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PubMed2004

The attachment and stylostome of Trombidium newelli (Acari: Trombidiidae), an ectoparasitic mite on adults of alfalfa weevil, Hypera postica (Coleoptera: Curculionidae).

Larvae of the mite Trombidium newelli Welbourn and Flessel are ectoparasitic on adult alfalfa weevil, Hypera postica (Gyllenhall), an insect pest of alfalfa. The mite larvae are found under the elytra, attached to the dorsal surface of weevils' abdomen. T. newelli larvae use their chelicerae to penetrate the pliable and weakly sclerotized areas of the host's integument, and to hold on firmly to the host. The attachment sites associated with larval mites of different degrees of engorgement were examined using both light and scanning electron microscopy. The ventral inside surface of parasitized host tergites revealed a characteristic injury as spots varying in color from white-yellow to golden-brown depending on the engorged size of the mite. In addition, spots associated with fully engorged mite larvae showed an aggressive dendritically radiating mass expanding outward from the site of cheliceral penetration. This mass, known as feeding tube or stylostome was branched, with each branch ending in a cluster of closed bulbs. Stylostomes appear to exist independently in the host's tissue. Stylostome mass corresponded with the engorgement state of the mite, increasing as the mite larva increased in size. The possible nature and mechanism of stylostome formation is discussed.

Animals↗
PubMed2006

Immigration of phytoseiid mites from surrounding uncultivated areas into a newly planted vineyard.

This study reports (1) a faunistic survey of phytoseiid mites observed inside a vine plot and in neighbouring vegetation (other vine plots and uncultivated areas) and (2) dispersal of phytoseiid mites into the plot studied. These data aim to raise some hypotheses concerning natural colonisation of a vineyard by predatory mites. The study was carried out over 3 years (1999, 2000 and 2001) in an experimental plot planted with two cultivars (Grenache and Syrah) and with Sorbus domestica in a framework of agroforestry investigations. Phytoseiid mites were collected in both cultivated and uncultivated areas surrounding the experimental plot, and their dispersal into the plot studied using "aerial" traps. Densities remained quite low compared to previous studies. The main species encountered in the uncultivated areas and in the traps was Typhlodromus phialatus. Despite the low numbers of phytoseiid mites trapped, densities of phytoseiid mites into the vine field increased during 3 years. Typhlodromus phialatus, the species mainly found in the neighbouring uncultivated areas, was rarely found in vineyards. Another morphologically close species was predominant on vines: Typhlodromus exhilaratus. However, Kampimodromus aberrans the main phytoseiid mite species in vineyards of Southern France was not found in the present survey. Hypotheses for this colonisation process are discussed.

Animals↗
PubMed2006

Intraspecies variation in the Kanzawa spider mite differentially affects induced defensive response in lima bean plants.

The Kanzawa spider mite, Tetranychus kanzawai, is a polyphagous herbivore that feeds on various plant families, including the Leguminacae. Scars made by the mite on lima bean leaves (Phaseolus lunatus) were classified into two types: white and red. We obtained two strains of mites--"White" and "Red"--by selecting individual mites based on the color of the scars. Damage made by the Red strain induced the expression of genes for both basic chitinase, which was downstream of the jasmonic acid (JA) signaling pathway, and acidic chitinase, which was downstream of the salicylic acid (SA) signaling pathway. White strain mites also induced the expression of the basic chitinase gene in infested leaves but they only slightly induced the acidic chitinase gene. The Red genotype was dominant over the White for the induction of the acidic chitinase gene. The amount of endogenous salicylates in leaves increased significantly when infested by Red strain mites but did not increase when infested by White strain mites. JA and SA are known to be involved in the production of lima bean leaf volatiles induced by T. urticae. The blend of volatiles emitted from leaves infested by the Red strain were qualitatively different from those infested by the White strain, suggesting that the SA and JA signaling pathways are differently involved in the production of lima bean leaf volatiles induced by T. kanzawai of different strains.

Animals↗
PubMed2001

Dust mites: update on their allergens and control.

Mites are ubiquitous organisms, and as a result, humans come into contact with mites and mite products in a variety of situations. Molecules from many mite species can induce IgE-mediated reactions. Best known among the allergy-causing mites are the house dust and storage mites. However, allergists should be aware that, in specific situations, contact with products of many other less-known species of mites also may cause IgE-mediated reactions.

Allergens↗
PubMed1979

The seasonal variation in a population of house dust mites in a North American city.

