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Thomas V Riley - One of the best experts on this subject based on the ideXlab platform.
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candida albicans adhesion to human epithelial cells and polystyrene and formation of biofilm is reduced by sub inhibitory Melaleuca alternifolia tea tree essential oil
Medical Mycology, 2012Co-Authors: Aurelia N Sudjana, Thomas V Riley, Christine F Carson, Kerry C Carson, Katherine A HammerAbstract:This study investigated the effects of the volatile terpene-rich oil from Melaleuca alternifolia (tea tree oil) on the formation of biofilms and the adhesion of C. albicans cells to both biotic and abiotic surfaces. Biofilm formation on polystyrene was significantly inhibited for 70% of the isolates at the lowest test concentration of 0.016% of tea tree oil (TTO) when quantified by XTT and 40% of isolates when measured by crystal violet staining. Adhesion to polystyrene, quantified by crystal violet staining, was significantly reduced for 3 isolates at 0.031%, 6 isolates at 0.062% and 0.125% and for all 7 isolates at 0.25% TTO. Reductions in adhesion were not due to loss of viability (at concentrations of ≤ 0.125%) or interactions between the TTO and polystyrene. Similarly, adhesion to buccal epithelial and HeLa cells was also significantly reduced in the presence of 0.016-0.062% TTO. Treatment with 0.125% TTO, but not 0.062%, decreased the cell surface hydrophobicity of C. albicans, indicating one potential mechanism by which adhesion may be reduced. These data demonstrate that sub-inhibitory TTO reduces the adhesion of C. albicans to both human cells and polystyrene, inhibits biofilm formation and decreases cell surface hydrophobicity.
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topically applied Melaleuca alternifolia tea tree oil causes direct anti cancer cytotoxicity in subcutaneous tumour bearing mice
Journal of Dermatological Science, 2012Co-Authors: Demelza J Ireland, Thomas V Riley, Sara J Greay, Cornelia M Hooper, Haydn T Kissick, Pierre Filion, Manfred W BeilharzAbstract:Abstract Background Melaleuca alternifolia (tea tree) oil (TTO) applied topically in a dilute (10%) dimethyl sulphoxide (DMSO) formulation exerts a rapid anti-cancer effect after a short treatment protocol. Tumour clearance is associated with skin irritation mediated by neutrophils which quickly and completely resolves upon treatment cessation. Objective To examine the mechanism of action underlying the anti-cancer activity of TTO. Methods Immune cell changes in subcutaneous tumour bearing mice in response to topically applied TTO treatments were assessed by flow cytometry and immunohistochemistry. Direct cytotoxicity of TTO on tumour cells in vivo was assessed by transmission electron microscopy. Results Neutrophils accumulate in the skin following topical 10% TTO/DMSO treatment but are not required for tumour clearance as neutrophil depletion did not abrogate the anti-cancer effect. Topically applied 10% TTO/DMSO, but not neat TTO, induces an accumulation and activation of dendritic cells and an accumulation of T cells. Although topical application of 10% TTO/DMSO appears to activate an immune response, anti-tumour efficacy is mediated by a direct effect on tumour cells in vivo . The direct cytotoxicity of TTO in vivo appears to be associated with TTO penetration. Conclusion Future studies should focus on enhancing the direct cytotoxicity of TTO by increasing penetration through skin to achieve a higher in situ terpene concentration. This coupled with boosting a more specific anti-tumour immune response will likely result in long term clearance of tumours.
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susceptibility of pseudomonads to Melaleuca alternifolia tea tree oil and components
Journal of Antimicrobial Chemotherapy, 2006Co-Authors: Chelsea J Papadopoulos, Katherine A Hammer, Christine F Carson, Thomas V RileyAbstract:Objectives: Thirty isolates of Pseudomonas aeruginosa, 15 isolates of Pseudomonas putida and 11 isolates of Pseudomonas fluorescens were tested for susceptibility to tea tree oil (TTO), the essential oil of Melaleuca alternifolia, and the components terpinen-4-ol, a-terpineol, cineole, g-terpinene and r-cymene. Methods: MICs were determined by broth microdilution in Mueller–Hinton medium supplemented with 0.002% (v/v) Tween 80. Results: The MIC90 of TTO for all isolates tested was 4% (v/v) or less. Susceptibility to components tested varied between species.
