Not Only Leptotrombidium spp. an Annotated Checklist of Chigger Mites (Actinotrichida: Trombiculidae) Associated with Bacterial Pathogens

Bat ectoparasites: chigger mites (Trombiculidae), ticks (Ixodidae and Argasidae), and bugs (Cimicidae) in the Eastern Palaearctic

Nine species-level taxa of bat ectoparasites, three chigger mites (Trombiculidae), three hard (Ixodidae), and one soft tick (Argasidae) species, as well as two bug (Cimicidae) species from nine bat species hosts were detected in the Eastern Palaearctic. Trombiculid larvae of Leptotrombidium schlugerae, Leptotrombidium album, and Ascoschoengastia latyshevi were first recorded on bats in the temperate zone of eastern Russia. L. schlugerae was more abundant than A. latyshevi in the same study sites in Eastern Siberia, and the main hosts of both chigger species were Plecotus ognevi and Eptesicus nilssonii. Ixodid ticks Dermacentor marginatus, Ixodes simplex, and Ixodes sp. were sampled from bats in Kazakhstan, the Far East, and Eastern Siberia, respectively. Phylogenetic analysis based on Cox1, 16S rDNA, and ITS2 sequences of I. simplex showed that the specimens from the Far East grouped into a clade distributed in the Eastern Palaearctic and India. In turn, the specimen of Ixodes sp. from Eastern Siberia was most closely related to Ixodes soricis and Ixodes angustus with p-distance of 9.8-10.7% (Cox1), suggesting that this tick probably belongs to a new species. Argas vespertilionis larvae were collected from three widespread bat species in Kazakhstan. Two bug species, Cimex pipistrelli and Cimex aff. lectularius, were recorded in the Far East and Eastern Siberia, respectively. Specimens from Transbaikalia were morphologically identified as Cimex lectularius. However, they differed from the latter by 12.5-12.9% of Cox1 sequences, indicating that C. aff. lectularius may be a new species.

The chigger microbiome: big questions in a tiny world

'Chiggers' (trombiculid mite larvae) are best known as vectors of rickettsial pathogens, Orientia spp., which cause a zoonosis, scrub typhus. However, several other pathogens (e.g., Hantaan orthohantavirus, Dabie bandavirus, Anaplasma spp., Bartonella spp., Borrelia spp., and Rickettsia spp.) and bacterial symbionts (e.g., Cardinium, Rickettsiella, and Wolbachia) are being reported from chiggers with increasing frequency. Here, we explore the surprisingly diverse chigger microbiota and potential interactions within this microcosm. Key conclusions include a possible role for chiggers as vectors of viral diseases; the dominance in some chigger populations of unidentified symbionts in several bacterial families; and increasing evidence for vertical transmission of potential pathogens and symbiotic bacteria in chiggers, suggesting intimate interactions and not simply incidental acquisition of bacteria from the environment or host.

Forest Matters Most for Hirsutiella zachvatkini (Schluger, 1948): A Survey of Rodent Infestation in Four Localities within the Mazury Lake District, NE Poland

The family Trombiculidae encompasses numerous and widespread mites, the larvae of which are obligatory parasites of vertebrates. Our research objective was to assess how trombiculid burdens on rodents inhabiting three forested and one open area in NE Poland vary in relation to host identity, sex and body size, and how they are influenced by qualities of the habitat. Trapped rodents (n = 240) were measured, weighted and screened for ectoparasites. Apodemus flavicollis (n = 42) and Myodes glareolus (n = 173) harbored a total of 4652 Hirsutiella zachchvatkini larvae. Statistical tests revealed that both prevalence and abundance were significantly higher in voles (93%, 27 larvae/ind.) than in mice (14%, 0.24 larvae/ind.) but there was no effect of host sex. Among the localities, H. zachvatkini was most prevalent (98%) and abundant (41 larvae/ind.) in rodents from the deciduous mixed forest in Tałty compared to fallow land (2.6%, 0.13 larvae/ind.). The highest prevalence and abundance were found in bank voles; in this host species in Tałty, prevalence reached 100% and the mean abundance was >42 larvae/ind. Significant positive correlations were found between the body mass and body length of voles and the number of attached larvae. Our results confirm the sylvan nature of H. zachvatkini and its preference for bank voles inhabiting deciduous forests with rich and humid undergrowth. The lack of a sex bias and the moderate correlation between mite burden and host size are in line with observations already made on other rodent-associated Trombiculidae.