Communities of Uropodina (Acari: Mesostigmata) in Nest Boxes Inhabited by Dormice (Glis glis and Muscardinus avellanarius) and Differences in Percentages of Nidicoles in Nests of Various Hosts

SIMPLE SUMMARY: Hanging nest boxes, which are used by various groups of animals such as birds or mammals (e.g., dormice and bats), increase the number of shelters and breeding places for these often rare animals. Nest boxes not only become habitats for the host, but are also inhabited by various groups of invertebrates, including insects, spiders, millipedes, snails, and also small arachnids, which are mites. In this article, we present an analysis of the community of one of the groups of mites—Uropodina—which also inhabit nest boxes. In the examined boxes, five species belonging to the discussed group were found, out of which only one (Leiodinychus orbicularis) is a nidicole, i.e., a species that inhabits the nests of various animals. This article also analyses the habitat preferences of the mentioned species and another Uropodina species associated with nests—Apionoseius infirmus. It was proven that L. orbicularis clearly dominated both in the examined dormouse, bat, and bird boxes, whereas A. infirmus, which was less numerous in the communities, preferred natural nests, including the nests of birds of prey. The clear dominance of L. orbicularis in the examined boxes can be explained by the specific microclimate, such as very low humidity, which prevails in the boxes. ABSTRACT: 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.