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PubMed1990

Morphometric analysis of Psoroptes spp. mites from bighorn sheep, mule deer, cattle, and rabbits.

A morphometric study of Psoroptes spp. mites was conducted to address difficulties encountered in species identification and to provide insights into the phylogenetic relationships between mites found on different hosts. A discriminant analysis employing 9 morphologic characters revealed that the lengths of the outer opisthosomal setae and the lateral margins of the opisthosomal knobs were the 2 most important characters for grouping mites according to host species. This analysis clearly separated mites collected from allopatric populations of bighorn sheep, rabbits, and cattle into discrete groups. However, differences were not detected between mites collected from sympatric populations of infested mule deer and bighorn sheep, suggesting that these mites were not host specific and represented a single interbreeding population. Differences also were not detected among mites collected from the ears and body of bighorn sheep and rabbits, demonstrating that the location of mites on a given host should not be used as a primary criterion in species identification.

Animals↗
PubMed1980

Relationship of wheat streak mosaic and barley stripe mosaic viruses to vector and nonvector eriophyid mites.

Large amounts of wheat streak mosaic virus (WSMV) accumulate in the midgut of its mite vector Eriophyes tulipae reared on virus infected plants. Masses of flexuous rod shaped virus particles persisted in the midgut, without degradation, for at least 5 of the 6--9 day adult life of mites. WSMV particles also were found distributed in the body cavity and in salivary glands of mites suggesting that the virus is "circulative" in E. tulipae. Abacarus hystrix, a nonvector of WSMV, when reared on virus infected plants, occasionally contained a small number of virus particles in its gut only. Extracts of such mites were not infective. Barley stripe mosaic (BSMV)--a rod-shaped virus, was not transmitted by E. tulipae, although a large concentration of virus particles was found in the midgut of mites reared on virus infected plants. Extracts of such mites were infective and the virus particles were retained for several days in the gut of such mites held on virus-free plants. BSMV particles were also found in the body cavity of mites. Possible reasons for E. tulipae being a nonvector of BSMV are discussed.

Animals↗
PubMed2002

Dust mite allergens: ecology and distribution.

The most important allergy-causing mites found in homes worldwide are the house dust mites Dermatophagoides farinae, D. pteronyssinus, Euroglyphus maynei, and the storage mite Blomia tropicalis. Most homes contain multiple species. The most prevalent mite species and allergen in homes differ geographically, between homes within a geographical region, and among areas within a home. Therefore, it is important to know which mite species are present in a geographical area when performing diagnostic testing and prescribing immunotherapy. The key factor that influences mite survival and prevalence is relative humidity. Mites are present in homes in humid geographical areas and are rare or absent in drier climates unless humidity is artificially raised. Generally speaking, dust mite allergen levels are low in public buildings and transportation compared to levels in homes.

Allergens↗
PubMed1992

Effective education of adults with asthma who are allergic to dust mites.

The effects of supplementary computer instruction in house dust mite-avoidance measures on adherence to implementing measures, on home dust mite-allergen levels, and on symptomatology were investigated in 52 adult patients with mite-associated asthma. Twenty-six patients received conventional instruction (counseling and written instruction) and the other 26 patients received conventional plus 22 minutes of interactive computer-assisted instruction. Instructions were aimed at mite-avoidance measures. Pre- and postinstruction dust samples were collected, and adherence was monitored. All patients kept symptom diaries twice a day. Patients' progress was followed for 12 weeks, and all patients completed the study. Adherence, number of observed and self-reported mite-avoidance measures implemented after visit, was higher for the computer group (p = 0.023). The computer-instructed group achieved significantly lower levels of mite allergen in bedroom carpets (p = 0.004) with mean levels of mite allergen declining from 6.5 +/- 7.6 to 2.2 +/- 4.3 micrograms/gm of dust (two-site monoclonal antibody assays), whereas levels for the conventional-instructed group did not change. Moreover, by study weeks 9 and 10, the computer-instructed group was significantly less symptomatic (p = 0.033). Mean symptom scores for this group decreased from 12.4 to 7.7, compared with 16.4 to 14.3. Conventional instruction supplemented with computer instruction is suggested in mite education.

Adolescent↗
PubMed2005

Bacterial 16S ribosomal DNA in house dust mite cultures.

