Current status of citrus gall wasp in Western Australia
Department of
Agriculture and Food
Draft Policy Review
Citrus gall wasp associated with the import of host nursery stock and cut flowers/foliage into Western Australia
Contributing Authors
Poole, MC Research Officer, Plant Health Policy and Management, Biosecurity and
Research
Tuten, SJ Research Officer, Plant Health Policy and Management, Biosecurity and
Research
Department of Agriculture and Food, Western Australia
February 2014
Document citation
Poole, MC and Tuten SJ 2014, Citrus gall wasp associated with the import of host nursery stock and cut flowers/foliage into Western Australia. Draft policy review. Department of
Agriculture and Food, Western Australia, Western Australia. 43 pp.
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Western Australian Agriculture Authority.
For further information or additional copies of this document, please contact
Simone Tuten
Plant Health Policy and Management
Biosecurity and Research
Department of Agriculture and Food
3 Baron-Hay Court
South Perth WA 6151
Telephone: +61 8 9368 3434
Mobile: +61 467 720 344
Facsimile: +61 8 9474 2658
Email: simone.tuten@agric.wa.gov.au
Post: Locked Bag 4 Bentley Delivery Centre WA 6983
Important disclaimer
The Chief Executive Officer of the Department of Agriculture and Food and the State of
Western Australia accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it.
Contents
................................................................................ 16
Figures
Figure 6: Western Australian climate match to reported citrus gall wasp locations ............... 18
Tables
Appendices
Executive summary
Citrus gall wasp is a native Australian species and has been known as a pest of citrus production in eastern coastal regions of Australia since the 1930s. The citrus gall wasp’s range has expanded since then to include the Riverina and Sunraysia regions of New South
Wales and Victoria and most recently South Australia. This expansion has been attributed to the introduction of citrus gall wasp infested nursery stock.
The absence of any records of this pest in Western Australia, the reported damage caused by this pest and the value of the Western Australian citrus industry were the triggers for this pest-initiated risk analysis (PRA).
The PRA process has verified that citrus gall wasp is a pest of quarantine concern as it satisfies the International Plant Protection Convention (IPPC) definition of a quarantine pest for Western Australia, that is ‘a pest of potential economic importance to the area endangered thereby and not yet present there, or present but not widely distributed and being officially controlled ’.
The pathways with the potential to lead to the entry of citrus gall wasp into Western Australia assessed in this PRA were nursery stock and cut flowers/foliage. Citrus gall wasp is not associated with the fresh citrus fruit pathway.
The PRA then evaluated the unrestricted risk of citrus gall wasp associated with the importation of host nursery stock and cut flowers/foliage from other Australian states and territories. The PRA found that the unrestricted risk for host nursery stock did not meet the
Appropriate Level of Protection (ALOP) and risk mitigation measures were required.
A range of phytosanitary measures are recommended to provide an appropriate level of protection, while aiming to minimise impediments to the trade in host nursery stock and cut flowers/foliage. The recommended specific requirements are based either of the following options:
State or territory freedom
Pre-shipment treatment and on-arrival inspection
Methyl bromide fumigation
Note: the general entry requirements for nursery stock includes the option for the treatment of above ground parts of plants with the systemic insecticide imidacloprid applied within 10 days prior to export. This option, in conjunction with a 600 unit visual inspection on arrival would be approved under the pre-shipment treatment and inspection option.
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Introduction
The document contains three parts:
Part one describes the scope of the analysis the events leading up to the initiation of the analysis and provides background information on Australian citrus production.
Part two describes the methodology used by the Department of Agriculture and Food,
Western Australia for state pest risk analysis. The methodology used conforms to the
International Standards for Phytosanitary Measures (ISPMs) and is similar to and compatible with the methodologies identified in the ‘Guidelines for Import Risk Analysis’
(Biosecurity Australia 2001) for plants and plant products.
Part three is the pest risk analysis. The affected pathway or pathways are identified and assessed for the likelihood of entry, establishment and spread, together with the potential economic consequences. A pest data sheet and the risk associated with these pathways determine the need and extent of risk mitigation requirements. Risk mitigation measures are proposed if the unrestricted risk exceeds Western Australia’s appropriate level of protection (ALOP).
2
Part one: Analysis scope, events prior to initiation and background information
Scope
In this policy review, the Department of Agriculture and Food, Western Australia (DAFWA) has considered the commercial and non-commercial movement of citrus gall wasp host nursery stock and cut flowers/foliage as the entry pathway for citrus gall wasp. Identifying and assessing the risks posed by other pests associated with these pathways are not considered and will be undertaken as part of DAFWA’s ongoing review process of interstate measures.
For the purpose of this analysis:
nursery stock means any potted or bare rooted or cuttings or any above or below ground part used for vegetative propagation of host plants of citrus gall wasp, but does not include plant tissue culture or seed
cut flowers/foliage means any part of citrus gall wasp host plants without roots, excluding fruit, seed and not used for human consumption.
Citrus gall wasp is not associated with the fresh citrus fruit pathway.
Events leading to PRA initiation
Current legislation restricts the entry into Western Australia of nursery stock, cut flowers/foliage, horticultural produce and other carriers due to exotic pest and disease concerns. This legislation, the Biosecurity and Agricultural Management Act 2007 was proclaimed to provide effective biosecurity and agriculture management for the state by providing the means amongst other things to control the entry, establishment, spread and impact of organisms that have an adverse effect on other organisms, human beings, the environment and agriculture or other related commercial activities.
Citrus gall wasp is a native Australian species and has been known as a pest of citrus production in eastern coastal regions of Australia since the 1930s. The citrus gall wasp’s range has expanded since the 1930’s to include the Riverina and Sunraysia regions of New
South Wales and Victoria and most recently the Riverland area of South Australia. This range expansion has been attributed to the introduction of citrus gall wasp infested nursery stock.
A severe infestation of citrus gall wasp can result in very little leaf or fruit production and tree dieback. As an example, Flett (2011) has described an incursion of citrus gall wasp first found in the Holland’s Lake area of Victoria’s Sunraysia district in the late 1990s. The incursion was first noticed as small I0 to 20mm galls on lemons. It has since spread over large areas in the district with severe infestations in 50ha of Valencia and Navel oranges and lemons over ten properties. Three properties had a very serious infestation of galls 150 to
300mm long covering 50% of the tree canopy while another five properties had galls up to
100mm long covering 40% of the canopy.
Citrus production in Western Australia is expanding with additional new plantings every year.
Since 2005, the area planted with citrus has increased by over 80%. Annual production was approximately 13 000 tonnes in 2009-10 with less than 10% being exported. As plantings approach full production the annual harvest is expected to reach 40 000 tonnes by 2015.
There are no records of citrus gall wasp ’s permanent presence in Western Australia and general import conditions for plant material entering Western Australia are in place.
The absence of records of this pest in Western Australia, the potential damage of this pest, the value of the Western Australian citrus industry and the reported damage caused by this pest in South Australia were the initial triggers for a pest initiated risk analysis (PRA).
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Following initiation of the pest risk analysis, citrus gall wasp was detected on citrus trees in two Perth suburban properties in May 2013. Citrus gall wasp is currently subject to an eradication program and the prognosis is good.
The PRA commenced by evaluating citrus gall wasp against the criteria for identifying quarantine pests. Quarantine pests are defined as ‘a pest of potential economic importance to the area endangered thereby and not yet present there, or present but not widely distributed and being officially controlled ’ (FAO 2004).
The PRA process establishes citrus gall wasp as a pest of quarantine concern as it satisfies the International Plant Protection Convention (IPPC) definition of a quarantine pest for
Western Australia.
Western Australian citrus production
This overview of the Western Australia citrus industry has been taken directly from
Biosecurity Australia (2011)
‘Market access submission for citrus fruit from inland
Queensland and Western Australia to the United States of America ’ and modified to include additional relevant information.
Western Australia has one of the world’s most pest and disease free production environments, within a country that has an envied reputation for animal and plant pest, disease and weed freedom. Western Australia’s pest and disease status is maintained by virtue of the state’s geographical isolation and effective state based quarantine systems.
Citrus production in Western Australia is a growth industry with the addition of new plantings every year (HAL 2008). From 2004 to 2011, the citrus planted area in Western Australia has increased by over 80% (DAFWA 2011). The majority of citrus production is found within
200km of Perth (Figure 1). However, citrus production also occurs from Kununurra in the far
north to Carnarvon, Wooramel and Northampton in the central coastal part of the state, to
Denmark in the far south (HAL 2008).
