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PubMed2003

Alpha-acaridial a female sex pheromone from an alarm pheromone emilting mite Rhizoglyphus robini.

The female sex pheromone of Rhizoglyphus robini Claparède (Astigmata: Acaridae) was identified as alpha-acaridial [2(E)-(4-methyl-3-pentenyl)-butenedial], which stimulated males sexually and enhanced the frequency of male mounting behavior. Although a hexane extract of females manifested alarm pheromone activity against tested males due to the presence of the alarm pheromone neryl formate, silica gel column fractions containing alpha-acaridial evoked increased mounting behavior by males at a dose of 0.1 female equivalent. Synthetic alpha-acaridial at a dose of 10 ng showed a peak of activity as a sex pheromone, with a convex dose-response relationship. Its content was determined to be 388 +/- 244 ng per female and 163 +/- 97 ng per male by GC. This is the first time that two pheromones (the alarm pheromone neryl formate, and the sex pheromone alpha-acaridial) have been demonstrated to be components of the same opisthonotal gland secretion in astigmatid mites. A mechanism for the appropriate expression of the two pheromones by the mites under different conditions is proposed.

Aldehydes↗
PubMed2003

Side-effects of three pesticides on the predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae).

Side-effects of three commonly used pesticides in Iran were evaluated on an introduced strain of the predatory mite. Phytoseiulus persimilis Athias-Henriot, reared for about 10 years without exposure to any pesticides. Application of pesticides was carried out either to detached bean leaves using a Potter tower at 1 mg wet deposit per cm2 or by a hand sprayer on bean plants until run off. According to an EPPO decision making scheme, pirimiphos-methyl was found to be harmful (E=90.8%) and heptenophos harmless (E=-3.7%) to the predatory mite in the residual initial toxicity tests. For determination of the hazard class of malathion a field test was found to be necessary (E=59.8%). Categories of 1, 2, 3 were determined for heptenophos, malathion and primiphos-methyl, respectively, using IOBC classification. Despite being harmful, it is possible to use pirimiphos-methyl 10 days before release of P. persimilis. Investigation of the contribution of both lethal and sub-lethal effects to total impact indicated the dominance of lethality in the case of pirimiphos-methyl, while malathion acted by both mechanisms. Heptenophos did not have negative effects on fecundity of P. persimilis but rather caused a higher rate of fecundity in comparison with the control. The mortality found in the heptenophos test was not significantly different from the control.

Analysis of Variance↗
PubMed2003

Orchid fleck virus: Brevipalpus californicus mite transmission, biological properties and genome structure.

Orchid fleck virus (OFV) causes necrotic or chlorotic ring spots and fleck symptoms in many orchid species world-wide. The virus has non-enveloped, bacilliform particles of about 40 nm x 100-150 nm and is sap-transmissible to several plant species. OFV is transmitted by the mite Brevipalpus californicus (Banks) in a persistent manner and efficiently transmitted by both adults and nymphs, but not by larvae. Viruliferous mites retain their infectivity for 3 weeks on a virus-immune host. The genome of OFV consists of two molecules of 6431 (RNA1) and 6001 nucleotides (RNA2). The RNAs have conserved and complementary terminal sequences. RNA1 contains five open reading frames (ORF), and RNA2 encodes a single ORF. Although some of the encoded proteins of OFV have sequences similar to those of proteins of plant rhabdoviruses, OFV differs from viruses in the family Rhabdoviridae in having a bipartite genome.

Animals↗
PubMed2003

The reproductive program of female Varroa destructor mites is triggered by its host, Apis mellifera.

Reproducing Varroa females begin oviposition on a host larva by laying an unfertilized (male) egg, followed by fertilized (female) offspring. Using transfer experiments, we examined whether the sequence of sexes in the brood cell is triggered by a host stimulus. When reproducing Varroa females were transferred from white-eyed pupae (worker brood) into freshly capped worker brood cells, 77% (n = 22 fertile mites after the transfer) began a new reproductive cycle by laying a male egg. The proportion of brood cells with male offspring was similar to naturally infested brood cells. Varroa females transferred into brood cells with young pupae reproduced, but only 6% (n = 16 fertile mites after the transfer) produced male offspring. This was significantly different from male production in naturally reproducing Varroa females and those transferred into freshly capped brood cells. We conclude that a host stimulus present in freshly capped brood cells triggers both the start of reproduction and the sequence of sexes.

