Importation of Leaves of Allium spp. from Hawaii

into the Continental United States

A Qualitative, Pathway-Initiated Pest Risk Assessment

October 3, 2013

Version 1

Agency Contact:

Plant Epidemiology and Risk Analysis Laboratory

Center for Plant Health Science and Technology

United States Department of Agriculture 

Animal and Plant Health Inspection Service

Plant Protection and Quarantine

1730 Varsity Drive, Suite 300

Raleigh, NC 27606
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 i

Executive Summary

The Animal and Plant Health Inspection Service (APHIS) of the United States Department of 

Agriculture (USDA) prepared this risk assessment document to examine plant pest risks 

associated with importing commercially produced leaves of Allium spp. (Liliaceae) for 

consumption from Hawaii into the continental United States. Based on the market access request 

from Hawaii, there are currently no known processes and conditions for the production and 

shipment of leaves of allium. 

Based on the scientific literature, port-of-entry pest interception data, and information from the 

Hawaii Department of Agriculture (HDOA), we developed a list of all potential pests with 

actionable regulatory status for the continental United States that are known to occur in Hawaii

and that are known to be associated with the commodity plant species anywhere in the world.

From this list, we identified and further analyzed five arthropods that have a reasonable 

likelihood of being associated with the commodity following harvesting from the field and prior 

to any post-harvest processing.

Of the pests selected for further analysis, we determined that the following are not candidates for 

risk management, either because there is no endangered area within the continental United 

States, or they did not meet the threshold to likely cause unacceptable consequences of 

introduction: Thrips alliorum (Thysanoptera: Thripidae) and Thrips palmi (Thysanoptera: 

Thripidae).

We determined that the following pests are candidates for risk management, because they met 

the threshold to likely cause unacceptable consequences of introduction, and they received 

an overall likelihood of introduction risk rating above Negligible:

Taxonomy Scientific name Likelihood of Introduction 

overall rating

Lepidoptera: Acrolepiidae Acrolepiopsis sapporensis 

(Matsumura)

Medium

Lepidoptera: Noctuidae Spodoptera litura (Fabricius) Medium

Thysanoptera: Thripidae Scirtothrips dorsalis Hood High

Detailed examination and choice of appropriate phytosanitary measures to mitigate pest risk are 

part of the pest risk management phase within APHIS and are not addressed in this document.
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 ii

Table of Contents

Executive Summary....................................................................................................................... i

1. Introduction............................................................................................................................... 1

1.1. Background .......................................................................................................................... 1

1.2. Initiating event...................................................................................................................... 1

1.3. Determination of the necessity of a weed risk assessment for the commodity.................... 1

1.4. Description of the pathway................................................................................................... 2

2. Pest List and Pest Categorization............................................................................................ 3

2.1. Pests considered but not included on the pest list ................................................................ 3

2.2. Pest list ................................................................................................................................. 6

2.3. Pests selected for potential analysis..................................................................................... 8

3. Assessing Pest Risk Potential ................................................................................................... 8

3.1. Introduction .......................................................................................................................... 8

3.2. Assessment results................................................................................................................ 9

4. Summary and Conclusions of Risk Assessment................................................................... 21

5. Acknowledgements ................................................................................................................. 22

6. Literature Cited ...................................................................................................................... 22

7. Appendix A.............................................................................................................................. 32

Pests with non-actionable regulatory status .............................................................................. 32
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1. Introduction 

1.1. Background

This document was prepared by the Plant Epidemiology and Risk Analysis Laboratory of the 

Center for Plant Health Science and Technology, USDA Animal and Plant Health Inspection 

Service (APHIS), Plant Protection and Quarantine (PPQ), to evaluate the risks associated with 

the importation of commercially produced fresh leaves of all Allium species for consumption 

from Hawaii into the continental United States. In addition to reviewing the pathway of all 

species of Allium, Hawaii has indicated specific interest in production and shipment of French 

chives, A. schoenoprasum L., which we considered in this assessment.

The International Plant Protection Convention (IPPC) provides guidance for conducting pest risk 

analyses. The methods used here are consistent with guidelines provided by the IPPC, 

specifically the International Standard for Phytosanitary Measures (ISPM) on ‘Pest Risk 

Analysis for Quarantine Pests, Including Analysis of Environmental Risks and Living Modified 

Organisms’ (IPPC, 2011). The use of biological and phytosanitary terms is consistent with the 

‘Glossary of Phytosanitary Terms’ (IPPC, 2012). 

Three stages of pest risk analysis are described in international standards: Stage 1, Initiation;

Stage 2, Risk Assessment; and Stage 3, Risk Management. This document satisfies the 

requirements of Stages 1 and 2.

This is a qualitative risk assessment. We express the risk based on qualitative ratings for the 

likelihood and consequences of pest introduction via the imported allium from Hawaii. The 

details of the methodology and rating criteria are found in the Guidelines for Plant Pest Risk 

Assessment of Imported Fruit and Vegetable Commodities, Version 6.0 (PPQ, 2012).

The appropriate risk management strategy for a particular pest depends on the risk posed by that 

pest. Identification of appropriate phytosanitary measures to mitigate pest risk is undertaken in 

Stage 3 (Risk Management) and is not covered in this risk assessment. Risk management will be 

specified in a separate document.

1.2. Initiating event

Currently under regulation 7 CFR 318.13 the entry of Allium leaves from Hawaii into the 

continental United States is not authorized. This assessment was prepared in response to a 

request from the Hawaii Department of Agriculture with support from the Hawaii State Plant 

Health Director to change the Federal Regulation to allow entry (Alontaga, 2011).

1.3. Determination of the necessity of a weed risk assessment for the commodity

In some cases, the imported commodity could become invasive in the PRA area. The likelihood 

that this may happen is evaluated in a weed risk assessment, conducted separately from the 

commodity risk assessment.
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Ver. 1 October 3, 2013 2

Weed risk assessments do not need to be conducted for plant species that are widely established 

(native or naturalized) or cultivated in the PRA area, for commodities that are already enterable 

into the PRA area from other countries, or when the plant part(s) cannot easily propagate on their 

own or be propagated. We determined that a weed risk assessment is not needed for Allium spp. 

because the proposed commodity does not contain any propagules (sexual or vegetative) that 

could lead to the establishment of Allium plants in the United States.

1.4. Description of the pathway

The IPPC (2011) defines a pathway as “any means that allows the entry or spread of a pest.” In

the context of commodity pest risk assessments, the pathway is the commodity to be imported, 

together with all the processes the commodity undergoes that may have an impact on pest risk. In 

this risk assessment, the specific pathway of concern is the importation of fresh leaves of species 

of Allium L. for consumption from Hawaii into the continental United States; the movement of 

this commodity provides a potential pathway for the introduction and/or spread of plant pests. 

The following description of this pathway focuses on the conditions that may affect plant pest 

risk, including morphological and physiological characteristics of the commodity, as well 

processes the commodity will undergo from production in Hawaii through importation and 

distribution in the continental United States. These conditions provided the basis for creating the 

pest list and assessing the likelihood of introduction of the pests selected for further analysis; 

therefore, all components of the pathway, as they are described below, should be considered 

mandatory conditions for importation of the commodity.

1.4.1. Description of the commodity

Hawaii seeks to export the leafy, aboveground portions of Allium spp. to the continental United 

States. If all Allium spp. are not acceptable, Hawaii requests specific information regarding 

French chives, A. schoenoprasum (Wong, 2011). The leaves of French chives, A.

schoenoprasum, are described as 6-10 inches long, slender, and tubular (Myers and Voss, 1998). 

Both fresh and dried chives are frequently used as garnish and seasoning (Myers and Voss, 

1998). We currently have no information about production practices for these crops. 

1.4.2. Production and harvest procedures in the exporting area 

Production and harvesting procedures in the exporting area have not been specified.

1.4.3. Post-harvest procedures in the exporting area

Post-harvest procedures in the exporting area have not been specified.

1.4.4. Shipping and storage conditions

Shipping and storage conditions have not been specified. McGregor (1987) describes shipping 

conditions for leeks to be bundled, 1-2 dozen per bunch, with rubber band, and refrigerated at 0 

degrees C and 95-100 percent relative humidity.

1.4.5. Summary of the pathway

In Figure 1, we summarize the pathway of concern: the importation of fresh leaves of Allium

species for consumption from Hawaii into the continental United States.
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Figure 1. Summary of the pathway for the importation of fresh leaves of species of Allium L. for 

consumption from Hawaii into the continental United States.

2. Pest List and Pest Categorization 

In this section, we identify the plant pests with actionable regulatory status for the continental 

United States that could potentially become established in the continental United States as a 

result of the importation of Allium leaves from Hawaii, and we determine which of these pests 

meet the criteria for further analysis. Pests are considered to be of regulatory significance if they

are actionable at U.S. ports-of-entry. Actionable pests include quarantine pests, pests considered 

for or under official control, and pests that require evaluation for regulatory action.

2.1. Pests considered but not included on the pest list

2.1.1. Pests with weak evidence for association with the commodity or for presence in the export 

area

Acrolepiopsis assectella. While we found many references indicating that A. assectella (Zeller) 

(Lepidoptera: Acrolepiidae) is established in Hawaii (e.g., Fullaway and Krauss, 1945; Mau and 

Lee, 1995), these are misidentifications of A. sapporensis (Gaedike, 1997). Acrolepiopsis

assectella is not known to be present in Hawaii and therefore we did not list it below. 

