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Molecular examination of representatives of Balaustium from several populations in SW Poland, performed using the sequence data from the mitochondrial cytochrome c oxidase subunit I, confirmed their common specific affiliation and identity with Balaustium murorum. The potential presence of distinct species in the studied material, preliminarily inferred from the discovery of clusters as a result of Principal Component Analysis exploring the metric data sets, was rejected due to the finding of only one haplotype, at intra- and inter-population sampling. An insight into meristic traits in larvae, focused on chaetotaxy of legs, revealed wider variation than hitherto recognized for the species. The variation was higher in laboratory-reared larvae compared to field-collected ones. The overall deviations from the mean character values at intra- and interpopulation levels, higher than hitherto observed for the species, vote for the reappraisal of the criteria adopted for discrimination of members of Balaustium with the application of an integrative approach., (© 2023. The Author(s).)

Trombiculid mites were collected from the edible dormouse (Glis glis) within the Carpathian-Balkan distribution gradient of host species. Representatives of five genera (Leptotrombidium, Neotrombicula, Brunehaldia, Hirsutiella, Schoutedenichia) and 10 species of chiggers were discovered in the material, based on morphological and/or molecular data. Brunehaldia, new to the fauna of Greece, was recorded for the first time from the edible dormouse. Neotrombicula talmiensis was new to the fauna of Greece and Neotrombicula vulgaris was new to the fauna of North Macedonia. Successful amplification and sequencing of COI was carried out in relation to three genera and six species. The intraspecific variation of taxa hitherto distinguished based on morphological criteria was juxtaposed with molecular data, using the distance method and the phylogenetic approach. The molecular methods indicated wider than hitherto recognized, intraspecific morphological variation for Leptotrombidium europaeum and N. talmiensis. On the other hand, an inference limited to morphology proved to be insufficient for species delineation, which was confirmed by the relatively low identity (%) of examined COI sequences as well as the size of inter-/intraspecific K2P distance threshold. Our study provides support for integrative taxonomy that combines different sources of evidence and contributes to recognition of the scope of intraspecific variation. The high degree of hidden diversity revealed with the application of molecular tools, votes for a careful approach to the identification of chiggers. The confirmed cases of co-invasion, including the representatives of various genera (Leptotrombidium and Neotrombicula, Brunehaldia and Neotrombicula, Neotrombicula and Schoutedenichia, Hirsutiella and Schoutedenichia) additionally support the need to include all larvae found on a given host specimen in the identification process., (© 2023. The Author(s).)

The study aims to ascertain the diversity of trombiculid species associated with Chiroptera in Poland, and for the first time in the case of research on Central European Trombiculidae, we use both DNA and morphology in an integrative taxonomic approach to determine species identities of trombiculids. The research was carried out from 2015 to 2019. In total, 2725 larvae were collected from 300 specimens of bats belonging to 11 species. Deutonymphs were obtained through laboratory rearing of larvae; few larvae and deutonymphs were collected also from bats' daily roosts. The presence of trombiculid larvae on hosts was observed between July and April of the following year, with the highest numbers recorded in autumn, during bat swarming. Male bats were infested more often than females (16.4 vs. 6.6%). The highest infestation rate was recorded for Barbastella barbastellus, Myotis nattereri and Plecotus auritus, and the highest prevalence of chiggers (> 30%) for Myotis bechsteinii and P. auritus. The larvae found on bats occupied the areas with free access to the host's skin: auricles, tragus, and snout. Morphological identification of specimens to the species level was hindered by the mosaic distribution of diagnostic traits. Morphological analyses indicated the presence of Leptotrombidium russicum and Leptotrombidium spp. in the examined material, whereas molecular analyses additionally suggested three other potential species assigned to the same genus based on the assessed scope of intrageneric variation (ASAP method). We argue that the identification of the parasitic larvae (chiggers) using morphological characters does not address the question of actual species boundaries, which, in turn, affects the inferences about host specificity and host range., (© 2021. The Author(s).)

Tyrophagus putrescentiae (Schrank), commonly known as the cereal mite, cheese mite, or ham mite, is a cosmopolitan species reported from various environments in the wild, including soil, plant material and vertebrate nests. It has also been recognized as a common pest of food storages, mycological collections as well as plant and invertebrate laboratory cultures. Laboratory observations indicate that T. putrescentiae feeds on a large range of dermatophytes, yeasts and molds. We have observed the interspecific relation between this mite and several species of true slime molds (Mycetozoa) under laboratory conditions, which confirms the very broad spectrum of feeding habits of T. putrescentiae. Mycetozoans were grown in semi-sterile in vitro cultures and fed with oat flour or oat flakes. Tyrophagus putrescentiae displayed affinity to all macroscopically identifiable stages of the life cycle of Fuligo septica (L.) F.H. Wigg, Physarum polycephalum Schwein and the Didymium sp. complex [Didymium iridis (Ditmar) Fr., Didymium nigripes (Link) Fr. and Didymium bahiense Gottsb.]: live, decaying or dead plasmodia, sporangia, aethalia, spores and sclerotia. The relation carrying symptoms of various types of interspecific interaction, is hypothesized to form an evolutionarily young phenomenon, which not only identifies a new aspect of mycetozoal biology, but also presents the cereal mite as a species of high adaptive potential.