Animals↗
PubMed2004

Effect of temperature on life history of the predatory mite Amblyseius (Neoseiulus) californicus (Acari: Phytoseiidae).

Amblyseius (Neoseiulus) californicus is an indigenous mite in Japan that feeds on many spider mite species. We evaluated the development, survivorship and life-history parameters of A. californicus on a diet of eggs of Tetranychus urticae (red form). More than 97.3% of A. californicus eggs hatched and more than 81.6% of newly hatched larvae attained maturity at temperatures between 15 and 35 degrees C. Females oviposited at 37.5 degrees C, but no eggs hatched. At 40 degrees C, no females laid eggs. The lower threshold temperature from egg to oviposition was 10.3 degrees C and the thermal constant was 86.2 degree-days. Based on these data, the maximum number of generations that could complete development in a year under field conditions in Ibaraki, central Japan, would be between 21 and 28. At 25 degrees C, females laid a mean of 41.6 eggs during a mean oviposition period of 19.4 days. The intrinsic rates of natural increase (rm) were 0.173 at 20 degrees C, 0.274 at 25 degrees C and 0.340 at 30 degrees C.

Animals↗
PubMed2004

The relationship between dietary specialism and availability of food and water on cannibalistic interactions among predatory mites in protected crops.

The interplay between dietary specialism, the tolerance of food and water stress and level of cannibalism is likely to be important in determining the outcome of biological control using inundative releases of multiple natural enemies, such as phytoseiid mites in protected crops. The dietary specialist, Phytoseiulus persimilis, with a short immature development time (4-5 days) when plentiful food was available had a low ability to survive without food (5 days), even with access to water. The dietary generalists, Neoseiulus californicus, N. cucumeris and lphiseius degenerans, had longer immature development times (by up to 2 days) than P. persimilis. Survival ability differed amongst the generalist species when they were starved but provided with constant access to water. Both N. californicus and N. cucumeris survived the longest (8-10 days) and I. degenerans survived the shortest period (4 days). No negative intra-specific interaction between immatures was observed with P. persimilis when food was available and in the absence of food this species tended to starve rather than act cannibalistically. Both N. californicus and N. cucumeris showed a low degree of cannibalism between immatures, either when food was available, or when starved but given access to water. Even when food was available survival of I. degenerans fell by 30% in 4 days and remained at 60-70% for 3 further days; survival continued to decline rapidly when they were starved but provided with water. This indicates that immatures of I. degenerans could either feed on dead conspecifics or that they were capable of a degree of cannibalism. Adult females of P. persimilis did not feed on conspecific eggs even when deprived of food but provided with water. Adult female N. californicus and N. cucumeris did feed on conspecific eggs but at a low level (<1 egg per day), which occurred only after 48 h starvation. Although egg cannibalism occurred more consistently with adult female I. degenerans than with other mite species it was at a low level (<1 egg per day). If the tendency to cannibalism, not just of eggs but with more susceptible life stages such as larvae, is reduced when water is available freely this could be important in determining the interactions that occur under natural conditions.

Animals↗
PubMed2004

Classifying life-style types of phytoseiid mites: diagnostic traits.

Several traits are useful for identifying life-style types of predaceous phytoseiid mites when either 2 (diet generalist-specialist) or 4 (specialist I and II-generalist III and IV) type models [McMurtry J.A. and Croft B.A. 1997. Annu. Rev. Entomol. 42: 291-321] are considered. Traits useful for both models are developmental time and oviposition rates when feeding on several food types. Discriminating for the 2-types model are dorsal shield setae lengths, and intra- and inter-specific predation. Another trait useful for both models is feeding preferences of adult female phytoseiids on eggs versus larvae of Tetranychus urticae Koch. In this paper, we review established and other traits that need more study such as mouthpart types, other morphological features, spider mite webbing effects, distributions relative to prey-foods, plant-host relationships including domatia and sap feeding, density-dependent responses to prey and predator-prey ratios required for biological control. Uses of life-style data in biological control decision-making are discussed.

