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PROCEEDINGS OF THtr
I't INTtrRNATIONAL SYMPOSIUM
ON
PYRETHRUM, THE NATURAL INSECTICIDE
..SCIENTTFIC AND INDUSTRIAL DEVELOPMENTS
IN THE RENEWAL OF A TRADITIONAL
INDUSTRY''
Convener
B. Chung
Launceston, Tasmania, Australia
November 2-4,2011
ISHS Section Medicinal and Aromatic Plants
ISHS Commission Plant Protection
ISHS Cornmission Plant Genetic Resources
ISHS Working Group Culture of Medicinal and Arornatic Plants
Acta Horticulturae 107 3
February 2015

3. and and in various
tere;-l dclse valve tct
vertising, leading to
ly high usage and
rs launclr their or,r,n
on has launched an
:luding a unique,
zarning light, thus
egment is currentll;
at 8.494 versus last
st three yeqrs since
:rease in household
ol is of the order of
rns of up to 50% of
ts15-$25 (depending
rum in Australia for
the dispensing unit
rave to aesthetically
Ln development and
ill be whether the
ebt different actives
i
Pyrethrum: the Natural Choice in Pest Control
R.F. Ryan
VAPORF AZE
PO Box 4, Sans Souci, NSW 2219
Atrstralia
M. Greenhill and B. Chuns
Botaniczrl Resources Austrll ia
PO Box 3251 , Ulverstone, Tasmania 73 l5
Australia
Keyn'ords: pyrethrum, liquid CO2 propellant, dispensing systems, developntent in
Australia, aerosol
Abstract
Pyrethrum is a well-known natural insecticide and has been in use for many
years. The development of a commercial size liquid CO2 high pressure aerosol
product by BOC Gases in Australia during the late 1970s proved verv successful
because of the inherent properties of pyrethrum and the dispensing system and rvas
lound to be ver.v effective for many commercial scale uses such as food lvarehouses.
The successes of this product lead to the commercial scale development of
pyrethrum crop production in Tasmania. This operation was purchased by the
majority Tasmanian owned company Botanical Resources Australia during 1996
and since that time, significant advancement in crop production and post-harvest
processing has been achieved and Australia now produces more than 50o of the
pyrethrum requirement of the lvorld.
INTRODUCTION
The active ingredients in pyrethrum, an extract from flowers, are the six individual
naturally occurring insecticidal active esters referred to as Pyrethrins lviz., pyrethrins I,
cinerin I, jasrnolin I, pyrethrins Il, cinerin ll, jasmolin Il]. The insecticidal properties of
pyrethrum have been known since ancient times. Pyrethrum was flrst mentioned in
historical documents fiom the Chou Dynasty in China, some 2000 years ago. The plant is
endemic to the eastern Balkans. Powdered pyrethrum flowers were used as an insecticide
which became known as Dalrnatian Flea Powder (it was widely grown in Dalmatia,
Croatia). Napoleon used pyrethrum to de-louse his Grand Annee and the insecticide was
sought after by both sides in the American Civil War. Pyrethrum r,l,as widely used in
homes and in large scale insect spraying well into the twentieth century, until its
predominance became superseded by the use of synthetic insecticides. However, more
widespread availability of pyrethrum combined with its unique position as a non-residual
natural insecticide has resulted in a resurgence of consumer interest in natural pyrethrurn
in recent years.
The pyrethrum from the cmshed flou,ers of the "chrysanthemum daisy" contains
-lo/o pyrethrum insecticide. The pyrethrurn flower (Tanacetum cinerariaefolium) is a
white daisy belonging to the chrysanthemum family that produces the natural insecticide.
Around each seed case (achene) in the flower's tightly packed head are many rnicroscopic
oil glands containing a plant oil that the flower has evolved over millennia to protect itself
from insect attack. The plant oil in these glands is an organic product made up of the six
pyrethrin esters collectively known as pyrethrum.
Pyrethrum is an extremelv fast acting natural insecticide that breaks down rapidly
in light and does not build up or persist in the environment. Pyrethrum is combined u'ith
the insecticide synergist, piperonyl butoxide to increase effectiveness. Pyrethrum is an
insect neurotoxin and piperonyl butoxide acts by preventing metabolic detoxif-rcation of
the insecticide. Applied correctly, it is safe for use around humans and warm blooded
animals and even in food preparation areas. It is particularly useful in sensitive
environments where the long-term environmental elTects of synthetics are a concern.
