Molecular identification of house dust mites and storage mites

Mites are known causes of allergic diseases. Currently, identification of mites based on morphology is difficult if only one mite is isolated from a (dust) sample, or when only one gender is found, or when the specimen is not intact especially with the loss of the legs. The purpose of this study was to use polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) of the ITS2 gene, to complement the morphological data for the identification of mites to the species level. For this, six species were cultured: Dermatophagoides pteronyssinus, D. farinae, Blomia tropicalis, Tyrophagus putrescentiae, Aleuroglyphus ovatus and Glycycometus malaysiensis. Genomic DNA of the mites was extracted, quantified, amplified and digested individually with restriction enzymes. Hinf I and Ple I differentiated the restriction patterns of D. pteronyssinus and D. farinae. Bfa I and Alu I enzymes differentiated B. tropicalis and G. malaysiensis. Ple I enzyme was useful for the differentiation between T. putrescentiae and A. ovatus. Bfa I was useful for the differentiation of G. malaysiensis from the rest of the species. In conclusion, different species of mites can be differentiated using PCR–RFLP of ITS2 region. With the established PCR–RFLP method in this study, identification of these mites to the species level is possible even if complete and intact adult specimens of both sexes are not available. As no study to date has reported PCR–RFLP method for the identification of domestic mites, the established method should be validated for the identification of other species of mites that were not included in this study.     

Carcases and mites

Mites are involved in the decomposition of animal carcases and human corpses at every stage. From initial decay at the fresh stage until dry decomposition at the skeletal stage, a huge diversity of Acari, including members of the Mesostigmata, Prostigmata, Astigmata, Endeostigmata, Oribatida and Ixodida, are an integral part of the constantly changing food webs on, in and beneath the carrion. During the desiccation stage in wave 6 of Mégnin’s system, mites can become the dominant fauna on the decomposing body. Under conditions unfavourable for the colonisation of insects, such as concealment, low temperature or mummification, mites might become the most important or even the only arthropods on a dead body. Some mite species will be represented by a few specimens, whereas others might build up in numbers to several million individuals. Astigmata are most prominent in numbers and Mesostigmata in diversity. More than 100 mite species and over 60 mite families were collected from animal carcases, and around 75 species and over 20 families from human corpses.     

Egg-shells in mites

Summary This communication presents results of studies on the formation and structure of the vitelline envelopes in three species of mites: Euryparasitus emarginatus (Gamasida), Erythraeus phalangoides (Actinedida), and Hafenrefferia gilvipes (Oribatida). In E. emarginatus and E. phalangoides, in which the oocytes are not covered with follicular cells, the material of the vitelline envelope appears first in vesicles under the surface of the oocytes prior to secretion by exocytosis. The formed vitelline envelope is built of a homogeneous material which is perforated by numerous channels containing oocyte microvilli. Later, as the microvilli are retracted, the channels disappear. In both of these species the formed vitelline envelope is incomplete and the micropylar orifice occurs as a transitional structure.In H. gilvipes follicular cells encircling the oocyte contain granules filled with material that is subsequently secreted into the perivitelline space forming the vitelline envelope on the oocyte surface. The inner layer of the vitelline envelope is granular, whereas the outer part is more homogeneous. Both lack channels containing microvilli and micropyle.     

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

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

Identification of house-dust mites

The term house-dust mite usually refers to those species of the mite family Pyroglyphidae, that are known to commonly occur, although sometimes regionally, in the dust of human dwellings. These species belong to five genera:Dermatophagoides, Euroglyphus, Hirstia, andMalayoglyphus. Related species ofDermatophagoides have the most world-wide occurrence, the commonest being:D. farinae, D. microceras, andD. pteronyssinus. A correct taxonomic identification of house-dust mites is very important, not only from a biological stand point, but also regarding the consequences of their respective allergenical properties. Several immuno-chemical studies revealed differences between the products of two hard to distinguish sibling species. A preliminary practical taxonomic key for the most common and important house-dust mites is presented.     

Temperature-mediated stability of the interaction between spider mites and predatory mites in orchards

The nonlinear behavior of the Holling-Tanner predatory-prey differential equation system, employed by R.M. May to illustrate the apparent robustness of Kolmogorov’s Theorem when applied to such exploitation systems, is re-examined by means of the numerical bifurcation code AUTO 86 with model parameters chosen appropriately for a temperature-dependent mite interaction on fruit trees. The most significant result of this analysis is that there exists a temperature range wherein multiple stable states can occur, in direct violation of May’s interpretation of this system’s satisfaction of Kolmogorov’s Theorem: namely, that linear stability predictions have global consequences. In particular these stable states consist of a focus (spiral point) and a limit cycle separated from each other in the phase plane by an unstable limit cycle, all of which are associated with the single community equilibrium point of the system. The ecological implications of such metastability, hysteresis, and threshold behavior for the occurrence of outbreaks, the persistence of oscillations, the resiliency of the system, and the biological control of mite populations are discussed.     

