Acaricidal target and mite indicator as color alteration using 3,7-dimethyl-2,6-octadienal and its derivatives derived from Melissa officinalis leaves.

Toxicities and color deformation were evaluated of essential oils of Melissa officinalis cultivated in France, Ireland, and Serbia and their constituents, along with the control efficacy of spray formulations (0.25, 0.5, and 1%) containing M. officinalis oils cultivated in France and its main compound against Dermatophagoides farinae and D. pteronyssinus adults. In a contact + fumigant bioassay, M. officinalis oil (France) was more active against D. farinae and D. pteronyssinus, compared to M. officinalis oils (Ireland and Serbia). Interestingly, color alteration of D. farinae and D. pteronyssinus was exhibited, changing from colorless to golden brown through the treatment with M. officinalis oils. The acaricidal and color alteration principle of three M. officinalis oils was determined to be 3,7-dimethyl-2,6-octadienal. M. officinalis oil (France) and 3,7-dimethyl-2,6-octadienal were significantly more effective in closed containers than in open containers, indicating that their acaricidal route of action was largely a result of vapor action. Sprays (0.5 and 1%) containing 3,7-dimethyl-2,6-octadienal and 1% spray containing M. officinalis oil (France) resulted in 100% mortality and color alteration against D. farinae and D. pteronyssinus. These results indicated that M. officinalis oil and 3,7-dimethyl-2,6-octadienal could be developed as a suitable acaricidal and mite indicator ingredient for the control of dust mites.

Therapeutic potential of a phospholipase D1 inhibitory peptide fused with a cell-penetrating peptide as a novel anti-asthmatic drug in a Der f 2-induced airway inflammation model.

Asthma is a chronic lung disease that causes airflow obstruction due to airway inflammation. However, its therapeutics remain inadequate. We previously reported that phospholipase D1 (PLD1) is a key enzyme involved in the production of pro-inflammatory cytokines in airway inflammation induced by the house dust mite allergen Dermatophagoides farinae 2 (Der f 2). We also revealed that PLD1 is specifically inactivated by AP180 (assembly protein, 180 kDa) and identified the PLD1-specific binding motif (TVTSP) of AP180. Therefore, the aims of this study were to develop a novel anti-asthmatic agent that could suppress airway inflammation by inhibiting PLD1 and examine its acute and chronic toxicity. We designed TAT-TVTSP, a PLD1-inhibitory peptide fused with a cell-penetrating peptide (CPP) delivery system. TAT-TVTSP was efficiently delivered to bronchial epithelial cells and significantly reduced Der f 2-induced PLD activation and Interleukin 13 (IL-13) production. Intranasally administered TAT-TVTSP was also efficiently transferred to airway tissues and ameliorated airway inflammation in a Der f 2-induced allergic asthma mouse model. Moreover, we investigated the safety of TAT-TVTSP as a therapeutic agent through single- and repeated-dose toxicity studies in a mouse model. Taken together, these results indicated that a PLD1-inhibitory peptide fused with a cell-penetrating peptide may be useful for treating allergic inflammatory asthma induced by house dust mites (HDMs).

Acaricidal toxicities and synergistic activities of Salvia lavandulifolia oil constituents against synanthropic mites.

BACKGROUND: The acaricidal activity of Salvia lavandulifolia oil and its major components was evaluated using contact and vapor bioassays. Synergistic interactions among components contained in S. lavandulifolia oil were studied. RESULTS: The 50% lethal dose (LD50 ) of S. lavandulifolia oil was 3.66, 3.37, and 5.04 µg cm-3 , respectively, in the vapor bioassay against Dermatophagoides farinae, Dermatophagoides pteronyssinus and Tyrophagus putrescentiae. The major components of S. lavandulifolia oil were (-)-camphor, camphene, 1,8-cineole, (±)-limonene, and α-pinene (79.11% combined). Several combinations of these components exhibited synergistic effects against D. farinae, D. pteronyssinus, and T. putrescentiae, particularly (-)-camphor, camphene, and α-pinene. (-)-Camphor usually had synergistic interactive effects in the mixtures. For the vapor action, the mixture of (-)-camphor, camphene and α-pinene was the most potent combination against D. farinae (R = 2.34), D. pteronyssinus (R = 2.75), and T. putrescentiae (R = 2.30) when used at their naturally occurring ratio. CONCLUSION: This study is the first report on the acaricidal activity of S. lavandulifolia oil and the synergistic interactive effects of its components against D. farinae, D. pteronyssinus and T. putrescentiae. The oil may be an alternative tool for the control of synanthropic mites. © 2018 Society of Chemical Industry.

