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At least 1,423 records · Page 79Linked to original sources
PubMed2004

Ontogenetic shifts in intraguild predation on thrips by phytoseiid mites: the relevance of body size and diet specialization.

In greenhouse agroecosystems, a guild of spider mite predators may consist of the oligophagous predatory mite Phytoseiulus persimilis Athias-Henriot, the polyphagous predatory mite Neoseiulus californicus McGregor (both Acari: Phytoseiidae) and the primarily herbivorous but facultatively predatory western flower thrips Frankliniella occidentalis Pergande (Thysanoptera: Thripidae). Diet-specialization and the predator body size relative to prey are crucial factors in predation on F. occidentalis by P. persimilis and N. californicus. Here, it was tested whether the relevance of these factors changes during predator ontogeny. First, the predator (protonymphs and adult females of P. persimilis and N. californicus): prey (F. occidentalis first instars) body size ratios were measured. Second, the aggressiveness of P. persimilis and N. californicus towards F. occidentalis was assessed. Third, survival, development and oviposition of P. persimilis and N. californicus with F. occidentalis prey was determined. The body size ranking was P. persimilis females > N. californicus females > P. persimilis protonymphs > N. californicus protonymphs. Neoseiulus californicus females were the most aggressive predators, followed by highly aggressive N. californicus protonymphs and moderately aggressive P. persimilis protonymphs. Phytoseiulus persimilis females did not attack thrips. Frankliniella occidentalis larvae are an alternative prey for juvenile N. californicus and P. persimilis, enabling them to reach adulthood. Females of N. californicus but not P. persimilis sustained egg production with thrips prey. Within the guild studied here, N. californicus females are the most harmful predators for F. occidentalis larvae, followed by N. californicus and P. persimilis juveniles. Phytoseiulus persimilis females are harmless to F. occidentalis.

Aggression↗
PubMed1992

A survey of mites on farm animals in Libya.

In 1985-1988, 2287 farm animals (cattle, camels, sheep, goats, horses, donkeys, dogs and rabbits) suspected of carrying parasitic mites were examined at 58 farms throughout Libya. Mites were identified on 1303 of these animals. The commonest parasites on cattle were Psoroptes and Chorioptes, on camels and sheep were Sarcoptes and Psoroptes, and on goats were Sarcoptes and Demodex. Infested horses carrier Psoroptes or Chorioptes, and one donkey carried Sarcoptes. Otodectes was common on dogs, but Sarcoptes was rare and no Demodex were seen. Rabbits often had psoroptic ear mange or sarcoptic body mange. Dermanyssus gallinae and Ornithonyssus bursa were seen on chickens, but no mites were found on pigeons, ducks or turkeys.

Animals↗
PubMed1994

Potentiation of infectivity and pathogenesis of influenza A virus by a house dust mite protease.

Common house dust mites (e.g., Dermatophagoides farinae) excrete a serine-type (Df) protease. Df protease obtained from cultured mites enhanced viral replication in vitro via proteolytic cleavage of viral hemagglutinin (HA) into HA1 and HA2, which confers potent viral infectivity. Its potency is 2- to 5-fold higher than bovine trypsin or human plasmin. Df protease also markedly accelerated virus propagation in vivo: A minute quantity of protease (estimated delivered amount, 0.8-3.2 micrograms) produced approximately 4- to 100-fold increases in infectious virus in the mouse lung. Similar augmentation of viral replication by Df protease was observed in ferret models of nasopharyngeal infections of influenza virus. All extracts from ordinary house dust contained a serine-type protease that cleaved HA into HA1 and HA2. Thus, mite protease in house dust may enhance the pathogenesis of influenza virus.

Amino Acid Sequence↗
PubMed1999

Phytoseiid mites on peppermint and effectiveness of Neoseiulus fallacis to control Tetranychus urticae (Acari: Phytoseiidae, Tetranychidae) in arid growing regions.

The humid-adapted species Neoseiulus fallacis (German) was the most common phytoseiid mite collected in either humid (> 100 cm annual rainfall) or arid (20-45 cm annual rainfall) mint growing regions of Washington, Oregon, Montana, Idaho, and California during 1991-1995. In experimental field plots, this predator gave excellent biological control of Tetranychus urticae Koch on mint grown under arid conditions in central Oregon when evaluated by an insecticide check method or by the caging of mites. N. fallacis is effective as a predator in arid areas probably because regular irrigation creates a humid environment in the canopy. The selective miticide propargite, when used in combination with predators, was effective at reducing high spider mite populations to below the treatment threshold faster than did N. fallacis alone.