Mattress dust collected at monthly intervals for 2 1/2 yr was examined for mites. Both Dermatophagoides pteronyssinus and D. farinae were found. There was a significant association between the presence of live mites and the relative humidity (RH): Live mites were seen only when the RH had been greater than or equal to 50% for at least part of every day during the month of collection. There was a seasonal variation in that live mites were found only in the warmer months and not in the winter. However, the peak in the mite population was consistent neither for month nor for numbers: In 1977 a slight peak in mite numbers occurred in October, while in 1978 the peak was higher and occurred in July. Use of data from previously published studies to preduct mite levels may therefore be misleading.

Animals↗
PubMed1986

Immunochemical and enzymatic analyses of extracts of the house dust mite Dermatophagoides pteronyssinus.

The allergenicity and enzyme content of extracts of Dermatophagoides pteronyssinus whole mite, cuticle (CUT), and spent-growth medium (SGM) used in its culture have been examined. Both direct RAST binding and RAST-inhibition studies demonstrated that the whole mite extract was approximately threefold more potent than either the CUT or SGM extracts. Crossed immunoelectrophoresis and crossed radioimmunoelectrophoresis demonstrated that whole mite extracts contained 36 antigens of which nine were judged to be allergens (Dpt 1, 3, 4, 7, 8, 12, 17, 22, and 31). In contrast, extracts of CUT and SGM both contained 15 mite antigens of which five were judged to be allergens (Dpt 4, 8, 12, 17, and 22). Enzyme studies demonstrated that whole mite extracts from various sources contained esterases, phosphatases, aminopeptidases, and glycosidases. Both the CUT and SGM extracts contained a similar spectrum of enzymes, although the glycosidases were present at relatively low levels. Combined crossed immunoelectrophoresis and enzymic studies identified three antigens (Dpt 6, 13, and 24) with esterase activity, one antigen (Dpt 27) with beta-glucuronidase activity, and one antigen (Dpt 14) with acid phosphatase activity. Thus far, none of these enzymes has been demonstrated to be allergenic. Both enzymic and immunochemical studies suggested that not all mite allergens are of an excretory/secretory origin, but some (e.g., Dpt 1, 3, 4, 7, and 31) are derived from the whole mite per se.

Allergens↗
PubMed1989

Correlations between levels of mite and cat allergens in settled and airborne dust.

Thirty homes in Rochester, Minn., 20 of which housed cats, were studied to compare cat and mite allergen concentrations in airborne and settled dust. With Air Sentinels in the bedroom and living room for airborne collections, and a Sample Vac for collections from living room carpet and bedroom mattress, immunochemical quantifications of each were made with various radiometric assays with polyclonal and monoclonal antibodies. The most significant correlations were found between airborne mite in the bedroom and living room (p less than 0.001) and airborne mite in the bedroom and dust from the bedroom mattress (p less than 0.001). Most houses had specific epitopes of both Dermatophagoides pteronyssinus and D. farinae, but D. farinae was present in greater amounts. In seven houses we found greater than 10 micrograms of group I mite allergen per gram of settled dust, indicating that some houses in Minnesota have concentrations of mite allergens high enough to cause allergic disease, even in the winter. Clinical interpretation of these data on air levels is hampered by uncertainty as to whether symptoms are more closely related to average steady-state exposure, which we measured, or to brief heavy concentrations. Further epidemiologic studies are needed to define the concentration of mite and cat allergens in the air that are risk factors for allergic disease. The concentration of cat allergen correlated with mite allergen in the air, but not in settled dust, presumably reflecting the fact that both are influenced by ventilation rate.

Air↗
PubMed1991

House dust mite-derived amylase: allergenicity and physicochemical characterization.

Amylase activity was found in extracts of both Dermatophagoides pteronyssinus whole mite (0.16 U/mg) and spent growth medium (0.01 U/mg) but not in unused growth medium. It was also detected in all extracts of house dust obtained from mattresses (n = 20; geometric mean, 1.95 U/gm) and in 18 extracts of dust obtained from lounge room carpets (n = 20; geometric mean, 0.54 U/gm). Although the origins of amylase in dust are unclear, enzyme activity correlated with mite counts (n = 40; r = 0.35; p less than 0.05) and Der p I concentrations (r = 0.41; p less than 0.01). Mite amylase was purified from spent growth medium by affinity chromatography, gel filtration, and chromatofocusing. It was physicochemically similar to mammalian amylase with regard to molecular weight (60,000), charge heterogeneity (isoelectric point, 5 to 7) and the capacity to bind to an organomercurial affinity matrix. The optimum pH for enzymatic activity was revealed to be 6.4. IgE immunoblot studies demonstrated that the enzyme was allergenic and that its expression was dependent on the integrity of intrachain disulfide bonds. Sera from 25% of mite-allergic children and 46% of mite-allergic adults contained specific IgE to mite amylase. IgE to amylase was associated (p less than 0.01) with increased concentrations of total mite-specific IgE determined with a direct RAST assay.

