|
Project
Title:
|
Evaluation
of tea tree oil as an insecticide in vegetables |
| RIRDC
Project No.: |
SAG-3A |
| Researcher: |
Keith
Lewis and Michael Gorton |
| Organisation: |
Serve-Ag
BFS |
| Phone: |
07
4091 3253 |
| Fax: |
07
4091 4027 |
| Email: |
sagbfs@austarnet.com.au |
| Objective |
To
evaluate tea tree oil for use as an insecticide in vegetables. |
| Background |
Anecdotal
evidence suggests that tea tree oil possesses insecticidal properties.
Should this be proven, then a valuable new use for this product would become
available. |
| Research |
Tea
tree oil emulsified with Agral® surfactant or Spraytech
oil® was applied at four rates to control infestations of
leaf eating pests on potatoes and cabbages. The pests targeted were heliothis,
cabbage white butterfly, diamond back moth, cabbage centre grub and cluster
caterpillar. |
| Outcomes |
In
potatoes, there was no control of the pest population after two applications
of the product, and no control of insect pests was obtained after one application
in the case of cabbages. |
| Implications |
There
was no evidence that tea tree oil possessed any significant insecticidal
effects, and the use of this product as an insecticide was not supported. |
|
Project
Title:
|
Regulation
of Immune Responses in Human Skin by Tea Tree Oil |
| RIRDC
Project No.: |
UF-8A |
| Researcher: |
Prof
John Finlay-Jones, Dr Prue Ms Annette Pearce, Ms Karen Koh |
| Organisation: |
Flinders
University, Adelaide, South Australia |
| Phone: |
08
8201 3909, 08 8204 5404 |
| Fax: |
08
8201 3905, 08 8204 3744 |
| Email: |
John.Finlay-Jones@flinders.edu.au,
Prue.Hart@flinders.edu.au |
| Objective |
This
project addressed the mechanisms by which tea tree oil is anti-inflammatory
in human skin. More specifically, it examined the effect of different formulations
of tea tree oil on the response to histamine challenge in the skin, and
similarly on nickel challenge in nickel-sensitive subjects. The objective
was to provide a greater scientific understanding of the basis by which
tea tree oil is anti-inflammatory in humans, as well as to allow the identification
of further medical conditions for which tea tree oil could be used as a
safe, topical anti-inflammatory, anti-itch and anti-oedema therapeutic
agent. |
| Background |
Studies
in the laboratory and the clinic have in recent times confirmed the anecdotal
anti-microbial properties of tea tree oil. On the basis of other anecdotal
evidence it has been suggested that tea tree oil may have a valuable ability
to treat a range of inflammatory conditions, examples of which include
insect bites and skin sensitivity reactions to a range of chemicals. We
previously established, in laboratory experiments, that tea tree oil can
regulate the inflammation-related activities of human white blood cells.
Further, tea tree oil limited several types of inflammation in an animal
model, with the timing of its application being an important factor in
obtaining a significant outcome. Typically, application was most effective
if made close to the time of onset of the inflammation. |
| Research |
1. The Effect of Tea
Tree Oil on the Response to Histamine Challenge in Human Skin: Development
of Wheal (swelling) and Flare (redness). Twenty-seven volunteers were
injected intradermally in each forearm (study and control assigned on an
alternating basis) with histamine. Redness and swelling were measured every
10 min for 1 hour. At 20 min, 100% tea tree oil was applied topically to
the study forearm of 21 volunteers. For six volunteers, paraffin oil was
applied instead of tea tree oil. In a repeat of this study, 15 volunteers
had an additional treatment with 100% tea tree oil, at 10 min as well as
20 min.
2. The Effect of Tea Tree
Oil on a Contact Hypersensitivity Response in Humans: the Response to Nickel
Challenge in Nickel Sensitive Subjects. Eighteen nickel-sensitive subjects
were evaluated for the effect of tea tree oil on a nickel-induced rash.
Nickel was applied to the back skin. Subsequently, 100% TTO, 5% TTO lotion,
a placebo lotion (no TTO), or 100% macadamia oil were applied at days 3
and 5 after nickel-exposure. The rash at each reaction site was measured
on days 3, 5 and 7.
|
| Outcomes |
With
respect to the response to histamine injection, the swelling was significantly
inhibited by either a single (20 min) or double (10 and 20 min) treatment
with TTO. In contrast, the reddening was only inhibited by the double treatment.
Paraffin oil was without effect.
Treatment of nickel-induced
rash with TTO significantly reduced the symptoms when compared to the nickel-only
sites. The anti-inflammatory effects were predominantly, but not exclusively,
seen in a subgroup of nickel-sensitive subjects with a prolonged development
phase of nickel-induced rash. The 5% TTO lotion, placebo lotion and the
100% macadamia oil were all without significant effect. |
| Implications |
This
is the first study to show experimentally that tea tree oil can reduce
histamine-induced skin inflammation. Topical application of 100% TTO may
have therapeutic benefit in nickel-induced CHS in human skin. The mode
of action of TTO requires further investigation.
