House dust mite allergens in domestic homes in Cheonan, Korea

House dust mites produce inhalant allergens of importance to allergic patients. We measured the major group 1 allergens, Der p 1 and Der f 1, from the house dust mites Dermatophagoides pteronyssinus and Dermatophagoides farina, respectively in 100 randomly selected domestic homes from Cheonan, Korea. Dust samples were collected by vacuuming from the living room floor and 1 mattress in each home. Der p 1 and Der f 1 were measured by double monoclonal ELISA. Der p 1 levels were very low, with geometric mean levels for floors and mattresses being 0.11 microgram/g (range: 0.01-4.05) and 0.14 microgram/g (range: 0.01-30.0), respectively. Corresponding levels of Der f 1 were higher, 7.46 microgram/g (range: 0.01-262.9) and 10.2 microgram/g (range: 0.01-230.9) for floors and mattresses, respectively. D. farinae appears to be the dominant house dust mite in Cheonan.     

Effectiveness of benzyl benzoate in elimination of house dust mites

The effect of elimination treatment with benzyl benzoate was examined in 30 adults with asthma caused by sensitivity to house dust mites. The patients were randomised into a control and an active group, who treated their mattresses with benzyl benzoate (Acarosan^®). The study lasted 12 months and the effect of the treatment was monitored by monthly dust sampling, analyzed for major allergens fromDermatophagoides pteronyssinus andfarinae by the ELISA method and for guanine by the Acarex^® method. The clinical effect was assessed by measuring lung function, daily peak flows, symptoms and medicine consumption as well as skin prick tests, and specific IgE to mite allergens. For both groups, a significant decrease was observed in house dust mite allergens, but there was no significant difference between the groups. No considerable differences were observed in clinical parameters within or between the groups. A good correlation was observed between ELISA and Acarex^®. but the latter showed a major variation in the different classes. In conclusion. treatment of mattresses with benzyl benzoate had no effect in a group of patients with asthma due to house dust mite allergy. Regular vacuum cleaning of the bed may reduce house dust mite allergen exposure.     

The influence of household pets on the composition and quantity of allergenic mite fauna within Irish homes: a preliminary investigation

Allergenic mites are responsible for inducing hypersensitive reactions in genetically predisposed people worldwide. Mites in dust from 30 Irish homes with pets (dogs, n = 23; cats, n = 7) were compared with those in 30 homes without pets. House dust mites constituted 78% of all mites recorded, with Dermatophagoides pteronyssinus (Acariformes: Pyroglyphidae) representing 57–72% of mites in furniture and mattresses in both home types compared with only 22% of mites in pet beds. Although storage mites accounted for just 13% of all mites recorded, they represented 46% of mites recorded in pet beds. Median levels of the dust mite allergen Der p 1 (µg/g) in dust samples from mattresses in homes without pets were significantly greater than in mattresses from homes with pets, reflecting the greater densities of D. pteronyssinus found in the former home category. Mite species richness was greater in homes with pets (17 species) than in homes without pets (13 species). This suggests that although the presence of pets can result in a wider variety of epidemiologically important mite species within households, increased competition among mite species may result in a more balanced mite fauna in the home, inhibiting the dominance of any one species and hence lowering allergen‐associated risks.     

Synanthropic Mites of Kolkata, India: An Ecological Appraisal

Ecological observations were made on house dust mites of Kolkata as they form a major part of synanthropic mite community. Dust samples were collected with regard to the abundance of mite in relation to certain socio-ecological parameters like, habitat preference, location of house, construction pattern of house, types of mattresses used and the frequency of cleaning of mattresses. Among two different habitats examined, bed dust contained significantly higher mite population (p < 0.01) than the corresponding bedroom floor dust. The density of total mites and glycyphagids are significantly higher in rural houses in comparison to those of urban houses. In contrast, rural houses contained least number of pyroglyphids/g of dust. The density of total mites as well as pyroglyphid mites/g of dust are higher in mud house in comparison to concrete house. The density of total mites, pyroglyphids and glycyphagids are higher in cotton mattress in comparison to that of foam mattress. The frequency of cleaning has a significant effect on reducing mite densities i.e., the more the frequency of cleaning the lesser are the mite densities.     

