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PubMed2005

Assessment of monitoring methods for early detection of three species of storage mite in bulk oilseed rape.

Two types of trap, the BT Trap and PC(TM) pitfall cone trap, were evaluated against the most widely used method of sampling and sieving for their ability to detect low numbers of storage mites (Acarus siro, Tyrophagus longior and Lepidoglyphus destructor) in bulk oilseed rape, under UK maritime conditions. In addition, a synthetic lure (2-nonanone) was incorporated into the two types of trap to assess whether its presence improved trapping performance. The BT traps and PC traps were significantly more effective in detecting low numbers of mites of all species compared with sampling and sieving. The PC trap with synthetic lure was the most effective method. As the PC trap is already widely used for monitoring insects in cereal bulks in the UK, extending its application to include oilseed rape, and to detect mites, would be a logical and cost effective extension of its use.

Acaridae↗
PubMed2005

Pathogenicity of Beauveria bassiana and Metarhizium anisopliae to the tobacco spider mite Tetranychus evansi.

Seventeen isolates of Metarhizium anisopliae (Metschnikoff) Sorokin and two isolates of Beauveria bassiana (Balsamo) Vuillemin were evaluated for their pathogenicity against the tobacco spider mite, Tetranychus evansi Baker & Pritchard. In the laboratory all the fungal isolates were pathogenic to the adult female mites, causing mortality between 22.1 and 82.6%. Isolates causing more than 70% mortality were subjected to dose-response mortality bioassays. The lethal concentration causing 50% mortality (LC5o) values ranged between 0.7 x 10(7) and 2.5 x 10(7) conidia ml(-1). The lethal time to 50% mortality (LT50) values of the most active isolates of B. bassiana and M. anisopliae strains varied between 4.6 and 5.8 days. Potted tomato plants were artificially infested with T. evansi and treated with B. bassiana isolate GPK and M. anisopliae isolate ICIPE78. Both fungal isolates reduced the population density of mites as compared to untreated controls. However, conidia formulated in oil outperformed the ones formulated in water. This study demonstrates the prospects of pathogenic fungi for the management of T. evansi.

Animals↗
PubMed2005

Baseline susceptibility of persea mite (Acari: Tetranychidae) to abamectin and milbemectin in avocado groves in Southern California.

Persea mite, Oligonychus perseae Tuttle, Baker, and Abatiello, susceptibility to abamectin and milbemectin was evaluated in 2003 to determine baseline susceptibility levels in avocado groves in San Diego and Ventura Counties (California, USA) where more than 70% of the state's avocado production is concentrated. Milbemectin has yet to be used in avocado production in California and abamectin has been available for use since 1999. Baseline susceptibility ratios (in relation to the most susceptible population) of five persea mite field strains to milbemectin varied 2.1- to 2.8-fold at the LC50 and LC90, respectively. The susceptibility of seven field strains to abamectin varied slightly more (2.1- to 3.5-fold) with one strain subjected to seven sprays over the past 4 years showing slight but significant separation of LC50 and LC90's from the most susceptible strain, which is suggestive of the early stages of resistance to this product. Based on these data, baseline susceptibility levels are proposed that might be used to monitor for future persea mite resistance to these chemicals as their use in California avocado production continues.

Animals↗
PubMed2005

Mating behavior of the predatory mite Kampimodromus aberrans (Acari: Phytoseiidae).

The mating behavior of the predatory mite Kampimodromus aberrans was studied in the laboratory at a constant temperature of 25 +/- 1 degrees C and a photoperiod of 16:8 (L:D). Forty pairs of newly emerged virgin females and unmated males, were maintained separately on leaf discs and their mating behavior, was observed continuously under a stereomicroscope. The mean time until first contact of female and male individuals was approximately 8.2 min. After the first contact the male moved to the top of the female's dorsum and subsequently underneath her in approximately 1.7 min and then the paired mites walked around on the leaf surface for approximately 7.5 min. Afterwards, the mites remained still in the mating position, i.e. the male beneath the female for an average period of 230.5 min. After mating, most of the females had one spermatophore in one of their spermathecae, whereas a few had one spermatophore in both spermathecae.

Animals↗
PubMed2006

Intraguild interactions between the predatory mites Neoseiulus californicus and Phytoseiulus persimilis.