Our results suggest that
tea tree oil can be used for the treatment of inflammatory reactions of
the skin including those following insect bites and exposure to nickel,
and it may be possible to extend that treatment to sensitivity reaction
to other chemicals including plant components and other irritants. |
| Publications |
Koh
KJ, Pearce AL, Marshman G, Finlay-Jones JJ, Hart PH (2002). Tea tree oil
reduces histamine-induced skin inflammation. Br J Dermatol., 147,
1212-7. |
|
Project
Title
|
Antimicrobial
activity of tea tree oil against oral microorganisms |
| RIRDC
Project No.: |
UWA-55A |
| Researcher: |
Prof
T. Riley |
| Organisation: |
University
of Western Australia
Dept of Microbiology
Queen Elizabeth II Medical
Centre
Nedlands WA 6009 |
| Phone: |
08
9346 3690 |
| Fax: |
08
9346 2912 |
| Email: |
triley@cyllene.uwa.edu.au |
| Objectives |
To
determine the susceptibility of oral microorganisms to tea tree oil and
evaluate its potential for use as a topical antimicrobial agent for oral
infection or conditions. |
| Background |
A
market for tea tree oil products that has not been fully realised is oral
healthcare. Therefore in vitro susceptibility data are urgently required
to support and give credence to these applications. |
| Research |
A
collection of 162 isolates from or related to those found in the oral cavity
was made. Many of these bacteria had to be isolated and identified from
oral cavity samples from volunteers since these kinds of bacteria are generally
not held in existing collections. The in vitro susceptibility of these
isolates to tea tree oil was determined. In addition, an isolate each of
Streptococcus
mutans and Lactobacillus rhamnosus, which are two of the species
involved in the causation and pathogenesis of dental caries, were selected
for time kill assays. Time kill assays assessed bacterial viability after
30 seconds, 5 and 10 min treatment with various concentrations of tea tree
oil. |
| Outcomes |
Approximately
half of all the oral isolates tested belonged to the genus Streptococcus
and for these isolates minimum inhibitory concentrations (MICs) and minimum
bactericidal concentrations (MBCs) both ranged from 0.25 - 2%. For non-streptococcal
isolates, which included members of the genera Actinomyces, Capnocytophaga,
Eikenella,
Fusobacterium, Lactobacillus, Porphyromonas,
Prevotella
and Veillonella, MICs and MBCs both ranged from 0.003 - 2%.
Time kill studies showed that significant killing of both S. mutans
and L. rhamnosus occurred after just 30 seconds treatment with ³
0.5% tea tree oil. Only moderate killing occurred with concentrations of
tea tree oil of less than this. |
| Implications |
These
data show that tea tree oil both inhibits and kills the bacteria found
in the oral cavity and may therefore be suitable and effective as an antimicrobial
agent in the oral cavity. Markets for the use of oral hygiene products
containing tea tree oil in both domestic and hospital settings should be
investigated. Data showing clinical efficacy would be required if hospital
use is to be pursued. This study provides the necessary data to both support
and encourage the progression to clinical studies. |
| Publications |
Hammer
KA, Dry L, Johnson M, Michalak E, Carson CF & Riley TV. 2002. In vitro
susceptibility of oral bacteria to Melaleuca alternifolia (tea tree)
oil. Manuscript in preparation. |
|
Project
Title
|
Clinical
efficacy of tea tree oil for treating coldsores |
| RIRDC
Project No.: |
UWA-56A |
| Researcher: |
Prof
T. Riley |
| Organisation: |
University
of Western Australia
Dept of Microbiology
Queen Elizabeth II Medical
Centre
Nedlands WA 6009 |
| Phone: |
08
9346 3690 |
| Fax: |
08
9346 2912 |
| Email: |
triley@cyllene.uwa.edu.au |
| Objectives |
To
increase the national and international acceptability of tea tree oil as
an anti-viral therapy in the treatment of coldsores. |
| Background |
Tea
tree oil is used as a topical remedy for many skin infections. There are
limited data to support its use in vivo. One of the applications is as
a cold sore treatment and tea tree oil has previously shown activity in
vitro against the causative agents, herpes simplex viruses type 1 and 2.
A small pilot study also suggested that tea tree oil may be efficacious
in the treatment of cold sores. This study aimed to assess the efficacy
of tea tree oil as a cold sore treatment in a larger randomised, double-blind,
placebo-controlled study. |
| Research |
A
randomised, double-blind, placebo-controlled study comparing the efficacy
of a 6% tea tree oil ointment to placebo ointment was conducted. A total
of 214 patients were recruited and 100 patients treated. |
| Outcomes |
The
6% tea tree oil ointment formulated for the study appears to reduce the
size and symptoms of cold sores. It may also reduce the duration of infectivity. |
| Implications |
Tea
tree oil should be promoted as an over-the-counter treatment for cold sores
and additional clinical work should be conducted to expand the findings
of this study. |
| Publications |
Manuscript
in preparation |
|
Project
Title
|
Multi-centre
randomised clinical trials for tea tree oil products for vaginal infections |
| RIRDC
Project No.: |
UWA-57A |
| Researcher: |
Prof
T. Riley |
| Organisation: |
University
of Western Australia
Dept of Microbiology
Queen Elizabeth II Medical
Centre
Nedlands WA 6009 |
| Phone: |
08
9346 3690 |
| Fax: |
08
9346 2912 |
| Email: |
triley@cyllene.uwa.edu.au |
| Objective |
To
demonstrate that tea tree oil is safe and efficacious for the treatment
of two vaginal infections (candida vaginitis and bacterial vaginosis)
using randomised clinical trials, following a pilot study, to show efficacy. |
| Background |
In
laboratory tests, tea tree oil exhibits activity against microorganisms
such as Candida yeasts and the anaerobic bacteria found in the female genital
tract. The pattern of activity suggests that tea tree oil may be useful
in the treatment of vaginal infections involving these microorganisms,
namely candida vaginitis (thrush) and bacterial vaginosis. Anecdotal
evidence also suggests this although there are no data from large randomised
clinical trials. |
| Research |
A
tea tree oil gel product formulated for intravaginal use is being evaluated
in a clinical trial setting for the treatment of bacterial vaginosis. The
tea tree oil gel is being compared to one of the standard treatments for
bacterial vaginosis, intravaginal metronidazole gel. Patients are randomised
to either the metrodidazole or tea tree oil treatment group and are assessed
in the clinic prior to treatment commencement and one month later. An interim
assessment is done by telephone 1 week after treatment. Clinical signs
and symptoms such as discharge and microscopy of vaginal bacteria are assessed
at the two clinic visits. |
| Outcomes |
Fifty
patients have been recruited and treated at the trial site in
Leeds, UK. Preliminary analysis
of the treatment outcomes in these patients suggests that there are fewer
complete resolutions in the tea tree oil group than in the metronidazole
group. It appears that the tea tree oil gel may not be performing as well
as the intravaginal metronidazole gel. |
| Implications |
This
particular formulation of tea tree oil may not be efficacious in the treatment
of bacterial vaginosis. Reformulation of the product or modification of
the treatment dose and/or frequency may be necessary prior to reassessment. |
| Publications |
Final
report to RIRDC and journal manuscript in preparation. |
|
Project
Title:
|
Development
of DNA markers for tea tree |
| RIRDC
Project No.: |
CSF-55A |
| Researcher: |
Dr
John Doran & Dr Gavin Moran |
| Organisation: |
CSIRO
Forestry & Forest Products
PO Box E4008
KINGSTON ACT 2604 |
| Phone: |
02
6281 8211 |
| Fax: |
02
6281 8266 |
| Email |
John.Doran@ffp.csiro.au
Gavin.Moran@ffp.csiro.au |
| Objective |
To
develop a dinucleotide microsatellite DNA library for tea tree and to characterise
10 microsatellite loci. The most useful microsatellite loci and primer
sequences for fingerprinting breeding lines identified by this research
will be documented in a Commercial-in-Confidence report to the RIRDC /ATTIA
Tea Tree Breeding Project meeting of August 2000. |
| Background |
DNA
markers provide a means of monitoring pollen flow and assessing the level
of contamination in seed orchards, testing the validity of controlled crosses,
of identifying selfs and fingerprinting clones. The study of genetic segregation
in full-sib progenies allows genetic linkage maps to be constructed. These
maps provide a framework in which genes of economic or practical significance
can be located. The RIRDC/ATTIA tea tree breeding project will produce
the first highly improved seed from its orchards in 2000. Unrestricted
access to its own DNA markers, as provided by this project, to monitor
the distribution and use of this seed and any clones released by the project
will be a powerful deterrent to the misuse of this material, vital to the
future of the industry in Australia. |
| Research |
Twenty-three
microsatellite loci have been characterised in Melaleuca alternifolia.