Main production regions
Kununurra
Kununurra is located in the far north-eastern corner of the state, close to the Northern
Territory border (Figure 1). Kununurra is located within the Ord River irrigation area, with
several lakes and lagoons surrounding the town itself. Horticultural production is varied and includes bananas, chia, chickpea, citrus, cotton, mango, melons, nursery production, other tropical fruit, papaya, pumpkins, rice & sorghum (DAFWA 2012). Horticultural production is irrigated from Lake Argyle, Australia’s largest man-made inland dam.
Kununurra experiences a tropical savanna climate (BoM 2013a), with wet humid summers and mild dry winters. The average daily minimum and maximum temperatures range from
15°C in winter to 38°C in summer. The mean annual rainfall is approximately 796mm, with most of the rain falling in the summer months (BoM 2013d).
Carnarvon and Wooramel
Carnarvon is located in the central coastal Gascoyne region of Western Australia. Carnarvon
lies at the mouth of the Gascoyne River (Figure 1). Horticultural production is varied and
includes avocado, banana, capsicum, citrus, grapes, mango, melons, pawpaw and tomatoes
(Harper 2012). Horticultural production is irrigated from the Gascoyne River.
Wooramel is located 40km south of Carnarvon along the Wooramel River and is part of the
Gascoyne region of Western Australia (Figure 1).
Carnarvon and Wooramel experience a desert climate (BoM 2013a), with summer droughts and low annual rainfall. Carnarvon’s average daily minimum and maximum temperatures range from 11°C in winter to 32°C in summer. The mean annual rainfall is approximately
225mm with most of the rain falling in the summer months (BoM 2013b).
4
Figure 1: Western Australia citrus production areas a .
Northampton
Northampton is situated on the North West Coastal Highway of Western Australia,
approximately 50km north of Geraldton (Figure 1). Northampton experiences a subtropical
climate with dry winters(BoM 2013a). The average daily minimum and maximum temperatures (nearby Nabawa) range from 7.4
°C in winter to 34.2°C in summer. The mean annual rainfall is approximately 445mm with most of the rain falling in the summer months
(BoM 2013e).
Areas surrounding Perth – Gingin to Capel
Perth is situated in the south-west region of Western Australia. Citrus is grown from Gingin in the north to Capel in the south with the main citrus production regions being Gingin to
Chittering (approximately 90km north of Perth) and Harvey (140km south of Perth).
Perth and the surrounding districts are situated in the Lower West region of Western
Australia (Figure 1). This area is characterised as having a subtropical climate with mild
winters and hot dry summers to a temperate climate to the south. The average daily minimum and maximum temperatures rang e from 8°C in winter to 32°C in summer. The a Source: CT07055 National Citrus Plantings Database Management 2008, Citrus Report (HAL 2008)
5
mean annual rainfall is approximately 778mm with most of the rain falling in the winter months (BoM 2013f).
Denmark
Denmark is situated in the south-west of Western Australia, approximately 400 km south of
Perth in the South Coastal region of Western Australia (Figure 1). The region is
characterised by a temperate climate, with warm dry summers and cooler winters. The average daily minimum and maximum temperatures range from 7°C in winter to 26°C in summer. The mean annual rainfall is approximately 995mm with most of the rain falling in the winter months (BoM 2013c).
Figure 2: Western Australian climate b
Production information
Western Australia is not a major citrus producer by Australian standards. The state produces an average of around 10 000 tonnes of fresh oranges annually which constitutes 2.2% of national production. Western Australia also produced 2300 tonnes of mandarins and 1500 tonnes of grapefruits in 2009-10. Approximately 3000 tonnes are produced for processing from the one juicing company operating in Western Australia (Radhakrishnan 2012). A
snapshot of the states citrus industry is provided in Table 1 .
Approximately half of the domestic demand for fresh consumption is met by supply from
Eastern States as well as from overseas. The USA is the major overseas supplier to the b Source: BoM 2013a. Australian climate zones - all climate classes: (based on the Köppen classification). Commonwealth of Australia, Bureau of Meteorology. viewed 16 September
2013, www.bom.gov.au/climate/environ/other/kpn_all.shtml.
6
Western Australian markets while Victoria and South Australia are the major eastern state suppliers (Radhakrishnan 2012).
Table 1: Snapshot of Western Australia’s citrus industry
Particulars Orange Mandarin Grapefruit
Total production (tonnes)
Imports (tonnes)
Supply from eastern states through Perth
Market Authority (tonnes)
8367c
2131
5605
2300d
616
1662
1500
231
64
Estimated fresh consumption (tonnes)
Per capita consumption (kg/year)
Estimated production by 2015 based on current plantings (tonnes)
15 075
6.94
20 100
3891
1.7
8000
1526
0.69
7500
Major overseas supplier USA USA USA, Israel
Source: industry communication, APC, Global Trade Atlas
Western Australia currently produces approximately 13 000 tonnes of citrus annually with less than 10% being exported (the majority being red fleshed grapefruit). As recent plantings approach full production the annual harvest is expected to reach 40 000 tonnes by 2015
(DAFWA 2011).
Oranges account for most of Western Australian citrus fruit production, with the Late Lane variety of navel oranges being the dominant variety grown (HAL 2008). Grapefruit, mandarin and orange (Valencia) are also produced in substantial numbers, with a smaller production volume of lemon and lime (HAL 2008).
Imperial variety mandarin is the most popular and most widely planted mandarin in Western
Australia, followed by the varieties of Hickson and Murcott (DAFWA 2006). Red fleshed grapefruit and summer lemons are mainly grown in the north of the state at Carnarvon and
Kununurra (DAFWA 2006). Ruby (pink) grapefruit, a sweet variety with a light pink flesh is also produced in Carnarvon.
The Western Australian citrus season extends all year round with oranges and lemons
available 12 months of the year (Table 2). Grapefruit is available from March to December,
with production in Kununurra commencing from March through to May, and continuing in
Carnarvon from May through to August. Mandarins are available from April to November and limes from October to March (DAFWA 2006, HAL 2008). c 10 000 tonnes as estimated by the industry d Industry estimates are much higher than this.
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Table 2: Western Australia citrus availability e
Navel orange
Valencia orange
Lemon
Mandarin
Grapefruit
Lime
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x
Australian citrus production
This overview of the Australia citrus industry has been taken directly from Plant Health
Australia (2009)
‘Industry Biosecurity Plan for the Citrus Industry (Version 2.0) ’
Citrus has grown to become Australia ’s largest fresh fruit exporting industry in terms of both tonnage and value. Around 600 000t of citrus fruit are produced each year in Australia with a
Gross Value Production (GVP) estimated at $512 million (Australian Bureau of Statistics
2006/2007). Exports accounted for around $173 million of this in 2006/07. In the southern hemisphere, Australia is ranked as the fourth largest producer of citrus, after Brazil,
Argentina and South Africa. On the global scene, Australia is a relatively small player producing less than 1% of the world ’s citrus.
The Australian industry is organised as a federation of growers, Citrus Australia Limited
(CAL), previously known as Australian Citrus Growers Inc., and has approximately 2400 orchardists. Around 12 million trees, covering 29 780ha, form the base of the industry. A large portion of citrus is bearing fruit (27 931ha) and a further 1845 ha is non-bearing.
Individual farms are often mixed fruit growing operations and are relatively small, with the average area harvested being 18ha. The majority of growers (41%) have total citrus areas of between 0.25 and 5ha. Citrus is produced commercially in all states except for Tasmania, with most of Australia ’s commercial citrus producers concentrated in the irrigated horticulture
regions of southern Australia and Queensland (see Figure 3), including the:
Riverina - located in the Murrumbidgee River area of southern New South Wales
Murray Valley growing area -located along both sides of the Murray River in northwestern Victoria, south-western New South Wales and Sunraysia
Riverland -along the Murray River in South Australia
Central Burnett and Emerald regions in Queensland.
Smaller growing areas are situated in various coastal and other locations in New South
Wales (Central Coast, Narromine), the Northern Territory (Darwin, Katherine), Queensland
(Bundaberg, Sunshine Coast, Mareeba) and Western Australia (Carnarvon, Donnybrook,
Gingin, Kununurra, Perth). e Source: DAFWA 2006, Citrus from Western Australia , Bulletin 4496, Department of
Agriculture and Food, Government of Western Australia.