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tolerance of pseudomonas aeruginosa to Melaleuca alternifolia tea tree oil is associated with the outer membrane and energy dependent cellular processes
Journal of Antimicrobial Chemotherapy, 2004Co-Authors: Chelsea J Longbottom, Katherine A Hammer, Christine F Carson, Brian J Mee, Thomas V RileyAbstract:Objectives: The essential oil of Melaleuca alternifolia (tea tree oil) and its components have antimicrobial activity against a wide range of Gram-positive and Gram-negative bacteria, fungi and viruses. The mechanism(s) by which Pseudomonas aeruginosa NCTC 10662 maintains a decreased susceptibility to tea tree oil and components was investigated. Results: Ethylene diamine tetraacetic acid enhanced the antimicrobial activity of tea tree oil and terpinen-4-ol against stationary phase P. aeruginosa while polymyxin B nonapeptide enhanced the activity of tea tree oil and γ-terpinene. Pre-treatment with the protonophore carbonyl cyanide m-chlorophenylhydrazone increased the susceptibility of exponential phase cells to sub-inhibitory concentrations of tea tree oil, terpinen-4-ol and γ-terpinene, indicating that intrinsic tolerance to tea tree oil and components is substantially energy dependent. Conclusions: Increased tolerance to tea tree oil in P. aeruginosa is directly related to the barrier and energy functions of the outer membrane, and may involve efflux systems.
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susceptibility of oral bacteria to Melaleuca alternifolia tea tree oil in vitro
Oral Microbiology and Immunology, 2003Co-Authors: Katherine A Hammer, Christine F Carson, L Dry, M Johnson, Ewa M Michalak, Thomas V RileyAbstract:The in vitro activity of Melaleuca alternifolia (tea tree) oil against 161 isolates of oral bacteria from 15 genera was determined. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) ranged from 0.003 to 2.0% (v/v). MIC90 values were 1.0% (v/v) for Actinomyces spp., Lactobacillus spp., Streptococcus mitis and Streptococcus sanguis, and 0.1% (v/v) for Prevotella spp. Isolates of Porphyromonas, Prevotella and Veillonella had the lowest MICs and MBCs, and isolates of Streptococcus, Fusobacterium and Lactobacillus had the highest. Time kill studies with Streptococcus mutans and Lactobacillus rhamnosus showed that treatment with ≥0.5% tea tree oil caused decreases in viability of >3 log colony forming units/ml after only 30 s, and viable organisms were not detected after 5 min. These studies indicate that a range of oral bacteria are susceptible to tea tree oil, suggesting that tea tree oil may be of use in oral healthcare products and in the maintenance of oral hygiene.
Christine F Carson - One of the best experts on this subject based on the ideXlab platform.
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candida albicans adhesion to human epithelial cells and polystyrene and formation of biofilm is reduced by sub inhibitory Melaleuca alternifolia tea tree essential oil
Medical Mycology, 2012Co-Authors: Aurelia N Sudjana, Thomas V Riley, Christine F Carson, Kerry C Carson, Katherine A HammerAbstract:This study investigated the effects of the volatile terpene-rich oil from Melaleuca alternifolia (tea tree oil) on the formation of biofilms and the adhesion of C. albicans cells to both biotic and abiotic surfaces. Biofilm formation on polystyrene was significantly inhibited for 70% of the isolates at the lowest test concentration of 0.016% of tea tree oil (TTO) when quantified by XTT and 40% of isolates when measured by crystal violet staining. Adhesion to polystyrene, quantified by crystal violet staining, was significantly reduced for 3 isolates at 0.031%, 6 isolates at 0.062% and 0.125% and for all 7 isolates at 0.25% TTO. Reductions in adhesion were not due to loss of viability (at concentrations of ≤ 0.125%) or interactions between the TTO and polystyrene. Similarly, adhesion to buccal epithelial and HeLa cells was also significantly reduced in the presence of 0.016-0.062% TTO. Treatment with 0.125% TTO, but not 0.062%, decreased the cell surface hydrophobicity of C. albicans, indicating one potential mechanism by which adhesion may be reduced. These data demonstrate that sub-inhibitory TTO reduces the adhesion of C. albicans to both human cells and polystyrene, inhibits biofilm formation and decreases cell surface hydrophobicity.
