22

Eastern roadblocksFruit fly larvae bred from fruit collected from easternroadblocks are Bactrocera species, mainly Qfly, consistentwith their movement from fruit fly areas in eastern states.

The first South Australian roadblock was established atYamba in 1957, primarily as a response to the discovery ofan outbreak of Qfly at Mildura. In 1965 a boom gate waserected across the Sturt Highway at Yamba to bettercontrol traffic. In 1997 the Yamba roadblock operates fulltime throughout the year, to monitor traffic from theMurray Valley.

Only one pic needed?

Staff at the Yamba roadblock inspected 301 926 vehicles in1996–1997.

Percent of vehicles carrying fruit by number plate of vehicle (1996-97).

Roadblock SA Vic NSW Qld WA Other

Yamba 36 24 24 8 3 5

Oodla Wirra 27 7 35 20 6 6

Ceduna 12 20 13 9 42 4

23

In 1962, a part-time roadblock was set up on theWentworth-Renmark road (12 km east of Renmark) toinspect traffic which had previously by-passed theroadblock at Yamba. This roadblock was manned three daysa week on random days and was finally closed inSeptember, 1977 because of the low volume of traffic whichused the road.

In 1959, part-time roadblocks were established atBlanchetown and Mt. Gambier for a trial period, but theseceased in 1961 as the volume of traffic and the limitedamount of infested fruit intercepted could not justify theexpense.

In 1960, a part-time roadblock was established at Cockburnbecause of outbreaks of Qfly at Broken Hill; it becamepermanent in 1961. Cockburn operated twenty-four hours aday year-round until May, 1980, when it was closed andrelocated to Oodla Wirra in December 1980, to operate fromDecember to May inclusive from 6am - 10pm. The new siteat Oodla Wirra was equipped with two boom gates to stopinterstate traffic and allow local traffic through withoutinspection. Oodla Wirra presently operates 16 hours perday, 6am - 10pm September-May and 7.6 hours per day,8am - 5pm June to August.

In 1963, in response to pressure from growers at Loxtonwho feared the introduction of Qfly from the east,inspectors from Yamba began to conduct a staggered four-hour daily survey at Pinnaroo. By June 1968, a part-timeroad block had been established there operating duringdaylight hours using a tent at first for a shelter for theon-duty inspectors. A casual employee erected a galvanisedtin shed at his own expense. The South AustralianGovernment approved the establishment of a Fruit FlyInspection Station at Pinnaroo in January, 1971. Staff at thisroadblock were halved in 1980 and it now operated sixteenhours a day (6am - 10pm) between the months October toMay inclusive and 7.6 hours per day 8am - 4pm June toSeptember.

An analysis in November 1977, of records from the fourmain border stations, Ceduna, Cockburn, Yamba andPinnaroo for nine year period 1968-1977 showed that thecritical period for inspecting traffic for Qfly was Decemberto April inclusive, while for the remainder of the year the

24

risk of fruit fly introductions were comparatively low.However, for Medfly there was no obvious low riskperiod, and year-round inspection of traffic was justified.The frequency of fruit intercepted at night was muchlower than during the day. As a result, the Cockburnstation was operated for the period December to Mayinclusive and then only between 6am to 10pm.

At Bordertown and Mt. Gambier there are quarantine“honesty” bins for the disposal of fruit by travellers.

Western roadblockSamples of fruit fly larvae reared from the westernroadblock have all been Medfly, consistent with an originin Western Australia.

In 1957 a temporary roadblock was set up on the bridge atPort Augusta on Highway 1 following an outbreak ofMedfly there. This roadblock was transferred in 1958 toCeduna , where it was easier to intercept east-boundtraffic, and in 1971 the roadblock was re-sited 1km fromthe original to prevent vehicles by-passing inspections. In1965, inspection site at the Ceduna roadblock wastightened by closing a stock route which was being usedas a by-pass. Two boom gates were erected at Ceduna inFebruary 1987 to prevent vehicles speeding through theroadblock, which operates full time.

Vehicles, interceptions of fruit and batches of fruit fly larvae per annum,averaged for the five year period 1991/2 - 1995/6.

