Astigmatid Mites Research Articles

The potential application of Czenspinskia transversostriata in biological control.

Phytoseiid predatory mites are one of the most important groups of biocontrol agents, commonly used in biological control. The ability to produce these predatory mites economically, at high density on cheap factitious food sources, is a major contributor to their success. Astigmatid mites are the most widely used factitious food for this purpose. In this study, we investigated the potential application of the leaf-dwelling astigmatid mite Czenspinskia transversostriata (Oudemans) (Acari: Winterschmidtiidae) as a prey mite in biological control. We tested whether C. transversostriata is a suitable food source for the predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae), both in the laboratory and on cucumber plants. Based on a reproduction trial, C. transversostriata proved to be an equally good food source compared to both pollen of Typha angustifolia L. (Poales: Typhaceae) and a frequently used prey mite Carpoglyphus lactis L. (Acari: Carpoglyphidae). In a pre-establishment trial on cucumber plants, populations of A. swirskii reached equally high densities when supplemented with C. transversostriata, compared to C. lactis. Lastly, we show that C. transversostriata is capable of feeding and reproducing on powdery mildew growing on cucumber plants, thereby slowing down the development of the pathogenic fungus. Results derived from this study show that C. transversostriata may have multiple potential applications in biological control programs.

Genomic and metagenomic analyses of the domestic mite Tyrophagus putrescentiae identify it as a widespread environmental contaminant and a host of a basal, mite-specific Wolbachia lineage (supergroup Q)

Tyrophagus putrescentiae (mould mite) is a global, microscopic trophic generalist that commonly occurs in various human-created habitats, causing allergies and damaging stored food. Its ubiquity and extraordinary ability to penetrate research samples or cultures through air currents or by active walking through tights spaces (such as treads of screw caps) may lead to sample contamination and introduction of its DNA to research materials in the laboratory. This prompts a thorough investigation into potential sequence contamination in public genomic databases. The trophic success of T. putrescentiae is primarily attributed to the symbiotic bacteria housed in specialized internal mite structures, facilitating adaptation to varied nutritional niches. However, recent work suggests that horizontal transfer of bacterial/fungal genes related to nutritional functionality may also contribute to the mite’s trophic versatility. This aspect requires independent confirmation. Additionally, T. putrescentiae harbors an uncharacterized and genetically divergent bacterium, Wolbachia, displaying blocking and microbiome-modifying effects. The phylogenomic position and supergroup assignment of this bacterium are unknown. Here, we sequenced and assembled the T. putrescentiae genome, analyzed its microbiome, and performed detailed phylogenomic analyses of the mite-specific Wolbachia. We show that T. putrescentiae DNA is a substantial source of contamination of research samples. Its DNA may inadvertently be co-extracted with the DNA of the target organism, eventually leading to sequence contamination in public databases. We identified a diversity of bacterial species associated with T. putrescentiae, including those capable of rapidly developing antibiotic resistance, such as Escherichia coli. Despite the presence of diverse bacterial communities in T. putrescentiae, we did not detect any recent horizontal gene transfers in this mite species and/or in astigmatid (domestic) mites in general. Our phylogenomic analysis of Wolbachia recovered a basal, mite-specific lineage (supergroup Q) represented by two Wolbachia spp. from the mould mite and a gall-inducing plant mite. Fluorescence in situ hybridization confirmed the presence of Wolbachia inside the mould mite. The discovery of an early derivative Wolbachia lineage (supergroup Q) in two phylogenetically unrelated and ecologically dissimilar mites suggests that this endosymbiotic bacterial lineage formed a long-term association with mites. This finding provides a unique insight into the early evolution and host associations of Wolbachia. Further discoveries of Wolbachia diversity in acariform mites are anticipated.

Enhancing the efficiency of egg collection of the astigmatid mite Carpoglyphus lactis (Acari: Carpoglyphidae) as a diet for predatory mites

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A novel Bartonella-like bacterium forms an interdependent mutualistic symbiosis with its host, the stored-product mite Tyrophagus putrescentiae.