Other benefits of pyrethrum are its broad spectrum activity, excellent flushing activity,
powerful insect repellence, non-residual activity and lack of recorded insect resistance.
This paper will focus on significant pyrethrum development in Australia which
Proc. l" IS on Pyrethrum, the Natural Insecticide: "scientific & lndustrial
Dev't. in the Renewal of a Traditional lnd "
Ed.: B. Chung
Acta Hort. 1073,ISHS 2015
131

4. includes local production and innovative dispensing systems.
BACKGROUND
There is a historical connection with pyrethrurn in Australia involving the
development of a corlmercial pest control aerosol product and the establishrnent of a
pyrethrum industry. The commercial pest control aerosol product r,r,as developed (1975)
followin-e a fatality fiorn mosquito transmitted encephalitis along the Murray River
(NSW/Vic border). Commonwealth Industrial Gases [CIC] 'uvas asked to supply a bulk
pesticide systern for the large scale control of mosquitoes. The CIG initiated R&D
resulted in the development of a "high pressure" industrial gas cylinder aerosol product
formulated using natural pyrethrum as the active ingredient and liquid carbon dioxide
(COz) as the solvent-propellant.
A precursor to the CIG "high pressure" commercial pest control product was the
"lorv pressure" pyrethrum aerosol fbrmulation initiated during 1943 by the US Army. The
USA distributed the pressurised aerosol spray canister ("Bug Bornbs") to troops fighting
in the "WW II Pacific War Theatre" to reduce death caused by mosquito transmitted
diseases. A modified commercial domestic pyrethrum aerosol product, "Mortein Pressure
Pak", was introduced during 1953 to the Australian market [Ryan et al., 2010] by the then
Samuel Taylor Company (now Reckitt Benckiser). While the development of the
pyrethrurn industry in Australia was initially supported by CSIRO in the early 1940s, the
University of Tasmania signed an R&D agreement with CIG which resulted in the
formation of "ClG Pyrethrurn". The University/Industry joint development resulted in the
first experimental growing of pyrethrum in Tasmania duringl98l. A signif-rcant milestone
was the takeover of the pyrethrum industry during 1996 by the majority Tasmanian
owned and operated company Botanical Resources Australia Pty Ltd (BRA).
LIQUID CO2 HIGH PRESSURE AEROSOL
The innovative Liquid CO2 propelled aerosol was launched by CIG in 1976 to the
commercial pest control market rvith applications of "fbgging" large spaces using manual
hand guns or fixed automatic installation systems. The original high pressr,rre Liquid CO2
pyrethrum aerosol product was Pestigas* IBOC International] rvhich was copied and
marketed in the USA as Turbocide* (Fairfield American / MGK) and more recently in
Australia as SupaPy* (SUPAGAS, Australia). The lbrmulation consists of 4 -elkg
pyrethrins" 20 glkg piperonyl butoxide (as the synergist), 100 g/kg paraffin hydrocarbon
dissolved in 876 g/kg liquid solvent-propellant COz. The unique solvent-propellant
properties of liquid COz were the basis for an international patent, Ryan et al. (1978).
This patent described a high pressure aerosol spray with natural pyrethrum as the quick
knockdown, non-residual and low mammalian toxicity insecticide. The solvent-
propellant, hi-eh pressure (5,000 kPa) liquid CO:, is a low cost solvent rvith fire retardant
properties enabling the formulation of a non-flammable product. Tlie Liquid COz
pyrethrins aerosol spray travels -30 meters, fills the total treatment space with a low
concentration of insecticide concentrate and the process is clean, fast and biolo-eicalli,
ef fective.
The Liquid COz tnixture, available in a range of industrial high pressure gas
cylinders, was fitted with an eductor tube (dip tube) to dispense an aerosol fog.
Measurement of the particle size of the Liquid COz aerosol; by Slatter et al. (l98l)
identified the efficient atomisation of the insecticide with spray cloud average particle
size of -5 microns which remained airborne for a long period (half life of -30 min.).
These researchers also concluded that Liquid CO2 aerosol produced a very efflcient and
eff-ective spray cloud that provided excellent control of flying insects at lorv dosages, and
useful control of crar,vling insects.
LIQUID CO2 UNIQUE FEATURES
The unique f-eatures of the Liquid COz solvent-propcllant mixture which resulted
in its continued acceptance include: non-flammability; ultra-t-rne particle size (ran_ec from
132
2 to 20 microns); st
automatic, fixed or
technology resulted
analytical techniquel
In order to f,acilitate
automatic disPensinl
concerning the beha
discharge, Nieass e
phenomena.
