RESUMEN
The genome of the spider mite Tetranychus urticae, a herbivore, is missing important elements of the canonical Drosophila immune pathways necessary to fight bacterial infections. However, it is not known whether spider mites can mount an immune response and survive bacterial infection. In other chelicerates, bacterial infection elicits a response mediated by immune effectors leading to the survival of infected organisms. In T. urticae, infection by either Escherichia coli or Bacillus megaterium did not elicit a response as assessed through genome-wide transcriptomic analysis. In line with this, spider mites died within days even upon injection with low doses of bacteria that are non-pathogenic to Drosophila Moreover, bacterial populations grew exponentially inside the infected spider mites. By contrast, Sancassania berlesei, a litter-dwelling mite, controlled bacterial proliferation and resisted infections with both Gram-negative and Gram-positive bacteria lethal to T. urticae This differential mortality between mite species was absent when mites were infected with heat-killed bacteria. Also, we found that spider mites harbour in their gut 1000-fold less bacteria than S. berlesei We show that T. urticae has lost the capacity to mount an induced immune response against bacteria, in contrast to other mites and chelicerates but similarly to the phloem feeding aphid Acyrthosiphon pisum Hence, our results reinforce the putative evolutionary link between ecological conditions regarding exposure to bacteria and the architecture of the immune response.
Asunto(s)
Bacterias/patogenicidad , Tetranychidae/inmunología , Tetranychidae/microbiología , Animales , Herbivoria , TranscriptomaRESUMEN
Wolbachia is an intracellular bacterium that has aroused intense interest because of its ability to alter the biology of its host in diverse ways. In the two-spotted spider mite, Tetranychus urticae, Wolbachia can induce complex cytoplasmic incompatibility (CI) phenotypes and fitness changes, although little is known about the mechanisms. In the present study, we selected a strain of T. urticae, in which Wolbachia infection was associated with strong CI and enhanced female fecundity, to investigate changes in the transcriptome of T. urticae in Wolbachia-infected vs. uninfected lines. The responses were found to be sex-specific, with the transcription of 251 genes being affected in females and 171 genes being affected in males. Some of the more profoundly affected genes in both sexes were lipocalin genes and genes involved in oxidation reduction, digestion and detoxification. Several of the differentially expressed genes have potential roles in reproduction. Interestingly, unlike certain Wolbachia transinfections in novel hosts, the Wolbachia-host association in the present study showed no clear evidence of host immune priming by Wolbachia, although a few potential immune genes were affected.
Asunto(s)
Tetranychidae/genética , Tetranychidae/microbiología , Wolbachia/fisiología , Animales , Citoplasma/fisiología , Femenino , Perfilación de la Expresión Génica , Masculino , Oxidación-Reducción , Fenotipo , Reacción en Cadena en Tiempo Real de la Polimerasa , Reproducción/genética , Simbiosis/genética , Tetranychidae/inmunología , TranscriptomaRESUMEN
BACKGROUND: Tetranychus urticae is a phytophagus mite found in the leaves of numerous plants. High sensitization rates have been demonstrated, however, provocation tests have only been performed in an occupational setting. OBJECTIVE: To assess accuracy of skin prick tests and clinical relevance of T. urticae sensitization by means of conjunctival provocation tests (CPT) in a population without occupational exposure and to evaluate possible environmental risk factors for T. urticae allergy. METHODS: Patients ≥ 18 years old sensitized to T. urticae (n = 12) and a non-sensitized control group (n = 12) were invited to perform CPT with T. urticae and fulfill a questionnaire including demographic data, questions on environmental exposure to T. urticae and allergy symptoms/diagnosis. A single-blinded placebo-controlled CPT with T. urticae (Leti®) was performed with increasing concentrations (0.002, 0.02, 0.2 and 2 mg/mL) and considered positive if conjunctival hyperemia, palpebral edema or lacrimation were observed in the tested eye. RESULTS: Of T. urticae sensitized patients (mean wheal 4.4 ± 1.5 mm), 9 had a positive CPT, including 3 monosensitized. A good diagnostic accuracy was found for skin prick tests: AUC = 0.952, sensitivity = 100%, specificity = 80%, positive likelihood ratio = 5 and negative likelihood ratio = 0 for a 3 mm wheal. No differences were found between allergic and non-allergic subjects regarding atopy, allergic disease or farming activities. CONCLUSIONS: A high prevalence of allergy to Tetranychus urticae was found in the north of Portugal. Future studies with a larger number of patients are needed to evaluate its relation to clinical symptoms and the impact of environmental factors.