8
Oranges are the most commonly grown citrus fruit in Australia, followed by mandarins, lemons and limes, and grapefruit. Varieties produced vary according to region. While oranges are the main citrus crop grown in the southern irrigation areas, mandarin production is dominant in Queensland. A summary of the main types of citrus fruit produced according
to region is supplied in Table 3.
Since the mid 1990s, citrus production in Australia has increased steadily, particularly due to expanding production of navel and Valencia oranges and mandarins. In 2000/01 citrus exports peaked at 180 640 tonnes but had declined 151 052 tonnes during 2006/07.
In 2006/07 oranges (primarily navel oranges) accounted for 86% of citrus exports. Mandarins accounted for a further 12%. Grapefruit, lemons and limes have decreased in production overall. Since 2000, there has also been an increasing trend in Australia towards the production of high quality fresh fruit for both domestic and export markets and production of fresh juices, with a shift away from production of juice concentrates.
Figure 3: Major citrus production areas in Australia
9
Total 236 (208) 200 (195) 103 (108) 28 (29) 10 (9) 577 (549)
Table 3: 2008/09 Australian citrus production (kt) by region
Navel f Valencia Mandarin Lemon
& lime
Grapefruit Total
WA
Qld
NSW (Riverina)
NSW (other)
Vic g
SA
NT
6
12
56
12
72
50
0
4
7
100
8
21
55
0
5
72
2
2
7
20
0
1
12
2
5
5
4
0
1 17
2 104
0 162
3 27
1 108
0.5 130
1 1
Approximately 25% of Australia ’s citrus is exported, representing about half of the total value of production. Major markets for Australian navel oranges are the USA, Hong Kong, Malaysia and the United Arab Emirates. Important markets for Australian Valencia oranges are
Malaysia, Hong Kong and Singapore. Most Australian mandarin exports go to Indonesia, the
USA, Hong Kong and New Zealand (Table 4). As a result of the industry
’s strong fresh fruit export focus, significant investments are made in pest disinfestation research and field control of fruit fly to overcome overseas market access barriers. Maintaining area freedom status for pests of concern to major overseas markets is also of high priority. f Includes Seville and other oranges g Murray River areas of NSW are included in production for Victoria
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Table 4: Australian citrus exports (t) for 2006/07
Region Orange Mandarin Lemon
& lime
Asia
Brunei
India
Indonesia
Japan
Korea
Malaysia
Singapore
Taiwan
Other
Total
24
Hong Kong 19 271
1999
2482
16 352
774
24 282
9132
1618
5431
16
2204
29
3314
875
26
226
560
792
741
0
73
0
13
323
0
0
24
0
1
America
Caribbean
Canada
USA 25 550
Total
26
3480
0
247
3298
0
2
97
Pacific
Fiji
New Caledonia
394
21
6151
0
0
2179
0
0
New Zealand
Papua New Guinea
Other
Total
Middle East
380
523
20
194
42
6
40
Kuwait
Bahrain
Qatar
Saudi Arabia
United Arab Emirates
Europe
Total
27
472
341
1745
7929
94
0
16
0
1799
0
0
10
0
79
Netherlands
United Kingdom
Other
Total
Africa
Cameroon
Maldives
Seychelles
Total
265
867
125
0
614
0
88
415
358
0
0
12
0
0
0
0
1
0
156
0
0
0
0
1
0
0
17
0
0
3
51
Grapefruit
& other
0
42
19
2
0
0
3
36
0
39
16
9
19
1
1
0
Total
28 945
30 717
394
24
8423
407
757
10 005
121
472
357
1745
9963
12 658
90
21 590
2047
5811
17 550
800
24 511
9752
2410
6212
84 773
26
3746
369
1291
502
2162
1
616
12
629
11
Part two: Risk analysis methodology
The methodology adopted by the Department of Agriculture and Food, Western Australia for
State Pest Risk Analyses (PRA) conforms to the International Standards for Phytosanitary
Measures (FAO 2009) and is similar to and compatible with the methodologies identified by
Biosecurity Australia in its ‘ Guidelines for Import Risk Analysis ’ (Biosecurity Australia 2001) for plants and plant products.
Stage 1: Initiation
The aim of Stage 1 is to identify the objectives of the PRA including identifying the initiation point, the PRA area being the area in relation to which a PRA is conducted and endangered area being the area where ecological factors favour the establishment of a pest.
Stage 2: Pest risk assessment
Stage 2 estimates the risk of quarantine pests associated with the pathway under consideration.
Stage 3: Pest risk management
Conclusions from the pest risk assessment are used to determine whether risk management is required and if the existing measures meet the appropriate level of protection (ALOP). Since zero risk is neither a reasonable nor achievable option, the guiding principle for risk management is to manage risk to achieve the required degree of safety that can be justified and is feasible within the limits of available measures and resources.
If no satisfactory measures can be found to reduce the risk to an acceptable level that is described as a ‘very low’ risk, a final option can be to prohibit importation of the commodity.
Prohibition is viewed as a measure of last resort and as it is highly trade restrictive, in these cases, there needs to be clear scientific evidence to justify such a measure. Prohibition may not be as efficacious as expected, especially in instances where the incentives for illegal import may be significant.
The implementation of phytosanitary measures is not considered to be permanent. After application, the success of the measures in achieving their aim will be determined by monitoring during use. This is often achieved by inspection of the commodity on-arrival, noting any interceptions or any entries of the pest to the PRA area. The information supporting the pest risk analysis will be periodically reviewed to ensure that any new information that becomes available will be used to evaluate the need to modify any phytosanitary measures in place.
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Part three: Pest risk analysis
Stage 1: Initiation
This pest risk analysis was initiated in response to recent range expansions of citrus gall wasp and as part of the Department of Agriculture and Food, Western Australia’s ongoing review of import conditions.
The ‘PRA area’ is defined in this analysis as the state of Western Australia. The ‘endangered area’ is defined as any area within Western Australia, where hosts are present, and in which ecological and environmental factors favour the establishment of the quarantine pest identified in this analysis.
Pathways under consideration in this PRA are host nursery stock and cut flowers/foliage originating from citrus gall wasp infested areas and imported into Western Australia. Citrus gall wasp is not associated with the fresh citrus fruit pathway.
Stage 2: Pest risk assessment
Pest data sheet
Preferred scientific name (ABRS 2013)
Bruchophagus fellis (Girault, 1928) [Hymenoptera: Eurytomidae]
Synonyms (ABRS 2013)
Eurytoma fellis Girault, 1928
Preferred common name
Citrus gall wasp
Alternative common names
None known
Common host plants (Smith et al. 1997)
Finger lime ( Microcitrus australasica ) is the native host for citrus gall wasp. All citrus varieties can be attacked but there are differences in susceptibility. Rough lemon and Troyer citrange rootstocks are very susceptible while grapefruit is the most susceptible cultivated variety.
Lemons and oranges can be seriously affected with mandarins being the least susceptible.
Plant part affected (Smith et al. 1997)
Young stem material
Distribution
Queensland (Smith et al. 1997)
New South Wales (Smith et al. 1997)
Victoria (VIAC 2013)
South Australia (Lamb 2011)
BAMA h status
Prohibited (s12) C1 Exclusion - whole of State. Keeping category - Prohibited
Current status of citrus gall wasp in Western Australia
Citrus gall wasp was identified on two properties in suburban Perth in April 2013. Following a positive second opinion on the identification, an incident was formally declared in May 2013 and an eradication program undertaken.
To delimit the extent of the infestation, an extensive survey of 176 properties in the immediate vicinity of the two properties and a survey of 780 citrus trees in the greater Perth h Biosecurity and Agriculture Management Act 2007 . Government of Western Australia
13
metropolitan area failed to detect any further infestations. Retail and production nurseries were surveyed, no evidence of citrus gall wasp was found. These surveys included a facility responsible for the majority of Western Australian citrus nursery stock production.
Citrus trees on the two properties were pruned to trunk and primary branches to remove first and second year growth in June 2013. Infested material was then mulched and kiln dried for seven days to render the material inert. A follow-up treatment consisting of soil drench of imidacloprid was applied in August 2013.
Surveys are scheduled for autumn 2014 and 2015 to validate ongoing state freedom.
An overview of the biology and ecology of citrus gall wasp
The biology and ecology of citrus gall wasp has been adapted from Smith et al . (1997) and
Hely et al. (1982) and modified to include additional relevant information.