Bactrocera cucurbitae. Dry onion (Allium cepa) is a doubtful host of B. cucurbitae Coquillett

(Diptera: Tephritidae) under induced oviposition (McBride and Tanda, 1949, as cited by Dhillon 

et al., 2005). For this reason, we did not include B. cucurbitae on the pest list.

Chrysodeixis chalcites. Chrysodeixis chalcites (Esper) (Lepidoptera: Noctuidae) is a highly 

polyphagous pest (CABI, 2012). One database indicates that Allium and A. cepa are hosts 

(Robinson et al., 2012) but we found no additional information that Allium species are natural 

hosts for C. chalcites. Therefore, we did not include this species on the pest list.

Cryptoblabes gnidiella. Evidence indicates that C. gnidiella (Millière) (Lepidoptera: Pyralidae) 

may damage stored garlic bulbs (El-Zemaity et al., 2009; Salama, 2008). We found no evidence 
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Ver. 1 October 3, 2013 4

indicating that this species affects Allium in production fields. Therefore, we did not include this 

species on the pest list.

Dysmicoccus neobrevipes. While Allium cepa is occasionally listed as a host for D. neobrevipes

Beardsley (Hemiptera: Pseudococcidae) (e.g., Ben-Dov et al., 2012), the original association was 

based on interception records (Williams, 2004). Dysmicoccus neobrevipes has only been 

intercepted twice in baggage at ports-of-entry in the United States (PestID, 2012), which is 

insufficient evidence for a host association. We found no other evidence for this host association. 

Therefore, we did not include D. neobrevipes on the pest list.

Gryllotalpa africana. The host status of Allium cepa for G. africana Palisot de Beauvois

(Orthoptera: Gryllotalpidae) is “Other” (CABI, 2012). We found no additional references 

indicating that G. africana is a pest of Allium spp. Moreover, mole crickets are root pests, and 

would not be associated with leaves of the host plant. Consequently, we did not list this pest.

Helicoverpa assulta. Helicoverpa assulta (Guenée) (Lepidoptera: Noctuidae) is a minor pest of 

Allium spp. (Hill, 1983) but we could not confirm its presence of in Hawaii, except for a mention 

in the Bishop Museum (2002) database. Therefore, we did not include this species on the pest 

list.

Leucania loreyi. Fifty years ago, L. loreyi (Duponchel) (Lepidoptera: Noctuidae) was reported to 

be a pest of Allium cepa (Le Pelley, 1959). More recently, sources only indicate that maize and 

sugar cane are infested by L. loreyi in the field (El-Sherif et al., 1972). Therefore, we did not 

include this pest on the pest list.

Liriomyza huidobrensis. Liriomyza huidobrensis is a leafmining fly that has repeatedly been 

listed as a pest of Allium in Hawaii (Hamasaki et al., 1999; Kobayashi and Bittenbender, 2002; 

Steck, 2008; Wong, 2011). It is morphologically identical to and synonymous with L. langei

(Spencer, 1973). While L. huidobrensis was thought to be present in California and Hawaii, 

recent advances in molecular systematics reveal that the leafminer found in California and 

Hawaii is a separate, cryptic species of L. huidobrensis (Scheffer, 2000; Scheffer and Lewis, 

2001; Scheffer et al., 2001). The name L. huidobrensis has thus been restricted to species from 

Central and South America, and L. langei is now used for the species in California and Hawaii 

(Scheffer and Lewis, 2001). Liriomyza huidobrensis is not currently present anywhere in the 

United States, and we did not include it on the pest list.

Spodoptera littoralis. Some confusion exists about the distribution of S. littoralis (Boisduval) 

(Lepidoptera: Noctuidae) in comparison with the distribution of the similar species, S. litura

(CABI, 2012). In general, only S. litura is established in the Pacific Islands (CABI, 2012). Thus, 

we did not list S. littoralis. 

Thrips florum. The polyphagous pest T. florum Schmutz (Thysanoptera: Thripidae) is listed as a 

pest of Allium cepa with unknown context (CABI, 2012). We found no additional information 

regarding the potential host status of Allium spp. for T. florum. Therefore, we did not include this 

pest. 
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Mollusks. Cornu aspersum Müller (Helicidae) (action only to FL, AL, PR), Lissachatina fulica

(Bowdich) (Achatinidae), and Sarasinula plebeia Fischer (Veronicellidae) are polyphagous 

grazers (CABI, 2012). Allium species are listed as “hosts” (e.g., CABI, 2012; Gallego and Velez, 

1992; Raut and Barker, 2002), but pest interceptions since 1984 do not indicate that Allium spp. 

are a common pathway for movement of these species (PestID, 2012). Various mollusk species 

have been intercepted 225 times at US ports of entry associated with Allium sp. (PestID, 2012). 

However, of the species of concern in this document, there is only one recorded interception of 

C. aspersum associated with permitted cargo (PestID, 2012), considered insufficient data for an 

open pathway. Thus, we did not include these species on the pest list.

Phytophthora manoana. While listed as a plant disease occurring on Allium in Hawaii by 

Nelson et al. (2009; from the market access request submitted by Hawaii), the authors do not 

consider P. manoana Sid. to be a valid species. We found no additional information regarding 

the status of this species, and therefore did not include it on the pest list.

Phytophthora meadii. Allium cepa became infected with Phytophthora meadii McRae via 

artificial inoculation (Erwin and Ribeiro, 1996, citing Tucker, 1933). Although P. meadii has a 

broad host range, we found no additional evidence that Allium species are natural hosts. 

Therefore, we did not include P. meadii on the pest list.

2.1.2. Organisms with non-actionable regulatory status

We found evidence of the organisms listed in Appendix A being associated with Allium and 

being present in Hawaii; however, because these organisms have non-actionable regulatory

status for the continental United States, we did not include them in Table 2 of this risk 

assessment.

2.1.3. Organisms identified only to the genus level

In commodity import risk assessments, the taxonomic unit for pests selected for evaluation 

beyond the pest categorization stage is usually the species (IPPC, 2011), as assessments focus on 

organisms for which biological information is available. Therefore, generally, we do not assess 

risk for organisms identified only to the genus level, in particular if the genus in question is 

reported in the import area. Often there are many species within a genus, and we cannot know if 

the unidentified species occurs in the import area and, consequently, whether it has actionable 

regulatory status for the import area. On the other hand, if the genus in question is absent from 

the import area, any unidentified organisms in the genus can have actionable status; however, 

because such an organism has not been fully identified, we cannot properly analyze its likelihood 

and consequences of introduction.

In light of these issues, we usually do not include organisms identified only to the genus level in 

the main pest list. Instead, we address them separately in this sub-section. The information here 

can be used by risk managers to determine if measures beyond those intended to mitigate fully 

identified pests are warranted. Often, however, the development of detailed assessments for 

known pests that inhabit a variety of ecological niches, such as internal fruit feeders or foliage 

pests, allows effective mitigation measures to eliminate the known organisms as well as similar 

but incompletely identified organisms that inhabit the same niche.
Table 1. Organisms identified to the genus level that are reported on Allium species in Hawaii and that 

have actionable or undetermined regulatory status.

Pest Name Evidence of 

presence on 

Allium in 

Hawaii

Genus 

present in 

continental 

United 

States?

Regulatory 

statusa

Plant part(s) 

associationb

On 

harvested 

plant 

part(s)?c

Remarks

BACTERIA

Xanthomonas sp. Nelson et al., 

2009

Yes 

(Schwartz 

and Gent, 

2011)

U Leaf (Schwartz 

and Gent, 2011)

Yes

NEMATODES

Meloidogyne sp. 

(Tylenchida: 

Meloidogynidae)

Nelson et al., 

2009

Yes 

(Walters 

and Barker, 

1994)

U Roots (Walters 

and Barker, 

1994)

No

Paratrichodorus

sp. (Triplonchida: 

Trichodoridae)

Hamasaki et al., 

1999

Yes (Crow, 

2004)

U Roots (Crow, 

2004)

No

a A=Actionable, U=Undetermined. If the genus does not occur in the continental United States, the organism has actionable 

status. If the genus occurs in the continental United States, the organism has undetermined regulatory status, because we 

cannot know if the unidentified species is one that occurs in the continental United States.

b The plant part(s) listed are those for the plant species under analysis. If the information is extrapolated, such as from plant 

part association on other plant species, this is noted.

c

“Yes” indicates the pest has a reasonable likelihood of being associated with the harvested plant part(s).

2.2. Pest list

In Table 2, we list the actionable pests associated with leaves of Allium species that occur in 

Hawaii. The list comprises those actionable pests that occur in Hawaii on any host and are 

reported to be associated with Allium species, whether in Hawaii or elsewhere in the world. For 

each pest, we indicate 1) the part of the imported plant species with which the pest is generally

associated, and 2) whether the pest has a reasonable likelihood of being associated, in viable 

form, with the commodity following harvesting from the field and prior to any post-harvest 

processing. We developed this pest list based on the scientific literature, port-of-entry pest 

interception data, and information provided by the government of Hawaii. Pests in shaded rows 

are pests identified for further evaluation, as we consider them reasonably likely to be associated 

with the harvested commodity; we summarize these pests in a separate table (Table 3). 
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Ver. 1 October 3, 2013 7

Table 2. Actionable pests reported on Allium spp. (in any country) and present in Hawaii (on any host).