Animals↗
PubMed2004

Traditional water mite fixatives and their compatibility with later DNA studies.

This work compares frozen water, 70% alcohol, Koenike's and Angelier's fluid as preservation media for water mites in terms of their eventual facilitation of DNA extraction and amplification. The time the mites spent in the fixatives ranged between 1 week and 25 years. Two molecular markers were amplified: 16S ribosomal DNA and CoI mitochondrial DNA. DNA was extractable and could be sequenced from specimens fixed in all the above media, although this generally became more difficult as time progressed. In the light of the known characteristics of these media, the results suggest Angelier's fluid to be the most practical, especially on long expeditions.

Animals↗
PubMed1999

Relationship between mite, cat, and dog allergens in reservoir dust and ambient air.

BACKGROUND: Standardized methods to measure allergen exposure are essential to assess the relationship between exposure, sensitization, and asthma. Most studies have measured allergen levels in reservoir dust, although air samples may be more representative as a measure of inhaled allergen. The aim of this study was to define the relationship between mite, cat, and dog allergen content in the reservoir dust and the levels in the ambient air. METHODS: Dust samples from the living-room floor (LF) and sofa (S) were collected in 127 homes: 62 without and 65 with pets (31 dogs, 34 cats). Air samples were taken in the same room, with a high-volume pump for 1 h (flow 60 l/min). Der p 1, Fel d 1, and Can f 1 were determined by mAb-based ELISA. RESULTS: Airborne Der p 1 was below the detection limit (0.8 ng/m3) in all homes, with reservoir levels (GM and range) being 1.14 microg/g (0.2-66) and 1.15 microg/g (0.2-127) in LF and S, respectively. Airborne Can f 1 was detected in 40/62 homes without pets (range 0.6-12.4 ng/m3) and in all homes with dogs (range 0.5-99 ng/m3). In the multiple linear regression analysis, Can f 1 level in the LF was an independent correlate of the airborne Can f 1 (P=0.01, homes with dogs; P=0.04, homes without dogs). Fel d 1 was detected in the air in 16/62 homes without pets (range 0.16-1.8 ng/m3) and in all homes with cats (range 0.4-22.3 ng/m3). Fel d 1 level in the LF was an independent correlate of the airborne Fel d 1 in homes without cats (P=0.008), but airborne levels in homes with cats did not correlate with reservoir levels. CONCLUSIONS: The aerodynamics of each allergen must be taken into account when assessing exposure: while levels in reservoir dust are the best available index for mite allergens, airborne levels might be more suitable for defining exposure to pets. If air samples are difficult to obtain, levels of Can f 1 and Fel d 1 in the LF samples should be used as a surrogate measure of personal exposure.

Air↗
PubMed1999

Continuous antihistamine treatment controls allergic inflammation and reduces respiratory morbidity in children with mite allergy.

BACKGROUND: Allergic reaction is characterized by a complex inflammatory process. Some of the new antihistamines have antiallergic effects and can affect the inflammatory cell recruitment via adhesion molecule downregulation. We aimed to assess in a 12-month study whether continuous treatment with an antihistamine (terfenadine) can reduce respiratory symptoms and local inflammation in children with mite allergy. METHODS: The study was double-blind and placebo-controlled: it involved two parallel groups of children suffering from rhinoconjunctivitis and/or mild intermittent asthma due to mite allergy. They received either terfenadine (1 mg/kg per body weight per day) or placebo for 1 year. Nasal, conjunctival, and bronchial symptoms were recorded by diary cards; at each of the programmed control visits, a nasal scraping for inflammatory cells and ICAM-1 was performed. Some additional clinical parameters were also recorded: days of school absence, extra visits for acute respiratory symptoms, and days of hospital admission. RESULTS: Only children treated with terfenadine achieved significant control of symptoms (P<0.05 in 8 out of 12 months) and allergic inflammation, as shown by inflammatory cell infiltrate and ICAM-1 expression at nasal level (P<0.001), and had significantly fewer extra visits and school absences than the placebo group (P<0.03). No side-effects were reported in either group. CONCLUSIONS: The present study demonstrates that continuous terfenadine treatment (1 mg/kg body weight per day) could decrease respiratory symptoms and allergic inflammation, and it had an additional antiallergic effect in reducing ICAM-1 expression on nasal epithelial cells. Therefore, the present results confirm the efficacy of a long-term therapeutic strategy in controlling allergic inflammation.

