DEPAR TMENT OF AGRICULT URE

Risk and Pathway Assessment for 

the Introduction of Exotic Insects 

and Pathogens That Could Affect 

Hawai‘i’s Native Forests

Gregg A. DeNitto, Philip Cannon, Andris Eglitis, Jessie A. Glaeser, 

Helen Maffei, and Sheri Smith

United States Department of Agriculture

Forest 

Service

Pacific Southwest 

Research Station

General Technical Report

PSW-GTR-250

December 

2015
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Authors

Gregg A. DeNitto is a forest pathologist, Forest Health Protection, 200 E Broadway, 

Missoula, MT 59807. Philip Cannon is a forest pathologist, Forest Health Protection, 

1323 Club Drive, Vallejo, CA 94592. Helen Maffei is a forest pathologist, and Andris 

Eglitis is a forest entomologist, Forest Health Protection, Central Oregon Insect and Disease Field Office, 63095 Deschutes Market Road, Bend, OR 97701. Jessie A. Glaeser is a 

forest mycologist, Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI 

53726-2398. Sheri Smith is a forest entomologist, Forest Health Protection, 2550 Riverside 

Drive, Susanville, CA 96130.
Abstract

DeNitto, Gregg A.; Cannon, Philip; Eglitis, Andris; Glaeser, Jessie A.; Maffei, Helen; 

Smith, Sheri. 2015. Risk and pathway assessment for the introduction of exotic insects 

and pathogens that could affect’s Hawai‘i’s native forests. Gen. Tech. Rep. PSWGTR-250. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 171 p.

The unmitigated risk potential of the introduction of exotic insects and pathogens to 

Hawai‘i was evaluated for its impact on native plants, specifically Acacia koa, Cibotium

spp., Dicranopteris linearis, Diospyros sandwicensis, Dodonaea viscosa, Erythrina sandwicensis, Leptecophylla tameiameiae, Metrosideros polymorpha, Myoporum sandwicense, 

Pandanus tectorius, Scaevola spp., Sophora chrysophylla, and Vaccinium spp. Assessments 

were made by estimating the likelihood and consequences of introduction of representative 

insects and pathogens of concern. Likely pathways of introduction were assessed. Twenty-four individual pest risk assessments were prepared, 12 dealing with insects and 12 with 

pathogens. The selected organisms were representative examples of insects and pathogens 

found on foliage, on the bark, in the bark, and in the roots and wood of the native hosts of 

interest—or closely related host species—in other parts of the world. 

Among the insects and pathogens assessed, high risk potentials were assigned to the 

following 16 organisms or groups of organisms: apple stem borer (Aeolesthes holosericea), 

coconut rhinoceros beetle (Oryctes rhinoceros; during the analysis this insect was identified as present in Hawai‘i), keyhole ambrosia beetle (Amasa truncata), summer fruit tortrix 

moth (Adoxophyes orana), West Indian sugarcane borer weevil (Diaprepes abbreviatus), 

white wax scale (Ceroplastes destructor), Acacia gall rust pathogen (Uromycladium 

tepperianum), Armillaria root disease pathogens (Armillaria luteobubalina, A. tabescens, 

A. limonea, A. novae-zelandiae), Calonectria morganii, Fomitiporia spp. (Fomitiporia 

australiensis, F. mediterranea, F. punctata species complex, F. robusta species complex, 

F. sonorae), guava rust/eucalyptus rust pathogen (Puccinia psidii), Phellinus noxious, pink 

disease pathogen (Erythricium salmonicolor), ramorum blight/sudden oak death pathogen 

(Phytophthora ramorum), Uromyces rust pathogens (Uromyces scaevolae, U. sophorae-japonicae, U. truncicola), and white thread blight pathogen (Ceratobasidium noxium). A 

moderate risk potential was assigned to the following eight organisms or groups of organisms: Botany Bay diamond weevil (Chrysolopus spectabilis), coconut stick insect (Graeffea 

crouanii), Erythrina scale (Toumeyella erythrinae), Eugenia psyllid (Trioza eugeniae), 

lemon tree borer (Oemona hirta), Platypodid ambrosia beetle (Megaplatypus mutatus), 

Aecidium rust pathogens (Aecidium atrocrustaceum, A. calosporum, A. carbonaceum, A. 