Mean per annum Eastern Roadblocks Western(1991/2-1995/6) (Qfly) Roadblock

(Medfly)

Yamba Pinnaroo Cockburn Ceduna

No.vehicles 305 072 129 335 122 254 63 571

% vehicles with fruit 6.8 5.8 5.4 11.3

Wt fruit (tonnes) 41.5 9.1 11.2 8.4

No. vehicles withinfested fruit 8.4 2.4 29.0 22.4

25

Administration of roadblocksAdministration of the roadblocks was first managed bystaff of the Department of Agriculture headquarters inAdelaide and in August, 1983, technical supervision wastransferred to the Officer-in-Charge, Pest EradicationUnit, Adelaide. When the Department of Agriculturechanged to a regional structure, roadblock staff werejointly administered by Plant Industry Division,and theChief Regional Officer of the Region. This dualmanagement was simplified when the Department wasreorganised in 1992 and roadblocks became a directresponsibility of the Horticultural Division, with localadministration carried out by Service Delivery Managers.

Inspections of other transport

Rail inspectionsFrom 1949 an endeavour was made to educate travellersabout the dangers of introducing fruit fly. Notices, postersand announcements over public address systems wereused at railway stations and police at Port Augusta andPort Pirie inspected trains as part of their duties. By 1974,Port Augusta had seven full-time and one part-timeinspectors, Port Pirie had one full-time and one part-time

14

12

10

8

4

6

2

0

16

19

57

/58

No

. veh

icle

s w

ith

fru

it f

ly p

er 1

0 00

0 ve

hic

les

19

91

/92

19

61

/62

19

63

/64

19

65

/66

19

67

/68

19

69

/70

19

71

/72

19

73

/74

19

75

/76

19

77

/78

19

79

/80

19

81

/82

19

83

/84

19

85

/86

19

87

/88

19

89

/90

19

59

/60

19

93

/94

19

95

/96

Rate of fruit fly interceptions at two roadblocks

Year

Ceduna (Medfly)

Yamba (Qfly)

26

inspector; and Peterborough had one part-time inspector.Route changes of trains from Perth in 1986 eliminatedinspections at Peterborough, and finally Port Pirie. By1992 all passenger train inspections ceased because littleinfested fruit was detected; during a three year period, forexample, only one batch of infested fruit was detected.

Interstate passenger trains were inspected for fruit duringa number of periods. The Melbourne-Adelaide train wasinspected after 1954 , when an Inspector boarded at Mt.Lofty each morning and inspected all passenger

compartments. Inspections of the east-boundtrain from Perth started 1959 by an inspectorat Pimba. Passenger trains from Perth toAdelaide were inspected between PortAugusta and Port Pirie until 1992. In thatyear, the timetable was changed so that trainsfrom Perth arrived at Port Augusta atmidnight; all inspections were cancelled toavoid disturbance to sleeping passengers.Inspections on west-bound trains from NewSouth Wales started in 1961 when the BrokenHill-Adelaide express stopped at Cockburnwhere inspectors boarded the train. In 1970the India-Pacific line came into operation andan inspector met passengers whodisembarked at Peterborough for Adelaide.The south bound passenger train (The Ghan)from Alice Springs was inspected between1959 and 1992 by an inspector who boardedat Telford.

Airport inspectionsAirline operators announced quarantine restrictions offruit to passengers on aircraft entering South Australia butthere was no check of luggage. By 1954, inspectors met allinterstate aircraft at Adelaide and by their presencereminded passengers of their quarantine obligations, inaddition to leaflets distributed by the airline companies.By 1965 every air-entry point either had honesty bins orinspection. Staff from the Ceduna roadblock inspectedlight aircraft at the Ceduna airport. The Internationalterminal in Adelaide opened in 1982 and quarantineofficers meet all aircraft from overseas.

Fruit collection by aninspector on an interstatetrain in the 1970s.

27

Port inspectionsIn 1949, inspections began at the Port Adelaide Inspectionand Fumigation Depot; and the few commercial imports offruit were all inspected. In later years, inspection ofcommercial horticultural imports is obviated by anInternational Health Certificate under the CommonwealthQuarantine Act. Garbage waste from all ships is incineratedat a Marine and Harbours facility.

Passengers on ships were also required to give up fruit intheir possession. On the occasion when a passenger shiparrives at Outer Harbour, customs screen passengers forfruit and supply a disposal bin. In the past, mail ships maderegular visits here; inspections of passengers revealed verylittle fruit.