Adult↗
PubMed1990

Immunohistochemical studies in mite antigen-induced patch test sites in atopic dermatitis.

The role of mite allergen in atopic dermatitis is still unclear. In this study, we investigated whether an eczematous reaction could be induced by patch testing with dust mite antigen. We succeeded in reproducing an eczematous lesion and the mite RAST-positive AD group showed a positive reaction much more than the RAST-negative group. Many mite antigen-bearing Langerhans cells, also possessing IgE molecules, were found by the use of an immuno-double labelling technique. By using immunoelectron microscopy, it was observed that the mite antigens were trapped by some macrophages, which were apposed to lymphocytes. To investigate the time-course of the reaction, the patch test reactions were read and biopsied after 1 h, 6 h, 24 h and 48 h. An eczematous reaction developed 24 h after patch testing. The mite antigen-bearing Langerhans cells were seen exclusively in the epidermis after 6 h, and mainly in the dermis after 24 h and 48 h. These results suggested that IgE-mediated contact hypersensitivity to mite antigen may develop and play an important role in AD.

Adolescent↗
PubMed2005

Predictions of summer diapause in the redlegged earth mite, Halotydeus destructor (Acari: Penthaleidae), in Australia.

A prediction for the onset of a summer diapause in the eggs of the redlegged earth mite, Halotydeus destructor, was developed for Australia. In this species diapause eggs pass the summer in the cadavers of adult female mites. Adult female mites were collected for several weeks from pastures in spring at 18 sites in south-western Australia and dissected to determine the timing of the production of diapause eggs. Some sites were sampled for several years between 1990 and 1997. A model was developed to predict the time for onset of diapause. The week at which 90% of eggs were in diapause was predicted best by daylength (80.1% of the variability), then by duration of the long-term plant growing season (10.4%, of variability), leaving 9.5% due to other factors. A single chemical spray in spring 2 weeks before the production of 90% diapause eggs resulted in 99% fewer mites present in autumn 7-8 months later at three sites. The timing of the spring spray was the factor leading to successful control. This model was tested at 17 sites across the whole geographical distribution of the redlegged earth mite in Australia between 1998 and 2001. The observed week of 90% diapause was within 1 week of the predicted week on 81% of occasions, and 2 weeks earlier on 15% of occasions. A database was created for the predicted date of onset of 90% diapause for the whole distribution of the redlegged earth mite in southern Australia on a 10 km(2) grid. Australian farmers are using this for timing a spring spray to control mites in the following autumn.

Animals↗
PubMed2005

Biotic interactions of mites, plants and leaf domatia.

Leaf domatia, minute structures that typically house mites and other small arthropods, are produced by an impressive number of plants; however, their role in mediating plant-mite mutualism has only recently been elucidated. New evidence indicates that domatia function primarily as refuges for beneficial mites against predators. The presence of domatia therefore results in more beneficial mites on leaves, fewer pathogen attacks and reduced leaf herbivory. Unexpectedly, herbivorous mites are specialized domatia inhabitants of some plants. By providing refuges for herbivores, however, domatia may stabilize interactions between predator and their mite prey and thereby reduce the chances of herbivore outbreaks. Understanding the ecological mechanisms that promote beneficial interactions between mites and plants could have important implications for pest management.

Animals↗
PubMed1992

Prevalence of dust mites in the homes of people with asthma living in eight different geographic areas of the United States.

The density and species prevalence of dust mites were determined at various times over a 5-year-period in 252 homes of dust mite sensitive people with asthma who lived in eight geographic areas of the United States (Cincinnati, Ohio; New Orleans, La.; Memphis, Tenn.; Galveston, Texas; Greenville, N.C.; Delray Beach, Fla.; San Diego and Los Angeles, Calif.). The most common dust mites found in the homes were Dermatophagoides farinae (DF), D. pteronyssinus (DP), Euroglyphus maynei (EM), and Blomia tropicalis. All homes in all locations contained Dermatophagoides spp. mites, but few homes were populated exclusively by either DF or DP alone. Most homes (81.7%) were coinhabitated by both DF and DP. In coinhabited homes one species was predominant and usually made up at least 75% of the total mite population. Prevalence of the dominant or only species present varied between homes within a geographic area. EM occurred in significant numbers in 35.7% of homes in New Orleans, Memphis, Galveston, Delray Beach, and San Diego. Blomia tropicalis occurred in these same cities but in low densities. For all dust samples, only 13 homes of the 252 sampled had 100 or fewer mites/gm dust, which is considered to be the threshold for sensitivity. Most homes had average mite densities of 500 or more mites/gm dust. The results of the present study suggest a significant and widespread occurrence of both DF and DP. Therefore extracts of both mite species should be considered for diagnostic tests and immunotherapy. Significant levels of EM were present in some areas. Thus sensitivity to EM should be considered in these areas.