Pest Name Evidence of 

presence in 

Hawaii

Host status1 Plant part(s) 

association2

On harvested 

plant 

part(s)?3

Remarks

ARTHROPODS

Diptera: Syrphidae

Eumerus aurifrons

(Wiedemann)

Wong, 2011 Type 2 (Wong, 

2011)

Bulb, root 

(Wong, 2011)

No May infest 

damaged host 

plants (Wong, 

2011).

Lepidoptera: Acrolepiidae

Acrolepiopsis 

sapporensis

(Matsumura)

Hamasaki et al., 

1999; Kobayashi 

and Bittenbender, 

2002; Landry, 

2007; Wong, 

2011

Type 1 (Hamasaki 

et al., 1999;

Kobayashi and 

Bittenbender, 2002; 

Landry, 2007; 

Robinson et al., 

2001; Wong, 2011)

Leaf, 

sometimes bulb 

(Hong, 1994; 

Landry, 2007)

Yes

Lepidoptera: Noctuidae

Spodoptera litura 

(Fabricius)

Hill, 1983; 

NAPIS, 2012; 

Zhang, 1994

Type 1 (Hill, 1983; 

Robinson et al., 

2001)

Leaf (Hill, 

1983)

Yes A minor pest of 

Allium spp. (Hill, 

1983).

Orthoptera: Pyrgomorphidae

Atractomorpha 

sinensis Bolivar

Kessing et al., 

2007; Kobayashi 

and Bittenbender, 

2002

Type 1 (Kobayashi 

and Bittenbender, 

2002)

Leaf, stem 

(Kessing et al., 

2007)

No. This large, 

very mobile 

grasshopper is 

highly 

unlikely to 

remain with 

harvested 

commodity.

Thysanoptera: Thripidae

Scirtothrips 

dorsalis Hood

CABI, 2010; 

Ludwig et al., 

n.d.

Type 1 (Kumar et 

al., 2010)

Leaf, stem 

(Kumar et al., 

2010)

Yes Present in 

Florida (Kumar 

et al., 2010).

 

1 Type 1 is a natural host, i.e., a plant species that becomes infested or infected by a plant pest in nature under natural 

conditions (e.g., natural, cultivated and/or unmanaged plants), and the plant pest is sustained on that plant species. Type 2 

is a conditional host, i.e. a plant species that is only a host or a non-host under certain conditions. Type 3 is a natural nonhost (pests for which the plant has this status are not included in the pest list). Type 4 refers to situations when the plant is 

not a food source but serves as a fomite, which is an object or material (including a harvested plant part) that may be 

contaminated with a pest and that could transmit that pest from one place to another.

2 The plant part(s) listed are those for the plant species under analysis. If the information is extrapolated, such as from plant 

part association on other plant species, this is noted.

3

“Yes” indicates simply that the pest has a reasonable likelihood of being associated with the harvested commodity; the level 

of pest prevalence on the harvested commodity (low, medium, or high) is qualitatively assessed in Risk Element A1 as part 

of the likelihood of introduction assessment (section 3).
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Pest Name Evidence of 

presence in 

Hawaii

Host status1 Plant part(s) 

association2

On harvested 

plant 

part(s)?3

Remarks

Thrips alliorum

(Priesner)

Kobayashi and 

Bittenbender, 

2002

Type 1 (Lewis, 

1997; Kobayashi 

and Bittenbender, 

2002)

Leaf (Lewis, 

1997)

Yes

Thrips palmi Karny Johnson, 1986; 

Nakahara, 1994

Type 1 (Capinera, 

2008; Johnson, 

1986; PestID, 2012; 

Seal, 2004)

Leaf (Capinera, 

2008)

Yes

NEMATODE

Tylenchida: Pratylenchidae

Radopholus similis

(Cobb) Thorne

Sipes et al., 2001 Type 1 (Keetch and 

Buckley, 1984)

Roots 

(O'Bannon, 

1977)

No

2.3. Pests selected for potential analysis 

We identified five pests that are potential candidates for further mitigation (Table 3). All of those 

organisms are actionable pests for the continental United States and have a reasonable likelihood 

of being associated with Allium leaves at the time of harvest and remaining with the commodity, 

in viable form, throughout the harvesting process.

Table 3. Arthropod pests selected for further analysis.

Taxonomy Scientific Name

Lepidoptera: Acrolepiidae Acrolepiopsis sapporensis

Lepidoptera: Noctuidae Spodoptera litura

Thysanoptera: Thripidae Scirtothrips dorsalis

Thrips alliorum

Thrips palmi

3. Assessing Pest Risk Potential

3.1. Introduction

For each pest selected for further analysis, we estimate its overall pest risk potential. Risk is 

described by the likelihood of an adverse event, the magnitude of the consequences, and 

uncertainty. In this risk assessment, we first determine for each pest if there is an endangered 

area within the import area. The endangered area is defined as the portion of the import area 

where ecological factors favor the establishment of the pest and where the presence of the pest 

will result in economically important losses. Once an endangered area has been determined, the 

overall risk of each pest is then determined by two separate components: 1) the likelihood of its 

introduction into the endangered area on the imported commodity (i.e., the likelihood of an 
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Ver. 1 October 3, 2013 9

adverse event), and 2) the consequences of its introduction (i.e., the magnitude of the 

consequences). In general, we assess both of these components for each pest. However, if we 

determine that the risk of either of these components is negligible, it is not necessary to assess 

the other, as the overall pest risk potential would be negligible regardless of the result of the 

second component. In other words, if we determine that the introduction of a pest is unlikely to 

have unacceptable consequences, we do not assess its likelihood of being introduced. Likewise, 

if we determine there is negligible likelihood of a pest being introduced, we do not assess its 

consequences of introduction.

The likelihood and consequences of introduction are assessed using different approaches. 

For the consequences of introduction, we determine if the pest meets the threshold (Yes/No) of 

likely causing unacceptable consequences of introduction. This determination is based on 

estimating the potential consequences of introduction in terms of physical losses (rather than 

monetary losses). The threshold is based on a proportion of damage rather than an absolute value 

or amount. Pests that are like to impact at least 10 percent of the production of one or more hosts 

are deemed “threshold pests.”

For likelihood of introduction, which is based on the likelihoods of entry and establishment, we 

qualitatively assess risk using the ratings Negligible, Low, Medium, and High. The risk factors 

comprising the model for likelihood of introduction are interdependent and, therefore, the model 

is multiplicative rather than additive. Thus, if any one risk factor is rated as Negligible, then the 

overall likelihood will be Negligible. For the overall likelihood of introduction risk rating, we 

define the different categories as follows:

High: Pest introduction is highly likely to occur.

Medium: Pest introduction is possible, but for that to happen, the exact combination of 

required events needs to occur.

Low: Pest introduction is unlikely to occur because one or more of the required events 

are unlikely to happen, or the full combination of required events is unlikely to 

align properly in time and space.

Negligible: Pest introduction is highly unlikely to occur given the exact combination of 

events required for successful introduction.

3.2. Assessment results

3.2.1. Acrolepiopsis sapporensis

We determined the overall likelihood of introduction to be Medium. We present the results of 

this assessment in the table below.

We determined that the introduction of Acrolepiopsis sapporensis in the continental United 

States is likely to cause unacceptable impacts. We present the results of this assessment in the 

table below.

Determination of the portion of the continental United States endangered by Acrolepiopsis 

sapporensis

Climatic suitability Acrolepiopsis sapporensis has been reported from Russia (Sattler, 
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Ver. 1 October 3, 2013 10

1985), Korea (Ahn et al., 1991), northern Japan (Ohtomo et al., 2001),

and Hawaii (Sattler, 1985). Given this temperate to tropical 

distribution, we estimate this species could establish in Plant Hardiness 

Zones 5-11 in the continental United States. This species is also a pest 

in greenhouses (Lim et al., 2012).

Potential hosts at risk 

in PRA Area

Hosts are restricted to species of Allium (Liliaceae) (Landry, 2007). 

Allium species at risk may be found throughout the continental United 

States (NRCS, 2013).

Economically

important hosts at riska

Onion, garlic, and leek production are economically important in the 

United States (NASS, 2013).

Pest potential on 

economically 

important hosts at risk

Acrolepiopsis sapporensis is considered a significant pest of “the onion 

group” of plants in Asia (Landry, 2007).

Defined Endangered 

Area

The endangered area is likely to encompass Allium species within Plant 

Hardiness Zones 5-11 in the continental United States.

a As defined by ISPM No. 11, supplement 2, “economically” important hosts refers to both commercial and nonmarket (environmental) plants (IPPC, 2011).