Eucalyptus oil-loaded microcapsules grafted to cotton fabrics for acaricidal effect against Dermatophagoides farinae.

The purpose of this study was to develop acaricidal cotton fabrics grafted with eucalyptus oil-loaded microcapsules (EOMCs) produced from green resources. EOMCs showed a broad size distribution between 0.5 and 6.5 µm, and had the average diameter 1.8 µm. EOMCs exhibited nonporous spherical shapes and individually remained on cotton fibres. Through AATCC mortality tests against house dust mites (HDMs) (Dermatophagoides farinae), the treated cotton fabric containing EOMCs resulted in 98.7% mortality. Acaricidal efficiency was due to the large amount of oxygenated monoterpene, 1,8-eucalyptol (75.8%) and hydroxylated monoterpenes such as α-terpineol (3.6%), terpinen-4-ol (0.4%) and linalool (0.3%) found in eucalyptus oil. These compounds are effective in enhancing penetration into HDMs. EOMCs produced from safe and natural sources can serve as a replacement for synthetic acaricides in controlling the population of HDM, leading to positive impacts on the human health and environment.

Toxicity of basil oil constituents and related compounds and the efficacy of spray formulations to Dermatophagoides farinae (Acari: Pyroglyphidae).

Pyroglyphid house dust mites are the most common cause of allergic symptoms in humans. An assessment was made of the toxicity of basil, Ocimum basilicum L, essential oil, 11 basil oil constituents, seven structurally related compounds, and another 22 previously known basil oil constituents to adult American house dust mites, Dermatophagoides farinae Hughes. The efficacy of four experimental spray formulations containing basil oil (1, 2, 3, and 4% sprays) was also assessed. Results were compared with those of two conventional acaricides benzyl benzoate and N,N-diethyl-3-methylbenzamide. The active principles of basil oil were determined to be citral, alpha-terpineol, and linalool. Citral (24 h LC50, 1.13 microg/cm2) and menthol (1.69 microg/cm2) were the most toxic compounds, followed by methyl eugenol (5.78 microg/cm2). These compounds exhibited toxicity greater than benzyl benzoate (LC50, 8.41 microg/cm2) and N,N-diethyl-3-methylbenzamide (37.67 microg/cm2). Potent toxicity was also observed with eugenol, menthone, spathulenol, alpha-terpineol, nerolidol, zerumbone, and nerol (LC50, 12.52-21.44 microg/cm2). Interestingly, the sesquiterpenoid alpha-humulene, lacking only the carbonyl group present in zerumbone, was significantly less effective than zerumbone, indicating that the alpha,beta-unsaturated carbonyl group of zerumbone is a prerequisite component for toxicity. These compounds were consistently more toxic in closed versus open containers, indicating that their mode of delivery was largely a result of vapor action. Basil oil applied as 3 and 4% sprays provided 97 and 100% mortality against the mites, respectively, whereas permethrin (cis:trans, 25:75) 2.5 g/liter spray treatment resulted in 17% mortality. Our results indicate that practical dust mite control in indoor environments can be achieved by basil oil spray formulations (3 and 4% sprays) as potential contact-action fumigants.

Evaluation of the acaricidal toxicities of camphor and its structural analogues against house dust mites by the impregnated fabric disc method.

BACKGROUND: The acaricidal activities of (±)-camphor structural analogues against house dust mites were evaluated using the impregnated fabric disc bioassay. RESULTS: The acaricidal effects of camphor and its structural analogues were evaluated against Dermatophagoides farinae and D. pteronyssinus. Based on the LD50 values against D. farinae, (±)-camphor (0.95 µg cm(-2) ) was 38.75 times more effective than N,N-diethyl-m-toluamide (DEET) (36.81 µg cm(-2) ), followed by (+)-camphor (1.41 µg cm(-2) ), (-)-camphor (2.03 µg cm(-2) ) and (1R)-camphor oxime (3.31 µg cm(-2) ) in the impregnated fabric disc bioassay. However, camphor-10-sulfonic acid and camphoric acid had no observable activity against D. farinae or D. pteronyssinus. The acaricidal activities of camphor and its structural analogues against D. pteronyssinus were similar to those against D. farinae. CONCLUSION: These results indicate that camphor and its structural analogues are suitable for producing acaricidal agents against house dust mites.