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susceptibility of pseudomonads to Melaleuca alternifolia tea tree oil and components
Journal of Antimicrobial Chemotherapy, 2006Co-Authors: Chelsea J Papadopoulos, Katherine A Hammer, Christine F Carson, Thomas V RileyAbstract:Objectives: Thirty isolates of Pseudomonas aeruginosa, 15 isolates of Pseudomonas putida and 11 isolates of Pseudomonas fluorescens were tested for susceptibility to tea tree oil (TTO), the essential oil of Melaleuca alternifolia, and the components terpinen-4-ol, a-terpineol, cineole, g-terpinene and r-cymene. Methods: MICs were determined by broth microdilution in Mueller–Hinton medium supplemented with 0.002% (v/v) Tween 80. Results: The MIC90 of TTO for all isolates tested was 4% (v/v) or less. Susceptibility to components tested varied between species.
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tolerance of pseudomonas aeruginosa to Melaleuca alternifolia tea tree oil is associated with the outer membrane and energy dependent cellular processes
Journal of Antimicrobial Chemotherapy, 2004Co-Authors: Chelsea J Longbottom, Katherine A Hammer, Christine F Carson, Brian J Mee, Thomas V RileyAbstract:Objectives: The essential oil of Melaleuca alternifolia (tea tree oil) and its components have antimicrobial activity against a wide range of Gram-positive and Gram-negative bacteria, fungi and viruses. The mechanism(s) by which Pseudomonas aeruginosa NCTC 10662 maintains a decreased susceptibility to tea tree oil and components was investigated. Results: Ethylene diamine tetraacetic acid enhanced the antimicrobial activity of tea tree oil and terpinen-4-ol against stationary phase P. aeruginosa while polymyxin B nonapeptide enhanced the activity of tea tree oil and γ-terpinene. Pre-treatment with the protonophore carbonyl cyanide m-chlorophenylhydrazone increased the susceptibility of exponential phase cells to sub-inhibitory concentrations of tea tree oil, terpinen-4-ol and γ-terpinene, indicating that intrinsic tolerance to tea tree oil and components is substantially energy dependent. Conclusions: Increased tolerance to tea tree oil in P. aeruginosa is directly related to the barrier and energy functions of the outer membrane, and may involve efflux systems.
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susceptibility of oral bacteria to Melaleuca alternifolia tea tree oil in vitro
Oral Microbiology and Immunology, 2003Co-Authors: Katherine A Hammer, Christine F Carson, L Dry, M Johnson, Ewa M Michalak, Thomas V RileyAbstract:The in vitro activity of Melaleuca alternifolia (tea tree) oil against 161 isolates of oral bacteria from 15 genera was determined. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) ranged from 0.003 to 2.0% (v/v). MIC90 values were 1.0% (v/v) for Actinomyces spp., Lactobacillus spp., Streptococcus mitis and Streptococcus sanguis, and 0.1% (v/v) for Prevotella spp. Isolates of Porphyromonas, Prevotella and Veillonella had the lowest MICs and MBCs, and isolates of Streptococcus, Fusobacterium and Lactobacillus had the highest. Time kill studies with Streptococcus mutans and Lactobacillus rhamnosus showed that treatment with ≥0.5% tea tree oil caused decreases in viability of >3 log colony forming units/ml after only 30 s, and viable organisms were not detected after 5 min. These studies indicate that a range of oral bacteria are susceptible to tea tree oil, suggesting that tea tree oil may be of use in oral healthcare products and in the maintenance of oral hygiene.
