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Final policy review: Alternative risk management measures to import Lilium spp cut flowers from Taiwan


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1.10Stage 3: Pest risk management


Pest risk management describes the process of identifying and implementing phytosanitary measures to manage risks to achieve Australia's ALOP, while ensuring that any negative effects on trade are minimised.

The conclusions from pest risk assessment are used to decide whether risk management is required and if so, the appropriate measures to be used. Where the unrestricted risk estimate exceeds Australia’s ALOP, risk management measures are required to reduce this risk to a very low level. The guiding principle for risk management is to manage risk to achieve Australia’s ALOP. The effectiveness of any proposed phytosanitary measure (or combination of measures) is evaluated, using the same approach as used to evaluate the unrestricted risk, to ensure it reduces the restricted risk for the relevant pest or pests to meet Australia’s ALOP.

ISPM 11 (FAO 2004) provides details on the identification and selection of appropriate risk management options and notes that the choice of measures should be based on their effectiveness in reducing the probability of entry of the pest.

Examples given of measures commonly applied to traded commodities include:

options for consignments – inspection or testing for freedom from pests, prohibition of parts of the host, a pre-entry or post-entry quarantine system, specified conditions on preparation of the consignment, specified treatment of the consignment, restrictions on end-use, distribution and periods of entry of the commodity

options preventing or reducing infestation in the crop – treatment of the crop, restriction on the composition of a consignment so it is composed of plants belonging to resistant or less susceptible species, harvesting of plants at a certain age or specified time of the year, production in a certification scheme

options ensuring that the area, place or site of production or crop is free from the pest – pest-free area, pest-free place of production or pest-free production site

options for other types of pathways – consider natural spread, measures for human travellers and their baggage, cleaning or disinfestation of contaminated machinery

options within the importing country – surveillance and eradication programs prohibition of commodities – if no satisfactory measure can be found.

Risk management measures are identified for each quarantine pest where the risk exceeds Australia’s ALOP. These are presented in the ‘Pest Risk Management’ section of this report.


Pest risk assessments for quarantine pests


Pest categorisation identified twenty quarantine pests associated with Lilium spp. from Taiwan. These pests are listed in Table 4.1. Full details of the pest categorisation are provided in Appendix A. Pests are listed according to their taxonomic classification, consistent with Appendix A.

Table 4.1 Quarantine pests for Lilium spp. cut flowers from Taiwan



      Pest

Common name

      ARTHROPODS

COLEOPTERA (beetles, weevils)




Harmonia axyridis (Pallas) [Coccinellidae]

Lilioceris formosana Heinze [Chrysomelidae]

Sangariola punctatostriata (Motschulsky) [Chrysomelidae]

Harlequin ladybird

Leaf beetle

Lily leaf flea beetle


DIPTERA (flies, gnats, midges)




Chromatomyia horticola Goureau [Agromyzidae]

Liriomyza huidobrensis (Blanchard) [Agromyzidae]

Liriomyza trifolii (Burgess) [Agromyzidae]

Leafminer

Leafminer

Leafminer


HEMIPTERA (aphids, leafhoppers, mealybugs, psyllids, scales, true bugs, whiteflies)

Pseudococcus comstocki (Kuwana) [Pseudococcidae]

Comstock's mealybug

LEPIDOPTERA (moths, butterflies)




Agrotis segetum Denis & Schiffermüller [Noctuidae]

Euproctis taiwana (Shiraki) [Lymantriidae]

Kaniska canace Linnaeus [Nymphalidae]

Orgyia postica Walker [Lymantidae]

Xylena formosa (Butler) [Noctuidae]

Cutworm, dark moth

Tussock moth

Blue admiral

Tussock moth

Cutworm


THYSANOPTERA (thrips)




Frankliniella intonsa (Trybom) [Thripidae]

Haplothrips chinensis Priesner [Phlaeothripidae]

Megalurothrips distalis (Karny) [Thripidae]

Flower thrips

Chinese thrips

Bean blossom thrips


VIRUSES




Lily mottle virus LMoV [Potyviridae: Potyvirus]

Lily virus X LVX [Flexiviridae : Potexvirus] (synonym Lily X potexvirus)

Plantago asiatica mosaic virus PlAMV [Alphaflexiviridae : Potexvirus]

Strawberry latent ringspot virus SLRSV [Secoviridae : Genus Unassigned] Tobacco ringspot nepovirus TRSV [Secoviridae : Nepovirus]





1.10.1Quarantine pests assessed in previous policies


The pests in Table 4.1 were considered in relation to the existing policy for the importation of cut flowers, which requires flowers to be non-propagable and free of arthropod pests. As the existing policy addresses the risk of arthropods and pathogens generally, a number of pests from Table 4.1 were examined in more detail.

The following pests have been assessed previously by the Department of Agriculture:

Harlequin ladybird (Harmonia axyridis) and Comstock’s mealybug (Pseudococcus comstocki) have previously been assessed for the importation of table grapes from China (Biosecurity Australia 2011).