The adult wasp is small, shiny-black and 2.5mm long. Larvae are 2mm long, thickset, white and have no legs. This is the only wasp that directly attacks citrus. The larval development in the young twig can produce distinctive woody galls typically up to 250mm long and 25mm thick containing hundreds of larvae. More recently galls of up to 500mm containing thousands of larvae have been reported by O’Neill (2013).
Adults emerge from infested galls in most areas from mid-September until early November.
Upon emergence, the adult wasps mate immediately and females begin to lay eggs soon afterwards as both sexes live for approximately one week. The female wasp lays eggs between the bark and wood of young twigs leaving scar-like flecks on the bark. Egg laying continues throughout October and finishes by mid-November.
Figure 4: Characteristic gall formation caused by citrus gall wasp larvae i
Eggs hatch in 2 to 4 weeks, and are all hatched by early December. The young larvae burrow into the bark, and a flask-like sheath of soft host tissue develops around each larva.
By late December, woody tissue begins to form around the sheath of soft tissue; the twig swells and begins to develop the characteristic gall. Heavily infested trees can be covered with galls, resulting in very little leaf or fruit production, and severe dieback.
Pupation occurs about a month before emergence. During this time the larvae ceases feeding, voids its waste material and begins to differentiate into the adult form (Noble 1936).
Spread by the adult is only local. The wasps are weak fliers and usually do not leave the tree from which they have emerged. However, there is probably some wind-borne transport of the adults. The most important means of spread to new localities is by the movement of infested i
Photo courtesy of DPI&F 2007, Unusual insect galling citrus - have you seen it?
, DPI&F note, The
State of Queensland Department of Primary Industries and Fisheries.
14
young trees. This risk would be greatest with young trees from home gardens. Heavily galled twigs have been carried away as curiosities by people who do not appreciate the danger of infesting new areas.
Severe infestations of citrus gall wasp can result in very little leaf or fruit production and tree dieback (Smith et al. 1997). As an example, Flett (2011) described an incursion of citrus gall wasp in the Holland’s Lake area of the Sunraysia district in the late 1990s. The incursion was first noticed as I0 to 20mm galls on lemons. It has since spread over large areas in the district with severe infestations in 50ha of Valencia and navel oranges and lemons over 10 properties. Three properties had a very serious infestation of galls 150 to 300mm long covering 50% of the tree canopy, while another five properties had galls up to 100mm long covering 40% of the canopy.
Figure 5: Old and new galls on citrus branch caused by citrus gall wasp larvae j
Control strategies
Cultural control
Removing and burning galled wood before the end of August is known to be an effective control measure. This gives satisfactory results when done thoroughly to all the trees in an area (Hely et al. 1982). j Photo courtesy of Creek, A & Hardy, S 2010, Citrus gall wasp , Primefact 1010, Industry &
Investment, NSW Government.
15
Phytosanitary measures
The spread of citrus gall wasp in Australia is thought to have occurred mainly through the distribution of infected nursery trees. Creek (2010) recommends that on arrival any new trees should be thoroughly inspected for the presence of galls, especially highly susceptible varieties such as lemons and grapefruit. If galls are found, the trees should be returned to the nursery of origin.
Biological control
Citrus gall wasp can be successfully controlled by the release of its natural enemies, the native parasitic wasps Megastigmus brevivalvus and M. trisulcus (Flett 2011) with rates of over 90% parasitism being reported by Smith et al. (1997). However, both these native wasps are absent from and have never been recorded in Western Australia.
Host plant resistance
Not allowing shoots to develop on Rough lemon or Troyer citrange rootstocks in the orchard will assist with the control of citrus gall wasp, as these can become heavily infested with the wasp (Smith et al. 1997).
Chemical control
Targeting emerging adults is difficult as they are short-lived and emerge over a protracted period. Therefore, pesticides must have systemic properties as contact insecticides will not penetrate the bark and kill larvae. However, the contact insecticide methidathion plus petroleum spray oil can kill most newly hatched larvae if timed correctly. The action level for spraying is when a third or more of the branches are infested with galls exceeding 50mm in length and low in parasites (Falivene 2008). Due to the broad spectrum nature of the insecticide, methidathion will kill off beneficial insects present in orchards (Flett 2011).
Recent trial work has shown that the systemic insecticide imidacloprid applied as a soil drench and foliar sprays of petroleum spray oil were both effective against citrus gall wasp
(Mo 2011a). Systemic insecticides such as imidacloprid target feeding larvae and work best before the tissues around the larval feeding sites become woody. Foliar sprays of oils are known to disrupt the normal behaviour of foliage-dwelling insects (Mo 2011b). The broad activity of imidacloprid is also toxic to parasitic wasps so its application is best when these wasps are absent or low in number (Mo 2013).
Climate matching using CLIMEX
®
CLIMEX
®
bioclimatic modelling systems Sutherst et al. 2007 is based on the assumption that if the modeller knows where a pest or other organism exists, an inference can be made to what climatic conditions that organism can tolerate. CLIMEX
®
utilises long-term climatic data such as temperature, rainfall and humidity from areas where the organism is known to occur to predict the climatic suitability of areas where the organism is not known to occur.
A broad assumption can be drawn that the organism under consideration would have similar chances of survival at these climatic locations to areas where the organism is known to be present. Although the climatic environment is a major influence in determining the suitability of a particular region for an organism, there is a range of other biotic and abiotic factors which influence the distribution and impact an organism has in a particular region; including the availability of host plants, availability of suitable soil types and interactions with other organisms.
Regional climate matching is a component of the CLIMEX
®
bioclimatic modelling system and matches climates at a regional level by aggregating long term climatic data for the locations where an organism exists and provides a Climatic Match Index (CMI) output for locations of interest. By convention, any Western Australian locations with a CMI greater than 0.6 suggest the climate at these locations are similar to the locations where a pest exists.
Regional climate matching in this scenario has been calculated with ambient temperatures
(maximum and minimum), rainfall (amount and pattern) and relative humidity (9am and 3pm).
16
A CLIMEX
®
regional climate match has been undertaken to identify locations within Western
Australia that have similar climatic conditions to several but not all locations where citrus gall
wasp is known to exist within Australia (Table 5).
The resulting CMI output (Figure 6) suggests that most major citrus production regions of
Western Australia except the Ord River production areas have similar climatic conditions to
those Australian locations outlined in Table 5. As a result of this similarity, climatic conditions
would not appear to be a constraint on citrus gall wasp establishing in citrus production areas as well as other locations within Western Australia.
Table 5: Recorded locations for citrus gall wasp
State Location
Closest Bureau of Meteorology weather station
Queensland Mareeba (Smith et al. 1997)
Charters Towers (Smith et al. 1997)
Atherton Tablelands (Papacek & Smith 1989)
Mareeba
Charters Towers
Atherton
Rockhampton (Smith et al. 1997)
Brisbane (Smith et al. 1997)
Mundubbera (Papacek & Smith 1989)
Rockhampton
Brisbane
Gayndah
New South Wales
Victoria
South Australia
Gosford (Smith et al. 1997)
Sydney (Smith et al. 1997)
Forbes (Smith et al. 1997)
Narromine (Smith et al. 1997)
Grafton (Smith et al. 1997)
Griffith (Creek & Hardy 2010)
Dareton (Mo 2011b)
Footscray (VIAC 2013)
Avon Plains (Cannard 2007)
Adelaide (Lamb 2011)
Riverland (Lamb 2011)
Gosford
Sydney
Forbes
Dubbo
Grafton
Griffith
Mildura
Melbourne
Donald
Adelaide
Renmark
17
Figure 6: Western Australian climate match to reported citrus gall wasp locations
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Risk assessment
The outcome of the risk assessment is the determination of an unrestricted risk estimate.
The unrestricted risk assessment considers basic standards of practice for the production of host nursery stock and cut flowers/foliage in the absence of risk management measures
(including inspection). Likelihoods and consequences are described using the processes and nomenclature outlined in ‘Guidelines for Import Risk Analysis’ Biosecurity Australia 2001 for plants and plant products (with the consequence scale updated to reflect the current A-G scale).
Probability of entry
The probability of entry is considered in two parts: the probability of importation (pre-border) and the probability of distribution (post-border). The probability of entry is determined by combining the probabilities of importation and distribution using the matrix rules outlined in
Probability of importation
Association of the pest with the pathway at its origin o Citrus gall wasp infests young growth in spring causing woody galls to form around
the developing larvae (Figure 4, Figure 5). Heavily infested trees can be covered with
galls Creek & Hardy 2010. o Larvae have the potential to be associated with host nursery stock on a year-round basis as adults emerge from infested galls in most areas from mid-September until early November. Upon emergence, the adult wasps mate immediately and females begin to lay eggs soon afterwards as both sexes live for approximately one week. o Host cut flowers/foliage would used for visual aesthetic purposes. Quality control would mean that obviously infested cut flowers/foliage would be unlikely to be picked for display purposes. o There is no intrastate or interstate legislation currently in place to specifically restrict the spread of citrus gall wasp in other Australian states and territories.