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antifungal activity of the components of Melaleuca alternifolia tea tree oil
Journal of Applied Microbiology, 2003Co-Authors: Katherine A Hammer, Christine F Carson, Thomas V RileyAbstract:K . A . H A M M E R , C . F . C A R S O N A N D T . V . R I L E Y . 2003. Aims: To investigate the in vitro antifungal activity of the components of Melaleuca alternifolia (tea tree) oil. Methods and Results: Activity was investigated by broth microdilution and macrodilution, and time kill methods. Components showing the most activity, with minimum inhibitory concentrations and minimum fungicidal concentrations of £0AE25%, were terpinen-4-ol, a-terpineol, linalool, a-pinene and b-pinene, followed by 1,8-cineole. The remaining components showed slightly less activity and had values ranging from 0AE5 to 2%, with the exception of b-myrcene which showed no detectable activity. Susceptibility data generated for several of the least watersoluble components were two or more dilutions lower by macrodilution, compared with microdilution. Conclusions: All tea tree oil components, except b-myrcene, had antifungal activity. The lack of activity reported for some components by microdilution may be due to these components becoming absorbed into the polystyrene of the microtitre tray. This indicates that plastics are unsuitable as assay vessels for tests with these or similar components. Significance and Impact of the Study: This study has identified that most components of tea tree oil have activity against a range of fungi. However, the measurement of antifungal activity may be significantly influenced by the test method.
Katherine A Hammer - One of the best experts on this subject based on the ideXlab platform.
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candida albicans adhesion to human epithelial cells and polystyrene and formation of biofilm is reduced by sub inhibitory Melaleuca alternifolia tea tree essential oil
Medical Mycology, 2012Co-Authors: Aurelia N Sudjana, Thomas V Riley, Christine F Carson, Kerry C Carson, Katherine A HammerAbstract:This study investigated the effects of the volatile terpene-rich oil from Melaleuca alternifolia (tea tree oil) on the formation of biofilms and the adhesion of C. albicans cells to both biotic and abiotic surfaces. Biofilm formation on polystyrene was significantly inhibited for 70% of the isolates at the lowest test concentration of 0.016% of tea tree oil (TTO) when quantified by XTT and 40% of isolates when measured by crystal violet staining. Adhesion to polystyrene, quantified by crystal violet staining, was significantly reduced for 3 isolates at 0.031%, 6 isolates at 0.062% and 0.125% and for all 7 isolates at 0.25% TTO. Reductions in adhesion were not due to loss of viability (at concentrations of ≤ 0.125%) or interactions between the TTO and polystyrene. Similarly, adhesion to buccal epithelial and HeLa cells was also significantly reduced in the presence of 0.016-0.062% TTO. Treatment with 0.125% TTO, but not 0.062%, decreased the cell surface hydrophobicity of C. albicans, indicating one potential mechanism by which adhesion may be reduced. These data demonstrate that sub-inhibitory TTO reduces the adhesion of C. albicans to both human cells and polystyrene, inhibits biofilm formation and decreases cell surface hydrophobicity.
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susceptibility of pseudomonads to Melaleuca alternifolia tea tree oil and components
Journal of Antimicrobial Chemotherapy, 2006Co-Authors: Chelsea J Papadopoulos, Katherine A Hammer, Christine F Carson, Thomas V RileyAbstract:Objectives: Thirty isolates of Pseudomonas aeruginosa, 15 isolates of Pseudomonas putida and 11 isolates of Pseudomonas fluorescens were tested for susceptibility to tea tree oil (TTO), the essential oil of Melaleuca alternifolia, and the components terpinen-4-ol, a-terpineol, cineole, g-terpinene and r-cymene. Methods: MICs were determined by broth microdilution in Mueller–Hinton medium supplemented with 0.002% (v/v) Tween 80. Results: The MIC90 of TTO for all isolates tested was 4% (v/v) or less. Susceptibility to components tested varied between species.