PublicityFruit-fly publicity within South Australia is aimed at raisingthe awareness of South Australian residents of the impact offruit flies on their lifestyle and to encourage them to reportoccurrences of larvae in fruit. It is also aimed at warningvisitors and returning residents not to bring fruit into South

Ceduna

Yamba25

20

10

15

5

30

0

Year

% V

eh

icle

s w

ith

fru

it

Road travellers carrying fruit into South Australia.

19

63

/64

19

93

/94

19

67

/68

19

69

/70

19

71

/72

19

73

/74

19

75

/76

19

77

/78

19

79

/80

19

81

/82

19

87

/88

19

83

/84

19

85

/86

19

89

/90

19

91

/92

19

65

/66

19

85

/96

28

Australia. The effectiveness of the publicity campaign maybe measured by changes in fruit being brought into SouthAustralia. The proportion of vehicles bringing fruit fromVictoria has remained fairly constant at less than 10%during 35 years, while the proportion of cars carrying fruitfrom Western Australia has declined from nearly 30% in1962-3 to about 12% in 1996-7.

Lectures and talksDuring the years 1970 to 1982, a special Education Officer,Sheila Morphett was appointed to visit schools andcouncils in the State and to give talks to interested groups.Talks were given to all class levels in primary andsecondary schools, when a simple story of the biology offruit fly and the ecological significance of the eradicationprogram in South Australia were presented. Studentsreceived transfers and project material which includedinformation for their parents. Most school teachers werepleased to receive this information, and many encouragedthe children to undertake fruit-fly projects in associationwith social studies.

Television commercialsFor many years, television advertising was found to beexpensive and outside the financial ability of the PestEradication Unit. In 1983, Channel 9 made two 10 secondcommercials at a reasonable cost, and these were shownin the 1983-84 and 1984-85 seasons.

SignboardsIn 1947, Department of Agriculture co-operated with thePhylloxera Board to erect eight notices on theVictoria-South Australia border roads aimed at warningroad travellers against transporting fruit and vines intoSouth Australia. These signs were erected at Frances,Pinnaroo, Penola, Coorong motor by-pass, Mt. Gambieraerodrome, Renmark-Mildura road and Parafieldaerodrome. Later, four new signs were erected at OuterHarbour and Pt. Adelaide, followed by Adelaide andMurray Bridge railway stations.

In 1963, a contract was let for the construction andmaintenance of 25 roadside border signs. One was on thewest coast, two in the far north, nine in the Murray Mallee

Sheila Morphett.

29

and thirteen in the South East. By 1965, all road, rail, airand sea entry points into the State were covered by eithera quarantine barrier or signboards. In 1973, these signswere replaced on major roads at Ceduna, Cockburn, Pt.Augusta, Renmark-Wentworth, Renmark-Lindsay Pt.,Pinnaroo, Bordertown, Naracoorte-Apsley, Glenburnieand Mt. Gambier-Nelson., each with a large sign, asatellite sign and an honesty bin. Twelve minor roads hadone large sign each; they were at Noora, Taplan, Murtho,Ellerslie, Wrattonbully, Penola-Casterton, Mt.Gambier-Casterton, Mil Lel-Casterton, Mt.Gambier-Heywood, Wanuarra, Francis and Binnum.Other signs in the State were at the Adelaide airport(two), Parafield airport (two plus bin), Yamba roadblock,Outer Harbour, and Nos. 2 and 18 Berths at Pt. Adelaide.

Eighteen signs on major road-entry points are currentlymaintained by a contractor and the remainder by theDepartment.

Signboard at Pinnaroo around 1947.

30

The successful eradication of outbreaks since 1947can be attributed to the early detection of fruit flies.Reports by householders of larvae in fruit, together

with a detection program based on traps for adult flies,has resulted in most outbreaks being restricted to one, ora small group, of infested trees or to a very small numberof flies trapped.

Reports from householders

The cooperation of householders is reflected in thenumber of outbreaks they report. The response to allpublic reports is attendance by an inspector who visits thehouse and examines the specimens. In most cases, otherinsects, commonly larvae of codling moth, lightbrownapple moth, dried fruit beetle, metallic-green tomato flyor ferment flies are identified. When putative fruit flylarvae are found, they are referred to an entomologist .

Detection traps for male Qfly and Medfly

The use of traps to detect the presence of adult fruit fliesin South Australia has evolved since the first outbreak in1947. The design of trap, the lure used to attract the flies,and the distance between traps in the grid has changed toreflect new technology (particularly in the composition oflures), new trap designs (an “improved” trap design isdescribed in the literature every two to three years) andthe resources available to service the detection grid.

