Real-Time Video Microscopy of In Vitro Demodex Death by Intense Pulsed Light.

Objective: To directly observe the in vitro real-time effects of intense pulsed light (IPL) on a Demodex mite extracted from an eyelash of a patient with ocular rosacea. Background: Demodex is a risk factor in the pathogenesis of oculofacial rosacea, meibomian gland dysfunction (MGD), and dry eye disease (DED). Recent studies suggested IPL to control or eradicate Demodex organisms in the periocular area. Despite encouraging reports, the direct effect of IPL on Demodex is not well understood. Methods: An eyelash infested with Demodex was epilated from a 62-year-old female patient with oculofacial rosacea. Following isolation and adherence of a mite onto a microscope slide, real-time video microscopy was used to capture live images of the organism before, during, and after administration of IPL pulses. IPL pulses were delivered with the M22 IPL (Lumenis), with IPL settings used for treatment of DED due to MGD (the "Toyos protocol"). A noncontact digital laser infrared thermometer was used to measure the temperature of the slide. Results: Before the IPL pulses, legs of the Demodex mite spontaneously moved in a repetitive and semicircular motion. During administration of IPL, spontaneous movements of the legs continued. Immediately after administration of five IPL pulses, the temperature of the slide increased from room temperature to 49°C. Immediately afterward, the Demodex mite became completely immobilized. The legs appeared retracted, smoother, less corrugated, bulkier, and less well-defined. Movement of the Demodex mite was not observed at the hourly inspections for 5 h and after 24 h following the application of IPL pulses. Conclusions: Our video directly demonstrates the effect of IPL on a live Demodex mite extracted from a freshly epilated eyelash. The results suggest that IPL application with settings identical to those used for treatment of DED due to MGD causes a complete destruction of the organism.

Intense Pulsed Light Therapy for Patients with Meibomian Gland Dysfunction and Ocular Demodex Infestation.

To observe the clinical changes of meibomian gland dysfunctipn (MGD) and ocular Demodex infestation after intense pulsed light (IPL) treatment to further examine the mechanism of IPL treating patients with MGD and ocular Demodex infestation. The medical records of 25 patients (49 eyes) with MGD treated with IPL, were retrospectively examined to determine outcomes. Associated ocular-surface parameters (ocular surface disease index, OSDI; lipid layer thickness, LLT; noninvasive first breakup time, NIF-BUT; noninvasive average breakup time, NIAvg-BUT; tear film breakup area, TBUA; Schirmer I Test, SIT; corneal fluorescein staining, CFS), eyelid margin abnormalities, meibum quality and expressibility, MG morphological parameters (macrostructure and microstructure), and the number of Demodex infestation were examined before and after treatment. The MG microstructure and the Demodex infestation were examined via in vivo confocal microscopy (IVCM). The results showed that there were statistically significant differences in associated ocular-surface parameters (all P<0.05) before and after IPL treatment, except SIT (P=0.065). Eyelid margin abnormalities, meibum quality and expressibility obviously improved in upper and lower eyelid after IPL treatment (all P<0.0001). MG macrostructure (MG dropouts) decreased in upper (P=0.002) and lower eyelid (P=0.001) after IPL treatment. The nine parameters of MG microstructure in upper and lower eyelid all distinctly improved after IPL treatment (all P<0.0001). The mean number of Demodex mites on the upper lid margin (6.59±7.16 to 3.12±3.81/9 eyelashes) and lower lid margin (2.55±2.11 to 1.29±1.53/9 eyelashes) significantly reduced after IPL treatment (all P<0.0001). The Demodex eradication rate was 20% (8/40) in upper lid margin and 34.15% (14/41) in lower lid margin. These findings indicate that IPL shows great therapeutic potential for patients of MGD and ocular Demodex infestation.

Darkness increases the population growth rate of the poultry red mite Dermanyssus gallinae.