携播螨与昆虫

文中指明了螨和昆虫之间的携播现象以及携播螨的特点 ,并讨论了螨和昆虫之间的携播现象与人类的关系。     

Negative interactions between Willamette mites and Pacific mites: possible management strategies for grapes

Willamette mites and Pacific mites are often negatively associated on grape vines. In particular, vineyards with early season infestations of the less damaging Willamette mite rarely develop high populations of the economically important Pacific mite. We report that Willamette mites had a negative effect on Pacific mite populations in both the greenhouse and field. In some experiments, the negative effect was more pronounced when vines had been damaged by previous feeding of Willamette mites and in other experiments concurrent feeding by both mite species was necessary to demonstrate a negative effect. Therefore, we cannot conclude if the mechanism of the response involves induced resistance against Pacific mites, more conventional interspecific competition, or both. Since predators were uncommon in our experiments, predator build up on Willamette mites did not cause the low Pacific mite population that we observed, although this mechanism may be important in many vineyards. Further, larger scale experiments are necesary to determine if growers can introduce Willamette mites to help control Pacific mites.

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Résumé E. willametti et T. pacificus sont souvent antagonistes dans les vignobles. En particulier, dans les vignobles contaminés tôt dans la saison par E. willametti,-dont les dégâts sont moins conséquents-, on observe rarement des populations élevées de T. pacificus, dont les dégâts sont économiquement importants. Nous avons constaté que E. Willametti a réduit les populations de T. pacificus, tant en serres qu'à l'extérieur. Dans quelques cas, l'effet antagoniste était plus marqué quand les vignes avaient été préalablement endommagées par l'alimentation de E. willametti. Dans d'autres expériences, la compétition alimentaire entre les deux espèces d'acariens était nécessaire pour produire un effet antagoniste. Cependant, nous ne pouvons pas en conclure que la réponse implique une résistance induite contre T. pacificus, ou une compétition interspécifique plus classique, ou les deux à la fois. Puisque les prédateurs étaient rares dans nos expériences, une explosion des prédateurs sur E. willametti n'a pu provoquer le faible niveau de population observé avec T. pacificus, bien qu'un tel méchanisme puisse être important dans certains vignobles. Quoi qu'il en soit, des expériences à plus grande échelle sont nécessaires pour déterminer si les vignerons peuvent introduire Eotetranychus willametti afin de limiter les populations de Tetranychus pacificus.

     

Indoor mites and forensic acarology

House dust mites (HDM) have been shown to produce allergens causing atopic allergies in human beings, known in medicine as house-dust-mite allergy or atopy. Over the past 25 years (1981–2006) a survey of dust samples from different places was made in the southern part of Poland, to determine the diversity of indoor acarofauna. In total, 1,532 samples were taken from dwellings, hospitals, libraries, research laboratories, drug-stores, and offices and other workplaces. More than 30 mite species were found of which the most abundant and common were HDM, especially Dermatophagoides farinae. Highest mite densities (g^?1 dust) were noted in dwellings. This survey revealed differences in the occurrence and prevalence of various species of domestic mites between and within (dwellings in) geographical areas. This knowledge may be useful in the field of forensic medicine.     

Control strategies against Varroa mites

In many cases, the easiest way to control a pest or a pathogen is to resort to chemical treatments. In the short period this option is often the most convenient economically and usually does not require refined knowledge of the biology of the pest. Many efforts have been directed to develop chemical treatments against Varroa destructor Anderson & Trueman. Nowadays, product based on organic acids, essential oils, pyrethroids, organophosphate, and formamidine are available. Resistance is serious problem in the chemotherapy of parasites and pathogens of the honeybee. High-level resistance to several active substances (the pyrethroids acrinathrin, flumethrin, fluvalinate; the organophosphate coumaphos; the formamidine amitraz) was detected with laboratory assays in different varroa populations and caused failure of the control in the field. At the end of the '80s, products based on pyrethroids, very effective against the mite, but without any appreciable side effect on bees, became available. Resistance to fluvalinate in Italy and later in other countries caused serious damage to beekeeping; early detection was crucial to reduce losses. The problem of developing suitable treatments was difficult in the case of the varroa mite because most substances active against V. destructor have unacceptable side effects on bees. The idea that the mite could be controlled indefinitely with these strategies began to gain ground.     

蒲螨与人类疾病

蒲螨为一类农业害螨,部分种类可暂时性或偶然地侵袭人体。该文简要介绍了蒲螨的生物学、生态学、引起人体皮炎的蒲螨种类、皮炎的发生特点以及蒲可寄生人体内引起的疾病。并提出治疗方法和除螨措施。     

捕食螨在我国农林害螨生物防治中的应用

捕食螨是农林生产中极具价值的生防作用物。文章对捕食螨在我国农林害螨生物防治中的应用作一综述,内容包括:与释放应用相关的研究(引进与风险评估,饲养、贮存与运输,食性与释放,捕食与繁殖,定殖与扩散,外界影响因子)、几种主要捕食螨(智利小植绥螨Phytoseiulus persimilis、西方盲走螨Typhlodromus occidentalis、伪钝绥螨Amblyseius fallacis、胡瓜钝绥螨A.cucumeris)的应用、释放应用前景与展望等,旨在提高我国的捕食螨研究与应用水平。     

Reducing house-dust mites by vacuuming

Two types of nozzles were compared for efficiency in extracting dust and house-dust mites from textile floor-coverings. From 21 homes, 2 m² from the wall-to-wall floor-covering in the bedrooms were vacuumed. On 1-m² the non-motorized nozzle was used, on the other 1-m² a motorized nozzle was used. Before this sampling both test surfaces were vacuumed using the non-motorized nozzle in order to assess the mite numbers at the beginning of the experiment. The motorized nozzle appeared to be significantly more effective in extracting dust; however, for the mites no such difference could be noted.