The ugly side of flowers

Feral Herald |
Imported roses and their many petals provide great hiding spots for invasive pests.
Imported roses and their many petals provide great hiding spots for invasive pests like thrips, ants and aphids.

Mother’s Day is one of the most dangerous events in the Australian calendar. In the preceding days millions of flowers are flown into the country – from Kenya, Colombia, Ecuador, Vietnam, Malaysia, China and more than a dozen other places [1].

And with these symbols of love – snug between petals, lurking in leaf crevices – come thrips, ants, aphids, mites, moths, beetles and other arthropods that are potential new invaders of Australia. Also along for the ride are pathogens and parasites that could harm Australia’s native plants or animals.

Over the decade to 2017, imports of cut flowers and foliage into Australia more than tripled, and detections of live arthropods (a group that includes insects and mites) at the Australian border more than quadrupled, from 13% to 58% of flower consignments [2]. Almost a quarter (23%) of the arthropods intercepted at the Australian border during this time arrived with flowers.

These are alarming figures. But it is no surprise that flowers and foliage harbour so many animals – there are millions of arthropods that pollinate, eat, parasitise or shelter on plants or that prey on or parasitise other animals on plants.

A high-risk pathway

Many of the flower and foliage hitchhikers are known invaders (note i). More than 250 mite, aphid and thrip species that travel with them are known to damage commercially valued plants or carry plant diseases [2] (note ii). More than half of these have already established within Australia – testifying to the porousness nature of borders to tiny animals.

The Invasive Insects Risks and Pathways project being undertaken by Monash University and the Invasive Species Council has found that the top three pathways by which insects travel around the world are all plant-based: contamination of imported plants and nursery material and the timber trade [3]. At least 70 insect species likely to travel with flower imports (mostly bugs, beetles and ants) have caused environmental harm somewhere in the world [3]. Because of the very limited research on insects causing environmental harm and the impossibility of identifying all such species, effective biosecurity requires a strong focus not just on ‘quarantine pests’ (note iii) or ‘regulated articles’ (note iv) (the species officially identified as biosecurity risks) but on pathways.

Flower imports are one of Australia’s highest risk pathways. The risks have escalated in recent years due to burgeoning imports, which now make up more than 20% of our flower consumption [2]. In the 12 years to 2018, consignments of cut flowers arriving in Australia more than tripled. And they have brought with them an enormous number of animals – there were 38,000 records of live arthropods intercepted at the border over the 18 years to 2018 [2].

The pathways by which invasive insects arrive in Australia are often unknown. According to the Victorian Farmers Federation the following invasive insects and pathogens that harm plant industries may have arrived on flower imports: Russian wheat aphid, western flower thrips, chrysanthemum white rust, alstomeria gall midge and myrtle rust (a serious environmental threat) [4]. The most recent arrival, Russian wheat aphid (Diuraphis noxia), causes stunting and sometimes the death of entire wheat and barley crops. It also attacks wild grasses. It was found in South Australia in 2016, and has spread to Victoria, Tasmania and New South Wales [5].

A focus on flowers

Thanks to an audit by the interim inspector-general of biosecurity in 2015 (and probably the years of agitation by Australia’s flower growers), the risks of the flower pathway have recently received a lot more attention. The audit identified shortcomings such as cartons of poor quality and with holes through which insects could escape, the failure of fumigation to kill all arthropods (due to complicated packaging impeding the circulation of methyl bromide) and the failure of some quarantine staff to adhere to inspection protocols [1].

At the time the agriculture department said it had ‘stringent offshore and border controls in place to manage the biosecurity risks posed by cut flower imports’ [quoted in 6]. All flower consignments were then being fumigated in Australia unless they were certified by the exporting country’s National Plant Protection Organisation or were consistently demonstrating freedom from live quarantine pests.

But two years later, a 2017 review by the agriculture department found that consignments from some countries were failing quarantine inspection more than half the time [2]. Since then, import conditions have been twice revised. The aim has been to better manage the biosecurity risks before flowers arrive in Australia, due to concern that over-reliance on methyl bromide fumigation in Australia increases the biosecurity risk [7].

From March 2018, each exporting country’s National Plant Protection Organisation (NPPO) was required to certify each consignment of flowers as pest-free, either through methyl bromide fumigation or other pest control treatment, or an NPPO-approved ‘systems’ approach (a combination of pest control measures in production, transport and packing areas) [8].

A media release by the agriculture department in November 2018 claimed that these new import conditions ‘effectively manage the associated biosecurity risks’ [9]. But the improvements have been minor at best – an interception rate of 50% in the year after the revised conditions compared to 58% the year before [2] (note v). In response, the agriculture department announced on 1 July 2019 that it would require importers of flowers from three countries with high trade volumes and poor compliance to apply for import permits (unless the flowers were fumigated), so as to enable greater oversight [10].

In June the agriculture department released part 1 of its pest risk analysis of flower imports, focusing on mites, thrips and aphids [2]. Part 2 focuses on other arthropods and is due later this year.