DETECTION

Proportion of outbreaks reported by members of the public; theremainder were detected by the trapping grid. During the period 1946-1978, the trapping grid was not as extensive nor the traps as efficient asin the period 1978-1997.

Period Qfly Medfly

1946-1978 67% 93%

1978-1997 49% 52%

31

Almost all the information used to construct the detectiongrid has been derived from research on Qfly by CSIRO andstate Departments of Agriculture in New South Wales,Queensland and Victoria, and the University of Sydneyand on Medfly by a number of foreign institutes,particularly the United Stated Department of Agriculture(USDA), but also by the Western Australian Department ofAgriculture. No research has be done in South Australia onthe comparative behaviour of the traps under SouthAustralian conditions.

The months in which male Qflies were caught in CuelureJackson traps 1985-1992 are shown in the figure below,and reflect a pattern of detection during summer andearly autumn. Outbreaks were declared on the basis ofcatches of many of these flies, but some were isolatedcatches of single males, assumed to have dispersed fromtheir point of introduction.

The pattern ofdetection of Medfly,as reflected in malecatches in CapilureJackson traps, 1985-92 is shown in theFigure. Detectionusually starts laterthan Qfly, andextends into winter.

Males of the inlandfruit fly, Dacusnewmani, areattracted to Cuelure,and are caughtcoincidentallyduring trappingoperations. Theybecome active inspring and peakduring summer.

25

20

15

10

5

0

% a

nn

ual

to

tal

Jun Aug Oct Dec Feb

Qfly: Monthly trap catch

MonthApr

25

20

15

10

5

0Jun Aug Oct Dec Feb

Medfly: Monthly trap

AprMonth

% a

nn

ual

to

tal

50

40

30

20

10

0Jun Aug Oct Dec Feb

Dacusnewmani:Monthly trapcatch

Apr

Month

% a

nn

ual

to

tal

32

Baits and lures.

Baits are food substances which attract fruit flies. Proteins derived from yeast (usuallyin the form of protein hydrolysate or protein autolysate) are produced commercially, andcan attract adult male and female flies from many metres away. Protein baits may bemixed with water in “wet traps”, in which attracted flies are drowned, and serve as anindication of the population of flies in an area.

Lures are usually synthetic substances which attract one sex, usually males. Lures areused in traps to detect the presence of fruit flies in an area. Lures have a greater rangeof attraction than baits. Lures are usually used in conjunction with sticky traps and “dry

traps”

Stopper

Trough forliquid attractant

McPhail trap

Entrance

Cotton wick

Entrance

Receptacle forFruit fly specimens

Wire gauze

Bateman trap modification

Wiregauze

Drain holeCotton wick

Funnel

Clip-on lid

Steiner trap (Queensland modification)

Pore

Container for attractant-insecticide mixture

Israeli trap

Rubber gromet

Retaining hook

Wire wickhook

Spring wirehook

Wick(dentalpads)

Stick-ontray lip

Jackson trap

Securing hook

Plastic nutWire wick hook

Lynfield trap Fro

m D

rew

, Ho

op

er

an

dB

ate

ma

n:1

97

8 ‘E

con

om

ic F

ruit

Flie

sof t

he S

outh

Paci

fic R

egio

n’.

33

Summary of traps and lures used for monitoring adult fruit flies in SouthAustralia. One trap each for Qfly and Medfly is located at each site.

YEAR QFLY MEDFLY NO. SPACINGS

OF OF GRID

SITES

IN SA

Trap Lure Trap Lure

1947 Treacle Clenseltins Agee

jars

1948 McPhail orange-ammonia

1950 McPhail vanillin- 500 1/2 mileammonia

1954 McPhail Vanillin-ammonia

1957 McPhail Staley No. 7 McPhail Medlure

1959

1960 Bateman Willison’s 800 1/2 mile

1961 McPhail Trimedlure 1,290

1962 (Dak-pots (Dak-potsunsuccessful) unsuccessful)

1963 Steiner Trimedlure 400 1/4 mileand glycerine

1964 Bateman Cuelure 1,386

1965 1,508

1970 Israeli Trimedlureand Dichlorvos

1973 1,875 400 m

1979 Steiner Cuelure(modified)

1981 2,463

1982 2,506

1983 2,712

1985 Jackson Cuelure Jackson Capilure 2,730

1986 3,362

1992 Lynfield Cuelure

1995 Lynfield Capilure 3,491

34

Sentinel traps to detect incursions ofother fruit flies

The lures used to attract Qfly and Medfly to traps do notattract many other fruit flies of economic importancewhich may be accidentally introduced to South Australia.There are a group of economically important fruit flieswhich are attracted to the lure methyl eugenol; these fliesinclude the mango fly Bactrocera papayae and the Orientalfruit fly, Bactrocera dorsalis.