Animals↗
PubMed1997

Spetial and temporal distribution of house dust mite (Astigmata:Pyroglyphidae) allergens Der p 1 and Der f 1 in Barbadian homes.

House features contribute to house dust mite abundance and, therefore, exposure to mite allergens. Our study assessed the hypothesis that modernization of the domestic environment in a tropical setting may lead to a level of allergen from the house dust mites Dermatophagoides pteronyssinus (Trouessart) and D. farinae Hughes that previously has been defined clinically as at risk for people who suffer from allergic disease. Allergen (Der p 1 and Der f 1) levels were measured at 4 sites (mattress, bedroom floor, living room floor, and furniture) in 17 houses in Barbados during dry and rainy seasons. Der p 1(17 of 17 homes) at all 4 sites did not vary significantly from the dry to rainy season. Allergen levels varied according to site, and were highest in living room furniture in both seasons (geometric mean 40.37 and 64.17 micrograms/g, respectively). Concentration of Der p 1 allergens were higher in concrete than in wood or mixed concrete and wood houses. Der f 1(9 of 17 homes) levels were lower than Der p 1 by 1/1,000 (both seasons). Results indicate that season is less important in regard to levels of Der p 1 than house construction and confirm other studies that implicate D. pteronyssinus as a more abundant source of allergen than D. farinae in this tropical setting.

Allergens↗
PubMed1997

Kinetics of allergen expression in cultures of house dust mites, Dermatophagoides pteronyssinus and D. farinae (Acari: Pyroglyphidae).

Laboratory cultures of house dust mites Dermatophagoides pteronyssinus (Trouessart, 1897) and Dermatophagoides farinae Hughes, 1961 were used to study the population dynamics of the mites and the kinetics of antigen appearance. The analysis of extracts obtained after different incubation periods, carried out by SDS-PAGE, immunoblotting, and enzyme-linked immunosorbent assay, allows for the definition of 3 different growth phases: the latency phase (F1); the exponential growth phase (F2) during which the allergenic proteins, including the Der 1 and Der 2 major allergens, were expressed more intensely and in larger quantities; and a final phase (F3), death, in which the lowest rates of allergenic components with a clearly different pattern were seen. The data obtained from this work demonstrates that mite cultures during the maximum growth phase (F2) contain the largest amount of allergenic components as well as the highest major allergen concentrations.

Allergens↗
PubMed2003

Novel anamorphic mite-associated fungi belonging to the Ustilaginomycetes: Meira geulakonigii gen. nov., sp. nov., Meira argovae sp. nov. and Acaromyces ingoldii gen. nov., sp. nov.

Three novel mite-associated basidiomycetous species are described in two new anamorph genera as Meira geulakonigii gen. nov., sp. nov. (type CBS 110052(T)=NRRL Y-27483(T)=AS 004(T)), Meira argovae sp. nov. (type CBS 110053(T)=NRRL Y-27482(T)=AS 005(T)) and Acaromyces ingoldii gen. nov., sp. nov. (type CBS 110050(T)=NRRL Y-27484(T)=AS 001(T)). Morphologically, these fungi are similar to the yeast-like fungi classified in the Ustilaginales, such as Pseudozyma species. However, analysis of the D1/D2 domain of the LSU rDNA suggests that they belong to two different lineages within the Exobasidiomycetidae of the Ustilaginomycetes (Basidiomycota). Furthermore, these fungi may be of interest for the biocontrol of mites, as they reduced mite numbers by approximately 80 % after inoculation.

Animals↗
PubMed2004

Combined transcript and metabolite analysis reveals genes involved in spider mite induced volatile formation in cucumber plants.

Many plants have an indirect defense against herbivores by emitting volatiles that attract carnivorous enemies of the herbivores. In cucumber (Cucumis sativus) the production of carnivore attractants can be induced by herbivory or jasmonic acid spraying. From the leaves of cucumber plants with and without spider mite infestation, two subtractive cDNA libraries were made that were enriched in cDNA fragments up- or down-regulated by spider mite infestation. A total of 713 randomly selected clones from these libraries were used to make a cDNA microarray. Subsequently, cucumber plants were sprayed with jasmonic acid, mechanically damaged, infested with spider mites, or left untreated (control). Leaf samples were taken at a range of different time points, and induced volatile compounds and mRNA (from the same leaves) were collected. cDNAs prepared from the mRNA were hybridized to the clones on the microarray. The resulting gene expression profiles were analyzed in combination with volatile production data in order to gain insight in the possible involvement of the studied genes in the synthesis of those volatiles. The clones on the microarray and the induced cucumber volatiles could be grouped into a number of clusters in which specific biosynthetic genes clustered with the product of that pathway. For example, lipoxygenase cDNA clones clustered with the volatile (Z)-3-hexenyl acetate and the volatile sesquiterpene (E,E)- alpha-farnesene clustered with an up-regulated sesquiterpene synthase fragment. This fragment was used to screen a cDNA library which resulted in the cloning of the cucumber (E,E)-alpha-farnesene and (E)-beta-caryophyllene synthases. The use of combined global gene expression analysis and metabolite analysis for the discovery of genes involved in specific biosynthetic processes is discussed.