BACKGROUND: The poultry red mite (PRM), Dermanyssus gallinae, is one of the most economically deleterious ectoparasites affecting egg-laying hens worldwide. It may be possible to control D. gallinae populations by manipulating lighting regimes within poultry units. However, no studies have clearly shown the effects of darkness on the population growth rate of D. gallinae. METHODS: The effect of darkness on the population growth rate of D. gallinae was investigated, together with the first description of the molecular identity of the mite from China. Mite variables under two lighting regimens (1:23 h L:D and 12:12 h L:D) were compared, including number of mites and eggs, survival and feeding rates, engorgement, oviposition, hatchability and the life-cycle of D. gallinae. RESULTS: The results showed that the number of mites (13,763 ± 956) and eggs (5424 ± 317) in the rearing system with prolonged darkness of 1:23 h L:D at 4th week were 2.4- and 3.6-fold higher than those under a conventional lighting regimen of 12:12 h L:D, respectively. The feeding rates of mites under prolonged darkness ranged from 36.7 ± 1.1% to 52.0 ± 7.0%, which were significantly higher than those under conventional lighting regimen (ranging from 22.6 ± 1.9% to 37.3 ± 1.6%). The mean weight of engorged females (0.26 ± 0.01 mg) and the mean number of eggs per female (on average 5.87 ± 0.36) under prolonged darkness were significantly higher than those under conventional lighting regimen (0.22 ± 0.01 mg and 3.62 ± 0.31, respectively). However, the survival rate ranging from 98.07 ± 0.10% to 98.93 ± 0.19%, hatchability of 97.93 ± 0.01% and the life-cycle of D. gallinae (9 days) was not affected by the lighting period. CONCLUSIONS: Our findings demonstrated that prolonged darkness significantly promoted the proliferation levels of D. gallinae, resulting in increased number of mites and eggs in the rearing system. The promoted population growth of D. gallinae was found to be related to the increased feeding rate, engorgement level and oviposition level of mites under prolonged darkness. The egg hatchability, the survival rates and the duration of life-cycle of D. gallinae were not affected by the light regimes.

Effects of UV-B radiation on the survival, egg hatchability and transcript expression of antioxidant enzymes in a high-temperature adapted strain of Neoseiulus barkeri.

Biological control of spider mites in hot and dry weather is a serious technical issue. A high-temperature adapted strain (HTAS) of the predatory mite Neoseiulus barkeri Hughes was selected from its conventional strain (CS), via long-term heat acclimation and frequent heat hardenings in our previous studies. However, the environment of high temperature is usually associated with enhanced ultraviolet (UV) radiation. In the present study, the physiological effects of UV-B radiation on survival rate and egg damage of N. barkeri were investigated, as well as the activities and expression profiles of antioxidant enzymes to UV-B radiation stress. UV-B radiation had deleterious effects on egg hatchability and survival of N. barkeri. Adults of the HTAS strain were less UV-B resistant than those of the CS strain; they also had lower levels of enzymatic activity of superoxide dismutase (SOD) and catalase against oxidative damage and weaker upregulation of SOD genes. The mRNA expression of three SOD genes of CS adult females immediately increased whereas that of HTAS showed almost no difference under UV-B stress for 1 h. The results showed the HTAS of N. barkeri had lower fitness under UV-B stress compared with the CS of N. barkeri. These results suggested that long-term heat acclimation may exert a profound impact on the developmental physiology of N. barkeri.

The rapid effect of pulsed dye laser on demodex density of facial skin.

BACKGROUND: Recently, treatment with acaricides, which is aimed at reducing excessive proliferation of demodex mites, has gained popularity due to its providing a significant improvement in the symptoms of diseases, such as rosacea, seborrhoeic dermatitis, and perioral dermatitis. The effect of IPL on demodex mites was reported in skin biopsy specimens in three patients; however, to the best of our knowledge, no study exists to date, which evaluates the effect of pulsed dye laser (PDL) on demodex density (Dd) in larger patient group. We aim here in to observe the Dd before and after PDL therapy with two different skin biopsy techniques. MATERIAL AND METHODS: Thirty-one patients diagnosed with rosacea were included in the study who received PDL treatment. Dds which were measured by using both the SSSB (standardized skin surface biopsy) and CTM (cellophane tape method) techniques before and after 3 weeks of PDL therapy were evaluated. RESULTS AND DISCUSSION: The Dd of patients before PDL treatment was 13.0 (interquartile range (IQR): 5.0-28.0) and after 3 weeks of PDL treatment it was 6.0 (IQR: 3.0-12.0) with SSSB. After PDL treatment, the Dd was significantly lower than pretreatment the Dd (p = 0.002). The present study shows that PDL significantly reduced Dd in facial skin with one session.

Tolerance of the eriophyid mite Aceria salsolae to UV-A light and implications for biological control of Russian thistle.

