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PROCEEDINGS OF THtrI't INTtrRNATIONAL SYMPOSIUM

ONPYRETHRUM, THE NATURAL INSECTICIDE

..SCIENTTFIC AND INDUSTRIAL DEVELOPMENTSIN THE RENEWAL OF A TRADITIONAL

INDUSTRY''

Convener

B. Chung

Launceston, Tasmania, Australia

November 2-4,2011

ISHS Section Medicinal and Aromatic PlantsISHS Commission Plant Protection

ISHS Cornmission Plant Genetic ResourcesISHS Working Group Culture of Medicinal and Arornatic Plants

Acta Horticulturae 107 3

February 2015

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vertising, leading toly high usage andrs launclr their or,r,non has launched an:luding a unique,zarning light, thus

egment is currentll;at 8.494 versus lastst three yeqrs since:rease in household

ol is of the order ofrns of up to 50% ofts15-$25 (dependingrum in Australia for

the dispensing unitrave to aestheticallyLn development andill be whether theebt different activesi

Pyrethrum: the Natural Choice in Pest Control

R.F. RyanVAPORF AZEPO Box 4, Sans Souci, NSW 2219Atrstralia

M. Greenhill and B. ChunsBotaniczrl Resources Austrll iaPO Box 3251 , Ulverstone, Tasmania 73 l5Australia

Keyn'ords: pyrethrum, liquid CO2 propellant, dispensing systems, developntent inAustralia, aerosol

AbstractPyrethrum is a well-known natural insecticide and has been in use for many

years. The development of a commercial size liquid CO2 high pressure aerosolproduct by BOC Gases in Australia during the late 1970s proved verv successfulbecause of the inherent properties of pyrethrum and the dispensing system and rvaslound 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 ofpyrethrum crop production in Tasmania. This operation was purchased by themajority Tasmanian owned company Botanical Resources Australia during 1996and since that time, significant advancement in crop production and post-harvestprocessing has been achieved and Australia now produces more than 50o of thepyrethrum requirement of the lvorld.

INTRODUCTIONThe 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 ofpyrethrum have been known since ancient times. Pyrethrum was flrst mentioned inhistorical documents fiom the Chou Dynasty in China, some 2000 years ago. The plant isendemic to the eastern Balkans. Powdered pyrethrum flowers were used as an insecticidewhich 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 wassought after by both sides in the American Civil War. Pyrethrum r,l,as widely used inhomes and in large scale insect spraying well into the twentieth century, until itspredominance became superseded by the use of synthetic insecticides. However, morewidespread availability of pyrethrum combined with its unique position as a non-residualnatural insecticide has resulted in a resurgence of consumer interest in natural pyrethrurnin recent years.

The pyrethrum from the cmshed flou,ers of the "chrysanthemum daisy" contains-lo/o pyrethrum insecticide. The pyrethrurn flower (Tanacetum cinerariaefolium) is awhite 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 rnicroscopicoil glands containing a plant oil that the flower has evolved over millennia to protect itselffrom insect attack. The plant oil in these glands is an organic product made up of the sixpyrethrin esters collectively known as pyrethrum.

Pyrethrum is an extremelv fast acting natural insecticide that breaks down rapidlyin light and does not build up or persist in the environment. Pyrethrum is combined u'iththe insecticide synergist, piperonyl butoxide to increase effectiveness. Pyrethrum is aninsect neurotoxin and piperonyl butoxide acts by preventing metabolic detoxif-rcation ofthe insecticide. Applied correctly, it is safe for use around humans and warm bloodedanimals and even in food preparation areas. It is particularly useful in sensitiveenvironments 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 & lndustrialDev't. in the Renewal of a Traditional lnd "Ed.: B. ChungActa Hort. 1073,ISHS 2015

131

includes local production and innovative dispensing systems.