Citrus gall wasp larvae survive and develop in young flush growth and are likely to be present within host nursery stock from infested areas that are destined for export.
Ability of the pest to survive existing pest management procedures o The preferred long-term management option for control of gall wasp is to rely on the use of the natural beneficial insects such as parasitic wasps (Creek & Hardy 2010). o Cultural practices such as the application time of fertilisers and the timing of pruning operations are important strategies to help reduce gall wasp numbers, by limiting the amount of suitable flush into which adults can lay their eggs (Creek & Hardy 2010). o The current chemical treatment is difficult to time, does not provide complete control of the pest and is disruptive to integrated pest management programs (Creek &
Hardy 2010). o The action level for spraying is 33% or more branches infested with galls exceeding
50mm in length and low in parasites (Falivene 2008).
Current best practices can be expected to reduce citrus gall wasp populations to below economic thresholds but not to eliminate populations
Ability of the pest to survive transport and storage o Larval development and pupation occur inside the stem material. It is expected that larvae could develop in healthy cut stems as well, but would have increasing difficulties as the stem deteriorates. It is expected that pupae would survive.
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o Adults are relatively short-lived and mobile and would be unlikely to be associated with the nursery stock or cut flower/foliage pathway at the point of origin. Any adults present are likely to be newly emerged individuals.
Transport and storage conditions are not expected to adversely impact upon the survivability of the larvae or pupa in either nursery stock or cut flowers/foliage.
Citrus gall wasp associated with the nursery stock pathway has been determined to have a high probability of importation. That is, its importation would be likely to occur under standard commercial and non-commercial production practices, harvesting and packing procedures for host nursery stock imported into Western Australia from regions where this species is present.
It would be unlikely that obviously infested cut flowers/foliage would be picked for display purposes. Therefore, citrus gall wasp associated with the cut flower/foliage pathway has been determined to have a moderate probability of importation. That is, its importation would occur with an even probability under standard commercial production and non-commercial production, harvesting and packing practises.
Probability of distribution
Distribution of the imported commodity in the PRA area o Host nursery stock and cut flowers/foliage are likely to be distributed to multiple destinations throughout Western Australia for retail and commercial sale. o Eggs may develop into larvae and larvae to adults within infested material throughout the distribution chain.
Transport and storage conditions are not expected to adversely impact upon the survivability of the larvae or pupa in either nursery stock or cut flowers/foliage.
Ability of the pest to move from the pathway to a suitable host o Citrus gall wasp emergence is closely linked with tree phenology and is associated with the appearance of the spring growth flush. After emergence the adult wasps normally do not move very far, but can be transported longer distances on prevailing winds (Creek & Hardy 2010). o Although the host range of citrus gall wasp is limited to citrus varieties, citrus is grown commercially as well as being found commonly in domestic gardens and may be found along roadsides and old homestead sites. Any wasps that survive transport and storage would be capable of locating a suitable host and establishing a founding population. o The ability of adults emerging from cut flowers/foliage in locating a suitable host would be somewhat limited compared to host nursery stock due to the environments associated with displayed and discarded material. o Emerging citrus gall wasps have the ability to be distributed to the PRA area from infested nursery stock or cut flowers/foliage.
Citrus gall wasp emerging from host nursery stock has been determined to have a high probability of distribution, that is, the distribution of this wasp to a suitable host within
Western Australia would be likely to occur.
Unlike citrus gall wasp emerging from host nursery stock, emergence from host cut flower or foliage has the added step of the wasp finding a viable host in order to establish. As such, it has been determined that citrus gall wasps emerging from host cut flowers or foliage has a moderate probability of distribution, that is, the distribution of this wasp to a suitable host within Western Australia would occur with an even probability.
20
Overall probability of entry (importation x distribution)
The overall probability of entry has been determined by combining the individual probabilities
of importation and distribution using the matrix rules outlined in Appendix 1. Citrus gall wasp
has been assessed as having an overall high probability of entry for host nursery stock and an overall low probability of entry for host cut flowers/foliage as a result of trade into Western
Australia from other Australian states/territories where this pest species occurs.
Probability of establishment
Availability of suitable hosts, alternative hosts and vectors in the PRA area o Citrus gall wasp is capable of surviving and reproducing on citrus and its varieties. o Citrus species are grown widely in tropical and subtropical areas of Western Australia as ornamental, shade and fruit trees. o Citrus production is widespread within Western Australia. o Wild and backyard citrus trees would be a continuous source of citrus gall wasp in infected areas in eastern Australia; a similar scenario is expected to occur in Western
Australia.
The availability of suitable hosts is not expected to limit the potential for citrus gall wasp to establish in Western Australia.
Suitability of the environment o Citrus gall wasp is native to the coastal districts of Queensland and New South Wales
(Hely et al. 1982) and currently has a distribution range extending to inland
Queensland and New South Wales as well as Victoria and South Australia. Western
Australia has similar environments that would be suitable for the establishment of this pest. Citrus gall wasp could presumably establish in any climate suitable for citrus production.
Climate matching scenarios indicate climate is not expected to limit the potential for citrus gall wasp to establish in Western Australia.
Cultural practices and control measures o Due to the wasp larvae being an internal pest of nursery stock, current insecticide spray regimes for other pests may not have any impact on the establishment of citrus gall wasp. o Specific parasites and other biocontrol agents have been identified for the species.
Megastigmus brevivalvus and M. trisulcus are important natural enemies of citrus gall wasp. These parasitic wasps have not been recorded from Western Australia.
Cultural practices and control measures undertaken by Western Australian citrus producers and domestic gardeners are not expected to limit the potential for citrus gall wasp to establish in Western Australia.
The reproductive strategy and survival of the pest o Adults emerge from infested galls in most areas from mid-September until early
November. They mate and immediately begin egg laying, as they only live for about a week. o The female wasp lays eggs between the bark and wood of young spring-flush twigs.
Twigs in which eggs have been deposited have scar-like flecks on the bark. Egg laying continues throughout October and finishes by about mid-November. o Eggs hatch in 2 to 4 weeks, and are all hatched by early December. The young larvae burrow into the bark, and a flask-like sheath of soft host tissue develops around each larva.
21
o By late December, woody tissue begins to form around the sheath of soft tissue; the twig swells and begins to develop the characteristic gall. o Adult mortality is high. Some adults are trapped in the galls unable to cut through the bark and emerge. Also ants of the genus Pheidole kill many wasps as they emerge, these ants are present in Western Australia. o If emergence coincides with a heat wave, large numbers will die although these conditions would be a rare event during mid September to early November in Western
Australia, especially in the southern parts of the state.
The reproductive and survival of citrus gall wasp is not deemed to limit the potential for its establishment in Western Australia.
Citrus gall wasp has been determined to have a high probability of establishment, that is, is, that citrus gall wasp would be likely to establish in Western Australia as a result of infested citrus nursery stock or cut flowers/foliage entering the managed and unmanaged environment.
Probability of spread
The suitability of the natural or managed environment for natural spread o Citrus gall wasp has been reported from tropical and subtropical environments in eastern Australia (Queensland, New South Wales, Victoria and South Australia).
There are similar natural and built environments of these states to those in Western
Australia. This suggests that citrus gall wasp would be able to spread within Western
Australia. o The greater majority of citrus gall wasp lifecycle occurs within the infested gall. Once the adult wasp emerges from the gall, the short-lived wasp usually stays close to the host tree. o If emergence coincides with a heat wave, large numbers will die although these conditions would be rare during mid-September to early November in Western
Australia, especially in the south of the state.
The suitability of the natural or managed environment for natural spread of citrus gall wasp would be expected to limit the potential for citrus gall wasp to spread in Western Australia.
Presence of natural barriers o The presence of natural barriers such as deserts or expanses of natural vegetation may restrict any long range natural spread of citrus gall wasp. Although the adult wasps are capable of flight, they are not strong fliers and are short-lived (Creek &
Hardy 2010). The distances between some of the main commercial citrus production areas in Western Australia would make it difficult for this pest to disperse unaided from one area to another. Adult wasps usually remain near the original infestation.