Adolescent↗
PubMed1996

Evaluation of household dust mite exposure and levels of specific IgE and IgG antibodies in asthmatic patients enrolled in a trial of immunotherapy.

BACKGROUND: Monitoring the response to immunotherapy entails understanding exposure to relevant allergens. For the major indoor allergens, this requires sampling of dust from the patient's house. The objectives of this study were to measure indoor allergen levels during a controlled trial of dust mite immunotherapy for asthma and to relate these results to serum antibody levels. METHODS: Eighty-eight asthmatic patients with mite allergy from seven geographic areas in the United States were enrolled in and completed a course of immunotherapy with Dermatophagoides extract or placebo control. Sensitization was evaluated by quantitative measurements of IgG and IgE antibodies. Dust samples were assayed for group I mite (Der p 1 and Der f 1), cat (Fel d 1), and cockroach (Bla g 1) allergens by monoclonal antibody-based ELISA. RESULTS: Over the 4 years of the study, each of the houses had at least one sample that contained more than 2 micrograms of group I mite allergen per gram of dust. Mean mite allergen levels, however, varied over a wide range, from 0.2 microgram/gm or less to more than 50 micrograms/gm. IgE antibodies to mite were present in sera from 78% of the patients, whereas IgE antibodies to cat and cockroach allergens were found in sera from 34% and 11% of patients, respectively. Sixty-four percent of the patients had exposure and sensitization to mite, whereas the comparable figure for each of the other allergens was 5%. CONCLUSIONS: Examination of the results suggested that allergen exposure, relative to a trial of immunotherapy, could be expressed as (1) the maximum level found in the house, (2) the percentage of sites having greater than 2 micrograms/gm, or (3) the mean value at the site with the maximum level. This report provides a background for evaluating the clinical results of immunotherapy in these patients and a model for the way in which sensitization and exposure should be monitored in studies of this kind.

Adolescent↗
PubMed1996

False-positive skin prick test responses to commercially available dog dander extracts caused by contamination with house dust mite (Dermatophagoides pteronyssinus) allergens.

BACKGROUND: In an outpatient population, a high frequency of positive skin prick test responses to dog dander was found in the absence of detectable IgE to dog dander in the RAST. The majority of these patients were sensitized to house dust mites (Dermatophagoides pteronyssinus) and had no obvious dog-related allergic symptoms. These findings prompted us to investigate whether dog dander skin test preparations are contaminated with house dust mite allergens in amounts sufficient to cause false-positive skin prick test responses in patients sensitized to house dust mites. METHODS: Antigen detection assays with monoclonal and polyclonal antibodies were used to determine concentrations of the major allergen Can f 1 from dog dander and the major allergens Der p 1 and Der p 2 from house dust mites in five commercially available dog dander skin prick test preparations (A to E). RESULTS: Can f 1 concentrations varied for the different extracts (A: 170 micrograms/ml, B: 11.1 micrograms/ml, C: 13.3 micrograms/ml, D: 3.8 micrograms/ml, and E: 59.4 micrograms/ml). Der p 1 was detectable in all extracts (A: 33.4 ng/ml, B:5.1 ng/ml, C:29.6 ng/ml, D: 0.4 ng/ml, and E: 1.9 ng/ml), and Der p 2 was detectable in some of the commercially available dog dander skin prick test preparations tested (A: 31.3 ng/ml, B: 3.0 ng/ml, and C: 7.5 ng/ml). The median house dust mite threshold in the skin prick test was found to be 5.8 ng/ml, of Der p 1 (range, 3.5 to 20.8 ng/ml) in nine patients tested. CONCLUSION: Contamination of commercially available dog dander skin prick test preparations with the major allergens (Der p 1 and Der p 2) of the house dust mite (D. pteronyssinus) was demonstrated. These contaminations cause false-positive responses to skin prick tests with dog dander in patients sensitized to house dust mite.