The morphology and formation of stylostomes (feeding tubes) in hosts' body during the parasitic phase of Allothrombium fuliginosum (Hermann) larvae were studied for the first time with light microscopy (LM) and transmission electron microscopy (TEM). The stylostomes were observed in three aphids species-Acyrthosiphon pisum (Harris), Elatobium abietinum (Walker), and Macrosiphum rosae (L.)-parasitized by mites under laboratory conditions. They consisted of 2-6 main branches, preliminarily unbranched, then producing secondary and sometimes also tertiary branches as finally formed structures. Their walls were uniformly electron-dense, without any longitudinal and transverse stratifications and showed rather irregular outlines. Distally, the stylostome branches revealed transparent pores and cavities in their walls, connecting the stylostome canal with surrounding haemocoelic space. The total length of stylostomes at the end of the parasitic phase was on average 16× greater than that recorded in the youngest stylostomes. No differences in the overall shape of feeding tubes between host species were stated. The stylostomes formed in different host species did not differ significantly, except their total length, which attained the highest value in tissues of Ac. pisum.

Morphology-based identification of Allothrombium spp., in view of the limited knowledge of intraspecific variation, hinders the recognition of species borders and affects the views on the actual distribution of species. Therefore, identification will benefit from reference to molecular methods. The separate species identity of specimens putatively representing Allothrombium fuliginosum and A. pulvinum, both reported as widely distributed in the Palaearctic region and considered as potential biological control agents, was checked using morphological and molecular analyses. The representatives of various Allothrombium spp. collected in the Palaearctic were included in the analysis in order to ascertain the distance between species. The results of the morphological examination, supported by statistical inference, along with the comparison of COI and/or ITS2 sequences, weaken the hypothesis of synoccurrence of both species in the Palaearctic region. Hence, we hypothesize that A. fuliginosum is widely distributed in the Palaearctic, whereas A. pulvinum should be regarded a Nearctic species.

Cases of co-invasion of various chigger species parasitizing murids and cricetids in various habitats were analysed using morphological and molecular approaches. Here we provide evidence for 25 new cases of co-parasitism of chigger mites on rodent hosts (Myodes glareolus, Apodemus flavicollis, Apodemus agrarius) accounting for 8.6% of all host-parasite associations observed in this study. The results confirm higher incidence of co-parasitism in vertebrate-associated Parasitengona mites compared to arthropod-associated ones. Among factors influencing the occurrence of co-parasitism in Trombiculidae the body constitution and year-round availability of hosts associated with lower host specificity of larvae should be considered.

Examination of host-associated variation in the chigger mite Hirsutiella zachvatkini (Schluger) revealed morphological differences among larvae infesting sympatric hosts: Apodemus agrarius, Apodemus flavicollis and Myodes glareolus. The analysis included 61 variables of larvae obtained from their gnathosoma, idiosoma and legs (measurements and counts). Statistically significant differences were observed for metric characters of the legs as opposed to the scutum. In view of the conspecificity of the mites, supported by comparison of COI gene products obtained from larvae and laboratory-reared deutonymphs, the observed variation is attributed to phenotypic plasticity. The knowledge of larval morphology, including intraspecific variation of metric characters, supported by molecular and host range data, places H. zachvatkini among the most comprehensively defined members of Trombiculidae.

An experiment on three differently-managed agricultural fields in Ahlum, Germany, which aimed at establishing the impact of different management systems on the biodiversity of predators and decomposers, yielded a significant number of spiders parasitized by larvae of Trombidium brevimanum (Actinotrichida, Parasitengona, Trombidiidae). Spider data from the whole sampling period (September 2010-July 2012), indicated that ectoparasitic larvae were recorded only on spiders in pitfall traps in the period of June-July 2011. In this period, only eight species of Linyphiidae--out of 42 species assigned to nine spider families recorded from the study area--were parasitized by mites; considerable levels of parasitism were recorded on Erigone atra, E. dentipalpis, and Oedothorax apicatus. The highest prevalence of parasitism was recorded on the organic field for E. atra (29%), while on the integrated and conventional fields significantly fewer parasitized spiders were observed. The preferred attachment sites on the spider host were regions with softer cuticle, especially regions on the carapace and on the abdomen, adjacent to the pedicel.