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At least 811 records · Page 45Linked to original sources

Development of precipitating antibody in chickens experimentally infested with northern fowl mite, Ornithonyssus sylviarum (Acari: Macronyssidae).

In order to examine the immune response of chickens to different population levels of mites, a microscopic slide modification of the Ouchterlony double-gel diffusion technique was adopted for examination of circulating antibody against the extract of northern fowl mite, Ornithonyssus sylviarum. Precipitating antibodies were detected in all the chickens infested with the mite. One to three clearly defined precipitation lines appeared in almost all the serum samples of infested birds. Titers of antibody correlated with population levels of the mite on chickens, and no differences in antibody development of hens and roosters were distinguished. These results suggest that the titration of precipitating antibodies appears to be useful for the assessment of mite population levels on chickens.

Animals↗

[Protease inhibitory activities of nasal secretion on house dust mite allergen].

OBJECTIVE: To elucidate the interaction of protease inhibitors and house dust mite allergen in vitro. METHODS: Nasal secretion was collected by suction from patients with house dust mite nasal allergy, diluted immediately with PBS pH 7.0, mixed with vortex for 10 minutes, and then centrifuged at 2,000 g for 10 minutes. The supernatant was kept at -80 degrees C for use. Synthetic low molecular weight fluorogenic peptide substrates were applied to evaluate protease activities. Crude mite extract and other proteases were used, each of them was preincubated in the presence or absence of nasal fluid or other protease inhibitors at 37 degrees C for 30 minutes. The intensity of fluorescence of aminomethylcoumarin released from the cleaved substrate was measured. RESULTS: Nasal fluid exhibited mild trypsin-like and other protease activities. It inhibited the activities of trypsin and trypsin-like serine proteases and papain-like cysteine proteases in crude mite extract in a dose-dependent manner. CONCLUSIONS: Nasal fluid possibly plays a role in inhibiting penetration of allergen into the nasal mucosa by producing protease inhibitor-protease complex in the nasal mucus layer of patients with mite allergy.

Adolescent↗

The pathogenesis of Demodex folliculorum (hair follicular mites) in females with and without rosacea.

In rosacea patients (ages 11-50 years old) 44% were infested with D. folliculorum as compared to normal controls (23.0%). The difference was significant. The mean +/-SD of mite density ranged between 13.2+/-0.9 to 18.2+/-1.2 as compared to normal controls with mite density ranged between 1.4+/-0.25 to 2.4+/-0.3. Demodex infestation in rosacea patients was 66.1% in squamous, 66.7% in erythemato-telangiectate and 83.3% in papulo-pustular rosacea. The highly infested site was check (27.3%) with mean mite density of 25.3+/-1.3, followed by the area around the orbit (23.4%) with a density of 19.0+/-1.2, the area around the nose (19.5%) with mite density of 7.1+/-1.5, then chin (15.6%) with a density of 8.2+/-1.4 and lastly the area around the mouth (14.1%) with a mite density of 14.2+/-1.3. Undoubtedly, infestation with D. folliculorum particularly in large number causes rosacea.

Adolescent↗

[Occurrence of a house-infesting tropical rat mite (Ornithonyssus bacoti) on murides and human beings in Munich: 3 case reports].

In Germany there is little information available about the distribution of the Tropical rat mite (Ornithonyssus bacoti) in rodents. A few case reports show that this hematophagous mite species may also cause dermatitis in man. All developmental stages are exclusively blood feeders. Three children (4, 11 and 15 years old) of a family, a 23-year-old medical student and a 17-year-old dental technician were attacked by the tropical rat mite. Prior to the consultation of our institute, the patients' conditions had been diagnosed as allergic dermatitis and treated by several antiphlogistic agents, however without success. The conclusive diagnosis of tropical rat mite dermatitis, was based on the identification of the arthropod O. bacoti in the flats of the patients (husbandry of gerbils, etc.) and in the dental practice. The diagnosis of rat mite dermatitis requires the detection of the parasite, which is more likely to be found in the environment of its host than on the host's skin itself.

Adolescent↗

Concentration of ivermectin in bovine serum and its effect on the fecundity of psoroptic mange mites.