diospyri, A. mabae, A. melaenum, A. muelleri, A. miliare, A. myopori, A. ramosii, A. reyesii, 

A. rhytismoideum, A. royenae, A. ulei, A. yapoense) and Pestalotia/Pestalotiopsis leaf and 

fruit pathogens (Pestalotia acacia, P. cibotii, P. diospyri, P. dodonaea, P. pandani, P. 

vaccinii, Pestalotiopsis sp., P. breviseta, P. glandicola, P. palmarum, P. photiniae, P. theae, 

P. uvicola, P. versicolor). 
Six priority findings resulted from the analysis:

1. Inspection alone is not 100 percent effective in preventing introductions. 

2. The primary sources of introductions are the mainland the United States and 

Asia-Pacific.

3. There is a strong need to make visitors aware that they are a significant potential 

source of unwanted introductions. 

4. Plant materials, especially live plants, are by far the most important source of pest 

problems for Hawai‘i. 

5. The solid wood packing material pathway needs more scrutiny. Many pests using 

this pathway have already become established in Hawai‘i, and many more are on the 

list of potentials. Because Hawai‘i Department of Forestry can only inspect wood 

packing material that is associated with agricultural commodities, and because 

wood packing material is not necessarily specified as associated with cargo, this is 

potentially a pathway that is being insufficiently inspected and regulated.

6. The interstate movement of certain plant materials from Hawai‘i to the mainland 

is restricted without treatment and certification. Similar restrictions on interstate 

movement into Hawai‘i are not in place. For the most part, Animal Plant and Health 

Inspection Service regulations do not discriminate between the mainland and 

islands of Hawai‘i as far as potential threats. This includes some organisms that are 

native or commonly found on the mainland. 

Numerous other observations, both specific and general, are included in the pest risk 

assessment concerning detection surveys, regulations, and public education/public awareness of the dangers of introduced pests and pathogens.

Keywords: Pest risk assessment, Hawai‘i, invasive species, Acacia koa, Cibotium, 

Dicranopteris linearis, Diospyros sandwicensis, Dodonaea viscosa, Erythrina sandwicensis, Leptecophylla tameiameiae, Metrosideros polymorpha, Myoporum sandwicense, 

Pandanus tectorius, Scaevola, Sophora chrysophylla, Vaccinium.
Executive Summary

Background, Objectives, and Scope 

Hawai‘i is unique amongst the 50 states; it was formed and developed over the millennia 

independently of any other land mass. This has resulted in very unique and distinct species 

and ecosystems on each island. Because of its geographic isolation, the state also has a rare 

economic situation, with almost all goods needing to be imported. Over the past decades, 

insects and pathogens accidently introduced into Hawai‘i threaten native forest ecosystems 

and urban forest trees. These introductions have increased awareness of the vulnerability 

of island ecosystems and the need for vigilance regarding invasive species beyond those 

affecting agricultural crops.

In September 2010, the Hawai‘i Division of Forestry and Wildlife (HDOFAW) 

requested the U.S. Department of Agriculture (USDA) Forest Service to prepare a pest risk 

assessment. The specific objectives of the risk assessment are to:

• Identify specific insect pest and pathogen species that could attack species of concern in Hawai‘i.

• Determine possible pathways for the introduction of insect pests and pathogens to 

selected native flora of Hawai‘i. 

• Provide risk assessments for selected pathway/pest or pathogen combinations that 

are determined to be of most risk to Hawai‘i forest ecosystems.

The insect and pathogen threats identified in this assessment should represent hereto 

unknown threats that use similar transport pathways and occupy similar ecological niches. 

Our expertise did not include other types of pests, such as invasive plants, and these are not 

included in this assessment.

The scope of this risk assessment is limited to insect and mite pests and disease threats 

to 13 plant species/genera (hereafter referred to as “taxa”) identified by HDOFAW.

Species of interest identified by Hawai‘i Department of Land and Natural Resources, 

Division of Forestry and Wildlife, included in this pest risk assessment:

Species of interest Family Native name Common English name

Acacia koa A. Gray Fabaceae Koa Koa

Cibotium spp. Kaulf. Cibotiaceae Hāpu‘u Hawaiian tree fern 

Dicranopteris linearis Gleicheniaceae Uluhe False staghorn fern 

 (Burm. F) Underwood

Diospyros sandwicensis Ebenaceae Lama Hawaiian ebony

 (A. DC.) Fosberg

Dodonaea viscosa Sapindaceae ‘A‘ali‘i Hawaiian hopseed bush

 (L.) Jacq.