BACKGROUNDThere is a historical connection with pyrethrurn in Australia involving the

development of a corlmercial pest control aerosol product and the establishrnent of apyrethrum 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 bulkpesticide systern for the large scale control of mosquitoes. The CIG initiated R&Dresulted in the development of a "high pressure" industrial gas cylinder aerosol productformulated 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. TheUSA distributed the pressurised aerosol spray canister ("Bug Bornbs") to troops fightingin the "WW II Pacific War Theatre" to reduce death caused by mosquito transmitteddiseases. A modified commercial domestic pyrethrum aerosol product, "Mortein PressurePak", was introduced during 1953 to the Australian market [Ryan et al., 2010] by the thenSamuel Taylor Company (now Reckitt Benckiser). While the development of thepyrethrurn industry in Australia was initially supported by CSIRO in the early 1940s, theUniversity of Tasmania signed an R&D agreement with CIG which resulted in theformation of "ClG Pyrethrurn". The University/Industry joint development resulted in thefirst experimental growing of pyrethrum in Tasmania duringl98l. A signif-rcant milestonewas the takeover of the pyrethrum industry during 1996 by the majority Tasmanianowned and operated company Botanical Resources Australia Pty Ltd (BRA).

LIQUID CO2 HIGH PRESSURE AEROSOLThe innovative Liquid CO2 propelled aerosol was launched by CIG in 1976 to the

commercial pest control market rvith applications of "fbgging" large spaces using manualhand guns or fixed automatic installation systems. The original high pressr,rre Liquid CO2pyrethrum aerosol product was Pestigas* IBOC International] rvhich was copied andmarketed in the USA as Turbocide* (Fairfield American / MGK) and more recently inAustralia as SupaPy* (SUPAGAS, Australia). The lbrmulation consists of 4 -elkgpyrethrins" 20 glkg piperonyl butoxide (as the synergist), 100 g/kg paraffin hydrocarbondissolved in 876 g/kg liquid solvent-propellant COz. The unique solvent-propellantproperties 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 quickknockdown, 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 retardantproperties enabling the formulation of a non-flammable product. Tlie Liquid COzpyrethrins aerosol spray travels -30 meters, fills the total treatment space with a lowconcentration 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 gascylinders, 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 particlesize 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 andeff-ective spray cloud that provided excellent control of flying insects at lorv dosages, anduseful control of crar,vling insects.

LIQUID CO2 UNIQUE FEATURESThe 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 ortechnology resultedanalytical techniquelIn order to f,acilitateautomatic disPensinlconcerning the behadischarge, Nieass e

phenomena.A Pecullar P

propellant system is

wtren all the liquid r

saseous COz couldIctive ingredient whdispensed from the c

not as noticeable as

of magnitude lower 1

APPLICATIONSUnlike the c<

distributed throughautomaticallY. The P

mosquitoes) and cracommercial, rural ar

The high Prehotels, restaurants,commercial office I

mushroom houses,horticultural aPPlicaadvantage bY contirlocations.

PYRETHRUM CCPYrethrum tt

household insect sP

organic farming inpi[eronyl butoxidestorase warehouseadulti-cirje and is inc

Liquid PYre

TasPY* (BRA) are

COz industrial gas c

DEVELOPING A'Australia is

"daisy" flower canneeds large amountat high altitudes irJapan, PaPua Newovrethrum growers^E'ast Af,rici lKenYTasmania grows o

pyrethrum industrYPvrethrum

sunny climate. higl

ralia inr.'olvir-rg theestablishrnent of a

rs developed (1975)the Murray River

ed to supply a bulkllc initiated R&Drder aerosol productprid carbon dioxide

.rol product rvas they the US Army. The'') to troops fightingrosquito transmittedt, "Mortein Pressure1.,20101 by the then,evelopment of thethe early 1940s, theich resulted in thement resulted in theignificant milestonenajority TasmanianBRA).

