Hyperparasitism of mosquitoes by water mite larvae

Meta-transcriptomics reveals potential virus transfer between Aedes communis mosquitoes and their parasitic water mites

Arthropods harbor a largely undocumented diversity of RNA viruses. Some arthropods, like mosquitoes, can transmit viruses to vertebrates but are themselves parasitized by other arthropod species, such as mites. Very little is known about the viruses of these ectoparasites and how they move through the host-parasite relationship. To address this, we determined the virome of both mosquitoes and the mites that feed on them. The mosquito Aedes communis is an abundant and widely distributed species in Sweden, in northern Europe. These dipterans are commonly parasitized by water mite larvae (Trombidiformes: Mideopsidae) that are hypothesized to impose negative selection pressures on the mosquito by reducing fitness. In turn, viruses are dual-host agents in the mosquito-mite interaction. We determined the RNA virus diversity of mite-free and mite-detached mosquitoes, as well as their parasitic mites, using meta-transcriptomic sequencing. Our results revealed an extensive RNA virus diversity in both mites and mosquitoes, including thirty-seven putative novel RNA viruses that cover a wide taxonomic range. Notably, a high proportion of viruses (20/37) were shared between mites and mosquitoes, while a limited number of viruses were present in a single host. Comparisons of virus composition and abundance suggest potential virus transfer between mosquitoes and mites during their symbiotic interaction. These findings shed light on virome diversity and ecology in the context of arthropod host-parasite-virus relationships.

The Biodiversity of Water Mites That Prey on and Parasitize Mosquitoes

Water mites form one of the most biodiverse groups within the aquatic arachnid class. These freshwater macroinvertebrates are predators and parasites of the equally diverse nematocerous Dipterans, such as mosquitoes, and water mites are believed to have diversified as a result of these predatory and parasitic relationships. Through these two major biotic interactions, water mites have been found to greatly impact a variety of mosquito species. Although these predatory and parasitic interactions are important in aquatic ecology, very little is known about the diversity of water mites that interact with mosquitoes. In this paper, we review and update the past literature on the predatory and parasitic mite–mosquito relationships, update past records, discuss the biogeographic range of these interactions, and add our own recent findings on this topic conducted in habitats around the Laurentian Great Lakes. The possible impact on human health, along with the importance of water mite predator–prey dynamics in aquatic food webs, motivates an increase in future research on this aquatic predator and parasite and may reveal novel ecological functions that these parasitic and predator–prey relationships mediate.

Water mite assemblages reveal diverse genera, novel DNA barcodes and transitional periods of intermediate disturbance

Water mites are important constituents of aquatic ecosystems, but their biodiversity is poorly understood. The goal of this study was to improve knowledge of water mite assemblages in the Detroit River through combined use of morphological and cytochrome oxidase I (COI) DNA barcode data and to elucidate seasonal water mite diversity. The diversity of water mites collected from Blue Heron Lagoon at Belle Isle, an island in the Detroit River, is described. Novel DNA barcodes for Albia, Hydrochoreutes, Madawaska, and Axonopsis are reported with a species level barcode for Lebertia. Novel DNA barcodes may represent the presence of previously undescribed variants or new species of several genera. The prevalence of water mites is higher in the summer, but a different pattern is observed for diversity. The diversity of water mites, by several measures, varies seasonally with lower diversity in summer and winter months and higher diversity during seasonal transitions. For these organisms, we interpret seasonal change as an intermediate disturbance resulting in increased biodiversity.

Hidden biodiversity revealed by integrated morphology and genetic species delimitation of spring dwelling water mite species (Acari, Parasitengona: Hydrachnidia)

BACKGROUND

Water mites are among the most diverse organisms inhabiting freshwater habitats and are considered as substantial part of the species communities in springs. As parasites, Hydrachnidia influence other invertebrates and play an important role in aquatic ecosystems. In Europe, 137 species are known to appear solely in or near springheads. New species are described frequently, especially with the help of molecular species identification and delimitation methods. The aim of this study was to verify the mainly morphology-based taxonomic knowledge of spring-inhabiting water mites of central Europe and to build a genetic species identification library.