Acaricidal activities of ß-caryophyllene oxide and structural analogues derived from Psidium cattleianum oil against house dust mites.

BACKGROUND: This study was to evaluate the acaricidal activities of an active compound isolated from Psidium cattleianum and structural analogues against Dermatophagoides farinae and D. pteronyssinus. ß-Caryophyllene oxide was isolated using chromatographic techniques. RESULTS: Based on the 50% lethal concentration (LD50) values against D. farinae using the fumigant method, ß-caryophyllene oxide (1.36 µg cm(-2)) was ∼ 7.52 times more toxic than benzyl benzoate (10.23 µg cm(-2)), followed by α-caryophyllene (1.75 µg cm(-2)) and ß-caryophyllene (3.13 µg cm(-2)). Against D. pteronyssinus, ß-caryophyllene oxide (1.38 µg cm(-2)) was ∼ 7.22 times more toxic than benzyl benzoate (9.96 µg cm(-2)), followed by α-caryophyllene (1.71 µg cm(-2)) and ß-caryophyllene (3.58 µg cm(-2)). In the contact toxicity method against D. farinae, ß-caryophyllene oxide (0.44 µg cm(-2)) was ∼ 17.27 times more active than benzyl benzoate (7.60 µg cm(-2)), followed by α-caryophyllene (0.67 µg cm(-2)) and ß-caryophyllene (0.91 µg cm(-2)). Against D. pteronyssinus, ß-caryophyllene oxide (0.47 µg cm(-2)) was ∼ 13.06 times more effective than benzyl benzoate (6.14 µg cm(-2)), followed by α-caryophyllene (1.71 µg cm(-2)) and ß-caryophyllene (3.58 µg cm(-2)). CONCLUSION: ß-Caryophyllene oxide and structural analogues have potential for development as preventive agents for the control of house dust mites.

Acaricidal toxicities of 1-hydroxynaphthalene from Scutellaria barbata and its derivatives against house dust and storage mites.

The essential oil of Scutellaria barbata was extracted using a steam distillation and then evaluated via fumigant and contact toxicity bioassays against Dermatophagoides farinae, Dermatophagoides pteronyssinus, and Tyrophagus putrescentiae. The acaricidal toxicities of 1-hydroxynaphthalene from S. barbata oil and its derivatives were determined and compared with those of benzyl benzoate. Based on the LD50 values of 1-hydroxynaphthalene derivatives against D. farinae, D. pteronyssinus, and T. putrescentiae, obtained using a fumigant toxicity bioassay, the acaricidal activity of 1-hydroxynaphthalene (2.11, 2.37, and 4.50 µg/cm2) was 4.76, 6.00, and 2.68 times higher than that of benzyl benzoate (10.05, 9.50, and 12.50 µg/cm2) in the corresponding order, which was followed by that of 2-hydroxynaphthalene (9.50, 9.00, and 11.50 µg/cm2). On the contact toxicity bioassay, the acaricidal activity of 1-hydroxynaphthalene (0.79, 0.92, and 2.50 µg/cm2) was 9.49, 6.52, and 3.76 times higher than that of benzyl benzoate (7.50, 6.00, and 9.41 µg/cm2), which was followed by that of 2-hydroxynaphthalene (4.21, 4.80, and 6.50 µg/cm2). In conclusion, our results indicate that S. barbata oil and 1-hydroxynaphthalene derivatives might be effective natural agents for the management of house dust and storage mites.

Contact and fumigant toxicity of Pinus densiflora needle hydrodistillate constituents and related compounds and efficacy of spray formulations containing the oil to Dermatophagoides farinae.