Box 1 below outlines the sequence of biosecurity assessments and revisions of import conditions as Australian authorities have attempted to reduce the number of flower consignments arriving in Australia with live arthropods.

System weaknesses

Lack of precaution: Not all flowers with live arthropods are fumigated when they arrive in Australia – only those with ‘actionable’ pests (those listed as quarantine pests or regulated articles). This means that arthropods with unknown impacts or carrying unknown diseases or parasites or that are misidentified or already in Australia and not under ‘official control’ are permitted to enter Australia (note vi).

While most crop pests are known, this is not the case for the natural environment. But the precautionary principle, which is meant to be applied in such circumstances, is not accepted under world trade rules. The current regime also enables entry to new strains or biotypes of species already established in Australia, which could boost their invasiveness, and new diseases or parasites. An exception is aphid species, which are all considered to be potential regulated articles because of their potential to carry quarantine viruses [2].

Lack of environmental information: The pest risk analysis for the flower pathway focuses mainly on economic risks, with potential environmental impacts considered as part of economic consequences. The risk assessments note ‘the potential for negative consequences such as environmental impact’ for 14 mite species, but not for any aphids or thrips [2]. None of the aphid species for which the Invasive Insects Risks and Pathways project found evidence of environmental impacts overseas are noted as environmental risks [3]. The assessment of environmental risks is greatly hampered by the scarcity of information on environmentally harmful species, but at the very least environmental consequences should be assessed separately from economic consequences and in as much detail as permitted by the available evidence.

Acceptance of risk: The agriculture department has said it aims to reduce non-compliance rates with flower imports from more than 50% to less than 10% [11]. Given the huge numbers of flowers being imported into Australia, this means the department accepts that a very large number of insects and mites will continue to arrive at our borders. It places a heavy reliance on biosecurity inspections at the Australian border to detect all non-compliant consignments. It is questionable whether this level of accepted non-compliance (even if it can be achieved) is consistent with Australia’s ‘appropriate level of protection’ (ALOP) – ‘a high level of protection aimed at reducing risk to a very low level, but not to zero’.

Rapid changes in risks: The pest risk analysis for flower imports reported that 17 new mite, aphid and thrip species had been intercepted in the prior year (March 2018 to February 2019), eight of which were assessed as quarantine pests and three as regulated or potential regulated articles. This occurred during a time when there was a concerted focus on this pathway due to the pest risk analysis. But what happens when there is not such a focus? The biosecurity system does not have enough resources to keep up with rapid changes in risk across all pathways. The risks of many pathways have not been comprehensively analysed. It wasn’t until 2017 that the department reviewed the import conditions for flower imports despite it being known as a high-risk pathway.

Trade pressures: Because Australia exports so much agricultural produce, the agriculture department comes under pressure to limit the import conditions it imposes on other countries to avoid retaliatory measures. This conflict of interest is intensified because the department is tasked both with increasing agricultural trade and managing biosecurity. (The agriculture department website says its overarching purpose is to ‘work with national and international governments and industry partners to grow the value of agricultural trade and reduce risk to the agricultural sector’[12]).

A 2019 submission by a company that says it is ‘Australia’s leading flower company’, WAFEX, accuses the department of being heavy-handed with exporting countries and warns they will retaliate [13]:

NPPOs resent the way they have been treated, resent the way in which they have been communicated with and will pay Australia back for its approach when it comes to trade the other way – an example being that China recently announced that it is ceasing approval of fumigation treatment for fruit flies in Australian exports.

Will the new import conditions prevent new harmful species arriving with imported flowers and establishing in Australia? That seems unlikely given the large numbers of insects and mites that will continue to arrive on flowers, the reliance on border inspections to detect non-compliant imports, and the non-precautionary release of imports with live arthropods despite the very poor knowledge of their environmental (and often industry) risks.

Box 1: A timeline of biosecurity changes for flower imports

1996: Because live ‘quarantine pests’ were frequently detected on imported flowers, it became mandatory for all consignments to be fumigated on arrival with methyl bromide [1].

2013: A new scheme was introduced to encourage suppliers to reduce pests on flowers before exporting them [1]. Suppliers in certain countries were exempted from fumigation in Australia if they were certified by their country’s National Plant Protection Organisation, and other suppliers were exempted if they could demonstrate freedom from live quarantine pests in five consecutive consignments. All imported flowers were to be inspected on arrival and fumigated if live quarantine pests were found.

January 2015: An audit of biosecurity controls for imported flowers by the interim inspector-general of biosecurity found several shortcomings [1]. Some flowers were arriving in cartons of poor quality or with holes that could allow pests to escape. The complicated packaging of flowers (cardboard, plastic and cellophane) can impede the circulation of methyl bromide and prevent full fumigation. Although live insects had been found after fumigation, the consignments were generally not re-inspected to check whether it had been effective. Some quarantine staff were not complying with inspection protocols – for example, by failing to check the required number of flowers and seal packages before consignments were moved and by clearing packages with holes.