Erythrina sandwicensis Fabaceae Wiliwili Hawaiian coral tree

 O. Deg.
Leptecophylla Ericaceae Pūkiawe Hawaiian heather

 tameiameiae

 (Cham. & Schltdl.) 

 C.M. Weiller

Metrosideros Myrtaceae ‘Ōhi‘a lehua Ohia

 polymorpha Gaud.

Myoporum sandwicense Scrophulariaceae Naio False-sandalwood 

 (A. DC.) A. Gray

Pandanus tectorius Pandanaceae Hala Hawaiian screwpine

 Parkinson ex Zucc.

Scaevola spp. L. Goodeniaceae Naupaka Naupaka

 kuahiwi

Sophora chrysophylla Fabaceae Māmane Mamani

(Salisb.) Seem.

Vaccinium spp. L. Ericaceae Ōhelo Ohelo

Risk Assessment Team

The USDA Forest Service Wood Import Pest Risk Assessment and Mitigation Evaluation 

Team (WIPRAMET) conducted the assessment. The team was originally chartered by 

the Chief of the Forest Service to provide a permanent source of technical assistance to 

the Animal and Plant Health Inspection Service in conducting pest risk assessments on 

forest trees. The team was chosen to perform this assessment because of its expertise and 

previous experience with similar assessments. Additional members with local knowledge 

of Hawai‘i and its resources were added to the WIPRAMET to supplement the original risk 

assessment team.

Pest Risk Assessment

The approach taken for this project followed protocols established by international plant 

protection organizations. The team evaluated the risk potential of the introduction of exotic 

insects and pathogens that could affect 13 native plant taxa.

We identified known pests on the hosts known to exist in Hawai‘i. We compiled a 

similar list of worldwide insects and pathogens not known to occur in Hawai‘i and recorded 

in association with the 13 taxa or other species of the same genera. These insects and 

pathogens were identified, listed, and targeted for further analysis as “agents of potential 

concern.” 

We assessed information on commodities associated with pathways of introduction. 

This included a variety of data from U.S. and foreign sources. This aided in determining 

the likelihood of pests associated with commodities and their likelihood of introduction to 

Hawai‘i.

Because major emphasis was placed on pests with the potential to be transported on, 

in, or with a variety of commodities, these insect and pathogen agents of concern were 

evaluated with respect to the four principal pathways by which introduction of these insects 
and pathogens might occur: (1) plant material, (2) wood products, (3) hitchhikers, and (4) 

potting media/compost/soil. 

Analysis of transport and establishment pathways also included assessment of the 

following: 

1. Identify probable major geographic sources of potential pest introductions (based on 

the origin of foreign trade by all means of transportation to Hawai‘i. 

2. Determine the likelihood of different pathways introducing exotic pests.

3. Evaluate pest interception records at Hawaiian ports of entry.

4. Evaluate historical information on the transport and establishment of damaging 

insects and pathogens in Hawai‘i or areas with similar climates and ecosystems. 

Insect pests and pathogens not known to occur in Hawai‘i and associated with a likely 

commodity were identified to aid the team in performing more detailed risk assessments. 

Individual pest risk assessments (IPRAs) were then developed for the highest ranked 

agents: 12 dealing with insects and 12 dealing with pathogens. These 24 agents are intended 

to serve as examples of specific pests that presently pose a significant threat to native 

Hawaiian shrubs and trees. They are also representatives of general types of damaging 

insect and disease agents, following select pathways, specific modes of establishment, 

and causing damage that is unknown to presently occur in Hawai‘i, but may emerge in 

the future. Ranking was based on the following overall criteria: the probability of pest 

introduction (likely pathway to Hawai‘i), including association with a commodity; transit 

success; colonization success; and potential for spread; and the consequence of introduction, including economic, environmental, and sociopolitical. The individual elements were 

ranked and an overall risk potential was assigned to each of the 24 species.