Species at the same trophic level may interact through competition for food, but can also interact through intraguild predation. Intraguild predation is widespread at the second and third trophic level and the effects may cascade down to the plant level. The effects of intraguild predation can be modified by antipredator behaviour in the intraguild prey. We studied intraguild predation and antipredator behaviour in two species of predatory mite, Neoseiulus californicus and Phytoseiulus persimilis, which are both used for control of the two-spotted spider mite in greenhouse and outdoor crops. Using a Y-tube olfactometer, we assessed in particular whether each of the two predators avoids odours emanating from prey patches occupied by the heterospecific predator. Furthermore, we measured the occurrence and rate of intraguild predation of different developmental stages of P. persimilis and N. californicus on bean leaves in absence or in presence of the shared prey. Neither of the two predator species avoided prey patches with the heterospecific competitor, both when inexperienced with the other predator and when experienced with prey patches occupied by the heterospecific predator. Intraguild experiments showed that N. californicus is a potential intraguild predator of P. persimilis. However, P. persimilis did not suffer much from intraguild predation as long as the shared prey was present. This is probably because N. californicus prefers to feed on two-spotted spider mites rather than on its intraguild prey.

Animals↗
PubMed2006

Odour-mediated responses of a predatory mirid bug and its prey, the two-spotted spider mite.

It has been shown that many natural enemies of herbivorous arthropods use herbivore induced plant volatiles (HIPVs) to locate their prey. Herbivores can also exploit cues emitted by plants infested with heterospecifics or conspecifics. A study was conducted to test whether green bean HIPVs as well as odours emitted directly by spider mites influenced the orientation behaviour of the predatory mirid bug, Macrolophus caliginosus and its prey, Tetranychus urticae in a Y-tube olfactometer. Our results show that both spider mites and M. caliginosus preferred spider mite infested green bean plants to uninfested plants. For M. caliginosus this response was mediated by HIPVs whereas for T. urticae it was mediated through a composite response to both HIPVs and odours emitted directly by the conspecifics (and their associated products). The results may be of use in practical biocontrol situations, through e.g., plant breeding for improved HIPV production, conditioning of mass-reared predators to appropriate cues, and employment of "push-pull-strategies" by using HIPVs.

Animals↗
PubMed2005

Volatile allelochemicals in the Ageratum conyzoides intercropped citrus orchard and their effects on mites Amblyseius newsami and Panonychus citri.

Ageratum conyzoides L. weed often invades cultivated fields and reduces crop productivity in Southeast Asia and South China. However, intercropping this weed in citrus orchards may increase the population of predatory mite Amblyseius newsami, an effective natural enemy of citrus red mite Panonychus citri, and keep the population of P. citri at low and noninjurious levels. This study showed that A. conyzoides produced and released volatile allelochemicals into the air in the intercropped citrus orchard, and these volatiles influenced the olfactory responses of A. newsami and P. citri. At test temperature (25 degrees C), A. conyzoides fresh leaves, its essential oil, and major constituents, demethoxy-ageratochromene, beta-caryophyllene, alpha-bisabolene, and E-beta-farnesene, attracted A. newsami and slightly repelled P. citri. Field experiments demonstrated that spraying A. conyzoides essential oil emulsion in an A. conyzoides nonintercropped citrus orchard increased the population density of A. newsami from below 0.1 to over 0.3 individuals per leaf, reaching the same level as in an A. conyzoides intercropped citrus orchard. However, this effect could not be maintained beyond 48 hr because of the volatility of the essential oil. In contrast, in the A. conyzoides intercropped citrus orchard, A. conyzoides plants continuously produced and released volatile allelochemicals and maintained the A. newsami population for a long time. The results suggest that intercropping of A. conyzoides not only made the citrus orchard ecosystem more favorable for the predatory mite A. newsami, but also that the volatile allelochemicals released from A. conyzoides regulated the population of A. newsami and P. citri.

Ageratum↗
PubMed1988

Preliminary characterization of toxins from the straw itch mite, Pyemotes tritici, which induce paralysis in the larvae of a moth.

Homogenates of whole mites (Pyemotes tritici) paralyze larvae of the greater wax moth Galleria mellonella. Injection of these homogenates into larvae produces symptoms identical to those obtained by bites from female mites. Since the paralytic activity is destroyed by heat and proteolytic enzymes and retained during dialysis, the toxic compounds appear to be proteins. Two protein fractions which differ both in molecular weight and toxicity were found following gel filtration of whole mite extracts. Larvae that are injected with proteins from the high molecular weight (c. 250,000) fraction (designated TxP-HMW) develop flaccid-muscle paralysis after 4-12 hr, while proteins in the low molecular weight fraction (c. 21,000) (designated TxP-LMW) induce a rapid, muscle-contracting paralysis.

