Bory Tucholskie National Park, founded in 1996, is one of the most recently established national parks in Poland, and therefore, has not been thoroughly examined yet. The authors of the current study present results of their research concerning communities of mites from the suborder Uropodina (Acari: Mesostigmata), inhabiting bird nesting boxes within the area of Bory Tucholskie National Park. The mite community comprises two nidicolous species, i.e. Leiodinychus orbicularis (C.L. Koch, 1839) and Chiropturopoda nidiphila (Wiśniewski and Hirschmann 1993). The former is a species characteristic of various types of nests, as well as nesting boxes, where it is usually the eudominant species. The latter is an extremely rare and scarce species of Uropodina, known thus far from woodpeckers’ hollows. The population of L. orbicularis in the analysed communities in the realm of Bory Tucholskie National Park has been estimated to be over 6,000 specimens, and in the case of Ch. nidiphila - over 400 specimens.

Bird and mammal nests and nest boxes constitute microenvironments in which various groups of invertebrates can live, including mites from the suborder Uropodina (Acari: Mesostigmata). The main aim of the current study was to ascertain the characteristics of mite communities from the suborder Uropodina, which inhabit the nests of dormice (Gliridae) built in nest boxes. The second aim of the study was to compare the habitat preferences of Leiodinychus orbicularis (C. L. Koch) and Apionoseius infirmus (Berlese), i.e., two typically nest-dwelling species of Uropodina. The material for the study was collected from nest boxes in six forest complexes in southwestern Poland. The conducted research revealed the presence of five species of Uropodina, with a total number of 559 specimens, in the examined boxes. Leiodinychus orbicularis was found in almost half of all of the examined boxes and was a superdominant species in the communities. The analysis of the habitat preferences of the two nest species of Uropodina showed that A. infirmus preferred old natural nests, in which the communities were formed from a larger number of species, without a significant statistical prevalence of one species. On the other hand, L. orbicularis occurred sporadically in open bird nests, but was very numerous and frequent in nest boxes. The significant dominance of L. orbicularis in nest boxes can probably be explained by the specific conditions prevailing in this type of microhabitat, including the very low humidity and food resources that this mite species prefers compared to other species of Uropodina.

A new nature reserve called Czarne Doły, established in 2022 in Wielkopolska (Greater Poland), was intended to protect the European pond turtle (Emys orbicularis (L)). This fact became an inspiration to initiate long-term monitoring research studies on soil mite communities. The planned studies are aimed to ascertain how the legal protection of this area will affect the biodiversity of acarofauna in the future, that is, whether the European pond turtle can be an umbrella species for soil mites. For the purpose of this research, 85 samples from soil and dead wood were collected in the area of the reserve in 2023 and 2024. The mite groups selected for the studies are species from the following orders: Prostigmata (family Labidostommidae), Oribatida (ptyctimous mites, family Nothridae, family Camisiidae), Mesostigmata (suborders Uropodina and Sejina). In the collected samples, a total of 40 mite species were identified, of which 14 new species were found in the second phase of the study. Among the found species, many common soil species occurring all over the country predominated, with a high percentage of the eurytopic species of Uropodina, such as Oodinychus ovalis (C. L. Koch, 1839), and synanthropic - Oodinychus karawaiewi (Berlese, 1904). It is expected that the percentage the latter species should decrease over time as the area is protected. In addition, specimens of two rare species were also recorded in one of the examined sites, i.e. Dinychus septentrionalis (Trägårdh, 1943) and Labidostomma luteum Kramer, 1889. It is planned to conduct regular observations every five years in order to ascertain the changes in communities of soil mites in this area.

Genetic rescue (GR) can restore fitness in small genetically depauperate populations, however, long-term effectiveness, impact of rescuer quality and introduced deleterious load on population persistence remains uncertain. Using a male-dimorphic mite we tested whether a condition-dependent sexually selected trait influences GR. Genome-wide diversity and genetic load increased similarly for both morphs, while population fitness trajectories differed, suggesting that genetic quality is associated with the trait. Overall, GR sustained fitness benefits over 20 generations. The benefits persisted under thermal stress lowering extinction risk regardless of the rescuer’s morph and introduced load indicating their minimal importance. These results provide experimental evidence that maximising genome-wide variation via GR can yield lasting benefits, even when many deleterious mutations are introduced to populations facing environmental change.

One of the key criteria used by the IUCN to assess species threat status is the extent of occurrence. Evaluating the true rarity of soil mesofauna, particularly mites, remains a major challenge in biodiversity research. In the suborder Uropodina, which includes numerous stenotopic species characterized by strong habitat selectivity, limited exploration of specific microhabitats may lead to underestimation of their actual distribution and abundance. As a result, species regarded as rare may represent habitat specialists occurring more frequently than current records suggest. The aim of this study was to analyze mite assemblages inhabiting nests of Lasius umbratus and to assess the significance of this microhabitat for species of the genus Oplitis, focusing on Oplitis franzi. The hypothesis that the apparent rarity of selected Uropodina species results from microhabitat specialization and association with a specific carrier was tested. Material was collected from nests of Lasius umbratus at three sites in western Poland (Bydgoszcz, Dabrówka, Krzesiny), representing an urban park, a semi-natural park, and a roadside tree site. Mites were extracted using Tullgren funnels and identified morphologically under an Olympus BX53 microscope with Nomarski contrast. Species composition and population structure within the studied microhabitats were analyzed. Numerous populations of Oplitis franzi were recorded at all sites. This species had previously been regarded as rare and was known only from isolated records in Spain, Poland, Slovakia, and Switzerland, with only females described in the literature. In the examined nests, individuals of both sexes and various developmental stages were found, indicating stable, reproducing populations associated with this microhabitat. Adult mites occurred both freely within the nest material and attached to the tibial spurs of Lasius umbratus workers, demonstrating a specialized dispersal strategy and close ecological association with the carrier. The findings indicate that the assumed rarity of this species resulted from incidental sampling outside its primary habitat and the lack of targeted studies focusing on this microhabitat. The analysis confirms that microhabitats such as ant nests (and other merocenoses) may represent important centers of biodiversity and play a key role in maintaining local invertebrate diversity. The study highlights the importance of precise microhabitat selection in mesofauna research for reliable assessments of species distribution, abundance, and conservation status.