These microsatellites have been grouped into 6 multiplexes for efficient
use in applications in the breeding program. The microsatellites showed
mendelian segregation in controlled crosses. The eight parental breeding
clones were typed for their DNA genotypes at the loci and could be distinguished
from each other on the genotypes on the just the first two loci. These
genotypes were used to certify ramets against ortets of several other breeding
clones and some ramets were found to be incorrect. |
| Outcomes |
Twenty-three
microsatellite loci are now available for use in the breeding of M.
alternifolia.
DNA fingerprinting of ramets
of breeding clones has revealed errors in labelling ramets used in a breeding
arboretum, confirming the value of the technique in quality control.
The assays of progeny from
controlled crosses without emasculation have shown that significant levels
of selfed seed can occur. This needs to be tested across a number of females. |
| Implications |
Microsatellites
can now be used to routinely to monitor for quality control in the breeding
program. Production of selfed seed in controlled crosses without emasculation
suggests that this method may have limited application in breeding programs. |
| Publications |
Commercial-in-Confidence
report to RIRDC/ATTIA Tea Tree Breeding Committee |
|
Project
Title
|
Herbicides
for weed control in tea tree oil plantations |
| RIRDC
Project No.: |
DAN-74A |
| Researcher: |
Tony
Cook |
| Organisation: |
NSW
Agriculture
Tamworth Centre for Crop
Improvement
Calala Lane
TAMWORTH NSW 2340 |
| Phone: |
02
6763 1100 |
| Fax: |
02
6763 1222 |
| Objective |
To
develop effective herbicidal weed control practices for Australian tea
tree oil plantations and ensure new herbicide recommendations do not affect
quality of oil. |
| Background |
Tea
tree oil is extracted from an Australian native species Melaleuca alternifolia.
Weed control is considered the major problem by growers. In 1990, there
were only four legalised herbicide treatments available and subsequently
left growers with very expensive and limited weed control options. In addition,
there is a need to maintain high production and quality of tea tree oil.
Clearly there will be a need to guarantee any new recommended treatments
do not contaminate the oil with herbicide residues. |
| Research |
A
survey was conducted to determine the major weed species and the techniques
used to control these weeds. In addition, 65 herbicides were screened for
a range of tea tree growth stages, in order to identify treatments that
were safe to tea tree, provided adequate weed control and were not too
cost prohibitive. |
| Outcomes |
Approximately
80% of growers surveyed stated that weeds are a major limitation to production
and half were dissatisfied with their current weed control techniques.
The five most abundant weeds were kidney weed (Dichondra repens),
carpet grass (Axonopus affinis), sedges (Cyperus spp.) fleabane
(Conyza spp) and couch grass (Cynodon dactylon). It was shown
that the majority of competition from weeds occurred in the first month
after planting. A 97% reduction in yield was a consequence of high weed
densities in the first few months after planting.
There are now eighteen registered
treatments with all but one being Pesticide Order treatments. In some cases,
recommended treatments arising from this project are 80% cheaper that previously
recommended treatments and exhibit little difference in weed control and
safety. There was no detectable level of herbicide residue in oil samples
from tea trees treated with some of the new recommended treatments.
A weeds identification and
weed control booklet will transfer information gained from this project
to relevant people and will be published in 1996. |
| Implications |
A
minimum of $1,100 per hectare can be returned to growers in weedy situations
by adopting the results of this project. Apart from these financial gains,
new recommendations will allow for increased managerial choices, superior
weed control and less likelihood of developing herbicide resistance.
Growers will possess better
weed identification skills as a result of the advisory booklet and will
be best advised to solve a particular weed problem.
Although considerable cost
savings were made with new treatments (blanket applied), there are further
savings and benefits if the practice of directed spraying was properly
developed. This could allow the use of herbicides normally damaging to
tea trees. |
|
Project
Title
|
Breeding
and selection of Australian tea tree for improved oil yield and quality |
| RIRDC
Project No.: |
DAN-87A |
| Researchers: |
John
Murtagh Gary Baker John Doran |
| Organisation: |
Agric.
Water Man. NSW Agriculture CSIRO
Wollongbar Ag. Inst. PO
Box E4008
WOLLONGBAR KINGSTON
NSW 2477 ACT 2604 |
| Phone: |
02
6626 1104 02 6281 8319 |
| Fax: |
02
6628 3264 02 6281 8266 |
| Email: |
bakerg@agric.nsw.gov.au
John.Doran@ffp.csiro.au |
| Objective |
To
select and breed seed for economic gains in oil characteristics. Gains
in yield and quality are considered essential if the Australian tea tree
industry is to prosper against overseas competition and the downward pressure
on oil prices. |
| Background |
The
Australian tea tree industry has developed from bush production to plantation
production. Seed for planting is collected from natural populations using
only rudimentary selection to ensure that oil quality meets industry standards.