METHODS

We sampled 65 crenobiontic species across the central Alps and tested the suitability of mitochondrial (cox1) and nuclear (28S) markers for species delimitation and identification purposes. To investigate both markers, distance- and phylogeny-based approaches were applied. The presence of a barcoding gap was tested by using the automated barcoding gap discovery tool and intra- and interspecific genetic distances were investigated. Furthermore, we analyzed phylogenetic relationships between different taxonomic levels.

RESULTS

A high degree of hidden diversity was observed. Seven taxa, morphologically identified as Bandakia concreta Thor, 1913, Hygrobates norvegicus (Thor, 1897), Ljania bipapillata Thor, 1898, Partnunia steinmanni Walter, 1906, Wandesia racovitzai Gledhill, 1970, Wandesia thori Schechtel, 1912 and Zschokkea oblonga Koenike, 1892, showed high intraspecific cox1 distances and each consisted of more than one phylogenetic clade. A clear intraspecific threshold between 5.6-6.0% K2P distance is suitable for species identification purposes. The monophyly of Hydrachnidia and the main superfamilies is evident with different species clearly separated into distinct clades. cox1 separates water mite species but is unsuitable for resolving higher taxonomic levels.

CONCLUSIONS

Water mite species richness in springs is higher than has been suggested based on morphological species identification alone and further research is needed to evaluate the true diversity. The standard molecular species identification marker cox1 can be used to identify species but should be complemented by a nuclear marker, e.g. 28S, to resolve taxonomic relationships. Our results contribute to the taxonomical knowledge on spring inhabiting Hydrachnida, which is indispensable for the development and implementation of modern environment assessment methods, e.g. metabarcoding, in spring ecology.

Mites (Acari: Trombidiformes) parasitizing mosquitoes (Diptera: Culicidae) in an Atlantic Forest area in southern Brazil with a new mite genus country record

In this study, a total of 4146 culicids collected in an Atlantic Forest area in Paraná state, southern Brazil were examined for the presence of mites. Forty larval Parasitengone mites (Arrenurus spp., Arrenuridae; Durenia spp., Trombellidae; Microtrombidium spp., Microtrombidiidae) parasitized 25 specimens of mosquitoes, with the intensity varying from one to nine mites attached. Most mites were found on Aedes serratus/nubilus, Culex vomerifer, Cx. pedroi and Cx. sacchettae. The overall percentage of parasitized mosquitoes was 0.6 %. The highest intensity of mites encountered was in an individual of Cx. pedroi with nine attached mites. Regarding the attachment site, most mite specimens were attached to the abdomen (n = 25), whereas 15 were located on the thorax. Specimens of Arrenurus spp. were only found on the abdomen of mosquitoes, and the same was observed for Microtrombidium spp., while Durenia spp. attached to both the thorax (n = 15) and abdomen (n = 4). This is the first record for the genus Durenia in Brazil. Additionally, some species of mosquitoes were, for the first time, reported as being parasitized by mites.

A Critical Review of All Known Published Records for Water Mite (Acari: Hydrachnidiae) and Mosquito (Diptera: Culicidae) Parasitic Associations From 1975 to Present

All published records of water mite-mosquito parasitic associations since Gary R. Mullen's comprehensive review in the 1970s of the literature were critiqued to provide an up-to-date account on the identity of water mites parasitizing mosquitoes and their geographic distribution. In total, 321 records in 62 sources were identified, with each record representing an association specific to a state, province, or region within a country. The greatest number of records were from the United States (120), followed by India (106) and Canada (40). In all, 105 species of mosquitoes were parasitized, with the majority belonging to the genera Aedes sensu lato (30), Anopheles (30), and Culex (21). Records were biased toward mosquito genera with the greatest number of freshwater species and medical importance. Most water mites belonged to the genus Arrenurus, or were Parathyas barbigera (Viets 1908). Arrenurus water mites were often not identified to species, but 15 different Arrenurus species were determined in 119 records. All but one of the species (i.e., Arrenurus madaraszi Daday 1898) were only reported from Canada, Germany, or the United States. Although a greater proportion of sources reviewed by us compared with Mullen's review identified water mites down to the level of genus, to better understand the biological significance of mite and mosquito interactions, more of an effort is needed to identify the species of water mites. The availability of molecular techniques such as DNA barcoding will make this goal more attainable.