associated with this vegetation. This study underlines that the species composition detected in burrows was affected by the methods used and hamster preferences for a specific habitat rather than the geographic proximity of the burrows. More extensive sampling across multiple habitats will be necessary to confirm our findings.

Abstract. During a study 20 hydrophilid beetle species and 2,457 individuals of beetles belonging to 4 genera: Cercyon, Cryptopleurum, Megasternum and Sphaeridium were collected. On the surface of the bodies of 59 beetles (2.40% of the beetles collected) belonging to six species, 174 cases of phoresy [55 deutonymphs of Uropoda orbicularis (Müller, 1776) and 119 pedicels without deutonymphs] were observed. New hydrophilid beetle carriers of phoretic deutonymphs of U. orbicularis are given. Most mites were carried by Sphaeridium species. The population dynamics of both groups of arthropods was also studied. Most cases of phoresy were recorded in May and in the second half of July. However, phoretic deutonymphs were not present on the body surface of hydrophilid beetles throughout the whole period of this study.

The aim of our study was to determine the limit of a beetle’s body size below which it is not able to carry phoretic mites. We tested the hypothesis that body size of the carrier is the vital factor in selecting a host in mites with facultative and nonspecific phoresy. The study was conducted on beetles of the family Hydrophilidae and deutonymphs of the mite Uropoda orbicularis (Müller, 1776). Among 20 species of hydrophilids collected, only 7 carried deutonymphs. The smallest hydrophilids with body lengths below 2.32 mm did not carry deutonymphs. These were Cercyon analis (Paykull, 1798), Cercyon nigriceps (Marsham, 1802), Cercyon pygmaeus (Illiger, 1801), Cercyon terminatus (Marsham, 1802), Cryptopleurum crenatum (Kugelann, 1794), Cryptopleurum minutum (Fabricius, 1775), Cryptopleurum subtile Sharp, 1884, and Megasternum concinnum (Marsham, 1802). On the contrary, the largest beetles, of the genus Sphaeridium Fabricius, 1775, were most heavily and frequently occupied by phoretic deutonymphs. Most representatives of the genus Cercyon Leach, 1817 did not carry mites or had a very low mite burden. Our study indicates that beetle infestation by nonspecific phoretic mites is strongly influenced by beetle body size.

The paper presents new data on the occurrence of 69 beetle species collected in 2017 in the Białowieża Forest, NE Poland. The list contains representatives of 27 families: Anthribidae, Bostrichidae, Ciidae, Cleridae, Coccinellidae, Corylophidae, Cryptophagidae, Curculionidae, Dasytidae, Elateridae, Endomychidae, Eucnemidae, Histeridae, Laemophloeidae, Latridiidae, Leiodidae, Lycidae, Melandryidae, Mycetophagidae, Ptinidae, Ripiphoridae, Salpingidae, Staphylinidae, Tenebrionidae, Tetratomidae, Throscidae, and Zopheridae. The majority of the species represents saproxylic, i.e. dead wood-dependent, beetles. Biology and distribution of some rarely recorded species are briefly discussed. All species are reported for the first time from the Białowieża Forest and, furthermore, Corticaria crenicollis Mannerheim, 1844 (Latridiidae) is new for the fauna of Poland.

A fine‐scale spatial genetic structure is rarely analysed within insect populations, although such a structure influences the level of inbreeding and kin dynamics and can have implications for long‐term population persistence. A high level of genetic structure is expected in a divided population of the hermit beetle Osmoderma barnabita due to its philopatry and habitat loss/fragmentation. To assess the variability and population genetic structure, sex contributions to genetic variation, and gene flow, the beetles were collected in a fragmented forest (2920 ha) employing sex pheromone‐baited traps, georeferenced, and morphologically identified to species and sex; 187 sampled specimens were then evaluated using 10 microsatellite loci. Based on our data, the population as a whole is characterised by low genetic diversity (He = 0.34) and a high level of inbreeding (FiAvg. = 0.31). Nevertheless, the level of differentiation between field subpopulations is low, indicating a high level of gene flow (a patchy model). This was evidenced by small pairwise FST estimates and slight differences in Ho, He, and allelic richness, a lack of well‐defined boundaries between subpopulations, and relatively low relatedness among neighbouring female and male dyads. Sex‐biased gene flow was evidenced from the analysis of isolation by distance (regression relatedness) but not from assignment tests. Mating between close kin and recent colonisation from a small source are presented as a possible explanation for high inbreeding, low genetic diversity, and minimal population structure. Still, additional evidence is required to support this hypothesis. The results suggest that the population can be treated as a single management unit.