BACKGROUND: Allergen extracts prepared from Dermatophagoides farinae contain significantly more endotoxin than Dermatophagoides pteronyssinus extracts, and extracts from both mite extracts contain more endotoxin than pollen extracts. Attempts to culture bacteria from mite cultures have failed to establish the sources of the endotoxin. OBJECTIVE: To determine the bacterial sources of endotoxin in mite extracts. METHODS: Live mites of both species were obtained from 2 sources, DNA was extracted from the mites, and DNA encoding bacterial 16S ribosomal RNA was amplified by using specific primers. The amount of bacterial DNA in each mite DNA sample was determined by quantitative PCR using an internal standard, and sequence homologies were determined from amplifications performed by using a high-fidelity DNA polymerase. RESULTS: DNA from D farinae appeared to contain between 11-fold and 24-fold more 16S ribosomal gene copies than the genomic DNA from D pteronyssinus (P < or = .003). Sequence analysis indicated the dominant presence of at least 3 phylogenetic clusters of Bartonella species (henselae, quintana, vinsonii, and grahamii), as well as uncharacterized alpha-proteobacteria, from both D farinae and D pteronyssinus. In a few clones, sequences from Escherichia coli, Pseudomonas species, and Acinetobacter species were also identified. CONCLUSION: House dust mite DNA contains evidence of Bartonella and other Gram-negative species. These Gram-negative species are likely to be the sources of the endotoxin found in mite allergenic extracts.

Animals↗
PubMed2004

Dust mites living in human lungs--the cause of asthma?

Asthma does not have a clear cause and may represent a cluster of diseases. We propose that asthma in house dust mite sensitive patients may be caused by recurrent inhalation of live dust mites which are able to live for some time in the bronchioles of the lung. To provide themselves with a food source, the mites may purposefully excrete proteolytic enzymes, including Der p1, which increase epithelial shedding by freeing cells from the basement membrane. The mites then feed on the shed respiratory epithelial cells. Consequent loss of an intact respiratory epithelium exposes underlying tissues to dust mite protein and other allergens triggering sensitisation to these proteins. Later, repeated infestation provokes an allergic response which manifests itself as asthma attacks. The evidence for this hypothesis was tested against the Bradford-Hill criteria for causation; consistency, strength, temporal association and dose response. Potential areas for further research were also identified. The association between asthmatic symptoms and pulmonary acariasis was consistent across a number of studies. Determining the strength of the association and any dose response requires more work which is dependent on the development of better tests for the detection of mites in sputum. There was tentative evidence of a temporal association in the published studies identified. Biological plausibility and experimental evidence was available for pulmonary acariasis in primates and arsenic treatment was effective in humans. Better tests for mites in sputum are needed, as is work to assess more modern anti-acaricidal drugs in dust mite sensitive asthmatics.

Allergens↗
PubMed1998

Isolation and characterization of a novel 98-kd Dermatophagoides farinae mite allergen.

BACKGROUND: Exposure to allergens from house dust mites is a significant cause of immediate hypersensitivity. Thus far, the active mite allergens defined are low molecular weight (MW) proteins or glycoproteins. However, other important mite allergens remain to be investigated. In this study a high MW mite antigen with a high IgE-binding activity was characterized. METHODS: An anti-Dermatophagoides farinae (Df) monoclonal antibody, mAb642, which recognized a 98-kd allergenic mite protein, was used for affinity chromatography. The purified Df642 was characterized biochemically and immunologically. RESULTS: Competitive ELISA demonstrated that mAb642 was inhibited by the interaction between serum IgE from allergic patients and Df642 antigen in a dose-dependent fashion. The IgE reactivity to both 98-kd and 92-kd components was removed or diminished by preincubation of asthmatic sera with Df642-coated CNBr-activated cellulose-4B gel. Two-dimensional immunoblot analysis revealed that there are at least 4 isoforms of Df642 that represent a minor component in the crude mite extract. The allergenicity of Df642 was assayed by IgE immunoassay with a large panel of 67 sera from asthmatic patients with positive skin reactions, and Df 642 showed positive IgE reactivity with more than 80% of the sera tested. Thus it should be classified as an important allergen. In addition, amino acid sequence analysis revealed that Df642 shares more than 50% homology with paramyosin from invertebrates. CONCLUSION: We have identified and characterized a 98-kd house dust mite allergen that showed greater than 80% IgE reactivity with sera from patients allergic to mites. This is the first high MW allergen characterized to date, and it shares high sequence homology with paramyosins in invertebrates.

Adolescent↗
PubMed2000

Partial mattress encasing significantly reduces house dust mite antigen on bed sheet surface: a controlled trial.