A Pecullar P
propellant system is
wtren all the liquid r
saseous COz could
Ictive ingredient wh
dispensed from the c
not as noticeable as
of magnitude lower 1
APPLICATIONS
Unlike the c<
distributed through
automaticallY. The P
mosquitoes) and cra
commercial, rural ar
The high Pre
hotels, restaurants,
commercial office I
mushroom houses,
horticultural aPPlica
advantage bY contir
locations.
PYRETHRUM CC
PYrethrum tt
household insect sP
organic farming in
pi[eronyl butoxide
storase warehouse
adulti-cirje and is inc
Liquid PYre
TasPY* (BRA) are
COz industrial gas c
DEVELOPING A'
Australia is
"daisy" flower can
needs large amount
at high altitudes ir
Japan, PaPua New
ovrethrum growers
^E'ast
Af,rici lKenY
Tasmania grows o
pyrethrum industrY
Pvrethrum
sunny climate. higl

5. ralia inr.'olvir-rg the
establishrnent of a
rs developed (1975)
the Murray River
ed to supply a bulk
llc initiated R&D
rder aerosol product
prid carbon dioxide
.rol product rvas the
y the US Army. The
'') to troops fighting
rosquito transmitted
t, "Mortein Pressure
1.,20101 by the then
,evelopment of the
the early 1940s, the
ich resulted in the
ment resulted in the
ignificant milestone
najority Tasmanian
BRA).
CIG in 1975 to the
ipaces using manual
)ressure Liquid CO2
ch was copied and
rd more recently in
;onsists of 4 g/kg
araffin hydrocarbon
: solvent-propellant
Ryan et al. (1978).
lthrum as the quick
:ide. The solvent-
Lt with fire retardant
. The Liquid COz
t space with a low
rst and biologically
high pressure gas
se an aerosol fog.
llatter et al. (1981)
ud average particle
I life of -30 min.).
a very efficient and
at low dosages, and
.ture which resulted
;le size (range from
2 to 20 microns): sized lbr conrrnercial and industrial ncecls (l kg to 37 kg cylinclcrs);
automatic, fixed. or. portablc-
.s1tace. Spra1, systerns. The developrneirt of the"t-iquicl CO2
technology resulted in the investigatior-r of the physical beiayioul', the eyoiLrtion ol
analytical techniques fbr product development, quality control and lirndalnental research.
In order to facilita.te the application of these products, Nieass and Ryan, 1983 researched
autontatic dispensing and distribution systerns. To cornpensate for the lack of informatiol
conceming t!.e behaviour of the liquid carbon dioxide-systern during isothermal product
discharge, Nieass et al. (l98l) developed a mathem-atical rnode-i ro describi these
phenomena.
.,
A peculiar property of the high pressure (-5000 kPa) carbon dioxide solvent-
propellant- system is tlre relative large t-"ulr of gaseous COz rerlaining in the cylinder
r.r'hen all the liquid.active ingredient and Liquid eoz has been dispensed'. The arnount of
gaseous CO2 coul{ 1e_present as much as 20Yo of the original iontents. However, the
active ingredient which il o{y dissolved in the Liquid COI propellant has already 6..n
dispensed.froin.the cylinder. This effect also existr in do.erti" u.rorol can; although it is
not as noticeable as the vapour pressure of the propellant (hydrocarbon, LpG) is an'order
of magnitude lower pressure (-300 kPa).
APPLICATIONS
Unlike the consumer aerosol ca, the high pressure Liquid COz formulation can be
distributed throughout. large building using high pressure pipe and dispensed
automatically. The pyrethrum products are used to coirtroi flying insecis (e.g. flies, hoths,
mosquitoes) and crawling insects (e.g. cockroaches, beetles, ants, silverfish) in industrial,
commercial, rural and domestic premises.
The high pressure
-pyrethrurn aerosol is used to control insect pest in dwellings,
hotels, restaurants, warehouses, f-actories, retail stores, nurseries, tobacco storage,
commercial off-rce buildings, communications centres, museums, herbariums, archives,
mushroom houses, grain handling equipment, animal houses, sewer mains, and in
horticultural applications. The effective insect repellent property of pyrethrins is used to
advantage by continuous spraying minute quantities to
-repel
flying insects in sensitive
Iocations.