Forest Resources of Hawai‘i

The archipelago of Hawai‘i consists of 132 islands, reefs, atolls, and shoals, over a distance 

of 2400 km, in the North Pacific Ocean. There are eight major islands. Hawai‘i is covered 

by about 707 400 ha of forest, which is 43 percent of the total land area. About 1,200 taxa of 

flora are native to the Hawai‘i Islands, including 1,158 that are endemic. The species chosen 

for this assessment include pteridophytes, woody trees and shrubs, and a monocotyledonous species. The 13 taxa are ecologically important forest species that provide habitat for 

native fauna and flora in Hawaiian forest ecosystems. If extirpated, it is assumed that any 

one of these species could have cascading deleterious effects on many other native species. 

It follows that improving biosecurity for these species will better protect Hawai‘i’s remaining biodiversity.

Numerous insects and pathogens have been identified on these 13 taxa, some of which 

are native and others introduced to Hawai‘i. For each of the 13 forest taxa, we examined 

the literature and consulted with other scientists and specialists to determine the insects 

and pathogens that occur on them in Hawai‘i. Nearly 500 insects and over 500 pathogens 

and saprobes were identified during this process. Although every effort was made to be 

complete, likely a number of species were missed.
Commodities and Pathways

Hawai‘i receives all of its commodities and visitors either by ship or aircraft. This provides 

many pathways and commodities to transit invasive species. Several pathways may exist 

for a single organism. We developed a means to identify pathways based on the location on 

the host plant where the pest can occur. Pathways included plant material, wood products, 

hitchhikers, and potting media/compost. Each of these pathways has multiple commodities 

in which exotic pests may find transport. 

A significant source of potential pest entry is on solid wood packing material. This 

includes dunnage, crating, pallets, packing blocks, drums, cases, and skids. The origin 

of this material is not necessarily the same as that of the shipment it accompanies, as it 

is routinely reused and reconditioned. On September 16, 2005, the United States started 

enforcing the International Plant Protection Convention’s standard ISPM No. 15 to reduce 

the risk posed by solid wood packing material.

Airline passengers are another major source for potential pest entry. Over 70 percent 

of airline passengers arriving by air to Hawai‘i from 2007 to 2011 were from the mainland 

United States. The principal country of origin for foreign arrivals was Japan, followed 

by Canada. The Animal and Plant Health Inspection Service (APHIS) intercepted over 

7,400 reportable pests at airports from 1984 through 2010. Many of these came in with 

passengers and their baggage.

Plants for horticultural use are continually arriving in Hawai‘i from foreign and domestic locations. Many of these have become invasive and are affecting native ecosystems. In 

addition, they may be carriers for invasive insects and pathogens. The primary and most 

consistent exporting countries for this material are Australia and the Netherlands.

During the period 2008 to 2010, the top countries exporting to Hawai‘i based on value 

of exports were Indonesia, Saudi Arabia, Vietnam, Russia, Thailand, and China. Eight 

of the top 10 are in the Asia-Pacific region. Using commodity value may not be the best 

measure to evaluate potential origins of pests but are the only data readily available.

Insects and Pathogens Posing Risk

The probability of pest introduction is determined by several related factors, including the 

likelihood of (1) a pest traveling with and surviving on a shipment from the place of origin, 

(2) a pest colonizing suitable hosts at the point of entry and during transport to processing 

sites, and (3) subsequent pest spread to adjacent territories. Many insects and pathogens 

could be introduced on various commodities into Hawai‘i from any origin in the world.

Nearly 500 insects and 400 pathogens were identified in this assessment as potentially 

posing risk. These were narrowed down to 12 insect species and 12 pathogens to do indepth 

IPRAs. The following table provides a summary of the ratings for the individual risk 

elements and the overall risk potential for each of the 24 species evaluated. 
Summary of risk potentials for pests of concern to 13 Hawai‘i forest taxa

Likelihood of introduction Consequences of introduction

Common name Host Entry Colonization Spread Economic Environmental Social/ Pest risk

(scientific name) association potential potential potential damage damage political potential

Insects:

 Apple stem borer Ha H H H H H M H

 (Aeolesthes holosericea)

 Botany Bay M H M M M M L M

 diamond weevil 

 (Chryosolopus spectabilis)

 Coconut rhinoceros beetle H H H H M M M H

 (Oryctes rhinoceros)