BACKGROUND: The most effective measure in house dust mite antigen reduction is mattress encasing with an impermeable membrane. A reduction in encasing costs will help increase patients' compliance in mite antigen avoidance. OBJECTIVE: To investigate the effectiveness of partial mattress encasing with a nylon sheet produced in Thailand on the reduction of group I mite antigens from beddings. METHODS: Sixty regularly-used beds from the house officers' dormitory of the Siriraj Hospital Mahidol University, Thailand, were randomly matched into two groups according to mite antigen levels. The control group (CG) used only regular cotton bed sheets whereas the partial encasing group (PG) used mattresses partially covered with a locally produced nylon sheet underneath the regular cotton bed sheets. Dust collection from the beddings was performed at baseline, 2, 4 and 6 months after application of the nylon sheet. Mite antigen levels were detected by a two step monoclonal antibody ELISA. RESULTS: Mite antigen levels in both groups were not different at the beginning of the study. The PG had significantly lower group I antigen levels on regular bed sheet surfaces than the CG (P < .004) at the 2, 4 and 6 month timepoints. However, antigen levels on the mattress surface of the PG was significantly higher than the CG at the end of the study (P < .004). The barrier efficacy of the nylon sheet in preventing migration of group I mite antigens from the mattress to the surface of the regular cotton bed sheet was 94% whereas that of the regular cotton bed sheet was 66% (P = .007). CONCLUSION: Partial mattress encasing with a locally made nylon sheet can reduce mite antigens on the regular cotton bed sheet surfaces for up to 6 months.

Animals↗
PubMed2000

Spider-mite problems and control in Taiwan.

Problems with spider mites first appeared in Taiwan in 1958, eight years after the importation of synthetic pesticides, and the mites evolved into major pests on many crops during the 1980s. Of the 74 spider mite species recorded from Taiwan 10 are major pests, with Tetranychus kanzawai most important, followed by T. urticae, Panonychus citri, T. cinnabarinus, T. truncatus and Oligonychus litchii. Most crops suffer from more than one species. Spider mites reproduce year-round in Taiwan. Diapause occurs only in high-elevation areas. Precipitation is the most important abiotic factor restricting spider-mite populations. Control is usually accomplished by applying chemicals. Fifty acaricides are currently registered for the control of spider mites. Acaricide resistance is a serious problem, with regional variation in resistance levels. Several phytoseiid mites and a chrysopid predator have been studied for control of spider mites with good effect. Efforts to market these predators should be intensified so that biological control can be a real choice for farmers.

Animals↗
PubMed2001

Comparison of cultivars of ornamental crop Gerbera jamesonii on production of spider mite-induced volatiles, and their attractiveness to the predator Phytoseiulus persimilis.

We investigated whether volatiles produced by spider mite-damaged plants of four gerbera cultivars differ in attractiveness to Phytoseiulus persimilis, a specialist predator of spider mites, and how the mite-induced odor blends differ in chemical composition. The gerbera cultivars differed in resistance, as expressed in terms of spider mite intrinsic rate of population increase (rm). In order of increasing resistance these were Sirtaki, Rondena, Fame, and Bianca. To correct for differences in damage inflicted on the cultivars, we developed a method to compare the attractiveness of the blends, based on the assumption that a larger amount of spider mite damage leads to higher attraction of P persimilis. Spider mite-induced volatiles of cultivars Rondena and Bianca were preferred over those of cultivar Sirtaki. Spider mite-induced volatiles of cultivars Sirtaki and Fame did not differ in attractiveness to P. persimilis. Sirtaki plants had a lower relative production of terpenes than the other three cultivars. This was attributed to a low production of cis-alpha-bergamotene, trans-alpha-bergamotene, trans-beta-bergamotene, and (E)-beta-farnesene. The emission of (E)-beta-ocimene and linalool was lower in Sirtaki and Fame leaves than in Bianca and Rondena. The importance of these chemical differences in the differential attraction of predatory mites is discussed.

Animals↗
PubMed2001

The occurrence of mites in cereal-based foods destined for human consumption and possible consequences of infestation.

Seven categories of cereal-based food products purchased at food retail outlets in UK were examined for the presence of mites by analysing 20 g samples using a flotation method. Mites were found in 21% of 571 samples, which were examined soon after purchase, and in 38% of 421 samples, derived from the 571 samples which were examined after 6 weeks of storage in volunteers' homes. Most of the samples where mites were detected had fewer than five mites. However, a few samples contained more than 20 mites with a maximum of 428 mites detected in a single sample. Sixteen families, genera or species of mites were recovered. The most common species were Acarus siro. Tyrophagus putrescentiae, Lepidoglyphus destructor and Glycyphagus domesticus. The level of contamination was broadly similar for each of the seven categories of products examined. It is likely that infestation occurs at every stage of food processing and storage. This is the first study of its kind and there is no reason to believe that results from similar studies carried out in other temperate countries would be markedly different. Increase in the percentage of contaminated samples following storage in a domestic situation suggests that the domestic environment is an important factor in developing infestation. The implications of mite contamination on food quality and on human health are briefly discussed.