Assessment of the likelihood of introduction of Acrolepiopsis sapporensis into the 

endangered area via the importation of Allium from Hawaii

Risk Element Risk Rating Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

Likelihood of Entry

Risk Element A1: Pest 

prevalence on the harvested 

commodity (= the baseline 

rating for entry)

High MU Acrolepiopsis sapporensis is a pest 

of Allium species in Hawaii, is 

known to feed on the leaves, and 

can be found mining and boring the 

leaves, stem, bulb, and flower buds 

(Landry, 2007). It is generally

concealed within the leaves 

(Landry, 2007) and may not be 

detected at harvest time.

Risk Element A2: Likelihood 

of surviving post-harvest 

processing before shipment

High U No post-harvest processing 

procedures were described; we did 

not change the previous rating.

Risk Element A3: Likelihood 

of surviving transport and 

storage conditions of the 

consignment 

High U No transport and storage

procedures were described that 

may mitigate the presence of this 

species on Allium.

Risk Element A: Overall risk 

rating for likelihood of entry

High N/A

Likelihood of Establishment 

Risk Element B1: Likelihood Low MC Larvae or pupae may be found 
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 11

Risk Element Risk Rating Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

of coming into contact with 

host material in the 

endangered area

associated with the Allium leaves 

(Landry, 2007). For development 

to be completed, the adult must

mate and find suitable hosts for egg 

laying, and climatic conditions 

must be suitable. A mated pair 

must be introduced and emerge at 

the same life stage and in close 

proximity to each other in order for 

population development to occur 

(Landolt et al., 1984). As with the 

similar species A. assectella

(Jenner et al., 2010), mortality rates

in the field for A. sapporensis

larvae are probably high. Mortality

is likely to be even greater on 

harvested and shipped Allium

leaves, thereby further reducing the 

likelihood of introduction of mated 

pair.

Risk Element B2: Likelihood 

of arriving in the endangered 

area

High C The endangered area includes more 

than 25 percent of the U.S.

population (PERAL, 2008).

Risk Element B: Combined 

likelihood of establishment

Medium N/A

Overall Likelihood of Introduction 

Combined likelihoods of

entry and establishment

Medium N/A

aC=Certain, MC=Moderately Certain, MU=Moderately Uncertain, U=Uncertain

Assessment of the consequences of introduction of Acrolepiopsis sapporensis into the 

continental United States (i.e., the PRA area)

Criteria Meets 

criteria? 

(Y/N)

Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

Direct Impacts

Risk Element C1: Damage 

potential in the endangered 

area

Yes MU Acrolepiopsis sapporensis is an 

economically important pest (Shimizu 

and Kuwahara, 2009). Hong (1994) 

documented yield losses of 6.3 to 35.5 

percent in Allium species. While 
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 12

Criteria Meets 

criteria? 

(Y/N)

Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

several other Acrolepiopsis species 

feed on Allium species in the 

continental United States, it is unclear 

whether or not current management 

schemes would be effective. Ongoing 

research on effective pest management 

strategies in Korea indicate that current 

pest control strategies for this species

in Allium may not be as effective as in 

other systems (Park et al., 2012), and 

additional measures may be needed. 

Risk Element C2: Spread 

potential

Yes MU Natural dispersal capabilities of A. 

sapporensis are unclear, but similar 

species disperse naturally in search of 

hosts throughout Canada, or recently

found as newly invasive species within 

North America (Landry, 2007).

Risk Element C: Pest 

introduction is likely to cause 

unacceptable direct impacts 

Yes N/A

Trade Impacts 

Risk Element D1: Export 

markets at risk

N/A N/A

Risk Element D2: Likelihood 

of trading partners imposing 

additional phytosanitary

requirements 

N/A N/A

Risk Element D: Pest is likely

to cause significant trade 

impacts 

N/A N/A

Conclusion

Is the pest likely to cause 

unacceptable consequences in 

the PRA area?

Yes N/A

aC=Certain, MC=Moderately Certain, MU=Moderately Uncertain, U=Uncertain

3.2.2. Spodoptera litura

We determined the overall likelihood of introduction to be Medium. We present the results of 

this assessment in the table below.
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Ver. 1 October 3, 2013 13

We determined that the establishment of S. litura in the continental United States is likely to 

cause unacceptable impacts. We present the results of this assessment in the table below.

Determination of the portion of the continental United States endangered by Spodoptera 

litura

Climatic suitability Distribution records in the literature reflect some confusion regarding the 

presence of S. litura vs. S. littoralis. At this time, S. litura is known to be 

established throughout tropical and temperate Asia, Australasia, and the 

Pacific Islands (CABI, 2013; EPPO, n.d.). Based on a comparison with 

USDA Plant Hardiness Zones (Magarey et al., 2008), it is estimated that 

S. litura may establish in zones 7-11 in the continental United States. 

Potential hosts at 

risk in PRA Area

Spodoptera litura feeds on leaves of more than 120 host plants (EPPO, 

n.d.), and many would be available throughout the relevant region. 

Economically

important hosts at 

riska

Economically important hosts of S. litura in the continental United States 

include apple (Malus domestica), beans (Phaseolus sp.), Brassica spp., 

citrus/lemon (Citrus spp., C. limon), corn (Zea mays), cotton (Gossypium

sp.), onion (Allium cepa), potato (Solanum tuberosum), soybean (Glycine 

max), sweet potato (Ipomoea batatas), and tomato (Lycopersicon 

esculentum) (Venette et al., 2003). 

Pest potential on 

economically 

important hosts at 

risk

Spodoptera litura can strip host plants of their leaves (Venette et al., 

2003).

Defined 

Endangered Area

The endangered area of the continental United States includes the hosts 

listed above that are present in USDA Plant Hardiness Zones 7-11.

a As defined by ISPM No. 11, supplement 2, “economically” important hosts refers to both commercial and nonmarket (environmental) plants (IPPC, 2011).

Assessment of the likelihood of introduction of Spodoptera litura into the endangered area

via the importation of Allium from Hawaii

Risk Element Risk Rating Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

Likelihood of Entry

Risk Element A1: Pest 

prevalence on the harvested 

commodity (= the baseline 

rating for entry)

High MC Spodoptera litura is a significant 

pest on onion until harvest time 

(Chandio, 1999). We have no 

information on standard industry

field practices that may reduce the 

prevalence of this pest. 

Risk Element A2: Likelihood 

of surviving post-harvest 

processing before shipment

High MU No standard post-harvest 

procedures have been indicated. 

While adults and older larvae are 

unlikely to be associated with 

leaves harvested during daylight 
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 14

Risk Element Risk Rating Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

hours (CABI, 2013), eggs and 

young larvae may be associated 

with the leaves.

Risk Element A3: Likelihood 

of surviving transport and 

storage conditions of the 

consignment

High MU No transport and storage

procedures were described that 

may mitigate the presence of this 

species on Allium. 

Risk Element A: Overall risk 

rating for likelihood of entry

High N/A

Likelihood of Establishment 

Risk Element B1: Likelihood 

of coming into contact with 

host material in the 

endangered area

Low MC Due to the large size of the larvae, 

eggs are the most likely life stage 

to be imported with Allium leaves. 

For establishment to occur, eggs 

must hatch, and larvae must be 

able to feed sufficiently to develop,

find suitable pupation sites in the 

soil, emerge, find hosts and mate

(CABI, 2013). The mated pairs

must be introduced and emerge at 

the same life stage and in close 

proximity to each other in order for 

population development to occur 

(Landolt et al., 1984).

Risk Element B2: Likelihood 

of arriving in the endangered 

area 

High C That area includes more than 25 

percent of the U.S. population

(PERAL, 2008).

Risk Element B: Combined 

likelihood of establishment 

Medium N/A

Overall Likelihood of Introduction 

Combined likelihoods of

entry and establishment 

Medium N/A

aC=Certain, MC=Moderately Certain, MU=Moderately Uncertain, U=Uncertain

Assessment of the consequences of introduction of Spodoptera litura into the continental 

United States (i.e., the PRA area)

Criteria Meets 

criteria? 

(Y/N)

Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

Direct Impacts

Risk Element C1: Damage Yes MC Spodoptera litura feeds and reproduces
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 15

Criteria Meets 

criteria? 

(Y/N)

Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

potential in the endangered 

area

on a wide variety of cultivated and 

wild host plants. Increasingly frequent 

outbreaks of S. litura in China have 

been occurring in recent years, 

regardless of various control measures 

in place (Huang et al., 2006). 

Insecticide usage must be closely 

monitored in order to minimize 

resistance and apply at the appropriate 

intervals for successful control 

(Saleem et al., 2008). It is likely that 

control measures currently used in the 

United States would need to be altered 

in order to prevent significant 

economic impacts due to infestations 

of S. litura. These additional 

monitoring and control measures 

would likely result in significant 

increases in the costs of production.

Risk Element C2: Spread 

potential

Yes MC Other Spodoptera species migrate

seasonally in the United States

(Heppner, 1998), so S. litura seems 

likely to be able to spread throughout 

the continental United States.

Risk Element C: Pest 

introduction is likely to cause 

unacceptable direct impacts

Yes N/A

Trade Impacts 

Risk Element D1: Export 

markets at risk

N/A N/A

Risk Element D2: Likelihood 

of trading partners imposing 

additional phytosanitary

requirements

N/A N/A

Risk Element D: Pest is likely

to cause significant trade 

impacts

N/A N/A

Conclusion

Is the pest likely to cause 

unacceptable consequences in 

the PRA area?