A novel Bartonella-like symbiont (BLS) of Tyrophagus putrescentiae was characterized. BLS formed a separate cluster from the Bartonella clade together with an ant symbiont. BLS was present in mite bodies (103 16S DNA copies/mite) and feces but was absent in eggs. This indicated the presence of the BLS in mite guts. The BLS showed a reduction in genome size (1.6 Mb) and indicates gene loss compared to Bartonella apis. The BLS can be interacted with its host by using host metabolic pathways (e.g., the histidine and arginine metabolic pathways) as well as by providing its own metabolic pathways (pantothenate and lipoic acid) to the host, suggesting the existence of a mutualistic association. Our experimental data further confirmed these potential mutualistic nutritional associations, as cultures of T. putrescentiae with low BLS abundance showed the strongest response after the addition of vitamins. Despite developing an arguably tight dependency on its host, the BLS has probably retained flagellar mobility, as evidenced by the 32 proteins enriched in KEGG pathways associated with flagellar assembly or chemotaxis (e.g., fliC, flgE, and flgK, as highly expressed genes). Some of these proteins probably also facilitate adhesion to host gut cells. The microcin C transporter was identified in the BLS, suggesting that microcin C may be used in competition with other gut bacteria. The 16S DNA sequence comparison indicated a mite clade of BLSs with a broad host range, including house dust and stored-product mites. Our phylogenomic analyses identified a unique lineage of arachnid specific BLSs in mites and scorpions.IMPORTANCEA Bartonella-like symbiont was found in an astigmatid mite of allergenic importance. We assembled the genome of the bacterium from metagenomes of different stored-product mite (T. putrescentiae) cultures. The bacterium provides pantothenate and lipoic acid to the mite host. The vitamin supply explains the changes in the relative abundance of BLSs in T. putrescentiae as the microbiome response to nutritional or pesticide stress, as observed previously. The phylogenomic analyses of available 16S DNA sequences originating from mite, scorpion, and insect samples identified a unique lineage of arachnid specific forming large Bartonella clade. BLSs associated with mites and a scorpion. The Bartonella clade included the previously described Ca. Tokpelaia symbionts of ants.

Predicting Blomia tropicalis allergens using a multiomics approach.

The domestic mite Blomia tropicalis is a major source of allergens in tropical and subtropical regions. Despite its great medical importance, the allergome of this mite has not been sufficiently studied. Only 14 allergen groups have been identified in B. tropicalis thus far, even though early radioimmunoelectrophoresis techniques (27 uncharacterized allergen complexes) and comparative data based on 40 allergen groups officially recognized by the World Health Organization (WHO)/IUIS in domestic astigmatid mites suggest the presence of a large set of additional allergens. Here, we employ a multiomics approach to assess the allergome of B. tropicalis using genomic and transcriptomic sequence data and perform highly sensitive protein abundance quantification. Among the 14 known allergen groups, we confirmed 13 (one WHO/IUIS allergen, Blo t 19, was not found) and identified 16 potentially novel allergens based on sequence similarity. These data indicate that B. tropicalis shares 27 known/deduced allergen groups with pyroglyphid house dust mites (genus Dermatophagoides). Among these groups, five allergen-encoding genes are highly expressed at the transcript level: Blo t 1, Blo t 5, Blo t 21 (known), Blo t 15, and Blo t 18 (predicted). However, at the protein level, a different set of most abundant allergens was found: Blo t 2, 10, 11, 20 and 21 (mite bodies) or Blo t 3, 4, 6 and predicted Blo t 13, 14 and 36 (mite feces). We report the use of an integrated omics method to identify and predict an array of mite allergens and advanced, label-free proteomics to determine allergen protein abundance. Our research identifies a large set of novel putative allergens and shows that the expression levels of allergen-encoding genes may not be strictly correlated with the actual allergenic protein abundance in mite bodies.

Kill rate as a tool in efficiency evaluation of Neoseiulus californicus (Acari: Phytoseiidae) mass reared on factitious food.

The predatory mites of the Phytoseiidae family are crucial biological control agents widely utilized in biological pest management targeting phytophagous mites and insects. Key factors in these control strategies are that phytoseiids must be able to find their main target prey and to maintain high populations and efficacy. To reduce expenses and time-consuming production methods of mass rearing of phytoseiids, pollen and other factitious (i.e., non-natural/nontarget) hosts need to be present as an alternative food for predatory mite populations. The mass-rearing possibilities of these predators on alternative food sources, such as astigmatid mites (i.e., house and stored mites) and pollen, must be evaluated not only by the cost of rearing settings but on the basis of their efficiency maintenance in killing prey. The pest kill rate (km) is the average daily lifetime killing of the pest by the natural enemy under consideration and can represent a useful indicator for phytoseiids efficacy to rank them as BCAs on the basis of their effective killing/predation on target prey. In this study, we evidenced that 2 astigmatid mites, Glycyphagus domesticus (De Geer) and Lepidoglyphus destructor (Schrank), and Quercus ilex L. pollen can be successfully adopted as substitute food sources for mass rearing of the phytoseiid Neoseiulus californicus (MgGregor); then, we determined that these populations of BCAs maintained a consistent km at new/first impact on the main target pest, Tetranychus urticae Koch.