Flower thrips (Frankliniella intonsa) has previously been assessed for the importation of stone fruit from California, Idaho, Oregon and Washington (Biosecurity Australia 2010a).



Strawberry latent ringspot virus has previously been assessed for the importation of hop propagative material (Biosecurity Australia 2010b).

The policy for these four pests was reviewed taking the following information into consideration, to determine if pest risk management measures are required for Lilium cut flowers from Taiwan.


1.10.2Probability of entry


The probability of entry describes the probability that a quarantine pest will enter Australia as a result of trade in a given commodity, be distributed in a viable state in the PRA area and subsequently be transferred to a host.

Probability of importation

  • Lilium spp. flowers are assumed to come from areas where the above pests occur and are, therefore, likely to enter on imported lily cut flowers.

  • The pests’ ability to survive on host cut flowers that are maintained in healthy condition during transport acts to assist their viability en route to, and during distribution across, Australia.

  • Viruses, as a rule, systemically infect all parts of host plants. Therefore, cut flowers provide a pathway for viruses.

  • The bulk of Taiwan’s imports of certified bulbs for planting are from the Netherlands. Planting stock is of high health status and certified for freedom from viruses of quarantine concern for Taiwan by the Netherlands. Additionally, new quarantine requirements for lily bulbs imported into Taiwan from many lily bulb producing countries (section 2.3.1) require that all imported bulbs be inspected or tested for Plantago asiatica mosaic virus (PlAMV) and found to be virus free during production (WTO 2013). Similar requirements are proposed for Arabis mosaic virus (ArMV) (WTO 2012). Therefore, the probability of infected mother plants in Taiwan will be reduced and the entry of infected cut flowers into Australia through cut flower importations will be similarly reduced.

  • Commercially grown lily cut flowers that are visibly infected with viruses or showing obvious pest damage would not be picked or suitable for sale.

  • Due to their short shelf life, Lilium spp. cut flowers will be transported in cool conditions, which are unlikely to adversely affect survival of arthropod pests and viruses.

  • Cut flowers may contain arthropod pests which may be hidden in stem sheaths or closed flowers. These pests may not be detected by inspection.

  • Due to the nature of packaging arthropod pests are likely to remain associated with the commodity.

The above information supports the estimates for the pests previously considered in the existing policies listed above. The probabilities of importation for Harmonia axyridis, Pseudococcus comstocki, Frankliniella intonsa and Strawberry latent ringspot virus were assessed as: HIGH.
Probability of distribution

  • Upon arrival in Australia, arthropod pests may readily be distributed to susceptible hosts. Identified pests such as thrips and coleopterans are quite mobile with wide host ranges and are likely to readily find a suitable host species. Lilium spp. cut flowers are likely to be widely distributed through florists and other points of sale. Due to the short shelf life of lily cut flowers, their distribution is likely to occur soon after importation, which will assist the probability of arthropods being distributed in a viable state.

  • Lilium spp. cut flowers may be disposed of via municipal waste systems, or could be discarded as green waste in backyard compost heaps, or on roadsides or in other locations. The disposal of lily cut flowers in municipal waste is likely to reduce the probability of arthropod pests locating a suitable host plant. However, disposal in other locations may place infested material in close proximity to suitable hosts.

The above information supports the estimates for the pests previously considered in the existing policies listed above. The probabilities of distribution for Harmonia axyridis and Strawberry latent ringspot virus were assessed as: HIGH. Pseudococcus comstocki and Frankliniella intonsa were assessed as: MODERATE.

Overall probability of entry

The overall probability of entry is determined by combining the probability of importation and the probability of distribution. The likelihood that these pests will enter Australia as a result of trade in lily cut flowers is HIGH for Harmonia axyridis and Strawberry latent ringspot virus, and MODERATE for Pseudococcus comstocki and Frankliniella intonsa.


1.10.3Probability of establishment


Establishment is defined as the ‘perpetuation for the foreseeable future, of a pest within an area after entry’ (FAO 2012).

  • The categorisation process has not highlighted any fungal or stramenopile pests that are associated with Lilium spp. cut flower imports from Taiwan. The pests of concern are viruses and arthropods.

  • Once arthropod pests have been distributed to a susceptible host, the likelihood of establishment is considered high.

  • Due to the systemic nature of viruses, propagative material is typically a major pathway for establishment. However, lily cut flowers that are free of bulbils are not readily propagable; therefore, systemic pests are unlikely to establish via propagation.

  • Australia currently permits the entry of millions of certified and non-certified bulbs imported mostly from the Netherlands, but also from New Zealand, Chile and the USA for production in open quarantine. Bulbs for production in Taiwan are also sourced from the Netherlands and other countries. The risk of establishment of viruses from imported cut flowers is not considered to be higher than from existing open quarantine production and subsequent retail sale of bulbs imported into Australia.