Yes N/A

aC=Certain, MC=Moderately Certain, MU=Moderately Uncertain, U=Uncertain
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 16

3.2.3. Scirtothrips dorsalis

We determined the overall likelihood of introduction to be High. We present the results of this 

assessment in the table below.

We determined that the establishment of Scirtothrips dorsalis in the continental United States is 

likely to cause unacceptable impacts. We present the results of this assessment in the table 

below.

Determination of the portion of the continental United States endangered by Scirtothrips 

dorsalis

Nietschke et al. (2008) conducted research regarding the threat of establishment of S. dorsalis in 

the continental United States. This research combined information based on the weather-based 

mapping tool, NAPPFAST, with the known impacts and potential impacts on host plants 

considered to be economically important in the United States. The final risk map as generated by 

Nietschke et al. (2008) is shown in Figure 2. Major crops considered to be at risk include 

peppers, eggplant, and tomatoes, which are predominantly grown in California and southern 

Florida (Nietschke et al., 2008). The potential for seasonal migration and greenhouse infestations 

were not included in the development of this model (Nietschke et al., 2008).

Figure 2. Risk map for S. dorsalis based on generation potential, minimum temperature 

exclusion, and host density (Nietschke et al., 2008).
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 17

Assessment of the likelihood of introduction of Scirtothrips dorsalis into the endangered 

area via the importation of Allium from Hawaii

Risk Element Risk Rating Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

Likelihood of Entry

Risk Element A1: Pest 

prevalence on the harvested 

commodity (= the baseline 

rating for entry)

High MC Scirtothrips dorsalis is a pest of 

Allium species, primarily feeding 

on leaves (Kumar et al., 2010). No 

standard industry field practices are 

being considered. 

Risk Element A2: Likelihood 

of surviving post-harvest 

processing before shipment 

High MC No standard post-harvest 

procedures have been indicated. 

The small size of these insects 

further reduces the likelihood of 

detection through inspection 

(EPPO, 2005).

Risk Element A3: Likelihood 

of surviving transport and 

storage conditions of the 

consignment

High MC No transport and storage

procedures were described that 

may mitigate the presence of this 

species on Allium.

Risk Element A: Overall risk

rating for likelihood of entry

High N/A

Likelihood of Establishment 

Risk Element B1: Likelihood 

of coming into contact with 

host material in the 

endangered area

High C Scirtothrips dorsalis is a 

polyphagous, mobile pest (Mound 

and Palmer, 1981), and suitable 

hosts are widely and regularly 

distributed throughout the 

endangered area (NRCS, 2013).

Risk Element B2: Likelihood 

of arriving in the endangered 

area

High C The endangered area contains more 

than 25 percent of the U.S.

population (PERAL, 2008).

Risk Element B: Combined 

likelihood of establishment

High N/A

Overall Likelihood of Introduction 

Combined likelihoods of

entry and establishment

High N/A

aC=Certain, MC=Moderately Certain, MU=Moderately Uncertain, U=Uncertain
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Ver. 1 October 3, 2013 18

Assessment of the consequences of introduction of Scirtothrips dorsalis into the continental 

United States (i.e., the PRA area)

Criteria Meets 

criteria? 

(Y/N)

Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

Direct Impacts

Risk Element C1: Damage 

potential in the endangered 

area

Yes C Yield loss in Capsicum annuum

production can reach as high as 74

percent (Kumar et al., 2013). 

Development of an effective 

management plan in the United States 

is still ongoing, and S. dorsalis is a 

significant pest in Florida (Kumar et 

al., 2010; Kumar et al., 2013).

Risk Element C2: Spread 

potential

Yes C Scirtothrips dorsalis was detected in 

Florida in 2005, and has been 

expanding its worldwide range in 

recent years, most notably in the 

Middle East, Africa (EPPO, 2005), and 

the Caribbean (Kumar et al., 2013).

Risk Element C: Pest 

introduction is likely to cause 

unacceptable direct impacts

Yes N/A

Trade Impacts 

Risk Element D1: Export 

markets at risk 

N/A N/A

Risk Element D2: Likelihood 

of trading partners imposing 

additional phytosanitary

requirements 

N/A N/A

Risk Element D: Pest is likely

to cause significant trade 

impacts 

N/A N/A

Conclusion

Is the pest likely to cause 

unacceptable consequences in 

the PRA area? 

Yes N/A

aC=Certain, MC=Moderately Certain, MU=Moderately Uncertain, U=Uncertain

3.2.4. Thrips alliorum

We determined that the establishment of Thrips alliorum in the continental United States is 

unlikely to cause unacceptable impacts. We present the results of this assessment in the table 

below. Because we determined there would not be significant impacts, no analysis of the 

likelihood of introduction was necessary.
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Ver. 1 October 3, 2013 19

Determination of the portion of the continental United States endangered by Thrips 

alliorum

Climatic 

suitability

Thrips alliorum has been reported from China, Japan, Korea (Hua, 2000), and

Hawaii (Kobayashi and Bittenbender, 2002). A comparison with USDA Plant 

Hardiness Zones (Magarey, 2008) indicates that this species may establish in 

Zones 5-11 in the continental United States.

Potential hosts 

at risk in PRA 

Area

Allium species are the only hosts for T. alliorum (Hua, 2000) and are present 

throughout the continental United States (Kartesz, 2013).

Economically

important hosts 

at riska

Onion, garlic, and and leek are economically important crops in the United 

States (NASS, 2013).

Pest potential 

on 

economically 

important hosts 

at risk

Li et al. (1997) classified T. alliorum primarily as “present, but not an important 

pest.” In six of the analyzed provinces in southern China, T. alliorum is classified 

as “important locally, or only in some years” (Li et al., 1997). Thrips alliorum

causes “silvery mottles or blotches on onion” in East Asia (Lewis, 1997), which 

may be important for commercial production of Allium leaves. It is also listed as a

known pests of onion in Hawaii (Kobayashi and Bittenbender, 2002). Therefore, 

with moderate uncertainty, we estimate that T. alliorum has pest potential on 

Allium in the United States.

Defined 

Endangered 

Area

The endangered area consists of Allium species within Plant Hardiness Zones 

5-11 in the continental United States.

a As defined by ISPM No. 11, supplement 2, “economically” important hosts refers to both commercial and nonmarket (environmental) plants (IPPC, 2011).

Assessment of the consequences of introduction of Thrips alliorum into the continental 

United States (i.e., the PRA area)

Criteria Meets 

criteria? 

(Y/N)

Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

Direct Impacts

Risk Element C1: Damage 

potential in the endangered 

area

No MC In the literature, T. alliorum is not 

considered a significant pest of onions. 

Multiple other species that may

overlap in distribution with T. alliorum

are considered to be important pests 

requiring mitigation. Some of these 

include species that are already 

regularly controlled for in the 

continental United States, including 

Frankliniella occidentalis and Thrips 

tabaci (Sparks and Liu, 2011). Control 

measures already in use in Allium
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 20

Criteria Meets 

criteria? 

(Y/N)

Uncertainty 

Ratinga

Justification for rating and 

explanation of uncertainty (and 

other notes as necessary)

production in the United States are 

highly likely to be effective against 

this species, should it become 

established.

Risk Element C2: Spread 

potential

N/A N/A

Risk Element C: Pest 

introduction is likely to cause 

unacceptable direct impacts

No N/A

Trade Impacts 

Risk Element D1: Export 

markets at risk 

No C Thrips alliorum is unlikely to be 

associated with Allium bulbs without 

leafy green parts attached. At least 

“some” fresh onion exports may

include edible green tops, however

(Burden et al., 2012). In 2010, total 

exports of fresh onion were valued at 

$202.8 million, with $126.1 million 

exported to Canada, and $14.1 million 

exported to Mexico (Burden et al., 

2012), where T. alliorum is not known 

to occur.

Risk Element D2: Likelihood 

of trading partners imposing 

additional phytosanitary

requirements 

No MC Thrips alliorum is not listed by any 

country as a harmful organism (PeXD, 

2013). Neither Canada nor Mexico 

appear concerned about thrips species, 

as neither country has Thrips spp. or 

Thripidae listed as potential harmful 

organisms (PeXD, 2013).

Risk Element D: Pest is likely

to cause significant trade 

impacts 

No N/A

Conclusion

Is the pest likely to cause 

unacceptable consequences in 

the PRA area? 

No N/A

aC=Certain, MC=Moderately Certain, MU=Moderately Uncertain, U=Uncertain
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 21

3.2.5. Thrips palmi

A full pest analysis is not needed for T. palmi because we determined that no endangered area 

exists in the continental United States. We present the results of this assessment in the table 

below.

Determination of the portion of the continental United States endangered by Thrips palmi

Climatic suitability Thrips palmi is distributed throughout tropical regions in Asia, Africa, 

South America, Oceania, and the Caribbean (CABI, 2013), as well as 

Hawaii and southern Florida (Capinera, 2010; Seal, 2001). While T.

palmi is an important greenhouse pest, and there is some concern that it 

may infest protected environments anywhere, it is estimated that outdoor 

establishment of permanent populations would be restricted to tropical 

regions (Capinera, 2010). Permanent populations have only been 

documented in Florida south of Orlando (Capinera, 2010). Initially

detected in 1990 (Capinera, 2010), it is not under official control. 