September 2016: The agriculture department started inspecting flowers after methyl bromide fumigation to assess its effectiveness [14]. The results are not publicly available.

September 2017: The agriculture department reviewed the import conditions for flower imports and found that consignments from some countries were failing quarantine inspection more than 50% of the time [8]. It recommended a shift in focus from fumigation in Australia to managing biosecurity risks before export.

March 2018: New import conditions require each exporting country’s National Plant Protection Organisation to certify flowers as free of quarantine pests before they are sent to Australia [8]. This can be achieved by fumigation with methyl bromide or other treatments, or by a systems approach.

June 2019: The Final Pest Risk Analysis for Cut Flower and Foliage Imports—Part 1 was released [2] (note vii). It assessed the 259 species of mites, aphids and thrips known to be associated with the flower pathway. Of these, 47 mites, 21 aphids and 84 thrips are identified as quarantine pests or regulated articles for Australia and 32 aphids are potential regulated articles because they can transmit viruses that are quarantine pests. The analysis found that the current risks for all three groups are too high to meet Australia’s ‘appropriate level of protection’. In 2017, live arthropods were detected in 58% of flower consignments and in the year after the March 2018 regulations, live pests of biosecurity concern were detected in 50% of consignments.

September 2019: Australia will require import permits for flowers from Kenya, Colombia and Ecuador that are produced under a ‘systems’ approach, to enable greater oversight [10]. These countries have ‘very high’ rates of non-compliance and high volumes of trade. Flowers that are treated in the exporting countries using methyl bromide or the like will not require an import permit.


1. Interim Inspector-General of Biosecurity (2015): Effectiveness of biosecurity controls for imported fresh cut flowers. Audit report. Australian Government.
2. Department of Agriculture (2019): Final pest risk analysis for cut flower and foliage imports—Part 1. Australian Government.
3. Invasive insects: risks and pathways. Unpublished data (2019): Monash University and Invasive Species Council.
4. Victorian Farmers Federation, Flowers Australia (2018): Submission on the draft pest risk analysis for cut flower and foliage imports – part 1. Victorian Farmers Federation.
5. Perry K, Kimber B (2016): Russian wheat aphid, Diuraphis noxia. CESAR. Retrieved from
6. Milman O (2015): As imported flower numbers bloom the biosecurity threat grows, report finds. The Guardian. 17 March. Retrieved from
7. Department of Agriculture and Water Resources (2018): Questions and answers. Australian Government. Retrieved from
8. Department of Agriculture (2017): Industry advice notice 86-2017. Changing of import conditions of fresh cut flowers. Australian Government. Retrieved from
9. Department of Agriculture (2018): Media statement. Biosecurity assurance for cut flower and foliage imports. 14 November 2018. Australian Government. Retrieved from
10. Department of Agriculture (2019): Industry advice notice 108-2019: Permits required from 1 September for imports of cut flowers and foliage from countries with high non-compliance and high volumes of trade. 1 July 2019. Australian Government. Retrieved from
11. Department of Agriculture and Water Resources (2018): Imported flowers and foliage regulation working group. Update on implementation of new import conditions. Australian Government.
12. Department of Agriculture (2019): What we do. Our purpose. Australian Government. Retrieved from
13. Wafex (n.d.): Wafex submission on the draft report for the pest risk analysis for cut flower and foliage imports—Part 1.
14. Department of Agriculture (2016): Industry advice notice 88-2016: Post fumigation verification inspections on cut flowers and fresh produce. 13 September 2016. Australian Government. Retrieved from


i. From hereon, when we refer to ‘flowers’ we mean ‘cut flowers and foliage’.

ii. These are listed in the Appendix G of reference 2. At 30 June 2019, 259 species were of ‘biosecurity concern’ to Australia: 152 species were identified as ‘quarantine pests’ and/or ‘regulated articles’ and 136 species are already present in Australia (26 of which are quarantine pests due to efforts to eradicate or contain them).

iii. Defined in reference 2 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 2019)’.

iv. Defined in reference 2 as ‘Any plant, plant product, storage place, packaging, conveyance, container, soil and any other organism, object or material capable of harbouring or spreading pests, deemed to require phytosanitary measures, particularly where international transportation is involved (FAO 2019).’

v. Furthermore, the 50% figure for the year after the revised conditions applied to ‘live pests of biosecurity concern’, whereas the 58% figure applied to all live arthropods, which includes many species that are not of biosecurity concern (see reference 2).

vi. Defined in reference 2 as ‘The active enforcement of mandatory phytosanitary regulations and the application of mandatory phytosanitary procedures with the objective of eradication or containment of quarantine pests or for the management of regulated non-quarantine pests (FAO 2019)’.

vii. The pest risk analysis does not examine all risks of the flower pathway, particularly many pathogens transmitted by arthropods.

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