Variation in the trophic morphology of Astigmatid mites common in UK beehives

The chelal moveable digit in Carpoglyphus lactis (Linnaeus), Glycyphagus domesticus (DeGeer), and Tyrophagus putrescentiae (Schrank) from UK beehives is described using quantitative measures within a 2D mechanical model. The location of maximum jerk on the profile of the chelal moveable digit indicates the end of the mastication surface, which in these mites is confirmed to be just before the theoretical cut-off point for a functioning chewing `machine`. All three species should be able to grasp yeasts, spores and mycelial hyphae in the hive. The moveable digit of C. lactis may be designed to enable pollenophagy. The mastication surface is 21.3 μm in C. lactis, 18.8 μm in G. domesticus, and 17.2 μm in T. putrescentiae. The wild-collected C. lactis shows the smallest chelal moveable digit tip velocity ratios (i.e., the lowest relative length of input to output moment arms). Glycyphagus domesticus has the most primitive geometry of its chela. The depth of the moveable digit matches the inferred resistive forces applied by the mite to food at that point. Condylar and moveable digit strengthening by sclerotisation is associated with eating tougher food. Effective chelal gape is 28.7 μm in C. lactis, 25.9 μm in G. domesticus and 24.8 μm in T. putrescentiae. Maximum food fragment size grabbed by the chela is estimated as 7786 μm<sup>3</sup> in C. lactis, 5348 μm<sup>3</sup> in G. domesticus and 4703 μm<sup>3 </sup>in T. putrescentiae. Morsel size pre-ingestion is estimated as 4031 μm<sup>3 </sup>in C. lactis, 5228 μm<sup>3 </sup>in G. domesticus and 4246 μm<sup>3</sup> in T. putrescentiae. Under reasonable assumptions one of these mites might be able to excavate its own body volume equivalent in about one hour.

Beyond the Limits of Light: An Application of Super-Resolution Confocal Microscopy (sCLSM) to Investigate Eocene Amber Microfossils.

Amber is known as one of the best sources of fossil organisms preserved with exceptional fidelity. Historically, different methods of imaging have been applied to amber, including optical microscopy and microtomography. These methods are sufficient to resolve millimeter-scaled fossils. However, microfossils, such as microarthropods, require another resolution. Here, we describe a non-destructive method of super resolution confocal microscopy (sCLSM) to study amber-preserved microfossils, using a novel astigmatid mite species (genus Histiogaster, Acaridae) from Eocene Rovno amber as a model. We show that the resolution obtained with sCLSM is comparable to that of scanning electron microscopy (SEM) routinely used to study modern mites. We compare sCLSM imaging to other methods that are used to study amber inclusions and emphasize its advantages in examination of unique fossil specimens. Furthermore, we show that the deterioration of amber, which manifests in its darkening, positively correlates with its increased fluorescence. Our results demonstrate a great potential of the sCLSM method for imaging of the tiniest organisms preserved in amber.

Growth, development, and host preference of Histiostoma feroniarum (Acaridida: Histiostomatidae): effects of temperature and types of mushroom cultivar.

One of the most common harmful mites in edible fungi is Histiostoma feroniarum Dufour (Acaridida: Histiostomatidae), a fungivorous astigmatid mite that feeds on hyphae and fruiting bodies, thereby transmitting pathogens. This study examined the effects of seven constant temperatures and 10 types of mushrooms on the growth and development of H. feroniarum, as well as its host preference. Developmental time for the total immature stages was significantly affected by the type of mushroom species, ranging from 4.3 ± 0.4 days (reared on Pleurotus eryngii var. tuoliensis Mou at 28°C) to 17.1 ± 2.3 days (reared on Auricularia polytricha Sacc. at 19°C). The temperature was a major factor in the formation of facultative heteromorphic deutonymphs (hypopi). The mite entered the hypopus stage when the temperature dropped to 16°C or rose above 31°C. The growth and development of this mite were significantly influenced by the type of species and variety of mushrooms. Moreover, the fungivorous astigmatid mite preferred to feed on the 'Wuxiang No. 1' strain of Lentinula edodes (Berk.) Pegler and the 'Gaowenxiu' strain of P. pulmonarius (Fr.) Quél., with a shorter development period compared with that of feeding on other strains. These results therefore quantify the effect of host type and temperature on fungivorous astigmatid mite growth and development rates, and provide a reference for applying mushroom cultivar resistance to biological pest control.