Cross-reactivity between storage and dust mites and between mites and shrimp

Many patients have sensitivities to multiple species of storage and house dust mites. It is not clear if this is because patients have multiple sensitivities to species-specific mite allergens or if these mites share many cross-reacting allergens. Our objective was to further define the cross-allergenicity between several species of storage and house dust mites using crossed-immunoelectrophoresis (CIE), crossed-radioimmunoelectrophoresis (CRIE), immunoblotting, and ELISA. CIE and CRIE reactions revealed that storage mites shared two cross-antigenic molecules and one of these bound IgE in a serum pool from mite allergic patients. Antibody in anti-sera built to each species of mite recognized many SDS–PAGE resolved proteins of other mite species and this suggested the potential for other cross-reactive allergens. Among patient sera, IgE bound to many different proteins but few had IgE that bound to a protein with common molecular weights across the mite species and this suggested mostly species-specific allergens. Antiserum built to each mite species precipitated one protein in shrimp extracts that bound anti-Der p 10 (tropomyosin) and IgE in the serum pool. Anti-Der p 10 showed strong binding to shrimp tropomyosin but very little to any of the mite proteins. ELISA showed the mite extracts contained very little tropomyosin. The storage and dust mites investigated contain mostly species-specific allergens and very small amounts of the pan-allergen tropomyosin compared to shrimp and snail.     

Collective Migration in House Dust Mites

House dust mites (Dermatophagoides pteronyssinus) are widespread in the furniture and mattresses of homes throughout Eurasia. Because human occupation induces wide diurnal fluctuations in temperature and relative humidity, the most favourable locations for mites change constantly and they must migrate repeatedly. Here, we triggered and studied mites migration movements to a new area. Mites migrated from a starting arena to a second arena through a diamond‐shaped corridor offering a choice between two branches of equal length. In this article, we show that local air dryness and a distant water source were both necessary to trigger collective migration. Males and nymphs had a higher probability of migration than larvae and females. When migrating, although both branches initially appeared to be chosen equally, most mites eventually ended up choosing one particular branch. When about 50 or more mites had passed, there was an obvious choice of branch. We used a modelling approach to show that these data support the hypothesis that mites lay an attractive trail that is reinforced by followers. Consequently, the consistency of the collective choice is higher as the number of migrants grows. This article is the first to observe dust mite migration as a collective phenomenon.     

Allergenic mites (Acariformes, Pyroglyphidae) in house dust

Paper is the second part of the literature review on house dust mites (including 1985). It deals with the diagnosis of the dust mite allergy, the nature of the mite allergens, distribution and population density of the mites in various premises, seasonal population dynamics and population age structure of the dermatophagoid mites, life cycle and breeding of Dermatophagoides pteronyssinus and D. farinae on different food substrates. The methods of the house dust mite control are discussed. The original data on the house dust mite distribution in Moscow is shown. A comparative estimation of the results of mite antigens in the house dust discovering by the acarological and three immunological methods are given.     

Protein chips for detection of mite allergens using Kunitz-type protease inhibitors

Stored-food and house-dust arthropods include many species of mites and beetles that affect human health. For diagnostic tests proteases such as trypsin are utilized as they are indicators of the presence of allergen contaminants in food. We recently characterized Kunitz-type protease inhibitors (KPIs) from Solanum palustre. Here we studied biotechnological applications of KPI-B1 and -B4. We manufactured a protein chip with immobilized KPI-B1 and -B4 and showed trypsin/chymotrypsin-binding specificity, indicating that the recombinant proteins have protease selectivity. We employed the protein chip to capture mite proteins belonging to the protease family with polyclonal anti-mite antibodies. The mite diagnostic chip can be useful for detecting mite allergens.     

Testing prey DNA fingerprinting on Amblyseius largoensis (Acari: Phytoseiidae) predation of Raoiella indica (Acari: Tenuipalpidae)

Molecular detection of predation by identifying prey markers in the digestive tract of predators has developed into a powerful tool to assess predator-prey systems in which diet identification is too time consuming or impossible. Here we explore its utility for detecting predation of the pest mite Raoiella indica Hirst by the predatory mite Amblyseius largoensis Muma, taking advantage of the color the predator acquires after eating this mite to cross-reference our results. For this, a ~410?bp segment of the cytochrome c oxidase subunit I (COI) mitochondrial gene marker specific for the subfamily Tetranychoidea was used. Amblyseius largoensis that had recently eaten were collected from greenhouse colonies containing both mites, and isolated from any other food source. Predator mites were taken for fingerprinting at 24, 48, 72 and 96?h of starving after collection, and the same process was repeated a second time, offering pollen as an alternative food source to see whether detection changed. Lastly, a sampling trial was conducted in the greenhouse, in which mites were collected regardless of their color and frozen immediately for fingerprinting. Raoiella indica DNA was detected for 48 h on starving predators, and for 96 h on those who had eaten pollen. The segment was detected in 26?% of the samples collected on the trial. This technique needs refinement specific for this system, but the results obtained here confirm that it could turn into a very useful tool for assessing aspects of this predator-prey system.     