PYRETHRUM CONCENTRATE PRODUCTS
P_yrethrum today is used in a wide range of environmentally sensitive areas fi'om
household insect sprays to industrial scale applications. Pyrethrum- is certif-red fbr use in
organic f-arming in several countries,_ although it must be used without the synergist
piperonyl butoxide and is used by profbssionaL pest controllers in both domestic ana 6oO
stgr.age.
_
warehouses "!rm1gati9ns". Pyrethrum is a particularly effective mosquito
adulticide and is increasingly being used in large-scale mosquito "fogging".
___ltqUa .Pyrethrum Concentrates including Turbocide Gold;-1MCf, USA) and
Iqtp.Vi (BRA) are specifically _suitable for on-site mixing with localiy available iiquid
CO2 industrial gas cylinders and high pressure mixing technblogy.
DE/ELOPING AUSTRALIAN PYRETHRUM
Australia is a re_latively recent producer of pyrethrum. The perennial pyrethrum
"daisy" flower can be harvested for some five years. For optirnal ilowering,^ ihe daisy
needs.large. amounts of sunlight and ample water. Traditionally, the daisy hasEeen grown
at high_altitudes in^equatorial regions, or at higher latitudes. In the twentieth ceitury,
Japan, Papua New Guinea, China, Ecuador and India amongst other countries, have been
pyrethrum growers, but the lar,qest two pyrethrum growing regions in the world are no r
East Afi'ica (Kenya, Rwanda, Tanzania) and the Australian-island state of Tasmania.
Tasmania grows over 50o% of the global pyrethrum total and has the most high-tech
pyrethrum industry in the u,orld.
Pyrethrum was first grown experimentally in Tasmania in 1981, when the cool,
sunny climate, high rainfall and fertile volcanic soils of the island's nofth and north-west
133

6. were found to be ideal for the plant. The Australian pyrethrum industry was taken over in
1996 by the majority Tasmanian owned and operated company Botanical Resources
Australia Pty Ltd (BRA) and the company now grows sorne thousands of hectares of
pyrethrum. Flowering takes place during December and January and the paddocks of
white flowers are a spectacular sight against the coastal backdrop of north-west Tasmania.
In the annual harvest in January and February, many specially adapted headers gather in
dried pyrethrum flowers.
After harvest the flower material from the field undergoes multi-stage process of
pelletising, extraction and refinery at BRA's state-of-the-ar1 plant at Ulverstone in
Tasmania's north-lvest (Ryan et al., 2002). Pyrethrum is extracted fi'om pyrethrum crop
pellets r-rsing the solvent hexane. The extracted oil, crude pyrethrum extract (oleoresin), is
a viscous dark green plant oil. Hexane is recovered ttom the oleoresin during the
extraction process by evaporation and condensation. Oleoresin contains waxes and other
co-extracted botanical impurities, rvhich makes it unsuitable to use in aerosol
formulations. Pyrethrum is decolourised and dewaxed by further refining of the oleoresin.
The BRA refining process utilises COz as a solvent to remove residual plant based
impurities. yielding a concentrated pyrethrum extract that is standardised using a light
petroleum based solvent to yield a high quality amber coloured 50% Refined Extract. The
pyrethrum extract are formulated on-site according to customer specifications and are
exported all over the world.
FUTURE DEVELOPMENTS
In addition to its efficacy, pyrethrum has excellent f'lushing and repelling qualities.
The popularity of outdoor entertainment has increased the focus on insect nuisance and
potential health issues. The treatment of lar,ee open occupied areas requires usage of a low
toxicity active. Pyrethrum is especially suitable for such applications as it is a very
effective flying insect repellent with lower risk OH&S issues of toxicity or pesticide
residues compared with nrany other materials. Repelling insects overcomes concerns of
alternative insecticide treatment because "no fly is preferred to a dead fly" in food
handling areas. This technique requires the regular micro dosing of sub l0 micron
pyrethrum particle which could be achieved using automatic dispensing. The dispensing
of pyrethrum product has options of pre-mix (e.g. SupaPY) and on-site post-mix with
CO2 (e.g. TasPY).
The grorvth in the marketing of organic fruit & vegetables has increased the
dernand for "organic" insecticides which can be satisfied by pyrethrum (preferably
rvithout the synergist Piperonyl Butoxide r,vhich has some issues with organic growers).