 Coconut stick insect M M M L L L M M

 (Graeffea crouanii)

 Erythrina scale M H L M M M M M

 (Toumeyella Erythrinae)

 Eugenia psyllid M H H M M M M M

 (Trioza eugeniae)

 Keyhole ambrosia beetle H H H H M L M H

 (Amasa truncata)

 Lemon tree borer M M H M M M L M

 (Oemona hirta)

 Platypodid M H H H M M M M

 ambrosia beetle

 (Megaplatypus mutatus)

 Summer fruit H H H H M H M H

 tortrix moth

 (Adoxophyes orana)

 West Indian sugarcane H H H H H H M H

 borer weevil 

 (Diaprepes abbreviatus)

 White wax scale H H H H H H M H

 (Ceroplastes destructor)

Pathogens:

 Acacia gall rust H H H H M M M H

 (Uromycladium

 tepperianum)

 Aecidium rusts M H M H L M L M

 (Aecidium

 atrocrustaceum, 

 A. calosporum, 

 A. carbonaceum, 

 A. diospyri, 

 A. mabae, 

 A. melaenum, 

 A. muelleri, 

 A. myopori, 

 A. ramosii, 

 A. reyesii, 

 A. rhytismoideum, 

 A. royenae, A. ulei, 
 A. yapoense)

 Armillaria root disease H H H H H H H H

 (Armillaria limonea, 

 A. luteobubalina, 

 A. novae-zelandiae, 

 A. tabescens)

 Calonectria morganii H H H H M M L H

 Fomitiporia spp. H H H H M H H H

 (Fomitiporia australiensis, 

 F. mediterranea, 

 F. punctata, 

 F. robusta, 

 F. sonorae)

 Guava rust/eucalyptus rust H H H H H H H H

 (Puccinia psidii)

 Pestalotia and Pestalotiopsis H H M H L M L M

 (Pestalotia Acacia, 

 P. cibotii, P. diospyri, 

 P. dodonaea, P. pandani, 

 vaccinii; Pestalotiopsis sp., 

 P. breviseta, P. glandicola, 

 P. palmarum, P. photiniae, 

 P. theae, P. uvicola, 

 P. versicolor)

 Phellinus noxius H H H H M H H H

 Pink disease H H H H H H H H

 (Erythricium salmonicolor)

 Ramorum blight H H H H H M H H

 /sudden oak death 

 (Phytophthora ramorum)

 Uromyces rusts M H M M L H L H

 (Uromyces scaevolae, 

 U. sophorae-japonicae, 

 U. truncicola)

 White thread H H H H M M M H

 blight/black rot 

 (Ceratobasidium noxium)

a

 H, M, and L = high, moderate, and low risk, respectively.

Conclusions

A major challenge of this analysis was to determine which of the world’s 400,000 fungal 

species and 900,000 insect species known to feed on plant/plant parts are not yet found 

in Hawai‘i and pose a risk to 13 native forest taxa in the Hawaiian Islands. Although this 

process may seem straightforward, the lists that were produced of potential pests and 

pathogens for each of the 13 taxa are considerable. For some species, like Acacia koa, this 

process produced lists of literally thousands of fungi and insect species that have been 

associated with Acacia species. This is, in large measure, due to the abundance of land area 

worldwide covered by the 700 different species of Acacia and the fact that thousands of 

forest health personnel, mycologists, entomologists, etc. have spent large portions of their 
careers looking at the flora and fauna that affect species in this genus. Metrosideros polymorpha was another key species that had a lot of fungi associated with it, no doubt because 

there are so many Metrosideros species scattered across the Pacific. By contrast, some of 

the other species, like Sophora chrysophylla, Myoporum sandwicensis, and Scaevola spp., 

had very short lists associated with them because their genera hold relatively small numbers 

of species and individuals.

We examined the lists of exotic fungal and insect species for those considered to have 

capacity to be effective pathogens or pests on living trees. We relied on information presented in the literature, where this was available, and also on the experience of the authors 

and reviewers of this document. This helped us narrow the list to the 400 insect pests and 

300 pathogens shown in tables 11 and 12, respectively (app. 7). These tables represent what 

we consider the insect pests and pathogens with the most potential for damaging the 13 taxa 

should they gain entry into Hawai‘i. 