The response in South Australia to the suspected outbreakof oriental fruit fly B. dorsalis in northern Australia in 1975was to put out 35 traps baited with methyl eugenol.,distributed over in the metropolitan grid. The numberswere later increased to 40. Seven Bateman traps wereplaced in Riverland towns in 1987. No B. dorsalis werecollected while these traps were in operation.

Attractiveness of lures

The range of attraction of lures varies withthe species of fruit fly, and the type of lure.Although no detailed observations have beendone of the attractiveness of Cuelure to Qflyunder South Australian conditions, anattractive range of several hundred metres isprobably reasonable, making the 400mdistance between traps a compromisebetween behaviour of the fly and the cost ofdetection.

Medfly does not appear to be nearly asattracted to lures as Qfly, and it is likely thatthe attraction to traps may be measured inscores of metres.

The proportion of males of a populationattracted to traps is probably less than 4% ofthe flies in the vicinity of the trap.

35

ERADICATION

Eradication is the destruction of all flies and larvaewithin the outbreak area. For quarantinepurposes, eradication is defined as when no flies or

larvae are detected within that area for a periodequivalent to three fly generations. Under local conditionsin summer in Adelaide, that period is 12 weeks, but this islonger in cooler seasons.

Eradication or suppression?

The operating model for fruit fly eradication in South Australia is of repeated introductionsof fruit fly into South Australia from outside the state; these are detected, usually beforethey produce a second generation, and are eradicated. The evidence from numbers offlies caught in traps, and larvae found in outbreak areas suggests that the number of fliesin each outbreak does not total more than several hundred.

It is likely that both Medfly and Qfly, left uncontrolled, could survive in many SouthAustralian areas, including Adelaide.

A comprehensive analysis of the South Australian outbreaks was done by Derek Maelzeron data up to 1987. Maelzer concluded that the pattern of outbreaks was consistent withrepeated introductions. Certainly, the data from roadblock interceptions indicates amechanism by which regular introductions could occur.

Management of detection, eradication and generaloperations associated with fruit flies in South Australia iscovered in the Pest Eradication Unit’s OperationalManual, which is revised annually. Operations associatedwith eradication in a commercial orchard district arecovered in the Fruit Fly Contingency Plan - Riverland,also revised annually.

From 1947, the first action taken after an outbreak wasproclaimed was to search for larvae in fruit in the suspectarea, to determine the extent of the outbreak. Fruit in allproperties within a half mile radius of the original

36

sighting, was examined for larvae of fruit fly. These earlychecks involved large numbers of staff from theDepartment of Agriculture, including those from countryareas, as it was considered important to determine theextent of the outbreak as quickly as possible. By 1971 theprocedure for eradicating outbreaks included stripping ofall host fruit in the area of one quarter mile radius of theoutbreak centre, cover spraying the area within a half-mile radius of the outbreak centre, baiting of the entirearea and placing of lure pads between the half mile andthe outer perimeter. Baits of protein hydrolysate 10 oz(283.5g); maldison 9 oz (255g); Water 3 gals (13.6L) weresquirted onto one or more trees in each house yard.

From 1975, less emphasis has been placed on intensivechecking and more emphasis placed the promptestablishment of a baiting program, particularly in theoutbreak zone. Technical checking and fruit strippingwere labour-intensive and stripping of fruit from treeshad little biological support.

Baiting

Baiting, to kill adult flies, has been an important part ofthe eradication program but, until the early 1970s, wasnot considered as important as the killing and removal oflarvae. The bait used in 1947 was brown sugar and tartaremetic (antimony potassium tartrate), the first as a foodlure and the second as a stomach poison.