BACKGROUND: The toxicity of red pine needle hydrodistillate (RPN-HD), 19 RPN-HD constituents and another 12 structurally related compounds and the control efficacy of four experimental spray formulations containing RPN-HD (0.5. 1, 2 and 3% sprays) to adult Dermatophagoides farinae were evaluated. RESULTS: RPN-HD (24 h LC50 , 68.33 µg cm(-2) ) was toxic to mites. Menthol was the most toxic compound (12.69 µg cm(-2) ), and the toxicity of this compound and benzyl benzoate did not differ significantly. High toxicity was also produced by α-terpineol, bornyl acetate, geranyl acetate, thymol, linalyl acetate, terpinyl acetate, citral, linalool and camphor (18.79-36.51 µg cm(-2) ). These compounds were more toxic than either deet or dibutyl phthalate. In vapour-phase mortality tests, these compounds were consistently more toxic in closed versus open containers, indicating that their mode of delivery was largely a result of vapour action. RPN-HD 3% experimental spray provided 95% mortality against adult D. farinae, whereas permethrin (cis:trans, 25:75) 2.5 g L(-1) spray treatment resulted in 0% mortality. CONCLUSION: In the light of global efforts to reduce the level of highly toxic synthetic acaricides in indoor environments, RPN-HD and the compounds described merit further study as potential biocides for the control of Dermatophagoides populations as fumigants with contact action.

Essential oil components from Asarum sieboldii Miquel are toxic to the house dust mite Dermatophagoides farinae.

In our effort to develop novel plant-derived acaricides, we examined the contact and fumigant toxicity of Asarum heterotropoides (Asarum sieboldii Miquel) essential oil constituents to the house dust mite Dermatophagoides farinae (Acari: Pyroglyphidae). Ten constituents, including methyl eugenol (relative amount 42.18 %), were identified by gas chromatography-mass spectroscopy (GC-MS) in the A. sieboldii Miq. essential oil. In contact toxicity tests, methyl eugenol (4.2 µg/cm(2), 24 h LD50) was most toxic to D. farinae, followed by benzyl benzoate (9.1 µg/cm(2)), A. sieboldii Miq. essential oil (37.7 µg/cm(2)), and dibutyl phthalate (DBP 57.9 µg/cm(2)). The potency of methyl eugenol and A. sieboldii Miq. essential oil was higher than benzyl benzoate and DBP, with mortalities of 100, 100, 94.6, and 13.2 %, respectively, after 2.5 h of exposure. In the vapor phase mortality bioassay, methyl eugenol and A. sieboldii Miq. essential oil resulted in 100 % mortality in closed containers after 24-h exposure, but only 4.7 and 7.9 %, respectively, in open containers, indicating that the toxicity in these tests was largely due to the vapor phase. Methyl eugenol and A. sieboldii Miq. essential oil merit further study as potential D. farinae control compounds.

Interference in foraging behaviour of European and American house dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae (Acari: Pyroglyphidae) by catmint, Nepeta cataria (Lamiaceae).

The European and American house dust mites, Dermatophagoides pteronyssinus and D. farinae, have a huge impact upon human health worldwide due to being the most important indoor trigger of atopic diseases such as asthma, rhinitis and atopic dermatitis. Preceding studies have shown that the behavioural response of house dust mites towards volatile chemicals from food sources can be assessed using a Y-tube olfactometer assay. In the current study, we used this assay to investigate, for the first time, the ability of the essential oil of the catmint plant, Nepeta cataria (Lamiaceae), known to repel other ectoparasites affecting human and animal health, to interfere with the attraction of D. pteronyssinus and D. farinae towards a standard food source (fish flakes). Two distinct chemotypes (A and B), enriched in the iridoid compounds (4aS,7S,7aR)-nepetalactone and (4aS,7S,7aS)-nepetalactone, and the sesquiterpene (E)-(1R,9S)-caryophyllene, were used. Initial assays with a hexane extract of fish flakes (FF extract) confirmed attraction of mites to this positive control (P < 0.001 and P < 0.05 for D. pteronyssinus and D. farinae respectively), but when presented in combination with either N. cataria chemotype, tested across a range of doses (10, 1, 0.1 and 0.01 µg), decreasing attraction of mites to their food source was observed as the dose augmented. Our study shows that N. cataria, enriched in iridoid nepetalactones and (E)-(1R,9S)-caryophyllene, exhibits potent repellent activity for house dust mites, and has the potential for deployment in control programmes based on interference with normal house dust mite behaviour.

Acaricidal activity of DHEMH, derived from patchouli oil, against house dust mite, Dermatophagoides farinae.