Asunto(s)
Hipersensibilidad/diagnóstico , Hipersensibilidad/epidemiología , Pruebas Inmunológicas/métodos , Tetranychidae/inmunología , Adulto , Animales , Área Bajo la Curva , Conjuntiva/inmunología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Exposición Profesional , Portugal/epidemiología , Prevalencia , Sensibilidad y Especificidad , Pruebas CutáneasRESUMEN
The herbivorous spider mite Tetranychus urticae usually remains on the lower leaf surfaces of its host plants. Although terrestrial animals are generally thought to be well protected from damage because of UV radiation, insect herbivory frequently increases when solar UV-B (280-315 nm) radiation is attenuated. As UV transmission through leaves is generally low because of the accumulation of compounds that act as selective sunscreens (e.g., phenolics), we hypothesized that T. urticae avoids solar UV-B radiation by staying on lower leaf surfaces. We examined whether artificial UV irradiation and solar UV affected the survival and reproduction of T. urticae and whether staying on lower leaf surfaces was beneficial to their performance under ambient UV radiation. We found that T. urticae was not well protected from UV-B radiation, because artificial UV-B irradiation strongly decreased survivorship and egg production. More importantly; compulsory solar UV irradiation treatments also had lethal effects on T. urticae, whereas the mites could avoid them if they remained on the lower leaf surfaces of their host plants. These results showed that access to habitats protected from sunlight, such as lower leaf surfaces, is likely essential for T. urticae survival under ambient UV-B radiation. The lethal effects of solar UV radiation may also affect the population dynamics of spider mites, and habitat (resource) limitation may increase the probability of interspecific interactions, such as competition and predation. In turn, the occurrence of these interactions in sheltered areas may be associated with observed increases in herbivory under conditions of solar UV-B-attenuation.
Asunto(s)
Conducta Animal , Tetranychidae/efectos de la radiación , Rayos Ultravioleta , Animales , Femenino , Cadena Alimentaria , Oviparidad/efectos de la radiación , Óvulo/efectos de la radiación , Hojas de la Planta , Dinámica Poblacional , Tetranychidae/inmunologíaRESUMEN
BACKGROUND: Recent studies have reported an increased prevalence of respiratory symptoms among farm workers. The aim of this study was to identify risk factors associated with spider mite allergy among table grape farm workers. METHODS: A cross-sectional study of 207 workers in table grape farms was conducted. Skin prick tests used extracts of 8 common aeroallergens, grape mould (Botrytis cinerea) and Tetranychus urticae. Specific IgE to T. urticae was quantified using ImmunoCAP (Phadia). Erythrocyte cholinesterase levels were determined using the Test-mate ChE Cholinesterase Test System (model 460). RESULTS: The average duration of employment of workers was 10 years and 12% were pesticide crop sprayers. Work-related wheeze (26%), ocular-nasal (24%) and urticaria/skin symptoms (14%) were more prevalent in the orchards. The prevalence of sensitization (skin prick test) was highest to T. urticae (22%) followed by house dust mite (16%), with 25% being atopic. The prevalence of allergy to T. urticae (skin reactivity and work-related symptoms) was 9.5%, with respiratory allergy (6%) more common than skin allergy (3%). Work-related ocular-nasal (OR = 4.9) and skin (OR = 3.7) symptoms were more commonly reported by pesticide crop sprayers. Workers with T. urticae-allergic rhino-conjunctivitis and probable asthma were more likely to be atopic, spray pesticides and have low (<30 U/g hemoglobin) erythrocyte cholinesterase levels. CONCLUSIONS: This study demonstrated that spider mite, T. urticae, is an important outdoor allergen among table grape farm workers. The increased risk of spider mite allergy appears to be related to high pesticide exposure among crop sprayers.