Adolescent↗
PubMed2000

Effect of current exposure to Der p 1 on asthma symptoms, airway inflammation, and bronchial hyperresponsiveness in mite-allergic asthmatics.

The existence of a dose-response relationship between indoor allergen exposure and sensitization has been widely described, but the effect of allergen exposure on asthma activity (symptoms, bronchial hyperresponsiveness [BHR], and inflammation) is not clear. Our aim was to determine the existence of an association among current exposure to mite allergens and symptoms, BHR, and airway inflammation assessed in blood and sputum from asthmatic patients sensitized to Dermatophagoides pteronyssinus. We selected 31 mild and recently diagnosed (12-24 months) asthma patients sensitized to D. pteronyssinus. Allergenic exposure (Der p 1, Der 2) was assessed by a commercial assay based on monoclonal antibodies (mAb), carried out on the dust samples collected from patients' beds in a standardized way. Patients completed an asthma symptom questionnaire and underwent skin tests, methacholine bronchial challenge, and sputum induction. Sputum cell profile was analyzed and eosinophil cationic protein (ECP), tryptase, albumin, and interleukin(IL)-5 levels were quantified in sputum supernatant. Total eosinophil numbers and ECP levels were measured in blood samples. Most patients were exposed to Der p 1 levels under 2 microg/g of dust. Der p 1 exposure was higher among the subjects with positive sputum tryptase detection (P = 0.020). Der p 1 levels showed a trend toward correlation with asthma symptoms (P = 0.066, r = 0.36) and correlated with sputum tryptase levels (P = 0.032, r = 0.42). No relationship between BHR, eosinophilic inflammation, and allergenic exposure was found. Our results suggest that asthma symptoms and lung mast-cell activation are at least partially dependent on current allergen exposure. The lack of correlation between mite exposure, eosinophilic inflammation, and BHR supports the role of other factors that enhance the immunologic response initiated by allergen, increasing the activity of asthma.

Allergens↗
PubMed2002

Atopy and house dust mite sensitization as risk factors for asthma in children.

BACKGROUND: Recent evidence suggests that asthma is not invariably related to atopy. The aim of this study was to evaluate the frequency of atopy, asthma and sensitization to eight common allergens in a large group of children with allergic symptoms. METHODS: 1426 children referred to our Paediatric Asthma and Allergy Center because of allergic symptoms were examined. Bronchial asthma, allergic rhino-conjunctivitis, food allergy and atopic dermatitis were diagnosed with standardized methods. Atopy was diagnosed if at least one skin test was positive. RESULTS: Of the 1426 children examined, 629 (44%) were atopic and 769 (56%) were non-atopic. Asthma was diagnosed in the same proportion (i.e., 64%) of atopic and non-atopic children. However, after division into age groups, non-atopic asthma was significantly more prevalent (chi2 = 8.46) in children between 0 and 3 years old (group 1). On the other hand, atopy was significantly associated with asthma only in group 3 (odds ratio 1.85). Furthermore, a significant association with asthma symptoms was found for house dust mite (HDM) in group 3 (odds ratio 4.8). CONCLUSIONS: Asthma is related to atopy in pre-selected children only from the age of 7 years. House dust mite sensitization seems to be an important determinant of asthma in these "older" children.

Age Factors↗
PubMed2003

The effect of specific immunotherapy on T-cell receptor repertoire in patients with allergy to house-dust mite.