The yields of oil from plantations are variable; there is much scope to
improve both the amount and quality of the yield. |
| Research |
During
the first three years of the project (1993-1996), seven field trials were
established to determine the genetic variability in oil yield and quality.
Two of these trials were then developed as seed orchards to provide improved
seed to the industry. A natural stand of 783 trees was sampled, trees were
analysed and ranked for oil concentration, terpinen-4-ol and cineole. Selecting
the best 74 trees for seed production provides a selection pressure of
>1:10. This ratio will enable genetic gain for selected traits.
A progeny trial of 204 families
will be further tested for oil characteristics, superior trees selected
and inferior trees culled to prevent them breeding with superior trees.
The superior trees will grow on and flower to produce genetically improved
seed. The coppicing ability of families grown at different sites will also
be used to select superior families in the orchard. |
| Outcomes |
Variation
of key commercial traits were significant at the provenance, family and
individual tree levels. Heritability (narrow sense) was high (0.51) for
oil concentration, moderate (0.37) for cineole% and low for the growth
parameters of plant height (0.21) and stem diameter (0.14). No adverse
genetic correlations were found between oil concentration and plant height
and diameter.
The performance of families
across two sites (family x site interaction) was reasonably consistent,
indicating that it will be possible to select families with good general
adaptability in a single breeding population, thus avoiding the extra cost
of establishing multiple breeding populations in different environments.
The best performing provenances
were identified and seed from these areas will be released to the industry.
The controlled pollinations in 1995 have produced seeds, indicating that
the methodology used has potential. |
| Implications |
All
the indicators from the first phase of breeding point to very substantial
economic gains being achieved by the breeding project. Three years is a
very short time in tree breeding and more time is needed to produce the
much improved seed required to ensure the successful development and survival
of this industry. |
| Publications |
Doran,
J. C. (1995). Estimating seed quantities for tea tree plantations.
Australian Tea Tree Industry Association Newsletter, April 1995.
Doran, J. C., Baker, G. R.,
Murtagh, G. J. Williams, E. R. and Morris, S. G. (1996). "Breeding and
selection of Australian Tea Tree for improved oil yield and quality 1993
to 1996" Review Report for the Rural Industries Research And Development
Corporation and the Australia Tea Tree Industry Association.
Doran, J. C., Baker, G. R.,
Murtagh, G. J. and Southwell, I. A. (1996). "Breeding and selection
of Australian Tea Tree for improved oil yield and quality" Final Report
for Rural Industries Research And Development Corporation. |
|
Project
Title
|
Insect
pest management in tea tree |
| RIRDC
Project No.: |
DAN-91A |
| Researchers: |
Mr
Gus Campbell |
| Organisation: |
NSW
Agriculture
PO Box 72
Alstonville NSW 2477 |
| Phone: |
02
6628 0604 |
| Fax: |
02
6628 5209 |
| Objectives |
To
develop an effective sustainable pest management strategy for the Pyrgo
beetle and other pests of tea tree by:
· correlating the
incidence of Pyrgo in the field with weather parameters, and refining the
maximum temperature threshold values for larval and egg survival to account
for field observations and to improve predictive modelling;
· evaluating a monitoring
procedure for detecting Pyrgo in the field; and
· screening selected
insecticides and other chemicals for efficacy against Pyrgo in the laboratory
and the field.
|
| Background |
The
tea tree industry of northern NSW and southern Queensland has developed
over the last 20 years from a fledgling cottage industry into a substantial
producer of some 260 tonnes of tea tree oil per annum. The early industry
was based on bush harvesting but has now progressed to one of plantation
culture using improved cultivars on more than 4,000 ha. Although the industry
faces a number of problems, one of the more important affecting production
is caused by a number of insect pests - the major one being Pyrgo beetle.
Insect problems are recognised
and acknowledged by most growers, but little is known about the ecology
of Pyrgo, and this has limited the development and implementation of appropriate
control strategies. The industry has been promoted as being "clean and
green", implying minimal or no use of insecticides, but this is belied
by the substantial evidence (residues in the oil) showing that unregistered
insecticides have been used on many crops. This is partly caused by the
paucity of insecticides (only one is registered for use in NSW) legally
available to growers, and there is clearly the need for a range of products
to be available for use.
If rational insect control
strategies are to be developed and implemented for the industry, then it
is important to have a better understanding of the ecology of the pests
concerned. Once this is established, potential insecticide and other control
measures can then be devised and evaluated. |
| Research |
Considerable
field and laboratory research has been undertaken over the last three years
to investigate the various factors which, collectively, result in loss
of foliage and oil production. These have included studies on the ecology
of the insects concerned, on the development of systems for monitoring
the first occurrence and incidence of insects in plantations, on screening
cultivars for insect resistance, and on evaluating a range of insecticides
and other chemicals for potential use in chemical control strategies. This
latter activity was instigated part of the way through the project, when
insecticide residues were detected in oil - from crops clearly treated
(illegally) with insecticides not registered for the purpose. |
| Outcomes |
There
is now an excellent understanding of the ecology of Pyrgo and some of the
other insects which also cause yield losses. A practical monitoring system
based on sticky yellow traps has been developed and this will allow the
more rational application of control strategies including the reduction
in use of insecticide treatments. Several alternative insecticides have
been evaluated, and been shown to provide more effective control than the
current sole product (methomyl). |
| Implications |
Growers
now have a better understanding of the population dynamics of Pyrgo, and
of the importance of other insect pests such as mites and psyllids. With
the development of improved monitoring using sticky yellow traps, there
is now the opportunity to detect the presence of Pyrgo earlier than on-plant
inspections, to allow the identification of localised areas of beetle activity,
and to reduce insecticide costs by rationalising their use. There may be
an added opportunity for the industry to employ scouts to undertake this
monitoring and to advise growers on the need to use insecticide treatments.
Illegal use of non-registered
insecticides is a potential "time bomb" that, if not addressed quickly,
will seriously harm the industry. Several potential insecticide products
have been evaluated and found to be more effective than the current permitted
product, methomyl. Steps should be taken urgently to secure their registration
for use on tea tree.