This study characterized the acaricidal activity of constituents of patchouli oil extracted from (Pogostemon cablin (Blanco) BENTH) against the house dust mite, Dermatophagoides farinae. A new compound, 2-(1,3-dihydroxy-but-2-enylidene)-6-methyl-3-oxo-heptanoic acid (DHEMH), was isolated from patchouli oil and characterized by (1)H-NMR, (13)C-NMR, LC-MS and elemental analysis (EA). This active component was identified as the hydrolysate of pogostone. Fifteen other constituents found in patchouli oil were also identified by GC-MS, including patchouli alcohol and pogostone. LD(50) studies carried out over 24 h using contact toxicity tests identified DHEMH as the most toxic compound to D. farinae (2.04 µg/cm(2)), followed by patchouli oil (6.11 µg/cm(2)), benzyl benzoate (BP) (9.31 µg/cm(2)) and dibutyl phthalate (DBP) (58.52 µg/cm(2)). In vapor phase toxicity tests, all of these compounds were more effective in closed than open containers, indicating that the most efficient mode of delivery for these compounds is the vapor phase. These results indicate that DHEMH and patchouli oil merit further study as potential agents for the control of D. farinae.

Effect of a commercial air ionizer on dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae (Acari: Pyroglyphidae) in the laboratory.

OBJECTIVE: To investigate the short and long term efficacy of a commercial air ionizer in killing Dermatophagoides pteronyssinus (D. pteronyssinus) and Dermatophagoides farinae (D. farinae) mites. METHODS: The effect of a commercial ionizer on D. pteronyssinus and D. farinae was evaluated in the laboratory, using a specially designed test. Mortality was assessed after 6, 16 and 24 hours for direct exposure and after 24, 36, 48, 60 and 72 hours for exposure in simulated mattress. New batches of mites were used for each exposure time. RESULTS: LT50 for direct exposure of ionizer was 10 hours for D. pteronyssinus and 18 hours for D. farinae. The LT50 for exposure in simulated mattress was 132 hours or 5.5 days for D. pteronyssinus and 72 hours or 3 days for D. farinae. LT95 for direct exposure of ionizer was 36 hours for D. pteronyssinus and D. farinae. Meanwhile, the LT95 for exposure in simulated mattress was 956 hours or 39.8 days for D. pteronyssinus and 403 hours or 16.8 days for D. farinae. CONCLUSIONS: This study demonstrates the increasing mite mortalities with increasing exposure time of a commercial ionizer and suggests that negative ions produced by an ionizer kill dust mites and can be used to reduce natural mite populations on exposed surfaces such as floors, clothes, curtains, etc. However, there is reduced efficacy on mites inside stuffed materials as in mattresses and furniture.

Contact and fumigant toxicity of Armoracia rusticana essential oil, allyl isothiocyanate and related compounds to Dermatophagoides farinae.

BACKGROUND: The toxicity to adult Dermatophagoides farinae of allyl isothiocyanate identified in horseradish, Armoracia rusticana, oil and another 27 organic isothiocyanates was evaluated using contact + fumigant and vapour-phase mortality bioassays. Results were compared with those of two conventional acaricides, benzyl benzoate and dibutyl phthalate. RESULTS: Horseradish oil (24 h LC(50), 1.54 µg cm(-2)) and allyl isothiocyanate (2.52 µg cm(-2)) were highly toxic. Benzyl isothiocyanate (LC(50) , 0.62 µg cm(-2)) was the most toxic compound, followed by 4-chlorophenyl, 3-bromophenyl, 3,5-bis(trifluoromethyl)phenyl, cyclohexyl, 2-chlorophenyl, 4-bromophenyl and 2-bromophenyl isothiocyanates (0.93-1.41 µg cm(-2)). All were more effective than either benzyl benzoate (LC(50) , 4.58 µg cm(-2)) or dibutyl phthalate (24.49 µg cm(-2)). The structure-activity relationship indicates that types of functional group and chemical structure appear to play a role in determining the isothiocyanate toxicities to adult D. farinae. In the vapour-phase mortality bioassay, these isothiocyanates were consistently more toxic in closed versus open containers, indicating that their mode of delivery was, in part, a result of vapour action. CONCLUSION: In the light of global efforts to reduce the level of highly toxic synthetic acaricides in indoor environments, the horseradish oil-derived compounds and the isothiocyanates described herein merit further study as potential acaricides for the control of house dust mite populations as fumigants with contact action.