Allergen exposure and control

Allergens produced by the house dust mites (family Pyroglyphidae) are probably the single most important allergens associated with asthma world wide. If exposure to these allergens in houses could be sufficiently reduced, then asthma symptoms may be markedly reduced and even prevented from being initiated. Only about half of the many attempts to reduce mite allergens in houses have shown any clinical benefit. One reason may be that exposure was not reduced enough-however exposure to mite allergens has never been measured in any trial. This review summarises previous allergen control trials and then provides an outline of allergen exposure, including the nature of exposure, the analytical methods available and the recognised risks of allergen exposure. This provides a perspective to evaluate the individual methods used to kill mites and to reduce exposure to the allergens. The object is to provide a framework to improve and develop allergen avoidance as an effective component of asthma management.The author is supported by a project grant from the National Heath and Medical Research Council of Australia.     

Grape downy mildew Plasmopara viticola, an alternative food for generalist predatory mites occurring in vineyards

Generalist phytoseiids are often observed for long periods on plants in the absence of prey, feeding on alternative foods and reaching high population levels. The persistence of generalist predatory mites on plants with a scarcity or absence of prey is a requirement for successful biocontrol strategies of herbivore mites. The importance of pollen as an alternative food for the support of generalist predatory mite populations is widely recognized. However, on grape the presence of pollen is often limited and thus other food sources should contribute towards generalist predatory mite persistence on perennial plants. Previous field observations reported the relationships between the population increases of generalist phytoseiids with late-season spread of grape downy mildew (GDM) Plasmopara viticola. In this study, we test the hypothesis that GDM could be a suitable food source for the predatory mites Amblyseius andersoni and Typhlodromus pyri. In the laboratory we compared the development times, oviposition rates and life-table parameters of predatory mites feeding on pollen or GDM mycelium and spores. Grape downy mildew supported the survival, development and oviposition of T. pyri and A. andersoni. Life-table parameters showed that GDM was a less suitable food source than pollen for both phytoseiid species and that it was more favorable for A. andersoni than for T. pyri. Implications for predator–prey interactions and conservation biological control in vineyards are discussed.     

Adaptive learning in arthropods: spider mites learn to distinguish food quality

Many herbivorous arthropods have been shown to possess learning capabilities, yet fitness effects of learning are largely unknown. In this paper, we test whether two-spotted spider mites (Tetranychus urticae) learn to distinguish food quality in choice tests, and whether this results in fitness benefits. Food consisted of cucumber plants with one of three degrees of feeding damage: undamaged (no mites), mildly damaged (infested by a mite strain adapted to tomato) and heavily damaged (infested by a mite strain adapted to cucumber). Mites were subjected to one choice test in a greenhouse and three sequential choice tests on leaf disks. Thereafter, individual mite performance was measured as oviposition rate over four days. In the course of the three small-scale choice tests, preference shifted towards less damaged food. The performance tests showed that learning was adaptive: mites learned to prefer the food type that yielded the higher oviposition rate. Interestingly, innate preferences in the greenhouse tests were close to those shown after learning in the small-scale tests. Given that both strains of mites had not experienced cucumber for several years, we hypothesize that the preference in the greenhouse was due to avoidance of mite odours rather than odours of damaged plants. Through its effect on foraging behaviour, adaptive learning may promote the evolution of host plant specialization in herbivorous arthropods.     

Grape powdery mildew as a food source for generalist predatory mites occurring in vineyards: effects on life-history traits

In several perennial cropping systems, generalist or omnivorous species represent important biocontrol agents. They can persist on plants by feeding on alternative foods when prey is scarce and potentially limit pest outbreaks. Among beneficials characterised by a wide food range, those belonging to the acarine family Phytoseiidae represent important biocontrol agents. Generalist predatory mites can develop and reproduce using various food sources as alternatives to their tetranychid prey. The presence of alternative food sources can also induce switching feeding behaviour of generalist predators from prey to alternative foods. We evaluated in the laboratory the role of the grape powdery mildew (GPM) for the survival, development and reproduction of Amblyseius andersoni and Typhlodromus pyri , two important beneficial phytoseiid mites, in European and North-American vineyards. We also compared life-history parameters obtained when feeding on GPM with those obtained feeding on tetranychids mite prey or cattail pollen. Results indicated that GPM is an adequate food source for generalist mite survival and development. Results suggest that GPM can sustain mite populations in the absence of higher quality food sources. Based on optimal foraging theory, comparison of life-history parameters on GPM and mite prey suggests that the disruption of phytophagous mite control by these predatory mites in the presence of GPM appears unlikely. Implications for biological control in vineyards are discussed.     