This project has highlighted
the need for further research on control of mites and psyllids, and on
the screening of insecticides to determine their potential for leaving
residues in oil. |
|
Project
Title
|
Significance
of cineole for the bioactivity and irritancy of tea tree oil |
| RIRDC
Project No.: |
DAN-104A |
| Researcher: |
Dr
Ian Southwell |
| Organisation: |
NSW
Agriculture
Wollongbar Institute
WOLLONGBAR NSW 2477 |
| Phone: |
02
6626 1224 |
| Fax: |
02
6628 3264 |
| Objective |
To
increase the market demand for tea tree oil by measuring and documenting
data on the skin irritancy and minimum inhibitory concentrations (MICs)
of different grades of tea tree oil that might be required by regulatory
bodies like the USFDA for monograph acceptance. |
| Background |
Approximately
200 tonnes of tea tree oil, valued (farm gate) at $10m, are currently produced
in Australia per annum. The product is used as an antimicrobial antiseptic
oil or formulated into value added creams, shampoos, soaps, mouthwashes,
toothpastes etc. A significant rural industry is being established around
the propagation, production, processing, formulation and marketing of tea
tree, the oil and its products. Plantations are expected to yield 400 tonnes
pa by the late 1990s.
However, one factor hindering
the broadening of the tea tree oil market base is that oil reach in cineole
is considered to be of high skin irritancy and therefore not of a marketable
standard. |
| Research |
Standard
clinical procedures were used to test cineole and tea tree oil for skin
irritancy. Twenty five human subedits were subjected to occlusive patch
testing applied to the upper arm or back for five days per week for three
consecutive weeks. The patch was removed at 24 hour intervals and any skin
reaction noted. Subjects reacting allergically to the test substances were
withdrawn from the irritancy trial and were used in further testing for
allergic reaction to individual components or fractions.
More than 20 strains of bacteria
were used to test numerous tea tree oils with varying levels of cineole
concentration for antimicrobial activity. |
| Outcomes
and Implications |
The
results of this research have major implications for the industry. Some
years ago, oils with 5-10% cineole were perfectly acceptable in the marketplace.
In recent years though, buyers have been seeking oils with less than 5%
and sometimes less than 3%.
This research shows clearly
that there are no grounds for promoting low cineole oils other than for
avoiding low terpinen-4-ol oils. If all buyers could be convinced of this,
more tea tree oil could be offered for sale, providing a yield boost to
many producers.
The results of the project
should aid the marketing of tea tree oil. It documents: 1) the absence
of skin irritancy for formulated preparations; 2) the non-allergenic nature
of most tea tree oil constituents; 3) methods for the removal of some possible
allergens; 4) a wider range of tea tree oil-susceptible microorganisns;
5) specific MIC values for a range of oils; and 6) enhanced MIC values
for specific oils. |
| Project
Title: |
The
improvement of Australian tea tree through selection and breeding (continuation
of project DAN-87A) |
| RIRDC
Project No.: |
DAN-151A |
| Researcher: |
Dr
Ian Southwell |
| Organisation: |
NSW
Agriculture
Wollongbar Agricultural
Institute
Wollongbar NSW 2477 |
| Phone: |
02
66261224 |
| Fax: |
02
66283264 |
| Email: |
ian.southwell@agric.nsw.gov.au |
| Objectives |
· To systematically
improve the yield and quality of oil from tea tree (Melaleuca alternifolia)
by:
· Continuing current
and establishing new selection trials.
· Production of improved
seed lines with yields up to 17% higher than current industry selections
by 1997, 30% higher by 2000 and 60% higher by 2003.
|
| Background |
The
Australian tea tree oil industry has developed from bush production to
plantation production. Currently, productivity in the industry is considered
below potential. A contributing factor is seed quality, as plantations
are established largely from seed collected from a limited number of bush
trees with only rudimentary selection. Clearly, any gains a breeding program
could achieve in oil quality and productivity would assist the local industry
in maintaining its international competitiveness. |
| Research |
During
the eight years of consecutive projects (1993-2001), multiple field trials
were established to determine variability in and genetic parameters for
oil yield and quality. One of these trials was progressively culled of
inferior trees to become a seedling seed orchard which produced the first
improved seed in 1999. Controlled pollination techniques have been developed
and employed in nucleus breeding and production of hybrids. Research in
these and related projects has provided methods for DNA fingerprinting
of breeding lines and demonstrated the potential of clonal plantations.
A second-generation seedling seed orchard was established in 2001. |
| Outcomes |
The
breeding project has distributed 7kg of seed to industry, enough to plant
over 1000ha of tea tree plantation, in four releases since 1997. Most of
this seed has been from the best natural provenances capable of providing
20% improvement in yield over industry standards, as demonstrated by project
yield trials. Seed from the seedling seed orchard and a clonal seed orchard
was released for the first time in 2000. A 30% increase in yield is predicted
through use of this seed and further culling of the orchard during 2000
is expected to give improvements of 60% by 2003. |
| Implications |
A
very favourable outcome from past investment in the breeding program has
been demonstrated by several financial analyses. The gains provided by
the tea tree breeding project are a vital part of ensuring the economic
viability of the industry in Australia. |
| Publications |
Baker,
G. (1999). Tea tree breeding. Pages 135-151 in Southwell I and Lowe
R eds., Tea Tree: The Genus Melaleuca. In Medicinal and Aromatic
Plants – Industrial Profiles, Hardman R ed. Vol. 9. Hardwood Academic Publishers:
The Netherlands.
Baker, G. and Doran, J. (1999).
Breeding Melaleuca alternifolia for essential oils. Proceedings
11th Australian Plant Breeding Conference, Adelaide. Vol. 2,
pp. 104-105.
Baker, G.R., Lowe, R.F. and
Southwell, I.A. (2000). Comparison of oil recovered from tea tree leaf
by ethanol extraction and steam distillation. J.Ag..Food Chem. 48:4041-43.
Doran, J. and Baker, G. (2000).
Using clones to establish tea tree plantations. The Short Report No. 73.
RIRDC: Canberra.