The above information supports the estimates for the pests previously considered in the existing policies listed above. The probabilities of establishment for Harmonia axyridis, Pseudococcus comstocki, Frankliniella intonsa and Strawberry latent ringspot virus were assessed as: HIGH.

Probability of spread


Spread is defined as ‘the expansion of the geographical distribution of a pest within an area’ (FAO 2012). The probability of spread considers the factors relevant to the movement of the pest, after establishment on a host plant or plants, to other susceptible host plants of the same or different species in other areas.

  • Some lily pests are polyphagous, so suitable hosts are likely to be widely available, increasing the likelihood of spread.

  • Gradual unassisted expansion of arthropod pest populations into new areas would be expected where favoured hosts are available and suitable environmental conditions are present. Some pests are capable of flying, or being carried by wind, for considerable distances.

  • Long distance dispersal of arthropod pests is likely to occur through movement of infested plant material such as nursery stock and garden waste.

  • Propagative material is a potential pathway for the dispersal of systemic pests (such as viruses). However, lily cut flowers that are free of bulbils are not readily propagable.

The above information supports the estimates for the pests previously considered in the existing policies listed above. The probabilities of spread for Harmonia axyridis, Pseudococcus comstocki and Frankliniella intonsa were assessed as: HIGH. Strawberry latent ringspot virus was assessed as: MODERATE.

Overall probability of entry, establishment and spread

The probability of entry, establishment and spread is determined by combining the probabilities of entry, of establishment and of spread. The overall probability that these pests will enter Australia as a result of trade in lily cut flowers, establish and subsequently spread was estimated to be HIGH for Harmonia axyridis, and MODERATE for Pseudococcus comstocki, Frankliniella intonsa and Strawberry latent ringspot virus.


1.10.4Consequences


The introduction of pests that meet the criteria of a quarantine pest will have unacceptable economic consequences in Australia as these pests will cause a variety of direct and indirect economic impacts. The identified pests are of economic concern and do not occur in Australia. A summary and justification is provided below:

  • Direct impacts of the introduction and spread of multi-host pests in Australia will not only affect the imported host but also other hosts. Introduction and establishment of quarantine pests in Australia would not only result in phytosanitary regulations imposed by foreign or domestic trading partners, but also in increased costs of production including control costs.

  • Quarantine pest introduction and establishment would also be likely to result in industry adjustment. The potential economic impact for cut flowers is high. Without controls these pests have the potential to spread further in the trade network and could potentially expand their host range.

  • Arthropod pests such as flower thrips can cause damage to ornamental flower buds, and to flowers of many leguminous plants or fruit crops, which will not only require control if they establish and spread; they will affect cut flower trade as phytosanitary restrictions can apply.

  • Most viruses of quarantine concern on lilies affect ornamentals and can cause deformation, asymmetrical opening of flowers, or necrosis and discolouration leading to decreased flower value and potential loss of markets locally and internationally. Others such as Tobacco ringspot nepovirus and Strawberry latent ringspot virus have a wide host range and can affect different crop species and ornamentals.

  • Viruses are considered important as they cause a variety of direct and indirect economic impacts, such as reduced yield, reduced commodity value and loss of foreign or domestic markets. Therefore, these pests have a potential for economic consequences in the PRA area. Cut flowers do not present a direct pathway for viruses, which need to be vectored into suitable hosts. However, the presence of these pathogens in Australia would impact upon Australia’s ability to access overseas markets.

The above information supports the estimates for the pests previously considered in the existing policies listed above. The consequences for Harmonia axyridis were assessed as: MODERATE. Pseudococcus comstocki, Frankliniella intonsa and Strawberry latent ringspot virus were assessed as: LOW.

1.10.5Unrestricted risk estimate


Unrestricted risk is the result of combining the probability of entry, establishment and spread with the outcome of overall consequences.

For the four pests reviewed above, the unrestricted risk was previously estimated to be MODERATE for Harmonia axyridis and LOW for Pseudococcus comstocki, Frankliniella intonsa and Strawberry latent ringspot virus.

The review of existing policy identified that these four pests had an unrestricted risk for Lilium spp. cut flowers above Australia’s appropriate level of protection (ALOP), a rating of greater than ‘very low’, and require pest risk management measures. These pest risk management measures will also address the risk posed by the quarantine pests listed in Table 4.1.

Table 4.2 Summary of unrestricted risk estimates for example quarantine pests






Likelihood of

Consequences

URE

Pest name

Entry

Establishment

Spread

P[EES]

Importation

Distribution

Overall

Beetles [Coleoptera: Coccinellidae]

Harmonia axyridis

H

H

H

H

H

H

M

M

Mealybugs [Hemiptera: Pseudococcidae]

Pseudococcus comstocki

H

M

M

H

H

M

L

L

Thrips [Thysanoptera: Thripidae]

Frankliniella intonsa

H

M

M

H

H

M

L

L

Viruses

Strawberry latent ringspot virus

H

H

H

H

M

M

L

L


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