Animals↗
PubMed1985

Purification and partial characterization of two major allergens from the house dust mite Dermatophagoides pteronyssinus.

Two major allergens of the house dust mite, Dermatophagoides pteronyssinus (Dp), were purified, and their molecular weight and isoelectric points (pIs) were determined. Dp 42 was purified from an acetone-precipitated mite-excrement extract by a combination of hydrophobic interaction chromatography on phenyl Sepharose and copper-chelate chromatography. The molecular weight was determined to be 18,000 and 25,000 to 30,000 by gel filtration (G-75) and sodium dodecyl sulphate-polyacrylamide gel electrophoresis, respectively, and pI values of 4.6, 5.6, and 6.6 were obtained by sucrose gradient isoelectric focusing (IEF). These values correspond well with those described for the identical allergen, P1. The pI 6.6 variant was considerably enriched in the purified material. Dp 42 constituted 6.4% of the dry weight of a reference whole mite-culture extract. Dp X was obtained partially purified by gel filtration (G-75), ammonium sulphate precipitation, and hydrophobic interaction chromatography. The molecular weight was 18,000 to 20,000 by gel filtration and sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Multiple pIs in the range 5 to 7 were found by sucrose gradient IEF and crossed IEF. The two purified allergens carried clearly distinct activities toward human IgE and appeared as potent allergens in crossed radioimmunoelectrophoresis, RAST, and RAST inhibition.

Allergens↗
PubMed1989

High mite-allergen exposure increases the risk of sensitization in atopic children and young adults.

Concentrations of major allergens of Dermatophagoides pteronyssinus (Dpt) and D. farinae (Df), Der p I and Der f I, were determined in 183 dust samples of mattresses of 133 atopic and 50 nonatopic children by a sandwich-type ELISA. Atopic children and young adults living in houses with high levels of Der p I and Der f I (greater than or equal to 2000 ng/gm of dust) were found to have significantly higher serum IgE levels to Dpt and Df (p less than 0.0001) compared to patients with low mite-allergen exposure. Washed leukocytes of 55 atopic children and 14 control subjects were investigated for in vitro histamine release to serial dilutions of Der p I; 86% of highly exposed (greater than or equal to 10,000 ng/gm) children demonstrated positive histamine release in response to Der p I compared to 17% in the group with very low exposure (less than 400 ng/gm). There was a positive correlation between basophil sensitivity (rs = 0.6; p less than 0.0001) and reactivity (rs = 0.54; p less than 0.0001) to Der p I and mite-allergen exposure. The relative risk for sensitization in the highly exposed group versus the group with very low exposure was sevenfold to 32-fold increased. We conclude that high concentrations of mite allergen (greater than or equal to 2000 ng/gm) increase the risk of specific sensitization in atopic children and young adults and thus may facilitate allergic airway disease.

Adolescent↗
PubMed1994

Mite allergen control with acaricide fails.

BACKGROUND: We compared the effects of an acaricide, benzyl benzoate, with the effects of baking soda control applied to bedroom and living room carpets on house dust mite allergen levels, lung function, and medication use in 12 adult patients with asthma for 12 months. METHODS: This was a randomized, double-blind, placebo-controlled study. Patients were enrolled from the allergy clinic of a large tertiary care center in a metropolitan area. All patients had positive dust mite puncture test results. Six patients used benzyl benzoate, and six used baking soda. Other aggressive mite control measures were implemented uniformly in each group. Subjects were to make two carpet applications, at baseline and at 6 months according to the manufacturer's recommendations. Dust samples were collected in bedroom and living room carpets at 0, 3, 6, 9, and 12 months; and quantities of Der p I and Der f I allergens were determined. Spirometry was done every 3 months, and peak flow rates were recorded for 10 days after each dust sampling. RESULTS: There were no significant differences in mean allergen levels between the two groups over time at either site. There were no significant changes in lung function or medication use for either group. CONCLUSIONS: Benzyl benzoate powder applications may not be effective when done according to manufacturer's instructions. Further studies are necessary to test effectiveness when applied more frequently and for longer periods.

Adult↗
PubMed1994

Mite allergen exposure is a risk for the incidence of specific sensitization.