Allergens↗
PubMed1996

MHC class II restriction for T cell proliferative response to mite antigen.

BACKGROUND: We investigated the immunoreguratory role of the major histocompatibility complex in peripheral blood lymphocytes' proliferative response to mite antigen. METHOD: Peripheral blood lymphocytes of Japanese asthmatic patients were incubated with antigen obtained from Dermatophagoides pteronyssinus with a molecular weight of about 15,000, with and without 0.05 microgram/mL of monoclonal antibody against HLA class I or class II for seven days at 37 degrees C humidified in 5% CO2 and 95% air. RESULTS: High and low responders to the mite body antigen were found among the patients while there were no high responders among the healthy individuals tested. In the mite-sensitive asthmatic patients, CD4+ T cells were the population that responded to the antigen. Depletion of CD8+ T cells from the peripheral blood lymphocytes of mite-insensitive individuals caused high responsiveness to the antigen, indicative that the mite-specific CD4+ T cells controlled the high responsiveness and the antigen-specific CD8+ T cells, the low responsiveness. Anti-HLA-DR monoclonal antibody inhibited responsiveness. In contrast, anti-HLA-DQ monoclonal antibody produced high responsiveness in low responders to mite antigen. CONCLUSION: High T cell proliferative responsiveness to mite antigen was restricted by HLA-DR antigen through CD4+ T cells in high responders, whereas HLA-DQ antigen is a restriction antigen of low responsiveness through CD8+ T cells in low responders and non-atopic individuals.

Animals↗
PubMed1987

Mite fauna of dust from passenger trains in Glasgow.

The mite fauna of dust from cloth-covered seats of four passenger trains and bedding from a British Rail linen store in Glasgow was investigated; 22 samples containing 4488 mg of dust from a total surface area of 5.5 m2 were taken. Sixteen samples were positive for mites and 33 specimens belonging to 10 species were found. The most common species were Dermatophagoides pteronyssinus (Trouessart), Glycyphagus domesticus (De Geer), G. destructor (Schrank) and Euroglyphus maynei (Cooreman). The species composition bore considerable resemblance to that of house dust (although the density of mites was far lower) and the mites have probably been transported from homes via clothing and pets. Only five intact specimens, which may have been alive at the time of sampling, were found. The dust from trains consisted mostly of particles of soot. Very few skin scales, the food source of house dust mites, were detected. The small numbers of intact mites found and the absence of an identifiable food source make it unlikely that permanent populations of mites survive in upholstered seats on trains.

Animals↗
PubMed1999

High temperatures eliminate Wolbachia, a cytoplasmic incompatibility inducing endosymbiont, from the two-spotted spider mite.

Wolbachia can induce cytoplasmic incompatibility (CI) in the arrhenotokous two-spotted spider mite between uninfected females and infected males. Cytoplasmic incompatibility is expressed through a male-biased sex ratio and a low hatchability, and can be suppressed by removing Wolbachia from spider mites reared on a diet with antibiotics. Here we investigated whether heat-treatment can elimate Wolbachia from infected mites. Using a PCR assay with a Wolbachia-specific primer pair (ftsZ), and by standard crosses, we were able to show that 71 per cent of the mites had lost the Wolbachia infection after rearing the infected population at 32+/-0.5 degrees C for four generations. The infection could be completely removed when mites were reared at 32+/-0.5 degrees C for six generations. Curing through high temperatures could be one of the reasons why mixed infected/uninfected populations occur in the field. An additional consequence of rearing mites at 32+/-0.5 degrees C was the shortened development time. The effect of environmental temperature on the abundance of Wolbachia and possible behavioural consequences for the spider mite are discussed.

Administration, Oral↗
PubMed2000

First detection in Israel of fluvalinate resistance in the varroa mite using bioassay and biochemical methods.

The aim of this study was to explore the extent of varroa mite resistance to fluvalinate in Israel and to determine the underlying biochemical mechanism. Assays at different apiaries indicated varroa mite resistance at three of the five sites tested. Dose response assays conducted with tau-fluvalinate on mites obtained from different sites indicated uneven resistance. A monooxygenase assay revealed an increased rate (approximately 20-fold) of activity in mites that were not controlled by the pesticide, as compared to activity in mites from untreated colonies. A minor, 1.5-2.5 fold, increase of esterase activity was also noted in the resistant mites. This first demonstration of a fluvalinate-resistance mechanism in varroa mites points to the need for more vigorous resistance management practices to control the pest.

Animals↗