The concentration-time profile of ivermectin in serum was determined for 3 Hereford heifers. The mean maximum serum concentration, 29 ng of ivermectin/ml, was obtained 48 hours after single subcutaneous injection of 200 micrograms/kg of body weight. The fecundity of mites placed on 9 treated animals at 5, 9, 12, 15, 18, and 21 days after injection was reduced by 96% to 99%. At 24 days after treatment, when serum concentration had decreased to about 2 ng/ml, the capability of mites to produce eggs increased to 50% of mites from nontreated calves. At 27 and 30 days after the drug was injected, egg production by mites on treated calves was equivalent to that of mites on nontreated calves. The reduced fecundity resulted from an almost complete cessation of oviposition by females after only a 1-day exposure to ivermectin-treated calves.

Animals↗

A new strategy in the control of house dust mite allergy.

Elimination of house dust mites by chemical means has so far been disappointing. Based on recent knowledge that house dust mites depend on fungi for their growth, a fungicide, natamycin was sprayed on the mattresses of patients at regular intervals. Forty patients with residual symptoms of allergy to house dust mites under optimal treatment, including house dust-free measures, were selected for the study. Among the 28 patients who completed the study, 15 were improved, 9 remained the same and 4 were worse. These data strongly suggest a beneficial effect of natamycin on the symptoms of allergy to house dust mite. They warrant further investigation with control groups and assessment of the mite population of the bedding.

Bedding and Linens↗

Reaginic hypersensitivity in Otodectes cynotis infestation of cats and mode of mite feeding.

Otodectes cynotis infestations were induced in barrier-reared mite-free cats. By monitoring the infested cats, sequence of humoral and cellular immune reactions to the mites was determined. Delayed hypersensitivity was not demonstrated in vivo, using intradermal skin tests. Reaginic (immunoglobulin E) antibodies, as detected by 72-hour passive cutaneous anaphylaxic reactions, were the earliest form of immune expression. Precipitating antibodies developed later in the course of the experimental infestation. Hematologic indices, including eosinophil counts, were not affected by established infestations. Antibodies prepared against feline whole blood, lymph, epithelium, and RBC indicated that these regularly occurred in extracts prepared from whole mites. It was concluded, therefore, that the feeding mode of mites required that they ingest feline tissue fluids. This mode is the interface by which the host becomes exposed to, and immunized against, mite antigens.

Animals↗

Mites (acari) infesting commensal rats in Suez Canal zone, Egypt.

Mites are arthropods distinguished from ticks by usually being microscopical in size and have a hypostome unarmed with tooth-like anchoring processes. They are group in a number of suborders, each with super-families and families including many genera of medical and economic importance. In this paper, commensal rodents (Rattus norvegicus, R. r. alexandrinus and R. r. frugivorous) were surveyed in the Suez Canal Zone for their acari ectoparasites. Four species of mites were recovered. In a descending order of mite indices, they were Eulaelaps stabularis (4.83 on 6 rats), Laelaps nuttalli (3.11 on 27 rats), Ornithonyssus bacoti (1.66 on 9 rats) and Dermanyssus gallinae (0.66 on 24 rats). The overall mite indices in the three governorates were 3.66 in Suez, 2.82 in Ismailia and zero in Port Said. The medical and economic importance of the mites were discussed.

Animals↗

[Parasitic pruritus: bird mite zoonosis].

In three women with persistent pruritus, aged 49, 28 and 4 years, infestation with the bird or chicken mite (Dermanyssus gallinae) was demonstrated. These mites live in narrow openings and cracks close to the bird housing during the daytime. At night they attack the birds on whose blood they live. When their host disappears, they may attack men, notably when their breeding places are in or near houses. Mite bites result in urticarial and itchy papulovesicular skin eruptions. Treatment of bird mite infestation consists of removing the old nests. Treatment of the patients is symptomatic. Epizoonosis belongs in the differential diagnosis of pruritus; infestation with bird or chicken mites is one of the possibilities.

Adult↗

Effects of fungicide treatment and vacuuming on pyroglyphid mites and their allergens in mattress dust.

House-dust mites (Pyroglyphidae) are an important source of indoor airborne allergens. Several methods may be applied to reduce the population growth of these mites and thus the quantity of allergen formed. One such method is to interfere with the mites' food chain. Fungi are a key factor in this food chain: they serve as an indirect food source. In this study we investigated the results of the repeated application of a fungicide (natamycin) on mattresses. As controls we treated some mattresses with a placebo, while others were left untreated. The application of natamycin appeared to hamper mite development. Additional vacuuming reduced the quantity of mite allergens present. In the usual household situation repeated treatment will be necessary to obtain a long-term reduction.