However, citrus is naturalised in Western Australia and is a common backyard and amenity plant.
The presence of natural barriers may limit the potential for the natural spread of citrus gall wasp in Western Australia.
Potential for movement with commodities or conveyances o The major means of dispersal to uninfected areas is through transport of immature stages in infested nursery stock (Creek & Hardy 2010). o Citrus gall wasp has demonstrated a capacity to spread from its original range in eastern Australia to many citrus growing districts (Flett 2011).
Movement associated with commodities or conveyances is not deemed to limit the potential for citrus gall wasp to spread in Western Australia.
22
Potential natural enemies o Specific parasites and other biocontrol agents have been identified for the species.
Both Megastigmus brevivalvus and M. trisulcus are important natural enemies of citrus gall wasp. Ants of the genus Pheidole kill many wasps as they emerge. o Natural enemies of citrus gall wasp may limit the potential for citrus gall wasp to spread in Western Australia.
Citrus gall wasp has been determined to have a moderate probability of spread, that is, there is an even probability that citrus gall wasp will spread within in Western Australia following its establishment.
Overall probability of entry, establishment and spread
The overall probability of entry, establishment and spread as a result of the importation of host nursery stock and cut flowers/foliage into Western Australia from other Australian states/territories where citrus gall wasp is present has been determined by combining the
individual probabilities using the matrix rules shown in Appendix 1.
For host nursery stock, citrus gall wasp has been assessed as having an overall moderate probability of entry, establishment and spread.
For host cut flowers/foliage, citrus gall wasp has been assessed as having an overall low probability of entry, establishment and spread.
Economic consequences
The International Standards for Phytosanitary Measures (IPSM No 11) - Pest Risk Analysis for Quarantine Pests including Analysis of Environmental Risks and Living Modified
Organisms (FAO 2004), indicates that the assessment of economic consequences is made using “a hypothetical situation where a pest is supposed to have been introduced and to be fully expressing its potential economic consequences (per year) in the PRA area ”. This is interpreted as an unabated incursion; however, it is acknowledged that existing control regimes for other pest species may impact on this expression. In light of this interpretation, an evaluation of the consequence of entry, establishment or spread of citrus gall wasp is
The expected economic consequences for the endangered area should citrus gall wasp enter, establish and spread within Western Australia has been determined to be low using
the decision rules outlined in Appendix 2.
Risk assessment conclusion
Using the matrix rules outlined in Appendix 3 an unrestricted risk estimate of
low
has been determined for host nursery stock and very low for cut flowers/foliage produced in regions where citrus gall wasp occurs
As the unrestricted risk estimate for host nursery stock is above Western Australia’s ALOP of
‘Very low’, the basic standards of practice for the control of citrus gall wasp would not provide an appropriate level of protection for Western Australia. As such, specific risk mitigating phytosanitary measures would be required for host nursery stock.
As the unrestricted risk estimate for host cut flowers/foliage is at Western Australia’s ALOP of
‘Very low’, the basic standards of practice for the control of citrus gall wasp would therefore provide an appropriate level of protection for Western Australia. As such, specific risk mitigating phytosanitary measures would not be required for host cut flowers/foliage.
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Table 6: Economic consequences of entry, establishment and spread
Criterion Estimate
Direct consequences
Plant life or health D – Major significance at the local level
Citrus gall wasp has the potential to cause significant production losses. Severe infestations can result in very little leaf or fruit production and tree dieback.
The commercial host range of citrus gall wasp is limited to citrus and Australian finger lime.
Any other aspects of the environment
A – Indiscernible at the local level
There are no known direct consequences of this pest on other aspects of the environment.
Indirect consequences
Eradication, control etc C – Significant at the local level
A control program would have to be implemented in infested orchards to reduce fruit damage and yield losses, and this would increase production costs.
Biological control programs and movement controls for citrus gall wasp are current best practice regimes in Australia.
Nursery stock movement controls can prevent citrus gall wasp from establishing in uninfested orchards.
The long development times within citrus wood and the existence of short-lived adults would make eradication difficult.
Domestic trade B – Minor significant at the local level
The presence of citrus gall wasp in commercial production areas within Western Australia would not impact significantly on interstate trade given current import conditions related to those states.
Trade within Western Australia may be restricted as a part of any area freedom protocols to be set up.
International trade B – Minor significant at the local level
The presence of citrus gall wasp in commercial production areas of Western Australia should not restrict access to overseas markets for citrus fruit where this pest is absent. However, should trading partners impose restrictions it may have ramifications at the local level.
Environment, including rural and regional economic viability
A – Unlikely to be discernible at the local level.
Although additional insecticide applications may be required to control citrus gall wasp, this is expected to be undiscernible for the environment at a local level.
24
Table 7: Unrestricted risk assessment summary for citrus gall wasp
Probability of
Nursery stock
Cut flowers/ foliage
Entry
Importation x Distribution = Entry
Establishment
High High High
Moderate Moderate Low
High
High
Spread
Moderate
Moderate
Overall probability of entry, establishment and spread
Economic consequence
Unrestricted risk
Moderate
Low
Low
Low
Low
Very low
25
Stage 3: Pest risk management
Certification and General Requirements are systems ensuring that the phytosanitary status of plants and plant material is maintained during the process of production and export to
Western Australia.
The conclusions from the pest risk assessment are used to decide whether risk management is required and the strength of measures to be used. Since zero risk is not a reasonable nor achievable option, the guiding principle for risk management is to manage risk to achieve the required degree of safety that can be justified and is feasible within the limits of available options and resources.
Risk management measures aim to reduce the likelihood that the importation of host nursery stock and cut flowers/foliage into Western Australia would lead to the entry, establishment and spread of citrus gall wasp. The primary methods of achieving this result is by reducing the likelihood that citrus gall wasp will reach the endangered area by imposing risk management measures on the population from which host material are sourced, or on other steps in the importation chain.
The unrestricted risk estimate
of ‘very low’ (Table 7) for host cut flowers/foliage being
imported into Western Australia indicates risk management measures against citrus gall wasp will not be required as this risk does not exceed the ALOP for Western Australia.
The unrestricted risk estimate
of ‘low’ (Table 7) for host nursery stock being imported into
Western Australia indicates risk management measures against citrus gall wasp will be required as this risk exceeds the ALOP for Western Australia.
Risk management options
The risk management measures described below form the basis of the proposed import conditions for host nursery stock being imported into Western Australia. The specific phytosanitary risk management measures for citrus gall wasp are detailed in the section titled
‘ Recommended import conditions’. The proposed risk management measures described below do not preclude consideration of alternative risk management measures should they be proposed by stakeholders.
Pest free areas
The pest free area phytosanitary measures reduce the likelihood of importation. A pest free area is described as ‘an area in which a specific pest does not occur as demonstrated by scientific evidence and in which, where appropriate, this condition is being officially maintained’ (FAO 1995, FAO 1999). In accordance with ISPM No. 4 (FAO 1995) there are three main components in the establishment and maintenance of a pest free area (PFA):
systems to establish freedom and
phytosanitary measures to maintain freedom and
checks to verify freedom has been maintained.
The declaration of a pest free area for citrus gall wasp may be either within a state or territory or for the whole of the state or territory.
Whole of state/territory pest free area
For areas suitable for citrus gall wasp to establish, whole of state/territory pest free area is considered acceptable if citrus gall wasp has not been recorded from the state or territory, there are phytosanitary measures in place to maintain freedom and there are checks in place to verify ongoing freedom.
Within state/territory pest free area
In order for a pest free area to be recognised within a state or territory, an inspection program will be required to demonstrate freedom within a state or territory. This risk
26
mitigation measure will require citrus and allied nursery stock to be grown and packed in an area free from citrus gall wasp. Area freedom is to be determined by:
inspection only (as there is no known practical trapping technique) and
legislative requirements to delineate pest free areas and
legislative requirements to restrict the movement of host nursery stock into and within the pest free area and
Ongoing checks to verify freedom
Pest free place of production or pest free production site
A pest free place of production is described as ‘a place of production in which a specific pest does not occur as demonstrated by scientific evidence and in which, where appropriate, this condition is being officially maintained for a defined period’ (FAO 1999). The pest free place of production phytosanitary measure reduces the likelihood of importation.
When a defined portion of a place of production can be managed as a separate unit within a place of production, it may be possible to maintain that site pest free. In such circumstances, the place of production is considered to contain a ‘pest free production site’.