The bait was applied using a knapsack, at the rate of 6 floz per ‘spot’ every 7 days. The sprayers were instructed toapply bait to all trees with fruit or berries that looked as ifthey may attract a fruit fly, and all ornamental shrubs.Baiting remained on a weekly basis and continuedthroughout winter until the 31st of October. There wereno reports of phytotoxity. This technique minimiseddanger of contact by householders and other non-targetorganisms.

After a conference on Fruit Fly, conducted by theDepartment in 1957, the tartar emetic sugar bait wasreplaced by a by a protein-insecticide bait, based on the

37

developments of a new attractant method by Dr. L.F.Steiner (USDA) in the early 1950s. In 1962, the bait wasaltered to a protein/hydrolysate/ maldison/sugar/watermixture, and was applied weekly until the end of Octoberwithin the outbreak area and in the following year thebait was modified to: protein hydrolysate 21.9% 170g;maldison 255grams active constituent formulated as awettable powder 142g; Water 4 gal (15.14L).

Baiting and cover sprays

Protein from yeasts is attractive to fruit flies and the females, inparticular, need to feed on yeasts naturally occurring on plantsurfaces to enable them to produce eggs. In the early days ofbaiting, a protein produced from flour was used, but it had ahigh salt content and tended to be phytotoxic. Proteinhydrolysate produced from brewer’s yeast as a by-product ofbeer-making is very attractive to fruit flies. Protein autolysate,made by a slightly different process, is presently used becauseof its low salt content. The bait attracts both male and femaleflies from many metres away.

Cover sprays are insecticides applied to foliage and fruit,which kill adult flies by direct contact or by residual action.Cover sprays may also be applied to the ground beneath treesto kill adults as they emerge from the soil. The insecticide mayalso be absorbed into fruit, and kill developing eggs andlarvae.

Operators with knapsack sprays applying proteinand insecticide to the foliage of backyard andstreet trees.

38

Improvements to baiting techniques

Dr Alan Bateman, CSIRO Division of Entomology in NewSouth Wales trials found that about 20 bait spots appliedat equal spacings over an acre of vegetation killed mostadult Qflies in the area, most of them within a few hoursfollowing the application of the bait. In 1972, Bateman’sspot- baiting method (each bait spot containing proteinhydrolysate 4gm; maldison 1g active in 100mL water) wasintroduced to South Australia.

On the 4 January 1974, these eradication procedures wereused for the first time on an outbreak of Medfly at KentTown. Other Medfly outbreaks had occurred in the sameyear in the metropolitan area. There appeared to be afailure in the bait spraying technique and a meeting washeld on the 13-14 February to discuss the problem.

Attending that meeting were Horticultural Branch staffassociated with the program and entomologists from theWaite Institute, Roseworthy College, West AustralianDepartment of Agriculture and the CSIRO Division ofEntomology. During the discussions, Alan Bateman foundthat the bait mixture was wrongly mixed, and theconcentrations of materials that were used in wereinadequate to attract and kill fruit flies; only 1/10th of thenecessary protein and 1/2 of the necessary maldison werebeing applied. At the time, the bait used was: Proteinhydrolysate 21% 56g actual instead of 620g; Maldison 25%70g actual instead of 154g; Water 13.2L.

The failure of baiting to achieve eradication was not afault in the technique itself, but was a result of the lowrates of materials used in the bait mixture. It was alsonoted that the formulation had been tried against Qfly,but not Medfly, the latter being more difficult to eradicateby baiting. A correctly mixed test batch was checked forphtytotoxicity in an abandoned garden with disastrousresults; most trees and shrubs showed extensive saltdamage within 72 hours. Following discussions withSanatorium Health Foods in Western Australia, a suitableprotein autolysate was produced with three times theconcentration of the (acid) hydrolysate but only one thirdof the salt (NaCl) content and the cost was the same by

39

weight. The first baiting of a commercial orchard usinglow-salt, high protein formulation was used in 1974 whenlarvae were found in peaches in a suburban backyard on 5March and in a nearby plum orchard on 7 March.

By March 1974, baiting was integrated with cover-spraying using fenthion within a 1/4 mile radius of thecentre of the outbreak, associated with the removal ofwindfalls and ripe fruit within a 1/8 mile radius. Later inthe year, officers of the Horticulture Branch decided that afurther investigation of the baiting approach should bemade, and that baiting should be the technique used toeradicate any outbreaks during the 1974-75 season.