A NEW GENUS AND SPECIES MYCETINOPUS STRIATIPEDIS GEN. AND SP. N. (ACARI: ACARIDAE) ASSOCIATED WITH THE HANDSOME FUNGUS BEETLE MYCETINA MARGINALIS IN THE EASTERN PALEARCTIC

We describe unusual heteromorphic deutonymph of Mycetinopus striatipedis gen. and sp. n. (Acari: Acaridae) phoretic on the handsome fungus beetle Mycetina marginalis (Coleoptera, Endomychidae) in the Eastern Palearctic. These deutonymphs have a unique combination of character states that make them very distinct in the family Acaridae: an unpaired pigmented spot on the anterior propodosoma is present; supracoxal setae scx filiform and bifurcate; genu I with two solenidia; tibia-tarsi I–II are distinctly elongated and striated; vertical setae ve are present, and tarsal setae aa are lacking. Our work emphasizes the importance of continued exploration and documentation of the biodiversity of astigmatid mites associated with invertebrate hosts.

Impact of temperature and prey type on biology and life-table parameters of Cheyletus malaccensis Oudemans (Acari: Cheyletidae)

ABSTRACT This study deals with biology and life table parameters of the predatory mite, Cheyletus malaccensis Oudemans were evaluated on three astigmatid mites as prey (i.e. Acarus siro (Linnaeus), Caloglyphus berlesei (Michael) and Tyrophagus putrescentiae (Schrank)) under laboratory conditions. Three constant temperatures (22, 27 and 32 ± 2°C) and constant relative humidity 80 ± 5% were used. Statistical analysis indicated significant difference between prey types and the three different temperatures. The shortest life cycle was recorded on A. siro (11.60 and 8.0 days) at 32°C, while the longest was on C. berlesei (29.5 and 21.2) at 22°C for females and males, respectively. Longest female longevity was on A. siro (43.6 days) at 22°C and shortest was 20.65 days on T. putrescentiae at 32°C. Highest fecundity was found on A. siro (196.50 eggs/female) at 27°C and lowest one was 69.10 eggs/female on C. berlesei at 22°C. The highest net reproduction rate of increase (R0) was 113.2 ♀/♀/generation at 27°C on A. siro. Obtained results suggested that C. malaccensis could develop and reproduce within a wide range of temperatures and prey types. It can also be used as a biological control agent to reduce the amount of acarid mite pests that infest stored commodities.

Essential Oils against Sarcoptes scabiei.

Herbal remedia are widely employed in folk medicine, and have been more and more often studied and considered in the treatment of several infections. Sarcoptic mange (scabies, when referring to human patients) is a highly contagious skin disease caused by Sarcoptes scabiei (sarcoptiformes, Sarcoptinae), an astigmatid mite which burrows into the epidermis, actively penetrating the stratum corneum. This parasitosis negatively affects livestock productions and represents a constraint on animal and human health. The treatment relies on permethrine and ivermectine but, since these molecules do not have ovicidal action, more than a single dose should be administered. Toxicity, the possible onset of parasite resistance, the presence of residues in meat and other animal products and environmental contamination are the major constraints. These shortcomings could be reduced by the use of plant extracts that have been in vitro or in vivo checked against these mites, sometimes with promising results. The aim of the present study was to review the literature dealing with the treatment of both scabies and sarcoptic mange by plant-derived agents, notably essential oils.