Amino Acid Sequence↗
PubMed2003

Interaction between genetic and inductive factors controlling the expression of dispersal and dormancy morphs in dimorphic astigmatic mites.

Some astigmatic mites display dimorphic deutonymphs (hypopus) which are facultatively intercalated in their development cycle between protonymph and tritonymph. Such species, among them Glycyphagus privatus and Glycyphagus ornatus show three potential developmental pathways: (1) to bypass the hypopus stage and develop directly from the protonymph to the tritonymph and the subsequent reproductive stage when conditions are favorable; (2) to leave the original site and disperse by means of a phoretic hypopus morph; or (3) to survive inimical life conditions in the natal environment by means of a sedentary hypopus morph. By producing both dispersing (and afterwards at the arrival site reproducing) and sedentary (drought-hardy and dormancy-prone) progeny each single parent attains a selective advantage through a risk-reducing insurance against irregularly fluctuating and often fatal life conditions of their temporary patch habitats. Both genetic heterogeneity and ecological plasticity for hypopus production adapt the Glycyphagus species to cope with variation in the environment. Both traits (for dispersal and survival) are extremely polymorphic with genotypes ranging from low to high propensities for production of each hypopus type. There is a substantial environmental effect on genetic expression such that expression of both morphs depends on the quality of food. This ecological response allows a fast reaction of the mite to the current trophic environment. Phoretic morphs are predominantly expressed at favorable trophic conditions and sedentary morphs at poor trophic conditions. Ecological influences may override genetic propensities and vice versa. Although selection imposed by changing environmental patterns adjusts the frequencies of genotypes over generations and provides for long-term adaptation, the short-term process of environmental induction adapts the population within a generation to transient-habitat disturbances. The interaction of genetic and ecological determinants explains the varying proportions of directly developing mites, phoretic hypopodes, and sedentary hypopodes, in a population at any moment.

Animals↗
PubMed1976

A case of Pyemotes dermatitis. With a note on the role of these mites in skin disease.

Acute dermatitis developed in a fisherman after contact with old cherry-wood. A Pyemotes mite, probably P. beckeri, found in the wood, was thought to be responsible--thus illustrating the importance of appropriate laboratory examinations for ectoparasites. Human skin erruptions caused by indigenous, in contrast to imported, Pyemotes species have not previously been reported in Britain. These tarsonemoid mites attack small insect hosts and their possible role in dermatoses is discussed. Dermatitis caused by these mites is probably world-wide in distribution, but during the last century the confusing acarological nomenclature surrounding Pyemotes has resulted in an equally confusing variety of dermatological diagnoses.

Dermatitis, Contact↗
PubMed1987

House dust mite allergy and atopic eczema: a case report.

Sequential measurements were made of total and specific serum IgE concentrations in an adult patient with severe atopic eczema. Initially, the total serum IgE concentration and the concentration of IgE antibody to house dust mite were very high. These concentrations decreased over the next 3 years, following amelioration of her eczema. However, they rose again when her eczema worsened as a result of marital problems and fell once again with amelioration of her eczema after separation from her husband. The IgE concentrations to other common allergens, however, remained stable during this period. These results suggest that large amounts of house dust mite antigen may be scratched into the skin during clinical exacerbations of the eczema, this in turn aggravating the state of the skin because of hypersensitivity to the mite.

Adult↗
PubMed1975

Methods of destroying house dust pyroglyphid mites.

Attempts to reduce the growth of house dust pyroglyphid mites by vacuum cleaning, and modifications of temperature and humidity are useful but not sufficient. Their absence in dust from hospital beds which are disinfected led the authors to test PARAGERM AK, a non toxic bactericidal and fungicidal spray. This proved highly effective as an acaricide, killing off cultures of Dermatophagoides spp. and other mites with acceptable and easily produced concentrations, thus providing a new way of combating the house dust allergy mite.

Dust↗
PubMed1975

Seasonal asthma and the house-dust mite in tropical Africa.