Surveys conducted over the last 20 years indicate that T. palmi is likely

established throughout the climate zone appropriate for population 

development. The possibility of T. palmi populations overwintering in 

greenhouses and then moving outdoors in summer (e.g., Kawai, 1990; 

McDonald et al., 1999) has not been realized.

Defined 

Endangered Area

Based on the current distribution of T. palmi in the continental United 

States and lack of official control, we determined that the endangered 

area is negligible.

a As defined by ISPM No. 11, supplement 2, “economically” important hosts refers to both commercial and nonmarket (environmental) plants (IPPC, 2011).

4. Summary and Conclusions of Risk Assessment

Of the organisms associated with Allium spp. worldwide and reported in Hawaii, we identified 

organisms that are actionable pests for the continental United States and have a reasonable 

likelihood of being associated with the commodity following harvesting from the field and prior 

to any post-harvest processing. We further evaluated these organisms for their likelihood of 

introduction (i.e., entry plus establishment) and their potential consequences of introduction.

Pests that meet the threshold to likely cause unacceptable consequences of introduction and 

receive an overall likelihood of introduction risk rating above Negligible are candidates for risk 

management. The results of this risk assessment represent a baseline estimate of the risks 

associated with the import commodity pathway as described in section 1.4.

Of the pests selected for further analysis, we determined that the pests identified in Table 4 are

not candidates for risk management, either because no portion of the continental United States is 

likely to be endangered by the pests or they do not meet the threshold to be likely to cause 

unacceptable consequences of introduction. We summarize the results for each pest in Table 4.

All the other pests selected for further analysis are candidates for risk management, because they

meet the threshold to likely cause unacceptable consequences of introduction, and they received 
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 22

an overall likelihood of introduction risk rating above Negligible. We summarize the results for 

each pest in Table 5.

Detailed examination and choice of appropriate phytosanitary measures to mitigate pest risk are 

part of the pest risk management phase within APHIS and are not addressed in this document.

Table 4. Summary for pests selected for further evaluation and determined not to be candidates 

for risk management.

Pest Reason the pest is not a candidate for 

risk management

Uncertainty statement 

(optional)a

Thrips alliorum Does not meet threshold to be likely to 

cause unacceptable Consequences of 

Introduction 

Thrips palmi No endangered area exists within the PRA 

area

aThe uncertainty statement, if included, identifies the most important source(s) of uncertainty.

Table 5. Summary for pests selected for further evaluation and determined to be candidates for

risk management. All of these pests meet the threshold for unacceptable consequences of 

introduction.

Pest Likelihood of Introduction overall 

rating

Uncertainty statement 

(optional)a

Acrolepiopsis sapporensis Medium

Spodoptera litura Medium

Scirtothrips dorsalis High

aThe uncertainty statement, if included, identifies the most important source(s) of uncertainty.

5. Acknowledgements 

Authors Cynthia Landry, Risk Analyst, Ecologista

Reviewers Shawn Robertson, Risk Analyst, Entomologista

Lisa M. Ferguson, Risk Analyst, Plant Pathologista

a

Plant Epidemiology and Risk Analysis Laboratory, USDA-APHIS-PPQ

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7. Appendix A

Pests with non-actionable regulatory status

We found some evidence of the below listed organisms being associated with Allium leaves and 

being present in the Hawaii; however, because these organisms have non-actionable regulatory

status for the continental United States, we did not list them in Table 2 of this risk assessment.

Below we list these organisms along with the references supporting their potential association 

with Allium leaves, their potential presence in Hawaii, their presence in the continental United 

States (if applicable), and their regulatory status for the continental United States. For organisms 

not present in the continental United States, we also provide justification for their non-actionable 

status.

Organism Evidence and/or other notes

ARTHROPODS

Acari: Acaridae

Rhizoglyphus echinopus Fumouze & 

Robin

Annecke and Moran, 1982; CABI, 2012; Koch and Waterhouse, 

2000

Acari: Tetranychidae

Tetranychus cinnabarinus

(Boisduval)

CABI, 2012; Maes, 2004; PestID, 2012

Tetranychus desertorum Banks Bolland et al., 1998; PestID, 2012

Tetranychus neocaledonicus Andre Bolland et al., 1998; PestID, 2012

Tetranychus urticae Koch Bolland et al., 1998; Jones et al., 1992; Maes, 2004; PestID, 

2012

Coleoptera: Anobiidae

Stegobium paniceum (Linnaeus) CABI, 2012

Coleoptera: Curculionidae

Listroderes costirostris obliquus 

Klug

CABI, 1994; CABI, 2012; Koch and Waterhouse, 2000; PestID, 

2012; Prado, 1991

Dermaptera: Carcinophoridae

Euborellia annulipes (Lucas) Capinera, 1999; Hill, 1983

Diptera: Agromyzidae

Liriomyza brassicae (Riley) Mau et al., 2007b; PestID, 2012; Wongsiri, 1991

Liriomyza langei Frick Hamasaki et al., 1999; Kobayashi and Bittenbender, 2002; 

Schwartz and Mohan, 2008; Steck, 2008; Wong, 2011.

There is some confusion regarding the identification of L. 

huidobrensis and L. langei in Hawaii (see discussion in section 

2.1.1). It is concluded that the species found in HI is the nonactionable species L. langei.

Liriomyza sativae Blanchard CABI, 2012; Hamasaki et al., 1999; Kobayashi and 

Bittenbender, 2002; PestID, 2012; Schwartz and Mohan, 2008;

Wong, 2011

Liriomyza trifolii (Burgess) CABI, 2012; Diez et al., 2007; Hamasaki et al., 1999; PestID, 

2012; Schwartz and Mohan, 2008; Spencer, 1973
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Organism Evidence and/or other notes

Diptera: Anthomyiidae

Delia (Hylemya) platura (Meigen) CABI, 2012; Hamasaki et al., 1999; Hill, 1983; Kessing and 

Mau, 1991; Koch and Waterhouse, 2000; Schwartz and Mohan, 

2008; Wong, 2011

Hylemya antiqua (Meigen) 

(= Delia antiqua)

Avidov and Harpaz, 1969; CABI, 2012; Hill, 1983; Prado, 1991; 

Schwartz and Mohan, 2008

Hylemyia cilicrura (Rondani) Avidov and Harpaz, 1969; Swezey, 1951

Diptera: Muscidae

Atherigona orientalis (Schiner) (= 

A. excisa Thomson)

Anonymous, n.d.; CABI, 2012; PestID, 2012; Yunus and Hua, 

1980

Diptera: Syrphidae

Eumerus figurans Walker Hill, 1987; Wong, 2011

Hemiptera: Aphididae

Aphis fabae Scopoli Blackman and Eastop, 2000; CABI, 2012

Aphis gossypii Glover CABI, 2012

Aulacorthum solani (Kaltenbach) CABI, 2012; Stoetzel, 1992; PestID, 2012

Lipaphis erysimi (Kaltenbach) Hill, 1983; Liu and Sparks, 2011; Mau et al., 2007a

Micromyzus formosanus Takahashi Fullaway and Krauss, 1945; PestID, 2012

Myzus persicae Sulzer Blackman and Eastop, 2000; CABI, 2012; Hill, 1983; Maes, 

2004; PestID, 2012; Schwartz and Mohan, 2008

Neotoxoptera formosana

(Takahashi)

Blackman and Eastop, 2000; Foottit et al., 2011; Hamasaki et 

al., 1999; Kobayashi and Bittenbender, 2002; PestID, 2012; 

Wong, 2011

Neotoxoptera oliveri (Essig) Blackman and Eastop, 2000; Foottit et al., 2011; PestID, 2012

Hemiptera: Pseudococcidae

Phenacoccus parvus Morrison Ben-Dov et al., 2012; Williams and Hamon, 1994

Pseudococcus viburni (Signoret) Ben-Dov et al., 2012; PestID, 2012

Lepidoptera: Noctuidae

Agrotis ipsilon (Hufnagel) CABI, 2012; Hill, 1983; Koch and Waterhouse, 2000; Prado, 

1991; Robinson et al., 2001; Schwartz and Mohan, 2008

Helicoverpa zea (Boddie) CABI, 2012; Koch and Waterhouse, 2000; Prado, 1991; 

Robinson et al., 2001

Mythimna unipuncta Haworth CABI, 2012

Peridroma saucia (Hubner) CABI, 2012; Koch and Waterhouse, 2000; Mau et al., 2007c; 

PestID, 2012; Prado, 1991; Schwartz and Mohan, 2008

Spodoptera exigua (Hubner) CABI, 2012; Hamasaki et al., 1999; Hill, 1983; Kobayashi and 

Bittenbender, 2002; PestID, 2012; Robinson et al., 2001; 

Schwartz and Mohan, 2008; Wong, 2011

Trichoplusia ni (Hubner) CABI, 2012; Maes, 2004; Gallego and Velez, 1992; PestID, 

2012

Lepidoptera: Pyralidae

Cadra cautella (Walker) Solis, 2006; PestID, 2012

Cadra figulilella (Gregson) Solis, 2006; PestID, 2012

Lepidoptera: Tineidae

Setomorpha rutella Zeller PestID, 2012; Robinson et al., 2001

Thysanoptera: Thripidae

Chaetanaphothrips orchidii 

(Moulton)

CABI, 2012
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Ver. 1 October 3, 2013 34

Organism Evidence and/or other notes

Frankliniella fusca (Hinds) CABI, 2012; PestID, 2012; Schwartz and Mohan, 2008

Frankliniella occidentalis

(Pergande)

CABI, 2012; Hamasaki et al., 1999; Lewis, 1997; PestID, 2012; 

Schwartz and Mohan, 2008; Wong, 2011

Frankliniella schultzei (Trybom) CABI, 2012; Gahukar, 2004; PestID, 2012; Schwartz and 

Mohan, 2008

Frankliniella williamsi Hood Maes, 2004; PestID, 2012

Thrips tabaci Lindeman CABI, 2012; Gahukar, 2004; Lewis, 1997; Hamasaki et al., 

1999; Hill, 1983; Kobayashi and Bittenbender, 2002; PestID, 

2012; Schwartz and Mohan, 2008; Wong, 2011

FUNGI

Alternaria alternata (Fr : Fr.) 