Learning behavior of Neoseiulus californicus from astigmatid to spider mites

Oulenziella bakeri is often used as an alternative prey for the mass rearing of Neoseiulus californicus in China. Long-term alternative prey feeding experience may cause a decline in the predatory capacity of phytoseiid mites toward their target prey. Learning behavior of predatory mites can help them adapt to the changes from preying on thrips to preying on spider mites (Rahmani et al., 2010), but there are few studies on the learning behavior of predatory mites from astigmatid mites to spider mites. Here, we compared the attack latency, prey preference, and functional response of N. californicus toward Tetranychus urticae among the “natural prey strains” (feeding only on T. urticae), “alternative prey strains” (feeding only on O. bakeri), and “learning behavior treatment” (alternative prey strains experienced in attacking but not feeding on T. urticae). The results showed that the attack latency of “alternative prey strain” of N. californicus on T. urticae was significantly longer than that of “natural prey strain” and “learning behavior treatment”. The “alternative prey strain” showed no obvious predatory preference between the protonymphs of T. urticae and O. baker. There were no significant differences in the capture rate and handling time among the three treatments. Our results indicated that the long-term rearing on alternative prey mainly prolonged the attack latency of N. californicus to the target prey and changed its prey preference, while learning behavior could help alternative prey strain of N. californicus to shorten the attack latency and restore its prey preference toward target prey (Zhu et al., 2022).

Learning behavior of Neoseiulus californicus (Acari: Phytoseiidae) can help in adapting from feeding on alternative prey to target prey

Neoseiulus californicus (Acari: Phytoseiidae) is a commercialized predatory mite that is used as a biological control agent against Tetranychus urticae (Acari: Tetranychidae). Long-term feeding on alternative prey could impact the predatory capacity of N. californicus. Although most studies on the learning behavior of predatory mites have indicated that learning behavior could help them adapt from feeding on thrips (alternative prey) to spider mites (target prey), the role of learning behavior in adapting from feeding on astigmatid mites to spider mites has not been studied thus far. Therefore, this study explored the learning behavior of N. californicus in adapting from feeding on alternative prey (Oulenziella bakeri [Acari: Winterschmidtiidae]) to target mites (T. urticae). The attack latencies, prey preferences, and functional responses of female N. californicus were compared between two strains, N. californicus fed on T. urticae (TU) or O. bakeri (OB), and a learning behavior (LB) treatment. The results showed that the attack latency of OB strain was significantly longer than those of TU strain and LB treatment; OB strain did not show obvious prey preference between protonymphs of T. urticae and O. bakeri; and the functional response among TU, OB, and LB-treated strains were not significantly different. Our results demonstrated that long-term feeding on alternative prey had little effect on the predatory ability of N. californicus. To a certain extent, learning behavior can help N. californicus shift from feeding on alternative prey to target prey. Therefore, in the long run, it is reasonable to rear N. californicus on O. bakeri.

A rapid identification method for common astigmatid species based on multiplex polymerase chain reaction.

Astigmatid mites are economically significant pests of stored products and sources of inhalant allergens causing allergic rhinitis and asthma worldwide. The morphological identification of astigmatid mites at the species level is often a difficult task due to their small size, phenotypic similarity and lack of diagnostic characters. We used multiplex polymerase chain reaction (PCR) to identify astigmatid mite species, which could complement the morphological data for the species-specific identification of mites. Internal ribosomal transcribed spacer (ITS) sequences (i.e., partial 18S, the full length of ITS1-5.8S-ITS2 and partial 28S) from eight astigmatid species (Acarus siro, Tyrophagus putrescentiae, Suidasia nesbitti, Dermatophagoides pteronyssinus, Dermatophagoides farinae, Lepidoglyphus destructor, Chortoglyphus arcuatus and Gohieria fuscus) were obtained by DNA extraction and then sequenced after PCR amplification. Specific primers were designed in the ITS2 region manually. Results revealed that an identification method for eight common astigmatid species was established based on multiplex PCR, which should be effective for the identification of other species of mites by redesigning species-specific primers in future experiments.

Scabies infection among boarding school students in Medan, Indonesia: Epidemiology, Risk Factors, and Recommended Prevention.

Introduction:Scabies has been a continuous health concern in residential institutions including boarding schools in Indonesia. The disease easily spreads in overcrowding residences. Using one of several boarding schools in Medan, Indonesia, as study site, we conducted this study to better understand the underlying factors behind scabies incidence in boarding schools. We hoped to be able to promote more effective preventive measures toward the disease.Materials and Methods:We included all of 220 students (115 males and 105 females) in a cross-sectional descriptive analytical study, whose ages were ranging from 10 to 18 years. The diagnosis of scabies was made based on interview and physical examination. Skin scraping followed by microscopic assessment was carried out upon finding scabies-related lesion. Data on risk factors were collected using a set of pretested questionnaire and direct observation. Data were analyzed using bivariate and multivariate analysis the with Chi square and logistic regression.Results:We found a high prevalence clinical scabies, i.e., 81 (36.8%) students, yet only one came out positive with skin scraping and microscopic examination. The factors associated with the infection were found to be younger age (odds ratio [OR]: 2.95, 95% confidence interval [CI] 0.97–6.09), sharing clothes (OR: 8.22, 95% CI 2.37–28.48), sharing bed (OR: 17.53, 95% CI 5.55–56.02), and unhygienic bedroom condition (OR: 8.18, 95% CI 3.30–20.28).Conclusions:The results imply the need for better strategies to prevent the transmission of astigmatid mites within the risky populations. We promote six recommendations for a more applicable approach toward scabies prevention in boarding schools and other institutional facilities alike.