BACKGROUND: The precise mechanism of specific immunotherapy (SIT), long used for treating allergic diseases, remains undefined. SIT was shown to act by modifying the immune response of T lymphocytes to antigens. We examined the effect of SIT on the expression and use V-alpha, -beta, -gamma and -delta chains of T-cell receptors (TCR) in patients allergic to house-dust mite. METHODS: Peripheral venous blood was taken for lymphocyte TCR analysis from 10 house-dust mite (HDM) allergic adults before initiating SIT and 6 months after initiating the treatment. Twelve similarly allergic patients without SIT served as controls. TCR chains were identified by fluorescence-activated cell sorter (FACS) using the following monoclonal antibodies: CD3, CD14, CD8, pan alpha-beta, pan gamma-delta, V-alpha2, V-alpha12.1, V-beta5a, V-beta5b, V-beta5c, V-beta8a, V-beta8b, V-beta3.1, V-beta13, V-beta12, V-beta6.7, V-delta1, V-delta2, V-gamma9, and V-gamma4. RESULTS: Analyzed before and 6 months after SIT initiation, lymphocyte TCR showed significantly increased V-beta5b, V-beta12 and V-alpha12.1 values compared to controls (without significant changes in other markers). CONCLUSIONS: SIT caused selective expansion of certain V-beta- and V-alpha-expressing T cells in patients allergic to HDM. Our results support the notion that the effect of SIT in patients with allergic rhinitis may be achieved by modifying the T lymphocyte response through the modulation of TCR usage.

Adult↗
PubMed2003

Effects on inflammation parameters of a double-blind, placebo controlled one-year course of SLIT in children monosensitized to mites.

BACKGROUND: Clinical documentation about effects on local markers of inflammation of sublingual immunotherapy (SLIT) in children is still poor. METHODS: Twenty-four children (age range 4-16 years, average 8.5 years) monosensitized to house dust mites (HDMs) were randomized to receive active or placebo SLIT for this allergen according to a double-blind, placebo-controlled design. Before treatment and 10-12 months later the following parameters were checked: ECP and tryptase in sputum and nasal secretion, serum and nasal mite-specific IgE (sIgE), allergen-specific nasal challenge test (sNCT), nasal symptoms and tryptase after sNCT. RESULTS: Nasal tryptase and nasal IgE in basal conditions were unchanged in treated children but significantly increased in untreated children (P = 0.0156 and P = 0.0313, respectively). The threshold for sNCT was unchanged in both groups of children, but the symptom score after sNCT was unchanged in the placebo group and significantly decreased in the active group (P = 0.0084). The nasal tryptase after sNCT was unchanged in the active group and significantly increased in the placebo group (P = 0.0218). Intergroup comparison showed a significant difference in oral tryptase and nasal tryptase after sNCT in favour of the active group. CONCLUSIONS: These interim results after only 1 year of treatment show that SLIT in children monosensitized to HDMs is able to avoid the spontaneous increase in both nasal sIgE antibodies and in local allergic inflammation in basal conditions. These outcomes are confirmed and supported by the decrease of symptoms in the active group combined with the increase of nasal tryptase only in the control group in both cases after sNCT.

Administration, Sublingual↗
PubMed2003

The upper and lower airway responses to nasal challenge with house-dust mite Blomia tropicalis.

BACKGROUND: The house dust mite Blomia tropicalis (B. tropicalis) was found to be the most prevalent domestic mite in Singapore. However, its pathogenicity in allergic airway diseases remains to be investigated. METHODS: Twenty adults with persistent allergic rhinitis (PAR) were studied. Five had a history of asthma, and all were asymptomatic except one who was under treatment with low-dose inhaled corticosteroid. Nasal challenge was carried out by nasal spray with phosphate-buffered saline (PBS) and with increasing concentrations of crude B. tropicalis extracts (0.6, 6.0 and 60 micro g/ml) at 15 min intervals. Subjective symptom scores and absolute number of sneezes were recorded together with objective measurements of spirometry (forced expiratory volume in 1 s, FEV1) and acoustic rhinomanometry (volume of the nasal cavity). These were performed at baseline, 5 min after each incremental challenge, and 30 min, 1 h, 3 h, 5 h and 7 h after the last challenge. Meanwhile, concentrations of mediators in nasal secretions (tryptase, leukotriene C4 (LTC4) and eosinophil cationic protein (ECP)) were measured in nasal aspirate samples at similar time intervals. An identical (control) challenge procedure with PBS alone was repeated in seven patients after a washout period of at least 2 weeks. RESULTS: Significant increases in the subjective and objective nasal symptoms, together with a significant increase of tryptase and LTC4 concentrations in nasal secretion, were found 5 min after each challenge with B. tropicalis, but not with PBS. There was no definitive pattern of the late-phase nasal response in either subjective symptoms or objective measurements. Three patients (3/5) with a history of asthma showed a fall in FEV1 readings (33%, 22% and 11% from baseline, respectively) at 7 h post challenge with concomitant mild wheezing in the night. CONCLUSIONS: Our study demonstrates direct evidence of allergic nasal response to B. tropicalis in sensitized adults. It shows that nasal provocation may also provoke concomitant asthmatic symptoms during the late-phase reaction, especially in people with a history of asthma.