Doran, J.C., Baker, G.R.,
Murtagh, G.J. and Southwell, I.A. (1997). Improving tea tree yield and
quality through breeding and selection. RIRDC Res. Paper Series No 97/53. |
|
Project
Title
|
Developing
the North Queensland tea tree industry |
| RIRDC
Project No.: |
DAQ-184A |
| Researcher: |
James
Drinnan |
| Organisation: |
Queensland
Department of Primary Industries
PO Box 1054
MAREEBA QLD 4880 |
| Phone: |
07
4092 8555 |
| Fax: |
07
4092 3593 |
| Objectives |
· To facilitate
the rapid development of the knowledge base on the production of tea tree
oil in the Mareeba Dimbulah Irrigation Area, Qld.
· To develop guidelines
for irrigation scheduling for maximising oil yield and quality.
· To establish a gene
pool of selected superior plants.
|
| Background |
Tea
tree oil production is a relatively new industry on the Atherton Tablelands
in North Queensland. Interest in tea tree oil production was generated
as an alternative crop for tobacco. The production systems being used now
are based on New South Wales information, use high densities, and are irrigated.
Due to differences in climate and soil types it is essential to adapt the
findings from New South Wales research work for North Queensland conditions.
Environmental and management effects, particularly irrigation, look to
have a major impact on oil yields. |
| Research |
Information
on tea tree production has been gathered from key researchers working with
tea tree. A soil moisture monitoring system (Environscan) has been used
to investigate water use and water requirements of tea trees in North Queensland.
Data has been collected on oil quality and quantity and the factors affecting
it. Several seedlings have been identified as having superior oil concentration
and quality. Superior planting material has also been sourced from the
tea tree breeding program and is being evaluated at two locations in the
Mareeba Dimbulah Irrigation Area. |
| Outcomes |
Information
was presented to growers via field days, newsletters, progress reports,
presentations at growers' meetings and farm visits.
Irrigation scheduling guidelines
have been developed. Mature trees use 0.8-1.0 times the pan evaporation
rate which is equivalent to a total water requirement of I OML/ha/year
or 7.5ML/ha/year when rainfall is subtracted.
Major factors influencing
oil concentration and hence yields identified include genotype, time of
year, nutrition, irrigation, and seedling vs coppice growth. |
| Implications |
This
project has helped with the very successful development of the North Queensland
tea tree oil industry. There has been a rapid expansion of the industry
and yields and oil quality has been excellent. |
|
Project
Title:
|
Plant
Nutritional Survey of the Australian Tea Tree Industry |
| RIRDC
Project No.: |
DAQ-252A |
| Researcher: |
James
Drinnan |
| Organisation: |
Queensland
Department of Primary Industries
PO Box 1054
Mareeba QLD 4880 |
| Phone: |
07
4092 8555 |
| Fax: |
07
4092 3593 |
| Email |
DrinnanJE@dpi.qld.gov.au |
| Objectives |
·
Determine the current nutritional status and corresponding yields of tea
tree grown in Australia (North Queensland and Northern New South Wales).
· Determine some ballpark
optimum fertiliser recommendations for tea tree.
· Improve the knowledge
base of the Australian producers on the nutritional requirements of tea
tree. |
| Background |
The
Australian tea tree industry is likely to face strong competition from
low cost overseas producers in the near future. Also, unless the demand
for tea tree oil continues to increase rapidly to meet increasing supply
there is likely to be pressure on the price of tea tree oil. Given these
circumstances, producers must reduce their costs of production. One area
highlighted by RIRDC (98/99 key issue) and the Australian Tea Tree growers
association to help achieve this is to determine the nutritional requirements
for maximising yields. In high production areas such as north Queensland
- where water, temperature and radiation are not limiting and soils are
relatively infertile, and in NSW on less fertile soils or where soil fertility
has declined (due to a number of cropping cycles), nutrition is considered
one of the major limitations to increased yields. By conducting this nutritional
survey the range in types and amounts of fertiliser being used and the
relationship with yields can be assessed. |
| Research |
A
survey was conducted of growers in QLD and NSW to determine current fertiliser
practices (types and quantities) and the biomass and oil yields achieved.
Leaf and soil analysis results were collected, collated and analysed. Information
on soil type and fertility, irrigation levels, leaf drop and plant size
at harvest was also collected. An estimate of fertiliser requirement was
made by calculating nutrient removal in the biomass. |
| Outcomes |
This
project has increased the knowledge base of the nutritional requirements
of tea tree. The survey has documented the current nutritional status of
the Australian Tea Tree Industry. While the survey indicated little correlation
between fertiliser inputs and oil yield, this may be due to the variety
of factors which influence yield. However, a conservative approach and
one which will apply in the long term is to use sufficient fertiliser to
replace the nutrients removed at harvest. Results have indicated the amounts,
types and timing of fertiliser being used and the range in yields being
achieved. The optimal leaf and soil nutrient levels established provide
a guide for growers to assess their fertiliser practices. From nutrient
removal calculations it is recommended growers in QLD use around 180 kg
N, 20 kg P and 220 kgK/ha/year and in NSW 130 kg N, 15 kg P and 158 kgK/ha/year.
This should be applied regularly in small amounts throughout the growing
season in approximately the following proportions - 10% from 0-2, 20% from
2-4 months, 20% from 4-6 months following harvest and 50% from 6 months
after harvest until the trees are harvested again. |
|
Project
Title:
|
The
anti- inflammatory activity of tea tree oil –second stage |
| RIRDC
Project No.: |
UF-5A |
| Researcher: |
Prof.
John Finlay-Jones Dr Prue Hart |
| Organisation: |
Flinders
University Flinders University |
| Phone: |
08
8201 3909 08 8204 5404 |
| Fax: |
08
8201 3905 08 8276 8658 |
| Email: |
John.finlay-jones@flinders.edu.au
prue.hart@flinders.edu.au |
| Objective |
To
assess the anti-inflammatory activity of tea tree oil, and its components. |
| Background |
The
anti-bacterial, anti-viral and anti-fungal properties of tea tree oil have
been well studied. However, reports that tea tree oil has anti-inflammatory
properties have, until recently, been anecdotal. This laboratory has considerable
experience in determining the anti-inflammatory properties of cytokines,
in particular, interleukin-4 in vitro. |
| Research |
In
the first study, blood monocytes (>90% enriched by centrifugal elutriation)
were stimulated in vitro for 24 and 48 hours with a potent activating
agent, lipopolysaccharide. In response, the monocytes produced large amounts
of mediators that have been well characterised to initiate and sustain
inflammation. The effect of co-incubation with tea tree oil, and its water
soluble components, was investigated. In the second study, both monocytes
and neutrophils were isolated from blood and activated in vitro
to give a respiratory burst, the products of which can oxidise and damage
body tissues. The effect of tea tree oil on the production of a respiratory
burst induced by multiple stimuli was examined. |
| Outcomes |
Tea
tree oil was toxic to monocytes and neutrophils at concentrations >0.016%.
