This paper presents an annotated checklist of 77 species of ectoparasitic mites, ticks (Acari: Trombidiformes, Mesostigmata, Ixodida) and insects (Insecta: Psocodea, Siphonaptera) found on ground-dwelling small mammals in the Baltic States (Estonia, Latvia, Lithuania). Eight species of five genera of chigger mites (Trombidiformes: Trombiculidae), 26 species of eight genera of laelapid mites (Mesostigmata: Laelapidae), six species of two genera of ixodid ticks (Ixodida: Ixodidae), 11 species of three genera of blood-sucking lice (Psocodea: Hoplopleuridae, Pediculidae, Polyplacidae) and 26 species of 15 genera of fleas (Siphonaptera: Ceratophyllidae, Ctenophthalmidae, Hystrichopsyllidae, Pulicidae) were recorded on ground-dwelling small mammals in the Baltic States. Neotrombicula japonica (Tanaka, Kaiwa, Teramura & Kagaya), Neotrombicula vulgaris (Schluger), Miyatrombicula muris (Oudemans), Hoplopleura edentula Fahrenholz and Polyplax hannswrangeli Eichler are recorded for the first time in the Baltic States.

The genus Sarcocystis is an abundant group of Apicomplexa parasites found in mammals, birds, and reptiles. These parasites are characterised by the formation of sarcocysts in the muscles of intermediate hosts and the development of sporocysts in the intestines of definitive hosts. The identification of Sarcocystis spp. is usually carried out in carcasses of animals, while there is a lack of studies on the detection of Sarcocystis species in blood samples. In the current study, blood samples of 214 yellow-necked mice (Apodemus flavicollis) and 143 bank voles (Clethrionomys glareolus) from Lithuania were examined for Sarcocystis. The molecular identification of Sarcocystis was carried out using nested PCR of cox1 and 28S rRNA and subsequent sequencing. Sarcocystis spp. were statistically (p < 0.01) more frequently detected in the bank vole (6.3%) than in yellow-necked mice (0.9%). The analysed parasites were observed in four different habitats, such as mature deciduous forest, bog, natural meadow, and arable land. Three species, Sarcocystis funereus, Sarcocystis myodes, and Sarcocystis cf. glareoli were confirmed in the bank vole, whereas only Sarcocystis myodes were found in yellow-necked mice. The obtained results are important in the development of molecular identification of Sarcocystis parasites in live animals.

Family Laelapidae is an ecologically diverse group that includes free-living species and parasites of vertebrates and invertebrates. At least seven genera in this family are associated with small mammals. In this study, ectoparasitic laelapid mites of rodents and shrews were investigated in Lithuania. In total, 2,274 small mammal specimens of 12 species were trapped and 6,089 laelapid mites were collected. The updated list of ectoparasitic mites in Lithuania included 21 mite species. Seven mite species were identified as highly specific for a host species or genus, one species was moderately specific, and four mite species were assigned to generalist parasites. All host species had one or two superdominant mite species. The prevalence and mean intensity varied significantly depending on host species and habitat. We analyzed the influence of the host (species, sex, age) and environmental factors (landscape morphology type, habitat, anthropogenic effect) on the abundance of the mite community and most numerous mite species, as well as the impact of the host community (Shannon's diversity index, species richness, host abundance) on mean abundance of the mite community. Only particular host species (Apodemus flavicollis, Microtus agrestis, and Microtus arvalis) and habitats (pastures, mixed forests) influenced the abundance of mites.

KELVEG – Roadside Vegetation of Lithuania (GIVD EU-LT-002) is a database that documents the diversity of roadside vegetation, tracks and monitors changes of non-native species’ impact on the roadsides, and adjacent habitats. The initiative was started in spring 2023. As of March 2025, 628 vegetation plots from randomly selected sites across the country have been included in the database. Vegetation plots were sampled along transects, starting at the edge of the roadside (road shoulder) and ending in an adjacent habitat. In each roadside part (road shoulder, first slope, second slope or flat part and adjacent habitat), 1 m² square-shaped vegetation plots were taken. Additionally, 100 m² square-shaped vegetation plots were sampled in adjacent habitats. In each vegetation plot, the cover of vascular plants and bryophytes was estimated using a percentage scale, and the cover and height of vegetation layers were measured. The aspect and inclination of slopes were measured using electronic compass and clinometer mobile applications, respectively. In each vegetation plot, soil samples were collected, and agrochemical analysis was performed to evaluate soil/substrate pH, the concentration of total nitrogen, humus, phosphate and potassium oxide, and microbiological activity. The data are available to potential users upon request from the corresponding author.

The main objective of the dissertation was to investigate the diversity of small mammal blood protozoans and ectoparasites, as well as to evaluate the influence of host, environment and co-infection factors on blood protozoan, gastrointestinal helminth and ectoparasite communities. During the research, we investigated the diversity of blood protozoans and ectoparasites, evaluated host specificity and ectoparasite dominance. Six ectoparasite and two blood protozoan species, as well as protozoans of one genus not identified to species were registered in Lithuania for the first time. The prevalence and mean intensity of parasites of thirteen orders significantly differed among host species and among habitats. Significant differences in seasonal dynamics were recorded for parasites of seven orders. Climatic conditions influenced seasonal dynamics of parasites of six orders. Non-random co-occurrence patterns (positive and negative) were registered among parasites of all orders. A comprehensive analysis of multiple host, environment, and co-infection factors was performed for the first time. Parasites of different orders were affected by two to eight factors (from 18 possible). Host species, habitat, and air temperature influenced parasite communities the most often.