Animals↗
PubMed2001

The role of cuticular compounds in the resistance of honey bees (Apis mellifera) to tracheal mites (Acarapis woodi).

This study examined the migration of tracheal mites (Acarapis woodi) into honey bees (Apis mellifera) from different colonies and the relative attraction of mites to hexane extracts from the external body surfaces of young bees. Relative resistance of bees from different colonies initially was assessed with a field bioassay that involved tagging newly emerged bees, pooling them in heavily mite-infested colonies, retrieving them 7 days later, and examining them for tracheal mite prevalence and abundance. For those colonies identified as most resistant and least resistant, cuticular chemicals were extracted in hexane from frozen, newly emerged worker bees. These extracts were presented to individual tracheal mites in pairwise fashion in a laboratory bioassay. The results demonstrated that mites prefer extracts of bees from some colonies more than others, however, no consistent differences were demonstrated. Our inability to predict mite responses to extracts based on our initial assessment of relative resistance indicates that other mechanisms of resistance influence mite success in colonizing new host bees.

Animals↗
PubMed2001

Predatory mites avoid ovipositing near counterattacking prey.

Attacking prey is not without risk; predators may endure counterattack by the prey. Here, we study the oviposition behaviour of a predatory mite (Iphiseius degenerans) in relation to its prey, the western flower thrips (Frankliniella occidentalis). This thrips is capable of killing the eggs of the predator. Thrips and predatory mites - apart from feeding on each other - can also feed and reproduce on a diet of pollen. Because thrips may aggregate at pollen patches, such patches may be risky for oviposition by the predatory mites. We found that, in absence of thrips, predatory mites lay their eggs close to pollen, but further away when thrips are present. Predatory mite eggs near pollen were killed more frequently by thrips than when they were deposited further away. The oviposition behaviour of the predatory mite was also studied in absence of thrips, but in presence of the alarm pheromone of thrips. This pheromone is normally secreted upon contact with predators or competitors. When applied close to the pollen. predatory mites oviposited significantly further away from it. When the alarm pheromone was applied away from the food source, most eggs were found near the pollen. These results indicate that female predatory mites show flexible oviposition behaviour in response to the presence of their counterattacking prey.

Animals↗
PubMed2003

Distribution of deformed wing virus within honey bee (Apis mellifera) brood cells infested with the ectoparasitic mite Varroa destructor.

The distribution of deformed wing virus (DWV) in adult female Varroa destructor and in their progeny in relation to the pupal host bee was investigated to evaluate acquisition and transfer of DWV by the mites. The results clearly show that adult female mites regularly act as competent vectors of DWV, however, they do not acquire or transfer virus on all possible occasions. Mother mites may contain DWV while the pupal host remains free from overt infection and both mother mites and mite progeny may not acquire detectable amounts of DWV from an infected host bee. However, a majority of mites feeding on pupae that emerge with deformed wings will contain DWV. The data also demonstrates that both adult and immature mite progeny most likely acquire DWV from DWV-infected host bees and not from their mother mites. Possible explanations for the obtained results are discussed.

Animals↗
PubMed2004

Molecular phylogeny of oribatid mites (Oribatida, Acari): evidence for multiple radiations of parthenogenetic lineages.

Nucleotide sequences of the D3 expansion segment and its flanking regions of the 28S rDNA gene were used to evaluate phylogenetic relationships among representative sexual and asexual oribatid mites (Oribatida, Acariformes). The aim of this study was to investigate the hypothesis that oribatid mites consist of species-rich clusters of asexual species that may have radiated while being parthenogenetic. Furthermore, the systematic position of the astigmate mites (Astigmata, Acariformes) which have been hypothesised to represent a paedomorphic lineage within the oribatid mites, is investigated. This is the first phylogenetic tree for oribatid mites s.l. (incl. Astigmata) based on nucleotide sequences. Intraspecific genetic variation in the D3 region was very low, confirming the hypothesis that this region is a good species marker. Results from neighbour joining (NJ) and maximum parsimony (MP) algorithms indicate that several species-rich parthenogenetic groups like Camisiidae, Nanhermanniidae and Malaconothridae are monophyletic, consistent with the hypothesis that some oribatid mite groups diversified despite being parthenogenetic. The MP and maximum likelihood (ML) method indicated that the D3 region is a good tool for elucidating the relationship of oribatid mite species on a small scale(genera, families) but is not reliable for large-scale taxonomy, because branches from the NJ algorithm collapsed in the MP and ML tree. In all trees calculated by different algorithms the Astigmata clustered within the oribatid mites, as proposed earlier.