Formation of Fruit Fly Technical CommitteeFollowing on from the meeting on fruit fly held inFebruary 1974, a group of senior Department ofAgriculture officers associated with the detection anderadication of fruit fly was organised to superviseoperations. On 12 September 1974, senior Departmentalstaff met to review the 1973-74 program and to discussproposals for 1974-75. At that meeting, a TechnicalCommittee called the Fruit Fly Technical Committee wasformed to undertake responsibility for the technicalaspects of detection and eradication programs. TheCommittee consisted of the Chief Horticulturist and Chair(Tom Miller), Principal Horticultural Officer (Bill Harris),Officer-in-Charge of the Pest Eradication Unit ( JackBotham) and the Senior Entomologist (Paul Madge). TheCommittee met again on 11 November and 2 and 19December, 1974. At these meetings an eradicationprogram for 1974-75 was prepared. The protocoldeveloped for treating an outbreak was recognised by theCommittee as a substantial ‘overkill’ and that eradicationshould consist of distribution of notices to householders;prohibition of the removal of fruit from the outbreak area,concurrent with prompt and intensive bait spraying, andprompt removal of fallen fruit in the outbreak zone.

The baiting program consisted of two baiting teams sentto the outbreak zone to begin spot-spraying, all trees andtall shrubs with theprotein-maldison bait, but avoidingthose likely to be damaged by the spray. Spot-spraying inthe outbreak zone is done twice weekly for six weeks,

40

then weekly as in the remainder of the outbreak area. Thebait now consisted of: protein autolysate 420g/L protein +1L; maldison 5% 142mL in 16 L water. Technical maldisonwith a minimum quantity of formulating solvent wasused, as the solvent acted as a repellent to the fruit fly; butsome was necessary to enable technical maldison to bemixed with water. Baiting in the remainder of theoutbreak area starts at the perimeter moves towards theboundary of the outbreak zone, applying bait at the rateof at least 100 ‘spots’ per hectare once a week. Baitingcontinues for 9-12 weeks (depending on temperatures andextent of the outbreak) after the last fly or larva is foundin the quarantine area.

Further improvements to baiting techniquesUntil 1977, baiting teams travelled in privately hired vanswith the driver employed by the owner of the van. Teamsconsisted of a ganger and six sprayers who worked inpairs. One sprayer carried a knapsack containing the baitmixture and applied the bait to trees and shrubs in frontand rear yards of household properties, while the othercarried additional protein and insecticide and assisted his

Baiters in the early days assembling to go out to theoutbreak area.

41

colleague. When the knapsack was empty, it was filledwith water (17 litres) in the street and the protein andinsecticide was added from the pre-measured bottlescarried. By 1978, government cars were used to towdepartmental and hired trailers that carried the necessaryequipment. The baiting teams were reduced to a gangerwho drove the vehicle and supervised four sprayers whoworked in pairs. About 170 properties were baited eachday by each pair of sprayers.

In an attempt at quality control, mixing was done at acentral point where bait preparation and application couldbe better supervised. The concentration of bait in theknapsack was checked at random by the Inspector incharge, using a hydrometer. The specific gravity readingwas to be 1015 and the checks showed that the bait settledin the knapsack, especially if left standing afterpreparation. In spite of these precautions, it was discoveredin July 1981 that the bait mixture was not correct. In aknapsack with 16 litres of water, the protein was reducedfrom 1 litre to 850 mL, and the maldison-Hymal® wasincreased from 142 mL to 147 mL.

In 1982, Bert Hayter, Officer-in Charge, and NickPerepelicia, supervisor, introduced a procedure in which apre-mixed bait wascarried in bulk tanks onDepartmental trailers.These tanks contained110 litres and were filled2 or 3 times a day underthe supervision of aDepartmental Inspector.The bait was kept mixedby a constant-runningelectric pump. Thisprocedure not onlyresulted in a more strictcontrol of thepreparation of bait(supervised by an Eradication Supervisor) but alsoresulted in the reduction in costs by reducing the size ofthe baiting team from five to three. The advantages of this

42

system over the previous was that it maintained a uniformand accurate mixture of bait, reduced costs by eliminatingthe need for a sprayer to carry refill bottles of protein andinsecticide; a team now consisted of a ganger and 2sprayers. Each sprayer need only carry in the knapsack,the actual quantity of bait required and hence reduce theworkload, more properties could be baited each day byeach sprayer and it was not necessary to rely onhouseholders to supply water.