However, the water-soluble components (terpinen-4-ol (42%), a -terpineol
(3%), 1,8-cineole (2%, respectively, of tea tree oil)) were not toxic and
suppressed inflammatory mediator production by activated monocytes. Terpinen-4-ol
was responsible for this activity. Neutrophils were unresponsive to tea
tree oil or any of its water soluble components for modulation of a respiratory
burst. In contrast, both terpinen-4-ol and ?-terpineol suppressed a respiratory
burst in activated monocytes. |
| Implications |
There
was selective regulation of monocyte, not neutrophil, inflammatory activity.
These results suggest that tea tree oil may enable neutrophils to be fully
active in an acute inflammatory response and eliminate foreign antigens,
while suppressing monocyte inflammatory mediator and superoxide production
and thereby preventing oxidative tissue damage that may be seen in more
chronic inflammatory states. These studies demonstrate the potential of
tea tree oil as a safe, topical, anti-inflammatory therapeutic agent. However,
as we are uncertain of the concentrations of terpinen-4-ol and ?-terpineol
that may penetrate beyond the stratum corneum. These results require documentation
of a reduction of inflammatory cells and mediators in skin after application
of tea tree oil. |
| Publications |
Hart
PH, C Brand, CF Carson, TV Riley, RH Prager, JJ Finlay-Jones. 2000. Terpinen-4-ol,
the main component of the essential oil of Melaleuca alternifolia
(tea tree oil), suppresses inflammatory mediator production by activated
human monocytes. Inflammation Research (in press).
Brand C, A Ferrante, RH Prager,
TV Riley, CF Carson, JJ Finlay-Jones, PH Hart. 2000. The water-soluble
components of the essential oil of Melaleuca alternifolia (tea tree
oil) suppress the production of superoxide by human monocytes, but not
neutrophils, activated in vitro. Inflammation Research (submitted). |
|
Project
Title:
|
The
anti-inflammatory and anti-itch properties of tea tree oil |
| RIRDC
Project No.: |
UF-6A |
| Researcher: |
Prof
John Finlay-Jones, Dr Prue Hart |
| Organisation: |
Flinders
University, Adelaide, South Australia |
| Phone: |
08
8201 3909, 08 8204 5404 |
| Fax: |
08
8201 3905, 08 8204 3744 |
| Email: |
John.Finlay-Jones@flinders.edu.au,
Prue.Hart@flinders.edu.au |
| Objective |
To
determine the anti-inflammatory and anti-itch properties of tea tree oil
in vivo |
| Background |
We
showed in a previous RIRDC project (UF-5A) that tea tree oil was anti-inflammatory
in
vitro. We showed that the water soluble components of tea tree oil
reduced inflammatory mediator and superoxide production by human monocytes
activated in vitro. In contrast, tea tree oil was not able to reduce
an inflammatory response by another blood-derived cell, the neutrophil.
We reasoned that this left the neutrophil to pursue anti-microbial activity.
In this study, we questioned whether tea tree oil was also anti-inflammatory
in
vivo. |
| Research |
Several
models of inflammation in mice were adopted. The effect of topically applied
tea tree oil on models of both delayed type (peak after 24 hours) and immediate
type hypersensitivities (peak in less than an hour) were analysed. The
former is similar to the inflammation seen upon re-exposure to mycobacterial
antigens in a Mantoux reaction or the inflammation detected by nickel-sensitive
people after exposure to some jewellery or jean studs. The latter is driven
by an immediate type allergy with histamine from mast cells causing fluid
retention in the skin. For studies of tea tree oil on the delayed type
hypersensitivity reaction, mice were sensitised to a small chemical on
their ventral skin and seven days later challenged or re-exposed on their
dorsal skin with the same hapten. For studies of the immediate type hypersensitivity
reaction, the effect of topically applied tea tree oil on histamine-induced
oedema in the ears of mice was examined. |
| Outcomes |
Tea
tree oil applied 30 minutes before, or up to 7 hours after, to the same
site as chemical challenge caused a significant reduction in skin swelling
after 24 hours. Tea tree oil reduced oedema but not the influx of inflammatory
cells. Tea tree oil did not suppress irritant- or ultraviolet B light-induced
oedema and suggests that memory T lymphocytes produce, or otherwise regulate,
the production of factor(s) that modulate the oedema associated with a
contact hypersensitivity response and this process can be regulated by
tea tree oil. For studies of immediate hypersensitivities, tea tree oil
applied immediately after, but not 30 minutes before intradermal injection
of histamine significantly suppressed oedema development. Studies suggested
that tea tree oil does not inhibit histamine-induced oedema by regulating
the activity of peripheral sensory neurons. |
| Implications |
(1)
Topical tea tree oil, specifically the tea tree oil components, terpinen-4-ol
and µ -terpineol can regulate the oedema associated with a delayed
type hypersensitivity response.
(2) Topical application of
tea tree oil may be effective in controlling histamine-induced oedema often
associated with Type I allergic immediate hypersensitivities. |
| Publications |
Brand
C, MA Grimbaldeston, JR Gamble, J Drew, JJ Finlay-Jones, PH Hart, Tea tree
oil reduces the swelling associated with the efferent phase of a contact
hypersensitivity response. Inflammation Research, submitted.
Brand C, SL Townley, JJ Finlay-Jones,
PH Hart, Tea tree oil reduces histamine-induced oedema in murine ears.