Active and frozen host mite Tyrophagus putrescentiae (Acari: Acaridae) influence the mass production of the predatory mite Blattisocius mali (Acari: Blattisociidae): life table analysis

Blattisocius mali (Oudemans) is a candidate predatory mite on some astigmatid mite pests like Tyrophagus putrescentiae (Schrank). In current study, life table parameters of B. mali were comparatively evaluated when fed on mixed life stages, frozen (one day at -20°C) and cold stored (90 days at -20°C and 4°C) eggs of T. putrescentiae. The highest and lowest values of fecundity, total longevity, oviposition period, life span and adult longevity of B. mali were observed when the predator provided with one-day and 90-days frozen eggs (stored at 4°C) of T. putrescentiae, respectively. Moreover, the highest values of net reproductive rate (R0), intrinsic rate of increase (r) and finite rate of increase (λ) of B. mali were obtained by feeding on one-day frozen eggs (23.94 offspring/individual, 0.332 day-1, 1.39 day-1, respectively), without significant differences from the predators reared on alive mixed stages of T. putrescentiae. However, the lowest values of R0 (1.54 offspring/individual), r (0.058 day-1) and λ (1.06 day-1) were recorded when B. mali was reared on 90-days frozen eggs (stored at 4°C). The results, as first evidence of life-history of B. mali, represent not only the potential of the predator as suitable biological control agent against T. putrescentiae, but also the possibility of its mass production by frozen host stages. Provision of one-day frozen eggs of T. putrescentiae were the best choice for B. mali survival and reproduction with no harmful effects of living stages (direct damage, frass and exuviae) on crop.

Interactions of the Intracellular Bacterium Cardinium with Its Host, the House Dust Mite Dermatophagoides farinae, Based on Gene Expression Data.

ABSTRACTDermatophagoides farinae is inhabited by an intracellular bacterium, Cardinium. Using correlations between host and symbiont gene expression profiles, we identified several important molecular pathways that potentially regulate/facilitate their interactions. The expression of Cardinium genes collectively explained 95% of the variation in the expression of mite genes assigned to pathways for phagocytosis, apoptosis, the MAPK signaling cascade, endocytosis, the tumor necrosis factor (TNF) pathway, the transforming growth factor beta (TGF-β) pathway, lysozyme, and the Toll/Imd pathway. In addition, expression of mite genes explained 76% of the variability in Cardinium gene expression. In particular, the expression of the Cardinium genes encoding the signaling molecules BamD, LepA, SymE, and VirD4 was either positively or negatively correlated with the expression levels of mite genes involved in endocytosis, phagocytosis, and apoptosis. We also found that Cardinium possesses a complete biosynthetic pathway for lipoic acid and may provide lipoate, but not biotin, to mites. Cardinium gene expression collectively explained 84% of the variation in expression related to several core mite metabolic pathways, and, most notably, a negative correlation was observed between bacterial gene expression and expression of mite genes assigned to the glycolysis and citric acid cycle pathways. Furthermore, we showed that Cardinium gene expression is correlated with expression levels of genes associated with terpenoid backbone biosynthesis. This pathway is important for the synthesis of pheromones, thus providing an opportunity for Cardinium to influence mite reproductive behavior to facilitate transmission of the bacterium. Overall, our study provided correlational gene expression data that can be useful for future research on mite-Cardinium interactions.IMPORTANCE The molecular mechanisms of mite-symbiont interactions and their impacts on human health are largely unknown. Astigmatid mites, such as house dust and stored-product mites, are among the most significant allergen sources worldwide. Although mites themselves are the main allergen sources, recent studies have indicated that mite-associated microbiomes may have implications for allergen production and human health. The major medically important house dust mite, D. farinae, is known to harbor a highly abundant intracellular bacterium belonging to the genus Cardinium. Expression analysis of the mite and symbiont genes can identify key mite molecular pathways that facilitate interactions with this endosymbiont and possibly shed light on how this bacterium affects mite allergen production and physiology in general.