Pre-shipment insecticide treatment and on arrival inspection
Host nursery stock sourced from a property infested with citrus gall wasp may be imported following a pre-shipment insecticide treatment registered or permitted by the Australian
Pesticides and Veterinary Medicines Authority (APVMA) and approved by DAFWA. Note that one treatment option available as part of the general condition of entry for nursery stock would be approved; that is, treatment (permit 9795) of above-ground parts with imidacloprid applied within 10 days prior to export.
However, due to the reduced efficacy of insecticides at the mature gall stage, any preshipment insecticide treatment would require a 600 unit visual inspection.
Fumigation with methyl bromide
State/territory and within state/territory area freedoms, pest free place of production, pest free production site and pre-shipment insecticide treatment for citrus gall wasp are not essential to export host nursery stock to Western Australia. However, in the absence of any of these measures methyl bromide fumigation will be required. The treatment can be performed either pre-shipment or on arrival. On arrival treatment is subject to approved packaging and direct delivery to the fumigation facility.
Recommended import conditions
Definitions
Approved – approved by the Director General of the Department of Agriculture and Food,
Western Australia (DAFWA)
Citrus gall wasp – Bruchophagus fellis (Girault, 1928) [Hymenoptera: Eurytomidae].
Citrus and allied cut flowers/foliage – any part of Citrus spp. or other host plants excluding roots, fruit, nursery stock, seed, that are not used for human consumption.
Citrus nursery stock
– any potted or bare rooted or cuttings or any above or below ground part used for vegetative propagation of Citrus spp. or other host plants of citrus gall wasp, but does not include plant tissue culture or seed.
Consignment – a quantity of plants, plant products and/ or other regulated articles being moved from one area to another and covered by a single plant health certificate. A consignment may be composed of one or more lots.
Lot – a number of units of a single commodity identifiable by its homogeneity of composition, origin, etc., that may include several varieties, forming all or part of a consignment.
27
Parts of plant – includes detached above ground parts of host plants of citrus gall wasp including cut flowers/foliage but does not include fruit.
Pest free area – an area in which a specific pest does not occur as demonstrated by scientific evidence and in which, where appropriate, this condition is being officially maintained.
Pest free place of production – a place of production in which a specific pest does not occur as demonstrated by scientific evidence and in which, where appropriate, this condition is being officially maintained for a defined period.
Pest free production site – a defined portion of a place of production in which a specific pest does not occur as demonstrated by scientific evidence and in which, where appropriate, this condition is being officially maintained for a defined period, and that is managed as a separate unit in the same way as a pest free place of production.
Place of production – any premises or collection of fields operated as a single production or farming unit. This may include production sites which are separately managed for phytosanitary purposes. It is a single continuous farm holding with no intervening titles which is managed as an entity and defined by GPS coordinates or other spatially clearly identifiable boundaries.
Production site –defined portion of a place of production that can be managed as a separate unit within a place of production.
Certification
General Requirements
Each consignment is to be accompanied by an Interstate Plant Health Certificate issued by the quarantine authority in the exporting state or territory or under a quality assurance arrangement approved by the Director General of the Department of Agriculture and Food,
Western Australia, endorsed as follows and as required under ‘specific requirements’:
the name of the commodity, identified by genus and species and
name and address of property on which the product was grown or approved registration number and
name and address of the packing house or approved registration number and
name and address of the place if any treatments were carried out and
the date if any treatments were applied.
Note : If the name and address of the property on which the product was grown is not compulsory under the ‘Specific Requirements’ it may be excluded from the endorsement.
However, any corrective action necessary will be taken at the packinghouse level.
Specific requirements for host cut flowers/foliage
None required.
Specific requirements for host nursery stock
Option 1: From a state/territory free from citrus gall wasp
To be certified as —
‘Grown in a state/territory free from citrus gall wasp under an approved area freedom program and packed under an approved packing program ’ or approved alternative.
OR
Option 2: Pre-shipment insecticide treatment and on arrival inspection of citrus gall wasp host nursery stock
28
To be certified as —
‘Treated with (insert chemical name, concentration of active ingredient and rate) on (insert date of application) ’ or approved alternative.
Note : treatment of above-ground parts with imidacloprid as per permit 9795, applied within
10 days prior to export will be approved.
AND
Subject to 600 unit visual inspection on arrival.
OR
Option 3: Methyl bromide fumigation treatment of citrus gall wasp host nursery stock
To be certified as
‘Fumigated with methyl bromide in accordance with AQIS methyl bromide fumigation standard. Version 1.5 November 2011 ’ and specifying:
name of the fumigation facility
date of fumigation
rate of methyl bromide used, that is initial dosage (g/m³)
concentration time (CT) product of methyl bromide achieved by the fumigation
(ghr/m³)
duration of fumigation (hrs)
ambient air temperature during fumigation (°C)
minimum pulp/core temperature during fumigation (°C).
To be carried out for a duration of 2 hrs according to the specifications below:
24 g/m³ at a pulp/core temperature of 26°C or greater but less than 32°C – minimum CT product of 47 ghr/m³
32 g/m³ at a pulp/core temperature of 21°C or greater but less than 26°C – minimum CT product of 47 ghr/m³
40 g/m³ at a pulp/ core temperature of 16°C or greater but less than 21°C - minimum (CT) product of 58 ghr/m³
48 g/m³ at a pulp/ core temperature of 11°C or greater but less than 16°C - minimum (CT) product of 70 ghr/m³.
OR
Approved alternative.
29
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ABRS 2013. Australian Faunal Directory. Australian Biological Resources Study.
Department of the Environment and Heritage, Australian Government. viewed 16
September 2013, www.environment.gov.au/biodiversity/abrs/onlineresources/fauna/afd/taxa/Bruchophagus_fellis .
Biosecurity Australia 2001, Guidelines for Import Risk Analysis , Draft September 2001,
Biosecurity Australia: Department of Agriculture, Fisheries and Forestry, Australia.
Biosecurity Australia 2011, Citrus fruit from inland Queensland and Western Australia to the
United States of America , Market Access Submission, Biosecurity Australia, Australian
Government.
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.
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.
BoM 2013c. Climate statistics for Australia locations: Denmark. Commonwealth of Australia,
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Australia, Bureau of Meteorology. viewed 16 September 2013, www.bom.gov.au/climate/averages/tables/cw_002038.shtml
.
BoM 2013e. Climate statistics for Australia locations: Nabawa. Commonwealth of Australia,
Bureau of Meteorology. viewed 16 September 2013, www.bom.gov.au/climate/averages/tables/cw_008028.shtml
.
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Cannard, M 2007, 'Native parasitic wasps released to control citrus gall wasp', Newsletter of the Murray Valley Citrus Board , vol. 51, pp.14-15.
Creek, A 2010, 'Managing citrus gall wasp', Coastal Fruitgrowers Newsletter , vol. 74, pp.18-
20.
Creek, A & Hardy, S 2010, Citrus gall wasp , Primefact 1010, Industry & Investment, NSW
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DAFWA 2006, Citrus from Western Australia , Bulletin 4496, Department of Agriculture and
Food, Government of Western Australia.
DAFWA 2011. Western Australian Citrus website. Department of Agricultureand Food,
Government of Western Australia. www.agric.wa.gov.au
(Available shortly).
DAFWA 2012, 2010/11 stats , Kununurra Agricultural Memo: August 2012, Department of
Agricultural and Food, Western Australia.
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DPI&F 2007, Unusual insect galling citrus - have you seen it?
, DPI&F note, The State of
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Falivene, S 2008, Citrus gall wasp spray workshop , Murray Valley Citrus Board.
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Standards for Phytosanitary Measures 1 to 32 (2009 Edition) . Secretariat of the
International Plant Protection Convention, Food and Agriculture Organisation of the United
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FAO 1999, Requirements for the establishment of pest free places of production and pest free production sites (ISPM 10) IN: International Standards for Phytosanitary Measures 1 to 32 (2009 edition) . Secretariat of the International Plant Protection Convention, Food and Agriculture Organisation of the United Nations, Rome, Italy, pp.132-139.
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Protection Convention, Food and Agriculture Organisation of the United Nations, Rome,
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Final report C08000, Horticulture Australia Limited.