Animals↗
PubMed2003

IgE-mediated sensitization to predatory mites in Swedish greenhouse workers.

BACKGROUND: Predatory mites are used as biological pesticides worldwide for control of spider mites and other pests in greenhouses. The aim of this study was to investigate if predatory and spider mites give rise to sensitization among greenhouse workers who use biological pesticides. METHODS: Blood samples were collected from 31 greenhouse workers from Stockholm area who were using the predatory mites Phytoseiulus persimilis and Hypoaspis miles for control of pesticides. Immunoglobulin E (IgE) binding to extracts of P. persimilis and H. miles and of the spider mite Tetranychus urticae was analysed with sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. RESULTS: A total of 16 workers displayed IgE antibodies to one or more of the three mite species, 32% (n = 10) to P. persimilis, 52% (n = 16) to H. miles and 26% (n = 8) to T. urticae. At least 17 IgE binding components in the molecular weight ranging from 28 to >94 kDa were identified in P. persimilis. In H. miles, at least 11 components were detected, among them at least one major component at about 70 kDa. Twenty-four IgE binding components were found in T. urticae. CONCLUSIONS: In this study we have for the first time shown that the predatory mites P. persimilis and H. miles can cause IgE-mediated sensitization among greenhouse workers. The clinical relevance of sensitization to predatory mites needs to be investigated in further studies.

Adult↗
PubMed2003

Lack of human IgE cross-reactivity between mite allergens Blo t 1 and Der p 1.

BACKGROUND: The group 1 mite allergens are the most significant indoor allergens and they belong to the papain-like cysteine protease family. To date there is only one published report on the isolation and characterization of group 1 allergens from Blomia tropicalis mites. The aims of the study are to determine the cross-reactivity between group 1 allergens and to evaluate their clinical importance in allergic patients. METHODS: The full-length Blo t 1 gene was obtained by SMART RACE cDNA amplification method using gene-specific primers. The sequence alignment was performed using LOOK followed by three-dimensional homology modeling. The cDNA was expressed in Pichia pastoris as a secretory protein. Identification of native Blo t 1 in crude mite and spent mite medium extracts was done by Western immunoblot using monoclonal antibody. Allergenicity of recombinant Blo t 1 and native Der p 1 was examined by human IgE ELISA with 80 asthmatic sera. RESULTS: The cDNA sequence consists of 1105 base pairs, including 5'- and 3'-untranslating regions, encoding an open reading frame of 330 amino acid residues. The predicted molecular weight of the deduced protein was approximately 38 kDa. Blo t 1 shared 53 and 34% nucleotide and amino acid, respectively, sequence homology with Der p 1. Native Blo t 1 was detected in both crude mite and spent mite medium extracts, and its estimated molecular weight was about 26 kDa. The recombinant Blo t 1 reacted positively with IgE in 90 and 65% of sera from asthmatic children and adults, respectively, indicating that it is a major allergen. The correlation of human IgE reactivity between Blo t 1 and Der p 1 was low in these sera. CONCLUSION: The full-length cDNA encoding group 1 Blomia tropicalis mite allergen (designated as Blo t 1) has been characterized and expressed from local mites in Singapore. This fecal allergen showed high frequency of human IgE reactivity with asthmatic sera in the tropics and there was a low correlation of IgE reactivity between Blo t 1 and Der p 1.

Adolescent↗
PubMed2001

Bumblebee commercialization will cause worldwide migration of parasitic mites.

We investigated natural populations of three Japanese native bumblebee species to determine the status of infestation by a tracheal mite, Locustacarus buchneri, which we had earlier detected in introduced commercial colonies of the European bumblebee, Bombus terrestris. We also investigated mite infestation in commercial colonies of a Japanese native species, B. ignitus, which are mass-produced in the Netherlands and reimported into Japan. We detected the mite in both natural and commercial colonies of the Japanese species. Comparison of 555 bp sequences of the mitochondrial DNA (mtDNA) cytochrome oxidase 1 (CO1) gene from the mite showed that there were seven haplotypes, on the basis of combinations of substitutions at eight sites in the gene. The haplotypes of the mites in the Japanese native bumblebees and the haplotypes of the mites in B. terrestris did not overlap; however, mtDNA of mites detected in the commercial colonies of B. ignitus possessed the same sequence as a European haplotype. These results indicate that transportation of bumblebee colonies will cause overseas migration of parasitic mites of different origins.

Animals↗