CIG in 1975 to theipaces using manual)ressure Liquid CO2ch was copied andrd more recently in;onsists of 4 g/kgaraffin hydrocarbon: solvent-propellantRyan et al. (1978).lthrum as the quick:ide. The solvent-Lt with fire retardant. The Liquid COzt space with a lowrst and biologically

high pressure gasse an aerosol fog.llatter et al. (1981)ud average particleI life of -30 min.).a very efficient andat 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 CO2technology resulted in the investigatior-r of the physical beiayioul', the eyoiLrtion olanalytical techniques fbr product development, quality control and lirndalnental research.In order to facilita.te the application of these products, Nieass and Ryan, 1983 researchedautontatic dispensing and distribution systerns. To cornpensate for the lack of informatiolconceming t!.e behaviour of the liquid carbon dioxide-systern during isothermal productdischarge, Nieass et al. (l98l) developed a mathem-atical rnode-i ro describi thesephenomena.

., 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 cylinderr.r'hen all the liquid.active ingredient and Liquid eoz has been dispensed'. The arnount ofgaseous CO2 coul{ 1e_present as much as 20Yo of the original iontents. However, theactive ingredient which il o{y dissolved in the Liquid COI propellant has already 6..ndispensed.froin.the cylinder. This effect also existr in do.erti" u.rorol can; although it isnot as noticeable as the vapour pressure of the propellant (hydrocarbon, LpG) is an'orderof magnitude lower pressure (-300 kPa).

APPLICATIONSUnlike the consumer aerosol ca, the high pressure Liquid COz formulation can be

distributed throughout. large building using high pressure pipe and dispensedautomatically. 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 inhorticultural applications. The effective insect repellent property of pyrethrins is used toadvantage by continuous spraying minute quantities to

-repel flying insects in sensitive

Iocations.

PYRETHRUM CONCENTRATE PRODUCTSP_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 inorganic f-arming in several countries,_ although it must be used without the synergistpiperonyl butoxide and is used by profbssionaL pest controllers in both domestic ana 6oOstgr.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 iiquidCO2 industrial gas cylinders and high pressure mixing technblogy.

DE\/ELOPING AUSTRALIAN PYRETHRUMAustralia is a re_latively recent producer of pyrethrum. The perennial pyrethrum

"daisy" flower can be harvested for some five years. For optirnal ilowering,^ ihe daisyneeds.large. amounts of sunlight and ample water. Traditionally, the daisy hasEeen grownat 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 beenpyrethrum 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-techpyrethrum 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

were found to be ideal for the plant. The Australian pyrethrum industry was taken over in1996 by the majority Tasmanian owned and operated company Botanical ResourcesAustralia Pty Ltd (BRA) and the company now grows sorne thousands of hectares ofpyrethrum. Flowering takes place during December and January and the paddocks ofwhite 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 indried pyrethrum flowers.

After harvest the flower material from the field undergoes multi-stage process ofpelletising, extraction and refinery at BRA's state-of-the-ar1 plant at Ulverstone inTasmania's north-lvest (Ryan et al., 2002). Pyrethrum is extracted fi'om pyrethrum croppellets r-rsing the solvent hexane. The extracted oil, crude pyrethrum extract (oleoresin), isa viscous dark green plant oil. Hexane is recovered ttom the oleoresin during theextraction process by evaporation and condensation. Oleoresin contains waxes and otherco-extracted botanical impurities, rvhich makes it unsuitable to use in aerosolformulations. Pyrethrum is decolourised and dewaxed by further refining of the oleoresin.The BRA refining process utilises COz as a solvent to remove residual plant basedimpurities. yielding a concentrated pyrethrum extract that is standardised using a lightpetroleum based solvent to yield a high quality amber coloured 50% Refined Extract. Thepyrethrum extract are formulated on-site according to customer specifications and areexported all over the world.

FUTURE DEVELOPMENTSIn addition to its efficacy, pyrethrum has excellent f'lushing and repelling qualities.