Ricoseius loxocheles,a phytoseiid mite that feeds on coffee leaf rust

One of the most important diseases of coffee plants is the coffee leaf rust fungus Hemileia vastatrix Berkeley and Broome (Uredinales). It can cause 30 % yield loss in some varieties of Coffea arabica (L.). Besides fungus, the coffee plants are attacked by phytophagous mites. The most common species is the coffee red mite, Oligonychus ilicis McGregor (Acari: Tetranychidae). Predatory mites of the Phytoseiidae family are well-known for their potential to control herbivorous mites and insects, but they can also develop and reproduce on various other food sources, such as plant pathogenic fungi. In a field survey, we found Ricoseius loxocheles (De Leon) (Acari: Phytoseiidae) on the necrotic areas caused by the coffee leaf rust fungus during the reproductive phase of the pathogen. We therefore assessed the development, survivorship and reproduction of R. loxocheles feeding on coffee leaf rust fungus and measured predation and oviposition of this phytoseiid having coffee red mite as prey under laboratory conditions. The mite fed, survived, developed and reproduced successfully on this pathogen but it was not able to prey on O. ilicis. Survival and oviposition with only prey were the same as without food. This phytoseiid mite does not really use O. ilicis as food. It is suggested that R. loxocheles is one phytoseiid that uses fungi as a main food source.     

Feather mites play a role in cleaning host feathers: New insights from DNA metabarcoding and microscopy

Parasites and other symbionts are crucial components of ecosystems, regulating host populations and supporting food webs. However, most symbiont systems, especially those involving commensals and mutualists, are relatively poorly understood. In this study, we have investigated the nature of the symbiotic relationship between birds and their most abundant and diverse ectosymbionts: the vane‐dwelling feather mites. For this purpose, we studied the diet of feather mites using two complementary methods. First, we used light microscopy to examine the gut contents of 1,300 individual feather mites representing 100 mite genera (18 families) from 190 bird species belonging to 72 families and 19 orders. Second, we used high‐throughput sequencing (HTS) and DNA metabarcoding to determine gut contents from 1,833 individual mites of 18 species inhabiting 18 bird species. Results showed fungi and potentially bacteria as the main food resources for feather mites (apart from potential bird uropygial gland oil). Diatoms and plant matter appeared as rare food resources for feather mites. Importantly, we did not find any evidence of feather mites feeding upon bird resources (e.g., blood, skin) other than potentially uropygial gland oil. In addition, we found a high prevalence of both keratinophilic and pathogenic fungal taxa in the feather mite species examined. Altogether, our results shed light on the long‐standing question of the nature of the relationship between birds and their vane‐dwelling feather mites, supporting previous evidence for a commensalistic–mutualistic role of feather mites, which are revealed as likely fungivore–microbivore–detritivore symbionts of bird feathers.     

Methods of assessment and control of house dust mites population and mite allergen exposure

The work is devoted to analysis of various methods of assessment and control of house dust mites population and mite allergens in city dwellings using own results and the literature data. Data about in-house dust mites biology and ecology, mechanisms of their migration and circulation in modern city conditions are presented. The comparison of several methods of mites number assessment and mite allergens exposure (classical acarological analysis, colorimetric method of guanine detection in house dust, immunochemical methods) has been performed and their advantages and disadvantages analyzed. As choice of adequate avoidance measures is one of the key question, various such measures (mechanical, physical and chemical) have been compared.     

Control of house-dust mites (Pyroglyphidae) with home disinfectants

Chemical disinfectants and biocidal preparations used in households were tested in the laboratory for their ability to kill the house-dust miteDermatophagoides farinae. Batches of ten specimens were soaked in aqueous solutions or suspensions containing 0.0, 0.1, 0.3, 1.0, 3.0 and 10.0% (by volume) of the test preparations. Direct effect was tested without food. Population effect was tested with food added.The results showed a high mortality with all preparations except for a regular carpet cleaner (containing detergents) and natamycin (a fungicide). Nevertheless, not all tested preparations are practical in the home environment. Best results in homes were obtained with a carpet cleaning solution which incorporates an acaricide (benzylbenzoate). This particular preparation has an outstanding acaricidal efficacy and can easily and routinely be used by the householder. The degree of cleanliness in the household is a measure of the number of house-dust mites and their allergens.     

Structural biology of mite allergens

Mite allergens contribute to a significant proportion of human allergic symptoms, including asthma and rhinitis. The development of therapies to treat and prevent these symptoms depends largely on our understanding of the properties of these allergens. Much effort has been devoted to determining the structure and organization of mite allergens, particularly of the house dust mites, toward understanding their activities and how they elicit immunological responses in humans. Here, we review the structural biology of the major allergens from two species of house dust mites, Dermatophagoides farinae and D. pteronyssinus, as well as allergens from a storage mite, Blomia tropicalis. The knowledge gained from the structural biology of these allergens will enable progress in producing novel, more effective treatments for mite allergies based on specific immunotherapy approaches.