There is a need for a niche volatile solvent (e.g. ethanol) alternative formulation to avoid
"oily deposits" on surfaces in high dose applications. While the deposits are minute they
can be observed on highly polished furniture surfaces. While "oily deposits" can be easily
removed by wiping with a cloth, it involves additional labour in the treatment of large
areas. The niche markets opportunities [e.g. insect repellence, organic and low solvent
fonnulations] may all be satisfied by a modified forrnulation which eliminates piperonyl
butoxide and substitutes the volatile ethanol (e.g. 2o/o refined pyrethrum extract, 8o/o
ethanol, 80% liquid COz).
CONCLUSIONS
A significant influence in the development of the pvrethrum industry in Australia
was the applications of liquid COz. The development of liquid CO2 as a solvent-
propellant by CIG and the marketing of PESTIGAS encolrraged CIG to persist with the
long tenn (-15 years) R&D investment required to develop the pyrethrum industry. The
active BRA focus on a quality lorv irritant pyrethrum concentrate required them to
develop a refining process using liquid CO2. While CIG's history publication "With
Enthusiasm Buruin-e" predates the pyrethrum development the title is appropriate to the
approach to this project. Enthusiasm and focus rvas the key to develop the many BRA
innovations required to solve a rnultitude of unforseen ditficulties. Today BRA continues
134
to secure its long tt
in expansion of its
highly re-earded be
control during the t
Literature Cited
Nieass, C.S. and R
Muy, p.413.
Nieass, C.S., We
Australasian C
August. p.169.
Ryan, R.F." Shervir
Ryan, R.F., Bown
Propelled Pesti,
Ryan, R.F., Bishc
"Pvrethrum: Ni
Ze'aland,29th S,
Slatter, R., Stewa
Pestigas BB, e
Using Pressuris

7. ' )rintry *'as tal(en ove
lJotanical Re sottrces
sands o1' hectares of
rnd the paddocks of
rorth- cst Tasrnania.
ted headers gather in
rulti-stage process of
.nt at Ulr,'erstone in
lrom pyrethrum crop
extract (oleoresin), is
oleoresin during the
ains waxes and other
to use in aerosol
ning o1'the oleoresin.
residual plant based
ardised using a light
Rel=rned Extract. The
pecifications and are
ird repelling qualities.
r insect nuisance and
:quires usage of a low
[ions as it is a very
toxicity or pesticide
'ercomes concetns of
a dead fly" in tood
g of sub 10 micron
rsing. The dispensing
rn-site post-mix with
es has increased the
yrethrurn (preferably
ith organic growers).
formulation to avoid
rosits are minute they
eposits" can be easily
he treatment of large
anic and low solvent
, elirninates piperonyl
rrethrum extract, 8o/o
industry in Australia
I CO2 as a solvent-
IG to persist with the
:ethrum industry. The
ate required them to
ry publication "With
: is appropriate to the
velop the many BRA
loday BRA continues
to secure its long tcnn tiitur-e n'ith on-going innovations and significant capital inve-strnent
in expansion. of.its opcrations. TI-re readily available supply o1- pyrethrum and its many
highly-regarded benef-i.cial properlies u ill insure pyrcthrun-r to be the natural ch<lice in pest
control dr-rring the environmentally A;are 21" Centurn'.
Literature Cited
Nieass, C.S. and Ryan, R.F. 1983. Proc.3'd Pacific Cliem. Eng. Congress, Seoul, Korea,
Muy, p.413.
Nieass, c.s., wainivright, M.s., chaplin, R.p. and Ryan, R.F. 1981. proc. 9th
Australasian Conference on Chemical Engineering, Christchurch, New Zealand,,
August. p. 169.
Byutt, R.F., Sliervington, E.A. and catchpoole, D.J. 1978. Aust. pat. 494,198.
Ryan, R.F., Bolvman, G.R. and Thompson, I.A. 2010. "Past, Present and Potential of
Propelled Pesticides" RACI National Conference
Ryan, R.F., Bishop, s.R., chung, B., Folder, [., Krishna, H. and Lemon, A. 2002.
"Pyrcthmm:,Nature's Pesticide" 9'n APCChE and CHEMICA 2002, Christchurch Nerv
Zealand,2g'n September to 3 October 2002.
Slatter, R., Stewart, D.C., Martin, R. and White, A.W.C. l98l. "An Evaluation of
feqtigry BB, a Neu'.System for Applying Synthetic Pyrethroids as Space Sprays
Using Pressurised Carbon Dioxide" lnternational Pest Control, NoviDec.
135