Allergens↗

Susceptibility of laboratory-reared northern fowl mites, Ornithonyssus sylviarum (Acari: Macronyssidae), to selected acaricides.

Toxicity was determined for 15 acaricides against a laboratory strain of northern fowl mites, Ornithonyssus sylviarum (Canestrini and Fanzago). Adult females were exposed to residues on filter paper for 24 h. Three organophosphorous compounds (monocrotophos, cythioate, and famphur) were more toxic to the northern fowl mite than was carbaryl, the most commonly used pesticide in the poultry industry. The other tested compounds were less toxic to the mite than was carbaryl. Four of these, not used previously for northern fowl mite control, had low LC50's for northern fowl mites:aldicarb (0.46); pirimiphos-methyl (0.73); exo, exo-2,8-dichloro-4-thiatricyclo[3.2.1.0.]octane-4-oxide (AI3-63182) (0.87); and diazinon (2.48).

Animals↗

Infochemical-mediated intraguild interactions among three predatory mites on cassava plants.

Carnivorous arthropods exhibit complex intraspecific and interspecific behaviour among themselves when they share the same niche or habitat and food resources. They should simultaneously search for adequate food for themselves and their offspring and in the meantime avoid becoming food for other organisms. This behaviour is of great ecological interest in conditions of low prey availability. We examined by means of an olfactometer, how volatile chemicals from prey patches with conspecific or heterospecific predators might contribute to shaping the structure of predator guilds. To test this, we used the exotic predatory mites Typhlodromalus manihoti and T. aripo, and the native predatory mite Euseius fustis, with Mononychellus tanajoa as the common prey species for the three predatory mite species. We used as odour sources M. tanajoa-infested cassava leaves or apices with or without predators. T. manihoti avoided patches inhabited by the heterospecifics T. aripo and E. fustis or by conspecifics when tested against a patch without predators. Similarly, both T. aripo and E. fustis females avoided patches with con- or heterospecifics when tested against a patch without predators. When one patch contained T. aripo and the other T. manihoti, females of the latter preferred the patch with T. aripo. Thus, T. manihoti is able to discriminate between odours from patches with con- and heterospecifics. Our results show that the three predatory mite species are able to assess prey patch profitability using volatiles. Under natural conditions, particularly when their food sources are scarce, the three predatory mite species might be involved in interspecific and/or intraspecific interactions that can substantially affect population dynamics of the predators and their prey.

Animal Communication↗

Leaf domatia mediate mutualism between mites and a tropical tree.

Although associations between mites and leaf domatia have been widely reported, their consequences for plants, especially for natural tree populations, particularly in the tropics, are largely unknown. In experiments with paired Cupania vernalis (Sapindaceae) saplings in a semi-deciduous forest in south-east Brazil, we blocked leaf domatia to examine their effect: (1) on mites and other arthropods, and (2) on damage caused by fungi and herbivorous arthropods. In general, plants with resin-blocked domatia had fewer predaceous mites on leaves than control plants with unaltered domatia, but the total abundances of fungivorous and of phytophagous mites remained unchanged. However, phytophagous eriophyid mites, the most numerous inhabitants of domatia, decreased on leaf surfaces with the blocking treatment. In a second experiment, treated plants lacking functional domatia developed significantly greater numbers and areas of chlorosis, apparently due to increased eriophyid attacks, whereas fungal attack, epiphyll abundance and leaf-area loss were unaffected. This seems to be the first experimental study to demonstrate that leaf domatia can benefit plants against herbivory in a natural system. The possible stabilizing effect of leaf domatia on predator-prey interactions is discussed.

Analysis of Variance↗

A new method to estimate the population size of coconut mite, Aceria guerreronis, on a coconut.

Studies of the coconut mite, Aceria guerreronis, often require accurate assessment of the population density on individual infested coconuts. Here an efficient and accurate method was developed to estimate its population density on an infested coconut. The coconut mites were removed by washing the bracts and surface of an infested coconut with 30 ml of a detergent solution. Shaking the wash for 5 s allowed the mites to distribute uniformly. The number of mites in the first 1 ml of the first wash (X) yielded a very accurate predictor of the total number of mites on a coconut (Y): Y = 30.1X (R2 = 0.99; p <0.0001), also confirming that the wash was indeed homogeneous. The advantages and disadvantages of this method are discussed.