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a review of the toxicity of Melaleuca alternifolia tea tree oil
Food and Chemical Toxicology, 2006Co-Authors: Katherine A Hammer, Jesper Bo NielsenAbstract:The essential oil of Melaleuca alternifolia, also known as tea tree or Melaleuca oil, is widely available and has been investigated as an alternative antimicrobial, anti-inflammatory and anti-cancer agent. While these properties are increasingly well characterised, relatively limited data are available on the safety and toxicity of the oil. Anecdotal evidence from almost 80 years of use suggests that the topical use of the oil is relatively safe, and that adverse events are minor, self-limiting and occasional. Published data indicate that TTO is toxic if ingested in higher doses and can also cause skin irritation at higher concentrations. Allergic reactions to TTO occur in predisposed individuals and may be due to the various oxidation products that are formed by exposure of the oil to light and/or air. Adverse reactions may be minimised by avoiding ingestion, applying only diluted oil topically and using oil that has been stored correctly. Data from individual components suggest that TTO has the potential to be developmentally toxic if ingested at higher doses, however, TTO and its components are not genotoxic. The limited ecotoxicity data available indicate that TTO is toxic to some insect species but more studies are required.
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tolerance of pseudomonas aeruginosa to Melaleuca alternifolia tea tree oil is associated with the outer membrane and energy dependent cellular processes
Journal of Antimicrobial Chemotherapy, 2004Co-Authors: Chelsea J Longbottom, Katherine A Hammer, Christine F Carson, Brian J Mee, Thomas V RileyAbstract:Objectives: The essential oil of Melaleuca alternifolia (tea tree oil) and its components have antimicrobial activity against a wide range of Gram-positive and Gram-negative bacteria, fungi and viruses. The mechanism(s) by which Pseudomonas aeruginosa NCTC 10662 maintains a decreased susceptibility to tea tree oil and components was investigated. Results: Ethylene diamine tetraacetic acid enhanced the antimicrobial activity of tea tree oil and terpinen-4-ol against stationary phase P. aeruginosa while polymyxin B nonapeptide enhanced the activity of tea tree oil and γ-terpinene. Pre-treatment with the protonophore carbonyl cyanide m-chlorophenylhydrazone increased the susceptibility of exponential phase cells to sub-inhibitory concentrations of tea tree oil, terpinen-4-ol and γ-terpinene, indicating that intrinsic tolerance to tea tree oil and components is substantially energy dependent. Conclusions: Increased tolerance to tea tree oil in P. aeruginosa is directly related to the barrier and energy functions of the outer membrane, and may involve efflux systems.
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susceptibility of oral bacteria to Melaleuca alternifolia tea tree oil in vitro
Oral Microbiology and Immunology, 2003Co-Authors: Katherine A Hammer, Christine F Carson, L Dry, M Johnson, Ewa M Michalak, Thomas V RileyAbstract:The in vitro activity of Melaleuca alternifolia (tea tree) oil against 161 isolates of oral bacteria from 15 genera was determined. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) ranged from 0.003 to 2.0% (v/v). MIC90 values were 1.0% (v/v) for Actinomyces spp., Lactobacillus spp., Streptococcus mitis and Streptococcus sanguis, and 0.1% (v/v) for Prevotella spp. Isolates of Porphyromonas, Prevotella and Veillonella had the lowest MICs and MBCs, and isolates of Streptococcus, Fusobacterium and Lactobacillus had the highest. Time kill studies with Streptococcus mutans and Lactobacillus rhamnosus showed that treatment with ≥0.5% tea tree oil caused decreases in viability of >3 log colony forming units/ml after only 30 s, and viable organisms were not detected after 5 min. These studies indicate that a range of oral bacteria are susceptible to tea tree oil, suggesting that tea tree oil may be of use in oral healthcare products and in the maintenance of oral hygiene.