Keissl. (Ascomycetes, 

Pleosporales)

Farr and Rossman, 2012; Valerin, 1994

Alternaria dauci (J.G. Kühn) J.W. 

Groves & Skolko

CABI, 2012

Alternaria porri (Ellis) Cif. 

(Ascomycetes, Pleosporales)

CABI, 2012; Farr and Rossman, 2012; Hamasaki et al., 1999; 

Holliday, 1980; Nelson et al., 2009; Schwartz and Mohan, 2008

Aspergillus niger Tiegh 

(Ascomycetes, Eurotiales)

Farr and Rossman, 2012; Hamasaki et al., 1999; Schwartz and 

Mohan, 2008; Valerin, 1994

Athelia rolfsii (Curzi) Tu & Kimbr. 

(Anamorph: Sclerotium rolfsii

Sacc.) (Basidiomycetes, 

Polyporales)

CABI, 2012; Crous et al., 2000; Farr and Rossman, 2012; 

Nelson et al., 2009; Singh, 1980; Schwartz and Mohan, 2008

Botryosphaeria rhodina (Berk. & 

M.A. Curtis) Arx (Anamorph: 

Lasiodiplodia theobromae (Pat.) 

Griffon & Maubl.) (Ascomycetes, 

Dothideales) 

CABI, 2012; Farr and Rossman, 2012

Botryotinia fuckeliana (de Bary) 

Whetzel (Anamorph: Botrytis

cinerea Pers.: Fr.) (Ascomycetes, 

Helotiales) 

CABI, 2012; Farr and Rossman, 2012; Hamasaki et al., 1999; 

Schwartz and Mohan, 2008

Botryotinia squamosa Vienn.-

Bourg. (Anamorph: Botrytis

squamosa J.C. Walker) 

(Ascomycetes, Helotiales) 

CABI, 2012; Farr and Rossman, 2012; Hamasaki et al., 1999; 

Nelson et al., 2009; Schwartz and Mohan, 2008

Botrytis aclada Fresen. 

(=B. allii Munn.) (Ascomycetes, 

Helotiales)

Farr and Rossman, 2012; Hamasaki et al., 1999; Schwartz and 

Mohan, 2008; Valerin, 1994

Chaetomium globosum Kunze : Fr. 

(Ascomycetes, Sordariales)

Farr and Rossman, 2012; Nelson et al., 2009; Shaw, 1973

Choanephora cucurbitarum (Berk. 

& Ravenel) Thaxt. (Zygomycetes, 

Mucorales)

Farr and Rossman, 2012; Peregrine and Ahmad, 1982; Singh, 

1980

Cladosporium cladosporioides

(Fresen.) G.A. De Vries 

(Ascomycetes, 

Mycosphaerellales)

Farr and Rossman, 2012; Nelson et al., 2009; Shaw, 1973
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Organism Evidence and/or other notes

Cochliobolus lunatus R.R. Nelson & 

Haasis (Anamorph: Curvularia 

lunata (Wakker) Boedijn) 

(Ascomycetes, Pleosporales) 

CABI, 2012; Farr and Rossman, 2012

Colletotrichum circinans (Berk.) 

Voglino (Ascomycetes, 

Phyllachorales)

Farr and Rossman, 2012; Nelson et al., 2009; Peregrine and 

Ahmad, 1982; Schwartz and Mohan, 2008

Cylindrocladiella parva (P.J. 

Anderson) Boesew. 

(=Cylindrocladium parvum P.J. 

Anderson) (Ascomycetes, 

Hypocreales) 

Farr and Rossman, 2012; Nelson et al., 2009

Diaporthe phaseolorum var. sojae

(Lehman) Wehm.

CABI, 2012

Fusarium moniliforme J. Sheld. 

(Ascomycetes, Hypocreales)

Farr and Rossman, 2012; Nelson et al., 2009; Schwartz and 

Mohan, 2008; Shaw, 1973

Fusarium oxysporum Schltdl.: Fr. 

(Ascomycetes, Hypocreales)

CABI, 2012; Dugan et al., 2007; Farr and Rossman, 2012; 

Holliday, 1980; Schwartz and Mohan, 2008

Fusarium oxysporum f. sp. cepae

(H.N. Hansen) W.C. Snyder & 

H.N. Hansen (Ascomycetes, 

Hypocreales)

Dugan et al., 2007; Farr and Rossman, 2012; Hamasaki et al., 

1999; Schwartz and Mohan, 2008; Valerin, 1994

Globisporangium debaryanum (R. 

Hesse) Uzuhashi, Tojo & Kakish. 

(= Pythium debaryanum R. 

Hesse)

Farr and Rossman, 2012; Valerin, 1994

Globisporangium irregulare 

(Buisman) Uzuhashi, Tojo & 

Kakish (= Pythium irregulare 

Buisman)

CABI, 2012; Farr and Rossman, 2012; Schwartz and Mohan, 

2008

Glomerella cingulata (Stonem.) 

Spauld. & Schrenk 

(Ascomycetes, Incertae sedis)

CABI, 2012; Farr and Rossman, 2012; Schwartz and Mohan, 

2008; Singh, 1980

Glomerella lindemuthiana Shear 

(Anamorph: Colletotrichum

lindemuthianum (Sacc. & Magn.) 

Scribn.) (Ascomycetes, Incertae 

sedis)

Farr and Rossman, 2012

Haematonectria haematococca

(Berk. & Broome) Samuels & 

Rossman (Anamorph: Fusarium

solani (Mart.) Appel & Wr.) 

(Ascomycetes, Hypocreales) 

Farr and Rossman, 2012; Nelson et al., 2009; Shaw, 1973

Hypocrea rufa (Pers.: Fr.) Fr. 

(Anamorph: Trichoderma viride

Pers.: Fr.) (Ascomycetes, 

Hypocreales)

Farr and Rossman, 2012; Valerin, 1994
Pest Risk Assessment for Allium leaves from Hawaii

Ver. 1 October 3, 2013 36

Organism Evidence and/or other notes

Leptosphaerulina trifolii (Rostr.) 

Petr. 

(= Pseudoplea trifolii (Rostr.) 

Petr.) (Ascomycetes, 

Pleosporales)

Farr and Rossman, 2012; Peregrine and Ahmad, 1982; Singh, 

1980

Leveillula taurica (Lév.) G. Arnaud 

(Ascomycetes, Erysiphales)

CABI, 2012; Farr and Rossman, 2012; Schwartz and Mohan, 

2008

Macrophomina phaseolina (Tassi) 

Goid. (Ascomycetes, Incertae 

sedis)

Farr and Rossman, 2012; Peregrine and Ahmad, 1982; Schwartz 

and Mohan, 2008

Nigrospora sphaerica (Sacc.) E.W. 

Mason (Ascomycetes, 

Trichosphaeriales)

Farr and Rossman, 2012; Peregrine and Ahmad, 1982

Ovatisporangium vexans (de Bary) 

Uzuhashi, Tojo & Kakish. 

(= Pythium vexans de Bary)

Farr and Rossman, 2012; Nelson et al., 2009

Penicillium digitatum (Pers.) Sacc. CABI, 2012; Schwartz and Mohan, 2008

Penicillium expansum Link CABI, 2012; Schwartz and Mohan, 2008

Penicillium funiculosum Thorn 

(Ascomycetes, Eurotiales)

Farr and Rossman, 2012; Nelson et al., 2009; Schwartz and 

Mohan, 2008; Shaw, 1973

Penicillium italicum Stoll CABI, 2012; PestID, 2012

Peronospora destructor (Berk.) 

Casp. ex Berk. (Oomycetes, 

Peronosporales)

Crous et al., 2000; Farr and Rossman, 2012; Hamasaki et al., 

1999; Schwartz and Mohan, 2008

Phytophthora cinnamomi var. 

cinnamomi Rands 

(= P. cinnamomi Rands) 

(Oomycetes, Pythiales) 

Farr and Rossman, 2012; Nelson et al., 2009

Phytophthora cryptogea Pethybr. & 

Laff.