BACKGROUND: Mite allergen exposure is essential for the process of specific allergic sensitization. However, it is not clear whether incidence of specific sensitization at school age depends on the level of mite antigen exposure. Therefore the relationship between mite allergen exposure and incidence of specific sensitization was investigated. METHODS: Eighteen hundred twelve primary school children were enrolled in a population-based 2-year follow-up study. In three consecutive skin prick tests (SPTs), each 12 months apart, sensitization to Dermatophagoides pteronyssinus (Dpt) and six non-Dpt allergens was ascertained. To assess exposure to Der p I between the first and second SPTs (period I) and the second and third SPTs (period II), the amount of antigen per gram of dust (taken from the children's mattresses was measured. By using the SPT reactions to Dpt as a basis, conversions after "no wheal" were classified as doubtful incidence (average yearly incidence = 6.7%) or definite incidence (average yearly incidence = 3.2%). Then, with the use of multiple logistic regression, the risk of exposure to Der p I (medians: 1.4 micrograms/gm in period I, 1.6 micrograms/gm in period II) was analyzed with adjustment being made for gender, low gestational age, parental atopy, and initial sensitization to non-Dpt allergens. RESULTS: Regarding doubtful incidence, the analysis failed to identify a reliable cutoff point of exposure. For definite incidence, the Der p I exposure represents a significant risk in the total population, starting from a concentration of 9 micrograms/gm. This effect is modified by an initial sensitization to non-Dpt allergens: for these children exposure to concentrations above 2 micrograms/gm poses a significant risk, whereas for the population without other initial sensitizations, only an extremely high cutoff limit (> 80 micrograms/gm) gains significance. CONCLUSION: Our data suggest that a concentration limit of 2 micrograms Der p I antigen per gram of dust should be regarded as minimal avoidance level for primary prevention in children with sensitization to other inhalant allergens.

Animals↗
PubMed1994

Cloning and characterization of a major allergen of the house dust mite, Dermatophagoides pteronyssinus, homologous with glutathione S-transferase.

A major allergen of the house dust mite, Dermatophagoides pteronyssinus, has been identified and characterized from a lambda gt11 cDNA library of the mite. IgE antibodies from the sera of allergic patients that recognise the cloned polypeptide bind to an approximately 26 kDa polypeptide on a Western blot of reduced mite polypeptides. Nucleotides sequencing of the clone revealed a 219 amino acid open reading frame encoding a protein with a derived molecular mass of 25,589 Da and a pI of 6.3. Comparison of the deduced amino acid sequence with amino acid sequence databanks revealed a strong homology with glutathione S-transferases. The nucleotide sequence of the clone displayed a strong homology with the active glutathione binding site of glutathione transferases and contained all but one of the 19 positionally conserved amino acid residues found in glutathione transferases. The cloned polypeptide was expressed in Escherichia coli and affinity-purified on glutathione agarose.

Allergens↗
PubMed2006

Efficacy of an injectable formulation of eprinomectin against Psoroptes cuniculi, the ear mange mite in rabbits.

Thirty rabbits naturally infected with ear mange mite, Psoroptes cuniculi, were subcutaneously administrated with a single dose of eprinomectin at 100, 200 and 300 microg/kg body weight or vehicle on day 0. The extent of lesions was scored on day -6 (prior to treatment), day 0 (treated), days 7, 14, 21, 28 and 35, the ear scabs were collected simultaneously; mites in scabs were examined and counted. The results showed that a single dose of eprinomectin at 200 or 300 microg/kg body weight following subcutaneous administration was able to eliminate P. cuniculi infection in rabbits, and a dose of eprinomectin at 100 microg/kg could significantly reduce mites but was unable to eliminate P. cuniculi.

Animals↗
PubMed2026

Comparative in silico analysis of Apis mellifera immune responses to Varroa destructor and Tropilaelaps mercedesae: Common and mite-specific molecular signatures.