Prior or coinstantaneous oral exposure to environmental immunosuppressive agents aggravates mite allergen-induced atopic dermatitis-like immunoreaction in NC/Nga mice.

BACKGROUND: Immunosuppressive environmental chemicals may increase the potency of allergens and thereby play a role in the development of allergic diseases such as allergic rhinitis, asthma and atopic dermatitis (AD). OBJECTIVES: This study's primary objective was to examine the mechanisms behind the development of allergic diseases and immunosuppression induced by some environmental chemicals. We focused on the aggravation of AD by the organophosphorus pesticide O,O-diethyl-O-4-nitro-phenylthiophosphate (parathion) and the organochlorine pesticide 1,1,1-trichloro-2,2-bis(4-methoxyphenyl)ethane (methoxychlor), in NC/Nga mice sensitized with extract of Dermatophagoides farinae (Df). METHODS: NC/Nga mice were exposed orally to parathion or methoxychlor prior or coinstantaneous with sensitization with Df. The mice were subsequently challenged with Df. One day after the last challenge with Df, we analyzed dermatitis severity and expression of genes in the ear auricle, immunoglobulin (Ig) E and IgG(2a) levels in serum, and in auricular lymph nodes, T- or B-cell numbers and cytokine production. RESULTS: Prior exposure to parathion or methoxychlor induced marked increases in the following: dermatitis severity and gene expression in the ear auricle, IgE and IgG(2a) levels in serum, expression of surface antigens on helper T-cell and IgE-positive B-cell, production of Th1 and Th2 cytokines, and production of IgE in auricular lymph-node cells. In contrast, coinstantaneous exposure to parathion or methoxychlor yielded, at most, small but significant decreases in all parameters. CONCLUSIONS: Our results indicate that atopic dermatitis can be aggravated by prior exposure to immunosuppressive environmental chemicals.

Acaricidal activities of apiol and its derivatives from Petroselinum sativum seeds against Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Tyrophagus putrescentiae.

The acaricidal effects of an active constituent derived from Petroselinum sativum seeds and its derivatives were determined using impregnated fabric disk bioassay against Dermatophagoides farinae , Dermatophagoides pteronyssinus , and Tyrophagus putrescentiae and compared with that of synthetic acaricide. The acaricidal constituent of P. sativum was isolated by various chromatographic techniques and identified as apiol. On the basis of LD(50) values against D. farinae and D. pteronyssinus, apiol (0.81 and 0.94 µg/cm(2)) was 12.4 and 10.2 times more toxic than benzyl benzoate (10.0 and 9.58 µg/cm(2)), respectively. In acaricidal studies of apiol derivatives, 3,4-methylenedioxybenzonitrile (0.04, 0.03, and 0.59 µg/cm(2)) was 250, 319, and 20.7 times more toxic than benzyl benzoate (10.0, 9.58, and 12.2 µg/cm(2)) against D. farinae, D. pteronyssinus, and T. putrescentiae. In structure-activity relationships, the acaricidal activities of apiol derivatives could be related to allyl (-C(3)H(5)) and methoxy (-OCH(3)) functional groups. Furthermore, apiol and its derivatives could be useful for natural acaricides against these three mite species.

Contact and fumigant toxicity of cinnamaldehyde and cinnamic acid and related compounds to Dermatophagoides farinae and Dermatophagoides pteronyssinus (Acari: Pyroglyphidae).