Animals↗

Anatomical injury induced by the eriophyid mite Aceria anthocoptes on the leaves of Cirsium arvense.

Anatomical injury of the leaves of the invasive species, Cirsium arvense (L.) Scop., caused by the eriophyid mite Aceria anthocoptes (Nal.), which is the only eriophyid mite that has been recorded on C. arvense worldwide, is described. The injury induced by the mite feeding on the leaves of C. arvense results in visible russeting and bronzing of the leaves. Other conspicuous deformations are folding and distortion of the leaf blade and curling of leaf edge, as well as gradual drying of leaves. The anatomical injury of the mature leaves of field-collected plants was limited to the epidermis of the lower leaf surface. However, on young leaves of experimentally infested plants, rust mite injuries extend to epidermal cells on both leaf surfaces and to those of deeper mesophyll layers. On these leaves, lesions on the lower leaf surface even affected the phloem of the vascular bundles. Leaf damage induced by A. anthocoptes is discussed with regard to the mite's potential as a biological control agent of C. arvense.

Animals↗

Brood-cell size does not influence the susceptibility of honey bees (Apis mellifera) to infestation by tracheal mites (Acarapis woodi).

Tracheal mites have been associated with the condition in honey bees that devastated colonies in Britain and Ireland in the early 1900s. The first outbreak of this condition, that became known as the 'Isle of Wight' disease, coincided with the period when brood-cell size was increased from about 5.0 mm to about 5.5 mm in width. We undertook an inoculation experiment over a 7-day period to establish if the act of increasing the brood-cell size could have triggered the onset of tracheal mites in honey bees. The standard-sized cells used had a cell width of 5.44 mm and the small-sized cells a width of 5.07 mm. Using callow (newly emerged) bees, from three colonies that had mixed cell sizes, we compared the susceptibility of bees reared in standard-sized cells with that of those raised in small-sized cells. The results indicated similar levels of female mite abundance (0.49 vs. 0.52 mites per bee) and mean fecundity (4.33 vs. 4.22 offspring per female mite), and produced no evidence of any difference in the overall susceptibility between the bees raised in the standard-sized cells versus small-sized brood cells.

Animals↗

Rickettsial pathogens in the tropical rat mite Ornithonyssus bacoti (Acari: Macronyssidae) from Egyptian rats (Rattus spp.).

We collected and tested 616 tropical rat mites (Ornithonyssus bacoti (Hirst)) from rats (Rattus norvegicus (Berkenhout) and R. rattus (Linnaeus)) throughout 14 governorates in Egypt and tested DNA extracts from pools of these mites for Bartonella spp., Coxiella burnetii, and Rickettsia spp. by PCR amplification and sequencing. Three different mite-associated bacterial agents, including one Bartonella and two Rickettsia spp., were detected in eight pools of mites. Further research could demonstrate the vector potential of mites and pathogenicity of these agents to humans or animals.

Animals↗

Adaptation, specificity and host-parasite coevolution in mites (Acari).

Parasitism by mites is widespread and involves all the classes of vertebrates, from fishes to mammals. Owing to their small size and their great plasticity, mites are able to adapt to a wide range of habitats. Most of the species are ectoparasites but endoparasitism, especially in the respiratory tract, is common in birds and mammals. The morphological modifications appearing during the process adaptation to parasitic life, especially in Myobiidae, are analysed. Two kinds of characters are particularly important: the constructive specialized characters, consisting of the production of new structures, especially attachment organs allowing the mite to attach to the skin and the hair of the host, and regressive characters. Regression of the external structures is the most important phenomenon appearing in the process of evolution of parasitic mites. The importance of the regression in the parasite is correlated with the degree of evolution of the host. Host and parasite have a parallel evolution, but they go in opposite directions. The author surmises that the regressive evolution is related to the immunological reactions of the host that tend to reject the parasite. To escape from this rejection the parasite tends to select the less antigenic and therefore the most regressed phenotype. Specificity is generally strict in permanent parasites. Coevolution of host and parasite is studied in the family Myobiidae which parasitizes marsupials, insectivores, bats and rodents. The concordance between the radiations of the mites and that of their hosts is very high.

Adaptation, Biological↗