Parasitic mites Varroa destructor and Tropilaelaps mercedesae represent major threats to global honey bee (Apis mellifera) health and productivity, yet comparative molecular insights into host responses remain limited. To address this, we systematically compiled published studies (2015-2025) reporting genes associated with honey bee interactions with V. destructor (11 studies, 87 genes), T. mercedesae (4 studies, 35 genes), and hygienic behavior (6 studies, 44 genes). Gene identifiers were harmonized to the Amel_HAv3.1 genome assembly, yielding three non-redundant sets: 64 Varroa-associated, 34 Tropilaelaps-associated, and 44 hygienic behavior-associated genes. Venn analysis identified 10 overlapping genes (including A0A088A8D5, A0A088ADL8, ABAE_APIME, Def1, Def2, Gapdh, HYTA_APIME, Imd, LOC726783, and Vg), suggesting conserved defense mechanisms, while 41 and 24 genes were uniquely associated with Varroa and Tropilaelaps, respectively. Enrichment analyses revealed Varroa-responsive genes were enriched in immune processes, chitin catabolism, and signaling pathways (Toll/Imd, MAPK, Wnt). Tropilaelaps-associated genes were enriched for antibacterial defense and stress response, with Toll/Imd signaling as the sole significantly enriched pathway. Overlapping genes reinforced core innate immunity activation. Protein-protein interaction network centrality analysis identified key hub genes: Def1, HYTA_APIME, ABAE_APIME, PPO, Imd, PGRP-LC, Vg for Varroa; and ACPH1_APIME, MRJP1, Vg, LOC726783 for Tropilaelaps. Results demonstrate that, despite differences in mite biology, honey bees show a conserved immune response against both parasites, centered on antibacterial defense, humoral immunity, and activation of the Toll/Imd pathway. Although limited by the in-silico nature and research asymmetries reflecting Tropilaelaps' emergence, this curated resource establishes a comprehensive framework for elucidating shared and distinct molecular defense mechanisms. Ultimately, this approach prioritizes diagnostic markers and candidate genes for functional validation and breeding strategies to enhance colony resilience against mite‑driven disease globally.

Animals↗
PubMed2000

A comparative survey of the hydrolytic enzymes of ectoparasitic and free-living mites.

Extracts of ectoparasitic mites of birds (Dermanyssus gallinae), sheep (Psoroptes ovis) and plants (Tetranychus urticae) and of free-living mites (Acarus siro) contained acid and alkaline phosphatase, C4 and C8 esterases, lipase, leucine and valine aminopeptidases and a range of glycosidase activities. Dermanyssus gallinae and P. ovis, species highly adapted to an animal parasitic lifestyle, had very similar profiles and contained low activities of glycosidases. In contrast, the polyphagous species A. siro contained moderate to high activities of every glycosidase examined, whereas the phytophagous species, T. urticae, displayed high activities of only beta-galactosidase and beta-glucuronidase. All extracts hydrolysed haemoglobin with optima below pH6, and this hydrolysis was associated with an aspartic proteinase and variable cysteine proteinase activity dependent on species. Inhibitor-labelling with biotinyl-Phe-Ala-FMK revealed the presence of cysteine proteinases with molecular masses of 25-33.5kDa. Each mite species contains the enzymes necessary to complete digestion of the diet in the intracellular lysosomal compartment. The absolute and relative activities of each enzyme varied, and are discussed according to phylogeny and dietary habit.

Animals↗
PubMed2002

The role of resting spores in the survival of the mite-pathogenic fungus Neozygites floridana from Mononychellus tanajoa during dry periods in Brazil.

Survival of pathogens during long periods of unfavorable conditions can be critical to their ecology and to their use in biological control. In northeastern Brazil, the mite pathogen Neozygites floridana must survive hot and dry conditions between wet seasons when it infects the cassava green mite Mononychellus tanajoa. We report on large numbers of mite cadavers bearing resting spores towards the end of epizootics in mid-1995. High within-leaf variability indicated that local factors may be important in determining resting spore formation. These spores remain in the host cadaver on a leaf until the cadaver breaks up, whereupon the spores fall freely to the soil, there to remain dormant. Laboratory simulation of field conditions led to ca. 25% of mycosed individuals bearing resting spores. Mummies (without resting spores) kept in hot and dry conditions showed little or no viability within 2 months, implying no role for survival over extended dry periods. It is proposed that resting spores form the principal means by which this pathogen survives the dry season in the study area. This has implications for its introduction to new areas in classical biological control.

Animals↗
PubMed1990

The control of house dust mite allergens in rugs.

Used rugs were vacuum cleaned, "wet cleaned," "shampooed," or heated in an autoclave. The effects on the live-mite population, on the allergen (Dermatophagoides pteronyssinus, Der p I and Der p II; and Dermatophagoides farinae, Der f II) content, and on the suitability of the rugs as a habitat for house dust mites was studied. Autoclaving was most effective in all three aspects. The cleaning methods were quite inefficient for killing the mites, but a significant reduction of allergens and deterioration of the habitat quality was established. "Wet cleaning" appears particularly promising.

Allergens↗