J.t. Callander - One of the best experts on this subject based on the ideXlab platform.
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Dipping and jetting with tea tree (Melaleuca alternifolia) oil formulations control lice (Bovicola ovis) on sheep.
Veterinary Parasitology, 2012Co-Authors: Peter James, J.t. CallanderAbstract:The in vivo pediculicidal effectiveness of 1% and 2% formulations of tea tree (Melaleuca alternifolia) oil (TTO) against sheep chewing lice (Bovicola ovis) was tested in two pen studies. Immersion dipping of sheep shorn two weeks before treatment in both 1% and 2% formulations reduced lice to non detectable levels. No lice were found on any of the treated sheep despite careful inspection of at least 40 fleece partings per animal at 2, 6, 12 and 20 weeks after treatment. In the untreated sheep louse numbers increased from a mean (+/- SE) of 2.4 (+/- 0.7) per 10 cm fleece part at 2 weeks to 12.3 (+/- 4.2) per part at 20 weeks. Treatment of sheep with 6 months wool by jetting (high pressure spraying into the fleece) reduced louse numbers by 94% in comparison to controls at two weeks after treatment with both 1% and 2% TTO formulations. At 6 and 12 weeks after treatment reductions were 94% and 91% respectively with the 1% formulation and 78% and 84% respectively with the 2% formulation. TTO treatment also appeared to reduce wool damage in infested sheep. Laboratory studies indicated that tea tree oil 'stripped' from solution with a progressive reduction in concentration as well as volume as more wool was dipped, indicating that reinforcement of active ingredient would be required to maintain effectiveness when large numbers of sheep are treated. The results of these studies suggest significant potential for the development of ovine lousicides incorporating TTO. (C) 2012 Elsevier B.V. All rights reserved.
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Dipping and jetting with tea tree (Melaleuca alternifolia) oil formulations control lice (Bovicola ovis) on sheep.
Veterinary parasitology, 2012Co-Authors: P J James, J.t. CallanderAbstract:The in vivo pediculicidal effectiveness of 1% and 2% formulations of tea tree (Melaleuca alternifolia) oil (TTO) against sheep chewing lice (Bovicola ovis) was tested in two pen studies. Immersion dipping of sheep shorn two weeks before treatment in both 1% and 2% formulations reduced lice to non detectable levels. No lice were found on any of the treated sheep despite careful inspection of at least 40 fleece partings per animal at 2, 6, 12 and 20 weeks after treatment. In the untreated sheep louse numbers increased from a mean (± SE) of 2.4 (± 0.7) per 10 cm fleece part at 2 weeks to 12.3 (± 4.2) per part at 20 weeks. Treatment of sheep with 6 months wool by jetting (high pressure spraying into the fleece) reduced louse numbers by 94% in comparison to controls at two weeks after treatment with both 1% and 2% TTO formulations. At 6 and 12 weeks after treatment reductions were 94% and 91% respectively with the 1% formulation and 78% and 84% respectively with the 2% formulation. TTO treatment also appeared to reduce wool damage in infested sheep. Laboratory studies indicated that tea tree oil 'stripped' from solution with a progressive reduction in concentration as well as volume as more wool was dipped, indicating that reinforcement of active ingredient would be required to maintain effectiveness when large numbers of sheep are treated. The results of these studies suggest significant potential for the development of ovine lousicides incorporating TTO.
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Bioactivity of tea tree oil from Melaleuca alternifolia against sheep lice (Bovicola ovis Schrank) in vitro.