Toxicities of (E)-cinnamaldehyde and (E)-cinnamic acid and their 41 structurally related compounds to adult Dermatophagoides farinae Hughes and Dermatophagoides pteronyssinus Trouessart (Acari: Pyroglyphidae) were examined using fabric-circle contact plus fumigant and vapor-phase mortality bioassays. Results were compared with those of two acaricides, benzylbenzoate and dibutyl phthalate. In contact plus fumigant mortality bioassays, the most toxic compounds were (E)-cinnamaldehyde, methyl (E)-cinnamate, cinnamyl acetate, and hydrocinnamaldehyde against adult D.farinae (17.5-23.3 mg/m2) and D. pteronyssinus (19.0-24.0 mg/m2), based on 24-h 50% lethal concentration (LC50) values. These compounds were significantly more toxic than either benzyl benzoate (LC50, 64.9 and 60.5 mg/m2) or dibutyl phthalate (218.9 and 232.3 mg/m2). The toxicity of allyl cinnamate versus benzyl benzoate was not significantly different. Structure-activity relationship indicates that structural characteristics, such as types of functional groups, carbon skeleton, and saturation, appear to play a role in determining the compound toxicities. In vapor-phase mortality bioassays, these compounds were effective against adult D. farinae in closed, but not in open containers, indicating that their mode of delivery was largely a result of vapor action. The active compounds described merit further study as potential house dust mite control fumigants with contact action in light of global efforts to reduce the level of highly toxic synthetic acaricides in indoor environments.

Acaricidal activities of clove bud oil and red thyme oil using microencapsulation against HDMs.

The purpose of this study was to produce a safer microcapsule loaded with clove bud oil and red thyme oil to reduce the population of house dust mites (HDMs). Gelatin-based microcapsules 4-85 µm in size were created, with agitation speed and type of oil playing a critical role in governing their size. Microcapsules made up of single spherical units less than 30 µm in diameter remained separate on the fibre, whereas larger microcapsules of over 30 µm ruptured or aggregated. Thermogravimetric analysis (TGA) demonstrated that microcapsules containing red thyme oil showed a more consistent range of oil loading, from 50 to 80%, than microcapsules containing clove bud oil, which ranged from 30 to 80% (more deviated). Mortality tests on Dermatophagoides farinae conducted on fabric with attached microcapsules showed that clove bud oil, containing a more phenolic monoterpenoid (eugenol), was more effective at reducing the live HDMs (94% mortality).

Effects of bleach activator, sodium alkyl acyloxybenzene sulfonate, on house dust mites (Dermatophagoides farinae).

House dust mites (Dermatophagoides farinae) in bedding and clothes are a major allergen. However, house dust mites cannot be killed by general washing conditions under 50 degrees C. Therefore, low-temperature washing conditions must be improved to eliminate house dust mites. Sodium alkyl acyloxybenzene sulfonate (OBS) is a bleach activator that is used to intensify the bleaching effects of some laundry products. The purpose of this study was to evaluate the effect of OBS on the elimination of house dust mites in low-temperature washing conditions. D. farinae was soaked in solutions containing different types of OBS for various durations and at various temperatures. The miticidal effects of the various washing conditions were also evaluated for D. farinae. Then sodium lauroyloxybenzene sulfonate (OBS-12) produced the highest D. farinae mortality rate among the OBS solutions that were examined and had a stronger miticidal effect than available chlorine under general washing conditions. OBS exhibited miticidal effects under general washing conditions at low temperatures. Since OBS is already used as an additive in some laundry products to increase the bleaching activity, OBS can be easily used to kill house dust mites under general washing conditions.

Acaricidal activities of traditional Chinese medicine against the house dust mite, Dermatophagoides farinae.

OBJECTIVE: This paper assessed the potential of traditional Chinese medicine (TCM) preparations for using as environmentally acceptable and alternative commercial acaricides. METHODS: 22 kinds of TCM, which contained abundant essential oils and showed insecticidal effects, were collected. Samples extracted with petroleum ether, ethyl acetate and methanol were tested against house dust mites Dermatophagoides farinae and their toxicity assessed. RESULTS: The results showed that 3 TCM of Cinnamonum cassia, Eugenia caryophyllata and Pogostemon cablin have higher activity, and the parallel tests showed that the petroleum ether extract had higher activities (0.0046 mg/cm2, 0.005 mg/cm2 and 0.006 mg/cm2 respectively, 24 h, LD50) than the extracts of ethyl acetate and methanol. The acaricidal activity of the ethyl acetate extracts from C. cassia, P. cablin and Asarum sieboldii (0.00144 mg/cm2, 0.00347 mg/cm2 and 0.05521 mg/cm2 respectively, 24 h, LD50) were almost comparable to that of benzyl benzoate and dibutyl phthalate. However, the methanolic extracts of were less effective. CONCLUSIONS. This study shows the use of extracts with petroleum ether of C. cassia, P. cablin and E. caryophyllata as eco-friendly biodegradable agents for the control of the house dust mite.