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Appendix 1: Matrix of rules (combination of likelihoods)
Likelihood 2
High Moderate Low Very low Extremely low Negligible
High high
Moderate
Low
Very low moderate low very low low low very low very low very low extremely low
Extremely low extremely low extremely low extremely low extremely low
Negligible negligible negligible negligible negligible negligible negligible negligible
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Appendix 2: Method for assessing economic consequences
FAO (2006) indicates that the analysis of economic consequences is made using ‘a hypothetical situation where a pest is supposed to have been introduced and to be fully expressing its potential economic consequences (per year) in the PRA area’. DAFWA interpret these criteria as an unabated incursion. DAFWA also acknowledges that existing control regimes for similar species may impact on this expression.
In order to estimate the potential economic importance of the pest, information is obtained from areas where the pest currently occurs. Consideration is given to whether the pest causes major, minor or no damage; frequently or infrequently. The situation in the PRA area is then carefully compared with that in the areas where the pest occurs. Case histories concerning comparable pests can also be considered. Expert judgement is then used to assess the potential economic consequences should the pest establish and spread in the
PRA area.
Economic assessments carried out for each quarantine pest are based on available information regarding each of the direct and indirect consequences outlined below. It should be noted that, in many instances, information regarding the likely consequences of incursions of the identified quarantine pests is often limited. In addition, it is often the case that the consequences of a pest in one country or environment are different to those in another.
Given these limitations, the economic assessment should be based on information available for each identified quarantine pest, or on information obtained for similar pests. In some cases, this means that a subset of the direct and indirect criteria listed below should be considered in the assessment.
The direct consequences considered include:
crop losses (yield and grade)
control and surveillance measures
environmental effects.
The indirect consequences considered include:
effects on domestic and export markets - this should include a consideration of any phytosanitary measures imposed by trading partners in the event of a pest incursion
changes to producer costs or input demands
changes to domestic or foreign consumer demand for a product resulting from quality changes
environmental or other undesired effects of control measures
feasibility and cost of eradication or containment
capacity to act as a vector for other pests
resources needed for additional research and advice
social and other effects.
If the pest has no significant economic consequence in the PRA area then it does not satisfy the definition of a quarantine pest and does not need to be considered any further.
In assessing the economic consequences the following nomenclature and criteria are used:
The relevant examples of direct and indirect consequences from ISPM 11 (FAO, 2004) are considered for each of the broad groups (as listed above) and estimates of the consequences are assigned.
34
The direct and indirect consequences are estimated based on four geographic levels. The terms ‘local’, ‘district’, ‘regional’ and ‘PRA area’ are defined as:
Local: An aggregate of households or enterprises or a local government area
— e.g. a rural community, a town
District: A geographically or geopolitically associated collection of aggregates — a recognised section of a state, such as the Albany, Broome, Bunbury,
Carnarvon, Derby, Esperance , Geraldton, Jerramungup, Kalgoorlie, Karratha,
Katanning, Kununurra, Lake Grace , Manjimup, Merredin, Moora, Narrogin,
Northam, Three Springs and Waroona districts.
Region: A geographically or geopolitically associated collection of districts — e.g.
Central Agricultural, Northern Agricultural, South-West Agricultural Region,
Southern Agricultural, Northern Pastoral Region and Southern Pastoral
Regions
PRA area: Western Australia
The consequence is described as ‘unlikely to be discernible’, of ‘minor significance’, significant’ or ‘highly significant’:
A n ‘unlikely to be discernible’ consequence is not usually distinguishable from normal day-to-day variation in the criterion;
A consequence of ‘minor significance’ is not expected to threaten economic viability, but would lead to a minor increase in mortality/morbidity or a minor decrease in production.
For non-commercial factors, the consequence is not expected to threaten the intrinsic
‘value’ of the criterion — though the value of the criterion would be considered as
‘disturbed’. Effects would generally be reversible;
A ‘significant’ consequence would threaten economic viability through a moderate increase in mortality/morbidity, or a moderate decrease in production. For noncommercial factors, the intrinsic ‘value’ of the criterion would be considered as significantly diminished or threatened. Effects may not be reversible; and
A ‘highly significant’ consequence would threaten economic viability through a large increase in mortality/morbidity, or a large decrease in production. For non-commercial factors, the intrinsic ‘value’ of the criterion would be considered as severely or irreversibly damaged.
The values are translated into a qualitative score (A –G) and are outlined in Table A.
35
Table A: Assessment for local, district, regional and PRA area consequences
G
F
E
-
-
-
-
-
Highly significant
-
Highly significant
Highly significant
Significant
Significant Minor significance
D
C
B
A
Highly significant
Significant
Minor significance
Unlikely to be discernible
Local
Significant
Minor significance
Unlikely to be discernible
Unlikely to be discernible
District
Minor significance
Unlikely to be discernible
Unlikely to be discernible
Unlikely to be discernible
Regional
Unlikely to be discernible
Unlikely to be discernible
Unlikely to be discernible
Unlikely to be discernible
PRA area
Geographic Level
The overall consequence for each pest was achieved by combining the qualitative scores
(A –G) for each direct and indirect consequence using a series of decision rules. These rules are mutually exclusive, and were addressed in the order that they appeared in the list — for example, if the first rule did not apply, the second rule was considered. If the second rule did not apply, the third rule was considered and so on until one of the rules applied:
Where the consequences of a pest with respect to any criteria is ‘G’, the overall consequences are considered to be ‘extreme’.
Where the consequences of a pest with respect to more than one criterion is ‘F’, the overall consequences are considered to be ‘extreme’.
W here the consequences of a pest with respect to a single criterion is ‘F’ and the consequences of a pest with respect to each remaining criterion is ‘E’, the overall consequences are considered to be ‘extreme’.
Where the consequences of a pest with respect to any direct or indirect criterion is ‘F’, the overall consequences are considered to be ‘high’.
Where the consequences of a pest with respect to all criteria is ‘E’, the overall consequences are considered to be ‘high’.
Where the consequences of a pest with respect to more than one criterion is ‘E’, the overall consequences are considered to be ‘moderate’.
Where the consequences of a pest with respect to a single criterion is ‘E’ and the consequences of a pest with respect to each remaining criterion is
‘D’, the overall consequences are considered to be ‘moderate’.
36
Where the consequences of a pest with respect to a single criterion is ‘E’ and the consequences of a pest with respect to remaining criteria is not unanimously ‘D’, the overall consequences are considered to be ‘moderate’.
Where the consequences of a pest with respect to all criteria is ‘D’, the overall consequences are considered to be ‘moderate’.
Where the consequences of a pest with respect to one or more criteria is ‘D’, the overall conseque nces are considered to be ‘low’.
Where the consequences of a pest with respect to all criteria is ‘C’, the overall consequences are considered to be ‘low’.
Where the consequences of a pest with respect to one or more criteria are considered
‘C’, the overall consequences are considered to be ‘very low’.
Where the consequences of a pest with respect to all criteria are ‘B’, the overall consequences are considered to be ‘very low’.
Where the consequences of a pest with respect to one or more criteria are consi dered ‘B’, the overall consequences are considered to be ‘negligible’.
Where the consequences of a pest with respect to all criteria is ‘A’, the overall consequences are considered to be ‘negligible’.
References cited
FAO 2004, Pest risk analysis for quarantine pests including analysis of environmental risks and living modified organisms (ISPM No 11). IN: International Standards for
Phytosanitary Measures 1 to 32 (2009 edition).
Secretariat of the International Plant
Protection Convention, Food and Agriculture Organisation of the United Nations. Rome,
Italy, P.140-166.
FAO 2006, Phytosanitary Principles for the Protection of Plants and the Application of
Phytosanitary Measures in International Trade (ISPM 1). IN: International Standards for
Phytosanitary Measures 1 to 32 (2009 edition).
Secretariat of the International Plant
Protection Convention, Food and Agriculture Organisation of the United Nations. Rome,
Italy, p.16-26.
37
Appendix 3: Risk estimation matrix
High
Moderate
Low
Very low
Negligible risk
Negligible risk
Negligible risk
Negligible risk
Very low risk
Very low risk
Negligible risk
Negligible risk
Extremely low
Negligible
Negligible risk
Negligible risk
Negligible impact
Negligible risk
Negligible risk
Very low impact
Low risk
Low risk
Very low risk
Negligible risk
Negligible risk
Negligible risk
Low impact
Moderate risk
Moderate risk
Low risk
Very low risk
Negligible risk
Negligible risk
Moderate impact
High risk
High risk
Moderate risk
Low risk
Very low risk
Negligible risk
High impact
Extreme risk
Extreme risk
High risk
Moderate risk
Low risk
Very low risk
Extreme impact
Economic consequence of entry, establishment and spread
38