Veterinary Parasitology, 2012Co-Authors: Peter James, J.t. CallanderAbstract:Tea tree oil (TTO) from the Australian native plant Melaleuca alternifolia has wide ranging bio-active properties, including insecticidal and repellent activity against arthropods. Furthermore, composition of commercially available Australian TTO is specified under an International Organization for Standardization standard (ISO 4730), reducing the potential for variable effects often noted with botanical pesticides. The effect of TTO, meeting the ISO standard for terpinen-4-ol chemotype, was tested against sheep lice (Bovicola ovis Schrank) in a series of laboratory studies. Immersion of wool for 60 s in formulations containing concentrations of 1% TTO and above caused 100% mortality of adult lice and eggs. Exposure to vapours from TTO, delivered as droplets in fumigation chambers and when applied to wool also caused high mortality in both lice and eggs. The main active component of TTO in the fumigant tests was terpinen-4-ol. Treated surface assays and tests with wool where the formulation was allowed to dry before exposure of lice indicated low persistence. These studies demonstrate that TTO is highly toxic to sheep lice and active at concentrations that suggest potential for the development of TTO-based ovine lousicides.
Peter James - One of the best experts on this subject based on the ideXlab platform.
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Dipping and jetting with tea tree (Melaleuca alternifolia) oil formulations control lice (Bovicola ovis) on sheep.
Veterinary Parasitology, 2012Co-Authors: Peter James, J.t. CallanderAbstract:The in vivo pediculicidal effectiveness of 1% and 2% formulations of tea tree (Melaleuca alternifolia) oil (TTO) against sheep chewing lice (Bovicola ovis) was tested in two pen studies. Immersion dipping of sheep shorn two weeks before treatment in both 1% and 2% formulations reduced lice to non detectable levels. No lice were found on any of the treated sheep despite careful inspection of at least 40 fleece partings per animal at 2, 6, 12 and 20 weeks after treatment. In the untreated sheep louse numbers increased from a mean (+/- SE) of 2.4 (+/- 0.7) per 10 cm fleece part at 2 weeks to 12.3 (+/- 4.2) per part at 20 weeks. Treatment of sheep with 6 months wool by jetting (high pressure spraying into the fleece) reduced louse numbers by 94% in comparison to controls at two weeks after treatment with both 1% and 2% TTO formulations. At 6 and 12 weeks after treatment reductions were 94% and 91% respectively with the 1% formulation and 78% and 84% respectively with the 2% formulation. TTO treatment also appeared to reduce wool damage in infested sheep. Laboratory studies indicated that tea tree oil 'stripped' from solution with a progressive reduction in concentration as well as volume as more wool was dipped, indicating that reinforcement of active ingredient would be required to maintain effectiveness when large numbers of sheep are treated. The results of these studies suggest significant potential for the development of ovine lousicides incorporating TTO. (C) 2012 Elsevier B.V. All rights reserved.
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Bioactivity of tea tree oil from Melaleuca alternifolia against sheep lice (Bovicola ovis Schrank) in vitro.
Veterinary Parasitology, 2012Co-Authors: Peter James, J.t. CallanderAbstract:Tea tree oil (TTO) from the Australian native plant Melaleuca alternifolia has wide ranging bio-active properties, including insecticidal and repellent activity against arthropods. Furthermore, composition of commercially available Australian TTO is specified under an International Organization for Standardization standard (ISO 4730), reducing the potential for variable effects often noted with botanical pesticides. The effect of TTO, meeting the ISO standard for terpinen-4-ol chemotype, was tested against sheep lice (Bovicola ovis Schrank) in a series of laboratory studies. Immersion of wool for 60 s in formulations containing concentrations of 1% TTO and above caused 100% mortality of adult lice and eggs. Exposure to vapours from TTO, delivered as droplets in fumigation chambers and when applied to wool also caused high mortality in both lice and eggs. The main active component of TTO in the fumigant tests was terpinen-4-ol. Treated surface assays and tests with wool where the formulation was allowed to dry before exposure of lice indicated low persistence. These studies demonstrate that TTO is highly toxic to sheep lice and active at concentrations that suggest potential for the development of TTO-based ovine lousicides.