Asunto(s)
Enfermedades de los Trabajadores Agrícolas/epidemiología , Asma/epidemiología , Hipersensibilidad Inmediata/epidemiología , Tetranychidae/inmunología , Vitis , Adulto , Enfermedades de los Trabajadores Agrícolas/inmunología , Agricultura , Alérgenos/inmunología , Animales , Asma/inmunología , Femenino , Humanos , Hipersensibilidad Inmediata/inmunología , Inmunoglobulina E/sangre , Masculino , Persona de Mediana Edad , Prevalencia , Factores de Riesgo , Pruebas CutáneasRESUMEN
It has been demonstrated that spider mites such as the two-spotted spider mite (Tetranychus urticae) are important allergens for fruit farmers. A total of 2,467 adults (795 metropolitan urban, 788 non-metropolitan urban, and 884 rural subjects) were enrolled. They responded to the questionnaire, and underwent methacholine bronchial provocation tests as well as skin prick tests to locally common aeroallergens including the two-spotted spider mite. The prevalences of asthma and rhinitis as reported on the questionnaire were 7.8% and 16.4% of adults aged 20-35, 9.4% and 24.7% of those 36-50, and 17.7% and 21.7% of those older than 50, respectively. Among the older group, the two-spotted spider mite was the most common sensitizing allergen, although it was second of that of house dust mites among the other two age groups. Sensitization to the two-spotted spider mite was significantly associated with the prevalence of asthma and rhinitis among the younger age group, and associated with the prevalence of rhinitis among the older age group. The two-spotted spider mite might be a common sensitizing allergen in the general population of adults, and sensitization to this mite may play a role in the manifestation of asthma and rhinitis symptoms during adulthood.
Asunto(s)
Asma/etiología , Rinitis Alérgica Perenne/etiología , Tetranychidae/inmunología , Adulto , Factores de Edad , Anciano , Alérgenos , Animales , Asma/inmunología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Rinitis Alérgica Perenne/inmunología , Factores de Riesgo , Encuestas y CuestionariosRESUMEN
It has been demonstrated that spider mites such as the two-spotted spider mite (Tetranychus urticae) are important allergens for fruit farmers. A total of 2,467 adults (795 metropolitan urban, 788 non-metropolitan urban, and 884 rural subjects) were enrolled. They responded to the questionnaire, and underwent methacholine bronchial provocation tests as well as skin prick tests to locally common aeroallergens including the two-spotted spider mite. The prevalences of asthma and rhinitis as reported on the questionnaire were 7.8% and 16.4% of adults aged 20-35, 9.4% and 24.7% of those 36-50, and 17.7% and 21.7% of those older than 50, respectively. Among the older group, the two-spotted spider mite was the most common sensitizing allergen, although it was second of that of house dust mites among the other two age groups. Sensitization to the two-spotted spider mite was significantly associated with the prevalence of asthma and rhinitis among the younger age group, and associated with the prevalence of rhinitis among the older age group. The twospotted spider mite might be a common sensitizing allergen in the general population of adults, and sensitization to this mite may play a role in the manifestation of asthma and rhinitis symptoms during adulthood.