The relationship between seasonal asthma and sensitivity to the house-dust mite has been investigated in a country with large seasonal variations in relative humidity. Of seventy-eight African asthmatics, 64.1% gave a history probably suggestive of sensitivity to house-dust, and 55.1% a history strongly suggestive of such sensitivity. On skin testing, 35.9% had strong reactions to the house-dust mite Dermatophagoides pteronyssinus, compared with 1.9% of fifty-one matched controls without symptoms of chest disease. Few had either a history or skin tests suggestive of pollen or mould sensitivity. Most of the asthmatics were worse during the hot, wet season when the humidity is highest. This is also the time when in-patient asthmatics are most numerous. D. pteronyssinus grows well in warm, damp conditions and it is suggested that sensitivity to this mite may play a significant role in the marked seasonal changes seen in our asthmatic patients.

Adolescent↗
PubMed1981

A cluster analysis of the effects of storage mites as allergens in relation to certain occupations and living conditions.

The method of cluster analysis was used to examine the data of Wraith, Cunnington & Seymour (1979) to assess the role and allergenic importance of storage mites in house dust and other environments in relation to certain factors thought to influence patients' exposure to these species. The analysis provided strong statistical evidence that (a) excessively damp housing and (b) occupational risks of exposure were the two main factors associated with allergy to these species. It also indicated that sensitivity to D. pteronyssinus remained unaltered in environmental conditions more favourable to the growth and development of storage mites. Furthermore, it was shown that the storage species form a group of similar allergens distinct from the house-dust mite.

Allergens↗
PubMed1983

Stabilization of a diluted aqueous mite allergen preparation by addition of human serum albumin. An intracutaneous test study.

Stability of diluted Spectralgen Dermatophagoides farinae allergen preparations in phenol-saline with, and without human serum albumin (HSA) has been studied by intracutaneous tests in mite-allergic patients. The phenol-saline reconstituted mite allergen preparation lost activity to less than 1/10 of initial activity within 1 week, while mite allergen preparation reconstituted with solvent containing HSA was stable for at least 8 months after reconstitution. Human serum albumin probably prevents adsorption of allergens to glass surfaces which may be a problem for very diluted allergen preparations.

Adolescent↗
PubMed1985

Housedust mites (D. pteronyssinus) in pets' beds and their relation to dust allergy.

Houses were surveyed by dust sampling to examine the occurrence and significance of storage mites in rural areas in the U.K. As a part of this project pets' beds were sampled, and it was discovered that not only do they contain storage mites, but that in nearly all instances the classical housedust mite (D. pteronyssinus) was present in significant numbers.

Animals↗
PubMed1986

Low dose sublingual therapy in patients with allergic rhinitis due to house dust mite.

In a double-blind placebo-controlled cross-over trial, low dose sublingual therapy with house dust mite was effective in relieving symptoms in 72% of the group of patients with perennial rhinitis due to house dust mite (P less than 0.03). Following active treatment, there was a significant increase in morning peak nasal inspiratory flow rate (P less than 0.01) in those who improved (thirteen out of eighteen) and resistance to nasal provocation with house dust mite also increased, in some cases up to 1000-fold (P less than 0.05). Oral therapy is safe and avoids the side effects of desensitizing injections which can be serious. The potential for oral desensitization is great and further studies on this form of treatment are needed.

Administration, Oral↗
PubMed1987

Predominance of mite allergy over allergy to pollens and animal danders in a farming population.

The prevalence of IgE-mediated hypersensitivity to respiratory allergens, including Lepidoglyphus destructor (a storage mite) and Dermatophagoides pteronyssinus, was studied in a rural population of Gotland, a Swedish island in the Baltic Sea. A sample of 440 farmers underwent examination, comprising skin-prick tests (animal danders, pollens, moulds, house dust mite and wheat) and blood sampling for radio-allergosorbent tests (RAST) (birch, Timothy grass, dog, D. pteronyssinus, Cladosporium and L. destructor). The highest prevalence of positive skin-prick tests was noted for D. pteronyssinus (6.0%). Low prevalences of positive skin-prick tests, 0.7-2.7%, were found for pollens, animal danders and moulds. Among the tested allergens, D. pteronyssinus and L. destructor yielded the highest prevalences of positive RAST results, namely 5.2 and 6.8%, respectively. Most farmers with allergy to pollens and animal danders had symptoms both from the upper and lower airways and from the eyes. Among farmers with both asthma and rhinoconjunctivitis, the prevalence of positive RAST results for L. destructor and D. pteronyssinus were simiar. The present study clearly demonstrates that mites are by far the most important allergens in the farming population on Gotland, whereas otherwise common allergens such as pollen and animal danders are clearly less significant.

Adolescent↗