Adult↗
PubMed1999

The prevalence of reported asthma is independent of exposure in house dust mite-sensitized children.

In areas with low house dust mite (HDM) allergen exposure, both mite sensitization and asthma prevalence are low. In most other areas, HDM allergen exposure is higher than the threshold for sensitization. In this setting, is HDM allergen exposure a factor which is causally related to the development of asthma in HDM-sensitive individuals? To answer this question, the cumulative prevalence of asthma was evaluated in a group of 157 schoolchildren, aged 10 and 11 yrs, who were allergic to HDM allergen, and compared it with HDM allergen exposure and atopic status, using univariate and multivariate analysis. HDM allergen levels were measured in mattress dust using an enzyme-linked immunosorbent assay (ELISA) method. Of mattress dust samples, 94% had an HDM allergen level >2 microg x g dust(-1). Atopy was evaluated by means of skin prick tests using five common allergens. Among the predictive variables studied by means of univariate analysis, only the number of positive skin tests and male sex correlated with asthma prevalence, but not HDM allergen exposure. Logistic regression analysis also demonstrated that the number of positive skin tests correlated with asthma prevalence (odds ratio (OR)=1.38, p=0.05), whereas the OR for HDM allergen exposure was 1.0. This survey suggests that, in a geographical area with high HDM allergen exposure, asthma prevalence is not linked with HDM allergen levels.

Allergens↗
PubMed2001

Exposure to a high concentration of mite allergen in early infancy is a risk factor for developing atopic dermatitis: a 3-year follow-up study.

The cause of allergy is multi-factorial, and the development of an allergic disease seems to be the result of an interaction between genetic and environmental factors. The goal for preventing the development of allergic diseases is to avoid sensitization to allergens. The aim of this work was to study whether or not exposure to environmental allergens early in infancy would influence the occurence of various allergic diseases in later life. On an annual basis, a total of 931 healthy newborns were followed-up until they reached 3 years of age. The occurence of allergic diseases was recorded by trained medical students during visits. Measurement of Dermatophagoides pteronyssinus (Der p 1) concentration in house dust was performed when each baby was 18 and 36 months old. Total and specific immunoglobulin E (IgE) antibodies against Der p 1, cow's milk, and egg white were evaluated at birth and at 18 months of age. The following results were obtained: at 3 years of age, 10.4% had bronchial asthma (BA), 21.4% atopic dermatitis (AD), 7.0% urticaria, and 46.8% had experienced wheezing; higher family allergy scores led to a higher incidence of AD (p=0.0012); exposure to a mite allergen concentration of 1 microg/g of dust may be associated with a higher incidence of AD (p=0.0156); the presence of Der p 1 IgE antibody at 18 months of age was associated with a higher incidence of BA (p=0.0001); and children sensitized to egg whites at 18 months of age had an increased risk of developing AD at 3 years of age (p=0.0187). Hence, early exposure to mite allergen is a risk factor for the development of atopic dermatitis, but seems not to be related to the development of bronchial asthma. Early sensitization to egg whites increases the risk of developing AD. The early detection of serum Der p 1 IgE antibody is associated with a higher incidence of bronchial asthma.

Age Factors↗

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