Aceria salsolae (Acari: Eriophyidae) is being evaluated as a candidate biological control agent of Russian thistle (Salsola tragus, Chenopodiaceae), a major invasive weed of rangelands and dryland crops in the western USA. Prior laboratory host range testing under artificial lighting indicated reproduction on non-native Bassia hyssopifolia and on a native plant, Suaeda calceoliformis. However, in field tests in the native range, mite populations released on these 'nontarget' plants remained low. We hypothesized that UV-A light, which can affect behavior of tetranychid mites, would affect populations of the eriophyid A. salsolae differently on the target and nontarget plant species, decreasing the mite's realized host range. Plants were infested with A. salsolae under lamps that emitted UV-A, along with broad-spectrum lighting, and the size of mite populations and plant growth was compared to infested plants exposed only to broad-spectrum light. Russian thistle supported 3- to 55-fold larger mite populations than nontarget plants regardless of UV-A treatment. UV-A exposure did not affect mite populations on Russian thistle or S. calceoliformis, whereas it increased populations 7-fold on B. hyssopifolia. Main stems on nontarget plants grew 2- to 6-fold faster than did Russian thistle under either light treatment. The two nontarget plants attained greater volume under the control light regime than UV-A, but Russian thistle was unaffected. Although Russian thistle was always the superior host, addition of UV-A light to the artificial lighting regime did not reduce the ability of A. salsolae to reproduce on the two nontarget species, suggesting that UV-B or other environmental factors may be more important in limiting mite populations in the field.

Egg hatching response to a range of ultraviolet-B (UV-B) radiation doses for four predatory mites and the herbivorous spider mite Tetranychus urticae.

Egg hatchability of four predatory mites-Phytoseiulus persimilis Athias-Henriot, Iphiseius [Amblyseius] degenerans Berlese, Amblyseius swirskii Athias-Henriot, and Euseius finlandicus Oudemans (Acari: Phytoseiidae)-and the spider mite Tetranychus urticae Koch (Acari: Tetranychidae) was determined under various UV-B doses either in constant darkness (DD) or with simultaneous irradiation using white light. Under UV-B irradiation and DD or simultaneous irradiation with white light, the predator's eggs hatched in significantly lower percentages than in the control non-exposed eggs, which indicates deleterious effects of UV-B on embryonic development. In addition, higher hatchability percentages were observed under UV-B irradiation and DD in eggs of the predatory mites than in eggs of T. urticae. This might be caused by a higher involvement of an antioxidant system, shield effects by pigments or a mere shorter duration of embryonic development in predatory mites than in T. urticae, thus avoiding accumulative effects of UV-B. Although no eggs of T. urticae hatched under UV-B irradiation and DD, variable hatchability percentages were observed under simultaneous irradiation with white light, which suggests the involvement of a photoreactivation system that reduces UV-B damages. Under the same doses with simultaneous irradiation with white light, eggs of T. urticae displayed higher photoreactivation and were more tolerant to UV-B than eggs of the predatory mites. Among predators variation regarding the tolerance to UV-B effects was observed, with eggs of P. persimilis and I. degenerans being more tolerant to UV-B radiation than eggs of A. swirskii and E. finlandicus.

Generic delimitation between Fragariocoptes and Sierraphytoptus (Acari: Eriophyoidea: Phytoptidae) and a supplementary description of Fragariocoptes gansuensis with remarks on searching for mummified eriophyoid mites in herbaria under UV light.

Generic concepts of Fragariocoptes Roivainen, 1951 and Sierraphytoptus Keifer, 1939 are discussed and the correct delimitation between these two genera is given. A supplementary description of Fragariocoptes gansuensis Wei, Chen & Luo, 2005 is included based on fresh specimens from Astrakhan, Russia and dried mummies found in old herbaria collected in 1919 from southern European Russia of the cinquefoil, Potentilla bifurca L. (Rosaceae) with pathological stem proliferation. The male of this species is described for the first time. The cuticle of eriophyoid mummies emitted a faint glow under UV light wavelength equal to 365 nm of a common UV Light-Emitting diode (LED) lamp showing that this characteristic could be useful for quickly detecting eriophyoids in old herbaria which would otherwise be almost indistinguishable against the background under the regular white light source of a stereomicroscope. This was only possible for plant material stored in appropriate conditions enabling the autofluorescent signal of the dried mite cuticle to remain strong enough for observation.

Joint Effect of Solar UVB and Heat Stress on the Seasonal Change of Egg Hatching Success in the Herbivorous False Spider Mite (Acari: Tenuipalpidae).