CABI, 2012

Phytophthora drechsleri Tucker 

(Oomycetes, Pythiales)

Farr and Rossman, 2012; Nelson et al., 2009

Phytophthora nicotianae Breda de 

Haan 

(= P. parasitica Dastur) 

(Oomycetes, Pythiales) 

CABI, 2012; Farr and Rossman, 2012; Nelson et al., 2009

Phytophthora palmivora var. 

palmivora (E.J. Butler) E.J. 

Butler (Oomycetes, Pythiales)

Farr and Rossman, 2012; Nelson et al., 2009

Pleospora herbarum (Pers.: Fr.) 

Rabenh. (Ascomycetes, 

Pleosporales)

Crous et al., 2000; Farr and Rossman, 2012; Nelson et al., 2009; 

Shaw, 1973

Pleospora tarda E.G. Simmons 

(Anamorph: Stemphylium

botryosum Wallr.) (Ascomycetes, 

Pleosporales) 

Farr and Rossman, 2012; Nelson et al., 2009

Puccinia allii F. Rudolphi 

(= P. porri Wint.) 

(Urediniomycetes, Uredinales) 

Crous et al., 2000; Farr and Rossman, 2012; Holliday, 1980; 

Nelson et al., 2009; Schwartz and Mohan, 2008
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Organism Evidence and/or other notes

Pythium graminicola Subram. CABI, 2012; Schwartz and Mohan, 2008

Rhizoctonia solani J.G. Kühn 

(= Thanatephorus cucumeris

(A.B. Frank) Donk)

Farr and Rossman, 2012; Nelson et al., 2009; Schwartz and 

Mohan, 2008

Rhizoctonia sp. Farr and Rossman, 2012; Nelson et al., 2009

Sclerotinia sclerotiorum (Lib.) de 

Bary (Ascomycetes, Helotiales)

CABI, 2012; Farr and Rossman, 2012; Nelson et al., 2009; 

Schwartz and Mohan, 2008

Sclerotium cepivorum Berk. 

(Basidiomycetes, Agaricales)

Farr and Rossman, 2012; Hamasaki et al., 1999; Holliday, 1980; 

Nelson et al., 2009; Schwartz and Mohan, 2008

Setophoma terrestris (H.N. Hansen) 

Gruyter, Aveskamp & Verkley 

(= Phoma terrestris Hansen, 

Pyrenochaeta terrestris (H.N. 

Hansen) Gorenz, J.C. Walker & 

Larson)

Farr and Rossman, 2012; Hamasaki et al., 1999; Holliday, 1980; 

Nelson et al., 2009

Stemphylium lycopersici (Enjoji) W. 

Yamam. (Ascomycetes, 

Pleosporales)

Farr and Rossman, 2012; Peregrine and Ahmad, 1982

Trichothecium roseum (Pers. : Fr.) 

Link (Ascomycetes, Incertae 

sedis)

Farr and Rossman, 2012; Nelson et al., 2009; Shaw, 1973

Verticillium albo-atrum Reinke & 

Berthier (Ascomycetes, 

Hypocreales)

Farr and Rossman, 2012

BACTERIA

Burkholderia cepacia (Palleroni & 

Holmes ex Burkholder) Yabuuchi 

et al.

APSnet, 1998; CABI, 2012; Schwartz and Mohan, 2008

Burkholderia gladioli (Severini) 

Yabuuchi et al. 

(= Pseudomonas gladioli

Severini)

CABI, 2012; Hamasaki et al., 1999; Lu et al., 2007; Schwartz 

and Mohan, 2008

Dickeya chrysanthemi (Burkholder 

et al.) Samson et al. 

(= Erwinia chrysanthemi

Burkholder et al.)

CABI, 2012; Nelson, 2009; Schwartz and Mohan, 2008

Enterobacter cloacae (Jordan) 

(Enterobacteriaceae)

Hamasaki et al., 1999; Horst, 2001; Schroeder et al., 2010; 

Schwartz and Mohan, 2008

Erwinia carotovora (Jones) Bergey 

et al.

Hamasaki et al., 1999; Horst, 2001; PestID, 2012

Erwinia carotovora (Jones) Bergey 

et al. var. carotovora (Jones) Dye

Bradbury, 1977; Nelson et al., 2009; Schwartz and Mohan, 

2008; Valerin, 1994

Pantoea agglomerans (Beijerinck) 

Gavini et al. 

(= Erwinia herbicola (Lohnis) 

Dye)

CABI, 2012; Delmas et al., 2008; Schwartz and Mohan, 2008

Pectobacterium carotovorum subsp. 

carotovorum (Jones) Hauben et 

al.

CABI, 2012; Schwartz and Mohan, 2008; UGA, 2011
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Organism Evidence and/or other notes

Pseudomonas cichorii (Swingle) 

Stapp

CABI, 2012

Pseudomonas viridiflava 

(Burkholder) Dowson

CABI, 2012; Schwartz and Mohan, 2008; UGA, 2011

Xanthomonas axonopodis pv. allii

(Dowson)

CABI, 2012; Schwartz and Gent, 2004; PestID, 2012; Schwartz 

and Mohan, 2008

Xanthomonas campestris (Pammel) 

Dowson

Hamasaki et al., 1999; PestID, 2012

VIRUS

Iris yellow spot virus (IYSV) 

(tospovirus)

CABI, 2012; Goldberg, 2005; Hu (Project director), 2012; 

Schwartz and Mohan, 2008; Wong, 2011

Tomato spotted wilt virus (TSWV) 

(tospovirus)

CABI, 2012; Schwartz and Mohan, 2008

NEMATODES

Aphelenchoides besseyi Christie 

(Tylenchida : Aphelenchoididae)

CABI, 2012; Lamberti et al., 1996; Uchida and Sipes, 1998; 

PestID, 2012

Aphelenchoides fragariae (Ritzema 

- Bos) Christie (Tylenchida : 

Aphelenchoididae)

CABI, 2012; PestID, 2012

Aphelenchus avenae Bastian 

(Aphelenchida: Aphelenchidae)

Keetch and Buckley, 1984; Nelson et al., 2009; PestID, 2012

Ditylenchus destructor Thorne 

(Tylenchida: Anguinidae)

CABI, 2012; DPI, 2006; PestID, 2012

Ditylenchus dipsaci (Kühn) 

(Tylenchida: Anguinidae)

CABI, 2012; Goodey et al., 1965; Hamasaki et al., 1999; 

McLeod et al., 1994; PestID, 2012; Schwartz and Mohan, 2008

Helicotylenchus dihystera (Cobb) 

Spher (Hoplolaimidae)

Benson et al., 1976; CABI, 2012; Evans et al., 1993; McLeod et 

al., 1994; Nelson et al., 2009

Helicotylenchus multicinctus (Cobb) 

Golden (Hoplolaimidae)

CABI, 2012; Evans et al., 1993; PestID, 2012

Meloidogyne arenaria (Neal) 

Chitwood (Tylenchida: 

Meloidogynidae)

Keetch and Buckley, 1984; Nelson et al., 2009; PestID, 2012

Meloidogyne chitwoodi Golden, 

O'bannon, Santo, and Finley 

(Tylenchida: Meloidogynidae)

Hamasaki et al., 1999; PestID, 2012; Schwartz and Mohan, 2008

Meloidogyne hapla Chitwood 

(Tylenchida: Meloidogynidae)

CABI, 2012; Gonsalves and Ferreira, 1994; Goodey et al., 1965; 

Hamasaki et al., 1999; McLeod et al., 1994; PestID, 2012; 

Schwartz and Mohan, 2008

Meloidogyne incognita (Kofoid & 

White) Chitwood (Tylenchida: 

Meloidogynidae)

Hamasaki et al., 1999; Keetch and Buckley, 1984; McLeod et 

al., 1994; Nelson et al., 2009; PestID, 2012; Schwartz and 

Mohan, 2008

Meloidogyne javanica (Treub) 

Chitwood (Tylenchida: 

Meloidogynidae)

CABI, 2012; Hamasaki et al., 1999; Keetch and Buckley, 1984; 

McLeod et al., 1994; PestID, 2012; Schwartz and Mohan, 2008

Nothocriconema mutabile (Taylor) 

de Grisse & Loof (Tylenchida: 

Criconematidae)

Keetch and Buckley, 1984; Nelson et al., 2009; PestID, 2012

Paratrichodorus porosus (Allen) 

Siddiqi

CABI, 2012
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Organism Evidence and/or other notes

Pratylenchus brachyurus (Godfrey) 

Filipjev & Schuurmans 

Stekhoven

CABI, 2012

Pratylenchus penetrans (Cobb) 

Filip. & Schuur. Stekh. 

(Tylenchida: Pratylenchidae)

Hamasaki et al., 1999; McLeod et al., 1994; Nelson et al., 2009; 

PestID, 2012; Schwartz and Mohan, 2008

Pratylenchus zeae Graham 

(Tylenchida: Pratylenchidae)

CABI, 2012; DPI, 2006; PestID, 2012

Rotylenchulus reniformis Lindford 

& Oliveira (Tylenchida: 

Tylenchoidea)

CABI, 2012; Hamasaki et al., 1999; Nelson et al., 2009; PestID, 

2012

PHYTOPLASMA

Aster yellows phytoplasma Borth et al., 2002; Horst, 2001; O'Mara et al., 1993; Schwartz 

and Mohan, 2008