We identified 12 insect pests and 12 pathogens to do indepth analyses or IPRAs. The 

objective was to include in the IPRAs representative examples of insects and pathogens 

found on seeds, roots, bark, sapwood, and heartwood that would have the greatest potential risk to forests and other tree resources of Hawai‘i. These agents were highly diverse 

ranging from leaf rollers and scales to root diseases, stem decay, and leaf blights. 

Among the insects and pathogens assessed, high pest risk potentials were assigned to 

the following 16 organisms or groups of organisms: apple stem borer (Aeolesthes holosericea), coconut rhinoceros beetle (Oryctes rhinoceros; during the analysis, this insect was 

identified as present in Hawai‘i), keyhole ambrosia beetle (Amasa truncata), summer fruit 

tortrix moth (Adoxophyes orana), West Indian sugarcane borer weevil (Diaprepes abbreviatus), white wax scale (Ceroplastes destructor), Acacia gall rust pathogen (Uromycladium

tepperianum), Armillaria root disease pathogens (Armillaria luteobubalina, Armillaria 

tabescens, A. limonea, A. novae-zelandiae), Calonectria morganii, Fomitiporia spp. 

(Fomitiporia australiensis, F. mediterranea, F. punctata species complex, F. robusta species complex, F. sonorae), guava rust/eucalyptus rust pathogen (Puccinia psidii), Phellinus 

noxious, pink disease pathogen (Erythricium salmonicolor), Ramorum blight/sudden oak 

death pathogen (Phytophthora ramorum), Uromyces rust pathogens (Uromyces scaevolae, 

U. sophorae-japonicae, U. truncicola), and white thread blight pathogen (Ceratobasidium 

noxium). A moderate pest risk potential was assigned to the following eight organisms or 

groups of organisms: Botany Bay diamond weevil (Chrysolopus spectabilis), coconut stick 

insect (Graeffea crouanii), Erythrina scale (Toumeyella erythrinae), Eugenia psyllid (Trioza 

eugeniae), lemon tree borer (Oemona hirta), Platypodid ambrosia beetle (Megaplatypus 

mutatus), Aecidium rust pathogens (Aecidium atrocrustaceum, A. calosporum, A. carbonaceum, A. diospyri, A. mabae, A. melaenum, A. muelleri, A. miliare, A. myopori, A. ramosii, 

A. reyesii, A. rhytismoideum, A. royenae, A. ulei, A. yapoense), and Pestalotia/Pestalotiopsis 

leaf and fruit pathogens (Pestalotia acacia, P. cibotii, P. diospyri, P. dodonaea, P. pandani, 

P. vaccinii, P. glandicola, Pestalotiopsis sp., P. breviseta, P. glandicola, P. palmarum, P. 

photiniae, P. theae, P. uvicola, P. versicolor). 
As part of our process, we solicited input on existing and potential pests, as well as 

comment on a draft risk assessment, from scientists and specialists around the world. We 

received over 400 comments. These were extremely helpful and informative to our assessment.

Six priority findings resulted from the analysis. Some of them have been reported in 

other assessments (Culliney et al. [n.d]., Meissner et al. 2009) and have been adopted by us 

as appropriate for Hawai‘i because they are integral to invasive species transport and risk 

around the world. Some are more peculiar to Hawai‘i.

The six findings discussed in detail are: 

1. Inspection alone is not 100 percent effective in preventing introductions. In fact, 

some studies have shown that port inspections, alone, have relatively low interception efficiency.

2. The primary sources of introductions are the mainland United States and 

Asia-Pacific. 

3. There is a strong need to make visitors aware that they are an important potential 

source of unwanted introductions. Given what we know about plant materials as an 

important pathway of pest introduction, there needs to be increased efforts to persuade visitors to voluntarily stop bringing live plant material into Hawai‘i.

4. Plant materials, especially live plants, are by far the most important source of pest 

problems for Hawai‘i. 

5. The solid wood packing material pathway needs more scrutiny. Many pests using 

this pathway have already become established in Hawai‘i, and many more are on 

the list of potentials. Because Hawai‘i’s Department of Agriculture can only inspect 

solid wood packing material that is associated with agricultural commodities, and 

because solid wood packing material is not necessarily specified as associated with 

cargo, it seems as if this could potentially be a pathway that is being insufficiently 

inspected and regulated.