Seasonal population dynamics of an herbivorous mite has been documented in terms of the relationship between thermoresponses and temporal biological factors such as resource availability or predation risk. Although recent studies emphasize the deleterious effects of solar ultraviolet-B (UVB; 280-320 nm wavelengths) radiation on plant-dwelling mites, how UVB affects mite population remains largely unknown. On a wild shrub Viburnum erosum var. punctatum in Kyoto, an herbivorous false spider mite, Brevipalpus obovatus Donnadieu, occurs only in autumn. Females of this species lay one-third of their eggs on upper leaf surfaces. Oviposition on upper surfaces is beneficial for avoiding predation by phytoseiids, but exposes eggs to solar UVB and heat stress. To test the hypothesis that the seasonal occurrence of this mite is determined by interactions between solar UVB radiation and temperature, we examined variation in egg hatching success under near-ambient and UV-attenuated sunlight conditions from spring to autumn. The UV-attenuation significantly improved hatching success. However, most eggs died under heat stress regardless of UV treatments in July and August. We established a deterministic heat stress-cumulative UVB dose-egg hatching success response model, which we applied to meteorological data. The model analyses illustrated lower and higher survivability peaks in late May and October, respectively, which partly corresponded to data for annual field occurrence, indicating the importance of solar UVB radiation and heat stress as determinants of the seasonal occurrence of this mite.

Vulnerability and behavioral response to ultraviolet radiation in the components of a foliar mite prey-predator system.

Ambient ultraviolet-B (UVB) radiation impacts plant-dwelling arthropods including herbivorous and predatory mites. However, the effects of UVB on prey-predator systems, such as that between the herbivorous spider mite and predatory phytoseiid mite, are poorly understood. A comparative study was conducted to determine the vulnerability and behavioral responses of these mites to ultraviolet (UV) radiation. First, we analyzed dose-response (cumulative irradiance-mortality) curves for the eggs of phytoseiid mites (Neoseiulus californicus, Neoseiulus womersleyi, and Phytoseiulus persimilis) and the spider mite (Tetranychus urticae) to UVB radiation from a UV lamp. This indicated that the phytoseiid mites were more vulnerable than the spider mite, although P. persimilis was slightly more tolerant than the other two phytoseiid mites. Second, we compared the avoidance behavior of adult female N. californicus and two spider mite species (T. urticae, a lower leaf surface user; Panonychus citri, an upper leaf surface user) in response to solar UV and visible light. N. californicus actively avoided both types of radiation, whereas P. citri showed only minimal avoidance behavior. T. urticae actively avoided UV as well as N. californicus but exhibited a slow response to visible light as well as P. citri. Such variation in vulnerability and avoidance behavior accounts for differences in the species adaptations to solar UVB radiation. This may be the primary factor determining habitat use among these mites on host plant leaves, subsequently affecting accessibility by predators and also intraguild competition.

Different scales of spatial segregation of two species of feather mites on the wings of a passerine bird.

The "condition-specific competition hypothesis" proposes that coexistence of 2 species is possible when spatial or temporal variations in environmental conditions exist and each species responds differently to those conditions. The distribution of different species of feather mites on their hosts is known to be affected by intrinsic host factors such as structure of feathers and friction among feathers during flight, but there is also evidence that external factors such as humidity and temperature can affect mite distribution. Some feather mites have the capacity to move through the plumage rather rapidly, and within-host variation in intensity of sunlight could be one of the cues involved in these active displacements. We analyzed both the within- and between-feather spatial distribution of 2 mite species, Trouessartia bifurcata and Dolichodectes edwardsi , that coexist in flight feathers of the moustached warbler Acrocephalus melanopogon. A complex spatial segregation between the 2 species was observed at 3 spatial levels, i.e., "feather surfaces," "between feathers," and "within feathers." Despite certain overlapping distribution among feathers, T. bifurcata dominated proximal and medial regions on dorsal faces, while D. edwardsi preferred disto-ventral feather areas. An experiment to check the behavioral response of T. bifurcata to sunlight showed that mites responded to light exposure by approaching the feather bases and even leaving its dorsal face. Spatial heterogeneity across the 3 analyzed levels, together with response to light and other particular species adaptations, may have played a role in the coexistence and segregation of feather mites competing for space and food in passerine birds.

Effects of ultraviolet radiation on predatory mites and the role of refuges in plant structures.