Inflammation Research, submitted. |
|
Project
Title:
|
Tea
Tree Oil as a topical decolonisation agent for adult inpatients with Methicillin-Resistant
Staphylococcus
aureus |
| RIRDC
Project No: |
UNC-7A |
| Researcher: |
Dr
John Attia |
| Organisation: |
University
of Newcastle
Centre for Clinical Epidemiology
& Biostatistics
University Drive, Callaghan,
NSW, 2308
AUSTRALIA |
| Phone: |
02
4923 6142 |
| Fax: |
02
4923 6148 |
| Objectives |
To
determine if a tea tree oil body wash and nasal ointment can be used in
hospitals to eradicate carriage of methicillin resistant Staphylococcus
aureus (golden staph) (MRSA) from skin and nasal passages. |
| Research |
A
randomised-controlled trial was used for the evaluation. A total of 180
adult inpatients with MRSA was randomly allocated to receive either intervention
care (IC) (TTO nasal ointment and bodywash) or routine care (RC) (Triclosan
bodywash/ mupirocin nasal ointment). Treatment consisted of the topical
application of a body wash solution for a minimum period of three days.
Following this, a series of swabs was taken to determine the absence (initially
clear) or presence (chronic carriage) of MRSA. The study period study extended
from 01/12/1999 until 11/07/2001. The study was undertaken at Westmead
Hospital, Sydney a university-affiliated tertiary referral teaching hospital,
with the support of the patients, clinical staff and the Institute of Clinical
Pathology and Medical Research. |
| Outcomes |
The
number of infected patients in the RC and IC groups was similar (48 versus
42, respectively). The most common site of isolation of MRSA was wounds,
accounting for 97 of 180 patients (54%). The median treatment period for
topical therapy for each treatment group was 3 days. Eleven participants
in the IC group and eight participants in the RC group did not complete
the topical therapy regimen of 3 days. A total of 70 patients was not evaluable.
This was generally due to the early discharge of participants, although
five participants died prior to completing the topical therapy stage of
the regimen. A final clearance rate of 21% in the IC group and 23% in the
RC group was calculated at the completion of the study period. Differences
in clearance rates between the two treatment groups were too small to be
statistically significant. |
| Implications |
The
outcome of this study is an important step in the process of developing
TTO-based products for use in the clinical setting. Although clearance
was low in both groups, there was no statistically significant difference
between the regimens, suggesting TTO products may be suitable for decolonising
patients carrying MRSA. The results can be used as a basis for further
research activities around such products as hand washing agents, body wash/shower
gels or wound management products. These are fields of interest to clinical
staff where support to undertake further research would be well received.
The study was well accepted by clinicians and participants at Westmead
Hospital. The use of an alternative natural therapy appealed to both the
clinical staff and participants. |
| Publications |
Articles
providing results of the studies undertaken to date have been presented
or published in the scientific literature and at international meetings
A randomised-controlled trial
to determine the clinical efficacy of Tea Tree Oil as an alternative topical
decolonisation agent for adult inpatients with MRSA Poster presented at
the 3rd Hospital Infection Society International Conference,
Edinburgh September 1998
Tea Tree Oil as an Alternative
Topical Decolonisation Agent for Methicillin-Resistant Staphylococcus
aureus Paper presented NSW Infection Control Conference, Batemans
Bay October 1999
A randomised-controlled trial
to determine the clinical efficacy of Tea Tree Oil as an alternative topical
decolonisation agent for adult inpatients with MRSA. Poster presented at
the 4th Decennial International Conference on Nosocomial and
HealthCare-Associated Infections, Atlanta March 2000
Caelli M, Porteous J, Heller
R, Riley T. Tea tree Oil as an alternative topical decolonisation agent
for methicillin-resistant Staphylococcus aureus. Journal of Hospital
Infection 2000; 46: 236-237.
Tea Tree Oil as an Alternative
Topical Decolonisation Agent for Methicillin-Resistant Staphylococcus
aureus - Results of the Pilot Study Paper presented Infection Control
Nurse’s Association Conference, Blackpool UK, September 2001 |
|
Project
Title
|
Towards
non-chemical control of weeds in tea tree |
| RIRDC
Project No.: |
US-20A |
| Researchers: |
Dr
BG Sutton, Dr RD Cousins and Dr J Murtagh |
| Organisation: |
University
of Sydney
Goonellabah NSW 2480 |
| Phone: |
02
9692 2050 |
| Fax: |
02
9692 4172 |
| Objectives |
· To survey
tea tree growers to establish the range of weed problems encountered, and
the scope of current weed control techniques used in tea tree cultivation.
· To identify
the mechanisms by which weeds inhibit the growth and oil production of
established tea tree plantations.
· To define
practical methods of weed control for plantation managers, which minimise
the use of herbicides.
|
| Background |
The
perception of the tea tree industry is that weeds inhibit plantation production
in two phases - establishment and regrowth.
The extent to which weeds
affect the regrowth of tea tree by competing for light, nutrients and water
has not been quantified, but the industry perception is that it is a real
but variable problem. It is postulated that weed problems are linked to
loss of fine roots of tea tree following coppicing. In these situations,
the tea tree plant has weakened competitive ability against rapidly growing
annual weeds until regrowth has been well established. The use of herbicides,
as is currently practiced, is seen as damaging to the image of the product
(tea tree oil), by growers and potential consumers. A range of cultural
practices additionally used by growers, could form the basis of a non-chemical
system of weed control in plantations.
This study seeks to evaluate
these alternatives. The information gained should provide guidance on when
weed control is required during the regrowth cycle, and what the method
used must achieve if it is to be successfully adopted. |
| Research |
A
wide range of pot and field experiments were conducted to provide more
information on the nature of root and top growth in coppiced tea trees,
to allow a better understanding of the physiology of the crop in competition
with weeds at different stages of its regrowth. The response to nitrogen
nutrition was also examined.
Concurrently, other studies
were undertaken to determine the effectiveness of various weed control
strategies such as herbicide use (overall and strip treatments), cover
crops, mowing, mechanical cultivation, and hand hoeing. These trials were
undertaken at several localities over a three year period. |
| Outcomes |
The
results of these studies showed that weeds reduced tea tree leaf yields
by an average 27% (range 9 to 47), but without affecting oil concentration
or quality. This loss in yiel |