6. Some pests not posing a risk to the mainland United States, or already present in the 

mainland, may be a potential threat to Hawai‘i. The interstate movement of certain 

plant materials from Hawai‘i to the mainland is restricted without treatment and certification. Similar restrictions on interstate movement into Hawai‘i are not in place. 

For the most part, APHIS regulations do not discriminate between the mainland and 

islands of Hawai‘i as far as potential threats. This includes some organisms that are 

native or commonly found on the mainland.

Numerous other observations, both specific and general, are included in the “Pest Risk 

Assessment” concerning detection surveys, regulations, and public education and awareness of the dangers of introduced pests and pathogens.
Contents

1 Chapter 1: Introduction

1 Background

2 Objectives

2 Scope of Assessment

3 Existing Import Regulations and Practices

4 Previous Hawai‘i Pest Risk Assessments

4 Pest Risk Assessment Process Overview

4 Outreach

5 Chapter 2: Forest Resources of Hawai‘i

5 Introduction

6 Description of Taxa Analyzed

6 1. Acacia koa Gray; Fabaceae (Bean family) 

8 2. Cibotium spp. Kaulf.; Cibotiaceae (Dicksoniaceae) (Tree fern family) 

9 3. Dicranopteris linearis (Burm. F.) Underwood; Gleicheniaceae (Forked 

fern family) 

9 4. Diospyros sandwicensis (A. DC.) Fosberg; Ebenaceae (Ebony family) 

10 5. Dodonaea viscosa (L.) Jacq.; Sapindaceae (Soapberry family) 

10 6. Erythrina sandwicensis O. Deg.; Fabaceae (Bean family) 

11 7. Leptecophylla tameiameiae (Cham. & Schltdl.) C.M. Weiller; Ericaceae 

(Heath family) 

11 8. Metrosideros polymorpha Gaud.; Myrtaceae (Myrtle family) 

12 9. Myoporum sandwicense (A. DC.) A. Gray; Scrophulariaceae (Figwort family) 

12 10. Pandanus tectorius Parkinson ex Zucc.; Pandanaceae (Screwpine family) 

13 11. Scaevola sp. L.; Goodeniaceae (Goodenia family) 

14 12. Sophora chrysophylla (Salisb.) Seem.; Fabaceae (Bean family) 

14 13. Vaccinium calycinum Sm., V. dentatum Sm., V. reticulatum Sm.; Ericaceae 

(Heath family) 