Hydrometer tests were gradually eliminated as themixing of bait became better supervised. As a furthermove towards greater efficiency, trailers with 400 litrebulk tanks for bait (a full day’s supply) were introducedin 1983. The bait was prepared in the morning and keptagitated during the day. The bait mixture has not beenaltered since corrections were made in 1982. To make 20litres of bait, the quantities are: low salt protein autolysate1L; Maldison 115WV Hymal® 174ml; Water 18.826L. Thebait is applied in 100 mL spots to 6-8 fruit trees, shadytrees or shrubs in each house yard or 100 spots perhectare.

Knapsack sprayer filled from a 400 L bulk tank services a sprayingteam for one day.

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Cover spraying

Cover spraying to kill adults sheltering on foliage, wasused extensively during early eradication campaigns. Asweetened tartar emetic spray was used during 1947 andwas replaced by DDT in 1948. Fruit trees near theoutbreak centre of infestations were sprayed thoroughlywith 0.1% DDT (2lbs of 50% WP DDT in 100 gallons ofwater). Applications of DDT were first applied in theoutbreak zone then extended outwards. The cover andground sprays were repeated every three weeks. Twosprayers operated each power unit with a 250 ft length ofhose attached. By 1950 the Department had 6 power sprayunits.

During the late 1950s it was found that DDT could harmbees, particularly if applied when the trees were inblossom. DDT killed natural enemies of insect pests

Clipping from ‘The News’ 29/1/52.

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causing secondary outbreaks, such as the upsurge of redscale at Klemzig in 1957. Nevertheless, DDT continued tobe used because the side-effects were not thought to besufficiently important to justify the omission of thisimportant part of the eradication campaign.

Review of use of DDTThe South Australian Fruit Fly Conference in 1957recommended that DDT be discontinued because of itsside-effects. It was recommended that trichlorfon(Dipterex®) be substituted as a cover spray, since it wasbeing used successfully by commercial growers.However, trichlorfon was not substituted because it hadgreater mammalian toxicity than DDT. In 1962, DDT wasapplied every 1 to 4 days within the 1/4 mile radius areaand every 21 days outside this area. Spraying continuedthroughout the winter and spring months. Boxthorns thatwere trimmed to dimensions laid down under theNoxious Weeds Act, were also sprayed. If these busheswere not trimmed within a specified time, they weresprayed with arsenic under supervision and destroyed.

Increasing public concern about the harmful side effectsof DDT led to replacement with a new organophosphateinsecticide fenthion (Lebaycid®) as a cover spray in 1963.The possibility of spraying it by air was suggested but itwas known that small birds were susceptible to fenthionand there was also a problem of contaminating drinkingwater collected from household roofs sprayed withinsecticide. So, the idea of aerial spraying outbreak areasin Adelaide was never put into practice.

The aim of cover spraying was to contact all susceptiblefruit on trees in the outbreak area by a fine deposit of theinsecticide. Applications of 0.05% fenthion were mademonthly and continued throughout the winter. Later, theconcentration of fenthion within the 1/4 mile radius areawas increased to 0.08% for the first spray and reduced to0.04% during each monthly spray thereafter. In the 1/4 to1/2 mile radius area, the concentration was 0.04%. Themixture at 0.08% concentration was 567g of fenthion (50%Lebaycid®) in 363.6 litres of water.

At that time, fenthion was not used in the United States ofAmerica and no analytical techniques were available and

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the breakdown products were unknown. However, inSouth Australia, fenthion proved to be satisfactory inkilling fruit fly eggs and larvae at all stages ofdevelopment in the fruit tissue.Fenthion was sprayed onan area at 14 day intervals. It could also be used on someplants previously burnt by DDT and was not likely tocause outbreaks of red scale. However, as it was verypoisonous to small birds, care was required whenspraying near aviaries. Fenthion was also tried as aground spray, but its usefulness was limited as it waseffective in the soil only for a short time.

To protect workers handling fenthion, gloves, overallsand respirators were supplied and the workers werebriefed on the correct method of handling and applyingcover spray. By 1973, there was the capacity to field 25teams of sprayers, operating from 25 power spray units.

From about 1972, householders were advised by cards ofspraying on their property. The leaflet also containedinformation on the withholding period before fruit couldbe consumed and advice on washing the fruit.

High pressure spray nozzles are used to treatdense foliage.