Asunto(s)
Persona de Mediana Edad , Masculino , Humanos , Femenino , Animales , Anciano , Adulto , Tetranychidae/inmunología , Factores de Riesgo , Rinitis Alérgica Perenne/etiología , Encuestas y Cuestionarios , Asma/etiología , Alérgenos , Factores de EdadRESUMEN
BACKGROUND: Clinical complaints in atopic subjects with asthma and rhinitis occur more frequently in the presence of high total and allergen-specific IgE serum levels. Here we report on the relationship between total and allergen-specific IgE serum levels and presence of symptoms in an unselected farmer population sensitized to Tetranychus urticae (TU). METHODS: Farmers were recruited as previously described. Total IgE and allergen-specific IgE were measured by immunoassay in TU-positive skin prick test (SPT) farmers (n = 58) and two control groups including Dermatophagoides pteronyssinus (Dp)-positive SPT subjects (n = 40) and non-atopic, TU-negative SPT healthy farmers (n = 25). RESULTS: Both TU+ and Dp+ subjects had significantly higher total IgE values (P < 0.001) than healthy non-atopic subjects. TU-specific IgE levels were significantly more elevated in symptomatic than non-symptomatic TU+ subjects (P = 0.028). Dp-specific IgE levels were higher in symptomatic than non-symptomatic Dp+ subjects (P = 0.003). Finally, total IgE levels were significantly higher in the symptomatic than non-symptomatic subgroups in both TU+ and Dp+ subjects (P < 0.0001 and P = 0.007, respectively). Logistic regression analysis showed that only total IgE concentrations were significant predictors of current symptoms in TU+ subjects. CONCLUSIONS: High total IgE and allergen-specific IgE levels are associated with symptoms in TU+ subjects. Definition of their predictive value requires further studies.
Asunto(s)
Enfermedades de los Trabajadores Agrícolas/inmunología , Enfermedades de los Trabajadores Agrícolas/terapia , Alérgenos/sangre , Alérgenos/inmunología , Epítopos/inmunología , Hipersensibilidad Inmediata/inmunología , Hipersensibilidad Inmediata/terapia , Inmunoglobulina E/sangre , Inmunoglobulina E/inmunología , Tetranychidae/inmunología , Adulto , Enfermedades de los Trabajadores Agrícolas/sangre , Reacciones Cruzadas/inmunología , Femenino , Humanos , Hipersensibilidad Inmediata/sangre , Inmunización , Masculino , Valor Predictivo de las Pruebas , Prevalencia , Ensayos Clínicos Controlados Aleatorios como Asunto , Método Simple Ciego , Pruebas Cutáneas , Estadística como AsuntoRESUMEN
The two-spotted mite (TSM) is commonly found on fruit trees, herbaceous plants, and greenhouse flowers. However, a recent investigation indicated that the sensitization rate to TSM was as high as that of house-dust mites (HDMs) in nonfarmers as well as in farmers working in orchards in this country. The aim of this study was to identify immunoglobulin E (IgE)-binding components within TSM and to evaluate the allergenic relationship with the citrus red mite (CRM) and HDM. Sera were collected from eight patients who were not farmers and who had asthma with high serum-specific IgE to the TSM and from unexposed controls showing negative responses to the TSM on skin-prick test. Twelve percent sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis were applied. To evaluate allergenic relationships with HDMs and CRMs, two kinds of sera pools were used: one (A) showing positive responses to both TSMs and HDMs and the other (B) showing an isolated positive response to TSMs. ELISA inhibition tests using A and B pooled sera were conducted. The TSM-ELISA inhibition test using sera A showed significant inhibition with addition of TSMs and CRMs, partial inhibition with HDMs, and minimal inhibition with other inhalant allergens. The ELISA inhibition test using sera B showed significant inhibition with TSMs and CRMs and minimal inhibition was noted with HDMs as well as other inhalant allergens. Immunoblot analysis using individual sera showed seven IgE-binding components (75, 56, 47, 41, 37, 28, and 14 kDa) and two (75 and 14 kDa) of them were bound to IgE in > 50% of the sera tested. Seven IgE-binding components were identified within the TSM extract and two (75 and 14 kDa) could be considered major allergens. It is suggested that the TSM contains species-specific allergen in addition to shared allergens with CRMs and HDMs.