The popularity of outdoor entertainment has increased the focus on insect nuisance andpotential health issues. The treatment of lar,ee open occupied areas requires usage of a lowtoxicity active. Pyrethrum is especially suitable for such applications as it is a veryeffective flying insect repellent with lower risk OH&S issues of toxicity or pesticideresidues compared with nrany other materials. Repelling insects overcomes concerns ofalternative insecticide treatment because "no fly is preferred to a dead fly" in foodhandling areas. This technique requires the regular micro dosing of sub l0 micronpyrethrum particle which could be achieved using automatic dispensing. The dispensingof pyrethrum product has options of pre-mix (e.g. SupaPY) and on-site post-mix withCO2 (e.g. TasPY).

The grorvth in the marketing of organic fruit & vegetables has increased thedernand for "organic" insecticides which can be satisfied by pyrethrum (preferablyrvithout 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 theycan be observed on highly polished furniture surfaces. While "oily deposits" can be easilyremoved by wiping with a cloth, it involves additional labour in the treatment of largeareas. The niche markets opportunities [e.g. insect repellence, organic and low solventfonnulations] may all be satisfied by a modified forrnulation which eliminates piperonylbutoxide and substitutes the volatile ethanol (e.g. 2o/o refined pyrethrum extract, 8o/oethanol, 80% liquid COz).

CONCLUSIONSA 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 thelong tenn (-15 years) R&D investment required to develop the pyrethrum industry. Theactive BRA focus on a quality lorv irritant pyrethrum concentrate required them todevelop a refining process using liquid CO2. While CIG's history publication "WithEnthusiasm Buruin-e" predates the pyrethrum development the title is appropriate to theapproach to this project. Enthusiasm and focus rvas the key to develop the many BRAinnovations required to solve a rnultitude of unforseen ditficulties. Today BRA continues

134

to secure its long ttin expansion of itshighly re-earded becontrol during the t

Literature CitedNieass, C.S. and R

Muy, p.413.Nieass, C.S., We

Australasian C

August. p.169.Ryan, R.F." ShervirRyan, R.F., Bown

Propelled Pesti,Ryan, R.F., Bishc

"Pvrethrum: NiZe'aland,29th S,

Slatter, R., StewaPestigas BB, e

Using Pressuris

' )rintry *'as tal(en ovelJotanical Re sottrcessands o1' hectares ofrnd the paddocks ofrorth-\\ cst Tasrnania.ted headers gather in

rulti-stage process of.nt at Ulr,'erstone inlrom pyrethrum cropextract (oleoresin), isoleoresin during theains waxes and otherto use in aerosol

ning o1'the oleoresin.residual plant basedardised using a lightRel=rned Extract. Thepecifications and are

ird repelling qualities.r insect nuisance and:quires usage of a low[ions as it is a verytoxicity or pesticide

'ercomes concetns ofa dead fly" in toodg of sub 10 micronrsing. The dispensingrn-site post-mix with

es has increased theyrethrurn (preferablyith organic growers).formulation to avoid

rosits are minute theyeposits" can be easilyhe treatment of largeanic and low solvent, elirninates piperonylrrethrum extract, 8o/o

industry in AustraliaI CO2 as a solvent-IG to persist with the:ethrum industry. Theate required them tory publication "With: is appropriate to thevelop the many BRAloday BRA continues

to secure its long tcnn tiitur-e n'ith on-going innovations and significant capital inve-strnentin expansion. of.its opcrations. TI-re readily available supply o1- pyrethrum and its manyhighly-regarded benef-i.cial properlies u ill insure pyrcthrun-r to be the natural ch<lice in pestcontrol dr-rring the environmentally A\\;are 21" Centurn'.

Literature CitedNieass, 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 ConferenceRyan, 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 NervZealand,2g'n September to 3 October 2002.

Slatter, R., Stewart, D.C., Martin, R. and White, A.W.C. l98l. "An Evaluation offeqtigry BB, a Neu'.System for Applying Synthetic Pyrethroids as Space SpraysUsing Pressurised Carbon Dioxide" lnternational Pest Control, NoviDec.

135