Most studies on ecological impact of solar ultraviolet (UV) radiation generally focus on plants. However, UV radiation can also affect organisms at other trophic levels. Protection against mortality induced by solar UV has, therefore, been hypothesized as one of the reasons why Typhlodromalus aripo hides in the apex of cassava plants during the day and comes out at night to prey on spider mites on leaves. In laboratory experiments using UV lamps, we determined the impact of UVA and UVB radiation on survival and oviposition of two leaf-inhabiting mites (Amblydromalus manihoti, Euseius fustis) and the apex-inhabiting mite (T. aripo), all three species being predators used for controlling the cassava green mite Mononychellus tanajoa in Africa. Whereas on leaf discs UVA has no negative impact on survival of the three predators, UVB is lethal to all of them. In contrast, nearly 85% of T. aripo survived after exposure to UVB inside apex of cassava plants. Exposure of A. manihoti and E. fustis to UVB radiation on the lower surface of a cassava leaf resulted in 36% survival. Oviposition and hatching of eggs laid after exposure to UVB were not affected, but eggs directly exposed to UVB did not hatch. Although caution should be exercised to extrapolate laboratory studies to the field, our results support the hypothesis that lower side of leaves, but especially plant apices, represent refuges that protect predatory mites from UVB. This might explain why T. aripo moves out of the apex to forage on leaves only during the night.

Effects of radiation (Cobalt-60) on the elimination of Brevipalpus phoenicis (Acari: Tenuipalpidae) Cardinium endosymbiont.

Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae) is a polyphagous mite with worldwide distribution and it is also a vector of several plant viruses. In citrus, B. phoenicis transmits Citrus leprosis virus (CiLV), the causal agent of leprosis, a disease that costs millions of dollars per year for its prevention and control. Brevipalpus phoenicis mites reproduce through thelytokous parthenogenesis, producing haploid females. This characteristic is attributable to the presence of an endosymbiont bacterium of the genus Cardinium; however, very little is known about the biological and ecological implications of the presence of this endosymbiont in Brevipalpus mites. In order to investigate the role of Cardinium in the transmission of CiLV to citrus plants, our goal was to eliminate the bacterium from the mite. We assessed the effectiveness of different doses of radiation from a Cobalt-60 source to cure B. phoenicis populations from Cardinium sp. The efficiency of irradiation on the elimination of the endosymbiont was determined by counting the number of females and males obtained in the F(1) generation after irradiation and confirming the presence of the endosymbiont by PCR. Both radiation treatments influenced the oviposition period and the number of eggs laid by irradiated females. Also, irradiation eliminated the Cardinium endosymbiont and increased the number of males in progeny of the exposed populations. Although macroscopic morphological abnormalities were not observed among the treated mites, the mortality was higher compared to the non-irradiated control group.

Effect of electric heating carpet on house dust mites.

An electric heating carpet (EHC) that had been especially modified to produce a steady surface temperature of 45 to 50 degrees C was set up in the bedroom of an asthmatic patient, and the density of floor dust mites in this room was compared monthly for 2 years with that in two non-EHC control rooms. When the EHC was used during the mite-growing summer season, the monthly variation in mite density in the EHC room was almost parallel to that in the non-EHC rooms, with a preponderance of floor mites in the non-EHC rooms. In contrast, when the EHC was used during the winter season, the density of floor mites in the EHC room increased as compared with that in the non-EHC rooms, and the ratio of mite density in the EHC room to that in the non-EHC rooms was transiently reversed during this period.

A new procedure for handling impervious biological specimens.

A new application of techniques for preparing impervious biological specimens for light microscopy (LM) and transmission electron microscopy (TEM) has been developed. Microwave irradiation was used to facilitate fixation. A priming technique was used to increase the bonding of the outer surface of the specimens with the resin. Priming the waxy or cuticular surface with Z-6040 (gamma-glycidoxypropyl trimethoxysilane) solved the problem of specimen "pull out" from the resin. Insect specimens with various types of cuticles (waxy or chitinous) and seeds were successfully studied ultrastructurally using this technique.

Effects of radiation on spermatogenesis in Acarus siro L. (Acari: Acaridae).

Modifications of spermatogenesis and anatomy of male reproductive tracts caused by radiation (fast electrons) are described in Acarus siro and compared with data from other arthropod taxa. Radiation induced severe changes in gonial cells, including dilatation of endoplasmic reticulum and disruption of mitochondrial cristae. The latter sometimes created roundish myelin structures inside the mitochondrial matrix. Damage in developing cells caused an interruption of spermatogenesis and reduced the number of spermatids produced; high doses can cause sterility.