Label-free proteomic analysis reveals differentially expressed Wolbachia proteins in Tyrophagus putrescentiae: Mite allergens and markers reflecting population-related proteome differences

Tyrophagus putrescentiae is an astigmatid mite of great economic, medical and veterinary importance. The microbiome, especially intracellular bacteria, may affect allergy/allergen expression. We targeted Wolbachia proteins, allergen comparisons and markers in Wolbachia–mite interactions in three mite populations. A decoy database was constructed by proteogenomics using the T. putrescentiae draft genome, Wolbachia transcriptome assembly and current T. putrescentiae-related sequences in GenBank. Among thousands of mite-derived proteins, 18 Wolbachia proteins were reliably identified. We suggest that peroxiredoxin, bacterioferritin, ankyrin repeat domain-containing protein and DegQ family serine endoprotease indicate a higher-level bacterium–bacterium–host interaction. We produced evidence that the host–Wolbachia interaction is modulated through pattern recognition receptors (PRRs), mannose-binding lectins/mannose receptors, the cholinergic anti-inflammatory pathway with TNF-α, and others. We observed Tyr p 3 suppression in mites with Wolbachia, linking trypsin to PRR modulation. Nine out of the 12 current WHO/IUIS official allergens were reliably identified, but the remaining three allergens, Tyr p 1, 8 and 35, were detected as only trace hits. This study provides numerous markers for further Wolbachia–host interaction research. For accuracy, mite allergens should be considered according to abundance in species, but mite populations/strains, as well as their microbiome structure, may be key factors. SignificanceThe astigmatid mites occurring in homes are significant producers of allergens that are highly dangerous to humans and domesticated animals. Mites are tightly associated with microorganisms that affect their biology and consequently allergy signatures. Mite populations were found to be infected with certain intracellular bacteria, but some populations lacked an intracellular bacterium. Our previous research showed that some populations of Tyrophagus putrescentiae are infected with Wolbachia, but some populations host additional bacteria of interest. Thus, there are not only interactions between the mites and Wolbachia but also likely an additional level of interaction that can be found in the interaction between different bacteria in the mites. These “higher-level” signatures and consequences that bacteria affect, including allergen production, are not understood in mites. In this study, we identified Wolbachia-specific proteins in mites for the first time. This study provides Wolbachia- and mite-derived markers that can be clues for describing “higher-level” mite-bacterium-bacterium interactions. Indeed, the microbiome contribution to allergies can potentially be derived directly from bacterial proteins, especially if they are abundant.

Complete mitochondrial genomes of the two Glycyphagoidea mites Lepidoglyphus destructor and Gohieria fusca (Acari: Sarcoptiformes, Glycyphagoidea): Revelation of a novel feature of the largest non-coding region

Mitochondrial genomes (mitogenomes) of metazoans typically contain 37 genes, comprising 13 protein-coding genes, 2 rRNA genes, and 22 tRNA genes. To date, complete mitogenome sequences of 15 species of Astigmatina have been elucidated; and they contain variations in several features, such as gene order, unconventional tRNA secondary structures, and the number and internal structures of control regions. Here, we sequenced the mitogenomes of Lepidoglyphus destructor and Gohieria fusca, thus representing the first reported complete mitogenome sequence of mite species from the superfamily Glycyphagoidea. In total, 37 mitochondrial genes were identified in both species. The same gene arrangement pattern was found in both species, and this pattern was consistent with that in the possible common ancestor of astigmatid mites. Most tRNAs were highly truncated in both species, which is typical of acariform mites. The largest non-coding region in L. destructor and G. fusca can be divided into two domains based on AT content and stem-loop structures. Domain I has a stem-loop structure; domain II is more AT-rich than domain I and includes several conserved sequences that are also observed in Acaridae and Pyroglyphidae. The largest non-coding region of Acalvolia sp. (Astigmatina, Hemisarcoptoidea) also exhibits similar features. The phylogenetic relationships found in our study are consistent with those identified by previous phylogenetic studies on astigmatid mites. Within Astigmatina, Glycyphagoidea was recovered as a monophyletic group.