15 Known Insect and Disease Pests in Hawai‘i

15 Previous Interceptions of Quarantine Organisms

17 Chapter 3: Pathways and Commodities for Pest Entry

17 Pathways

17 Significant Pathways for Potential Pest Entry

17 Wood Packing Material

18 Airline Passengers

18 Live Plant Material
19 Commodities Entering Hawai‘i

21 Potential Origins of Pests

24 Known Pests at Potential Origins

25 Chapter 4: Insects and Pathogens Posing Risk

25 Introduction

25 Analysis Process

25 Potential Insects and Pathogens of Concern

26 Individual Pest Risk Assessments

26 Insect IPRAs

26 Apple Stem Borer

28 Botany Bay Diamond Weevil

29 Coconut Rhinoceros Beetle

34 Coconut Stick Insect

36 Erythrina Scale

37 Eugenia Psyllid

39 Keyhole Ambrosia Beetle

42 Lemon Tree Borer

45 Platypodid Ambrosia Beetle

48 Summer Fruit Tortrix Moth

50 West Indian Sugarcane Borer Weevil

53 White Wax Scale

54 Pathogen IPRAs

54 Acacia Gall Rust

57 Aecidium Rusts

61 Armillaria Root Disease

69 Calonectria morganii

74 Fomitiporia spp. 

78 Guava Rust/Eucalyptus Rust

83 Pestalotia and Pestalotiopsis

87 Phellinus noxius

91 Pink Disease

96 Ramorum Blight/Sudden Oak Death

104 Uromyces Rusts

106 White-Thread Blight/Black Rot
109 Chapter 5: Summary and Conclusions

109 Summary

113 Issues and Findings

121 Additional Issues and Findings

121 General

122 Ecology

122 Detection Surveys

124 Regulations

124 Education/Public Awareness

125 Acknowledgments

125 English Equivalents

125 References

 Appendix 1—Reviewers and Contributers

 Appendix 2—Scientific Authorities, Chapters 1, 2, 3, and 5

 Appendix 3: Host Scientific Authorities, Potential Insects and 

Potential Pathogens

 Appendix 4: Pest Risk Assessment Process

 Appendix 5: Known Insect and Disease Pests in Hawai‘i

 Appendix 6: Pest Interceptions at Hawai‘i Ports of Entry From 1984 

Through 2010

 Appendix 7: Potential Insects and Pathogens of Concern
Assessment Team

Dr. Gregg A. DeNitto, Team Leader

Forest Pathologist/Field Office Leader

USDA Forest Service, Forest Health Protection

Missoula Field Office

P.O. Box 7669

Missoula, MT 59807

Dr. Andris Eglitis

Forest Entomologist

USDA Forest Service, Forest Health Protection

Central Oregon Insect and Disease Field Office

63095 Deschutes Market Road

Bend, OR 97701

Dr. Jessie A. Glaeser

Research Plant Pathologist

USDA Forest Service

Forest Products Laboratory

One Gifford Pinchot Drive

Madison, WI 53726-2398

Dr. Philip Cannon

Regional Forest Pathologist

USDA Forest Service, Forest Health Protection

1323 Club Drive

Vallejo, CA 94592

Dr. Helen Maffei

Forest Pathologist

USDA Forest Service, Forest Health Protection

Central Oregon Insect and Disease Field Office

63095 Deschutes Market Road

Bend, OR 97701

Sheri Smith

Regional Forest Entomologist

USDA Forest Service, Forest Health Protection

2550 Riverside Drive

Susanville, CA 96130
1

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Background

As a tourist destination, military base, and center for commerce at the “crossroads of the Pacific,” Hawai‘i is especially vulnerable to the introduction and establishment of 

exotic organisms. The likelihood is especially high because 

Hawai‘i imports 80 percent of its consumable goods and has 

a climate favorable to many insects and pathogens yearround. An estimated 9,277 terrestrial arthropod species are 

known from Hawai‘i; 3,432 (37 percent) are nonindigenous 

(Eldredge 2006). Some 500 species of arthropods and 

mollusks in Hawai‘i can be classified as pests (Beardsley 

1991). Of these, 98 percent have been introduced. It is 

estimated that 20 to 40 new terrestrial arthropod introductions occured in Hawai‘i each year from 1937 through 

1967 (Beardsley 1979a), with about 10 percent becoming 

significant pests. In recent years, the rate of new pest arthropods and mollusks establishing in Hawai‘i has averaged 

3.5 species annually (Beardsley 1991). In addition, over 

1,100 plant parasitic and pathogenic species (nematodes, 

bacteria, fungi, and other micro-organisms) are known 

to occur in Hawai‘i (Raabe et al. 1981). Most of these are 

nonindigenous. The islands of Hawai‘i have a large number 

of endemic species. Because most of these endemic species 

have evolved in isolation—free from pressures such as 

grazing, predation, virulent pests, and diseases (Westbrooks 

1998)—the biota lacks defenses against introduced grazers, 

predators, parasites, and pathogens (Simberloff 1995). Thus, 

like other oceanic islands, Hawai‘i is particularly vulnerable 

to biological invasions. For example, although Hawai‘i 

is one of the smallest U.S. states, comprising just 0.2 

percent of its total land mass, more than 25 percent of the 

endangered species in the United States occur there (U.S. 

Congress OTA 1993). 

Over the past decade, insects and pathogens accidently 

introduced into Hawai‘i threaten native forest ecosystems 

and urban forest trees. These introductions have increased 

awareness of the vulnerability of island ecosystems, and 

the need for vigilance regarding invasives beyond those 

affecting agricultural crops.

Chapter 1: Introduction

For example, the two-spotted leafhopper (Sophonia 

rufofascia1) was discovered on O‘ahu in 1987 after being 

detected on plants exported to California (Fukada 1996). By 

1995, the insect was widespread on the six largest Hawaian 

Islands, and causing major damage to uluhe (Dicranopteris 

linearis), ‘ōhi‘a lehua (Metrosideros polymorpha), and 

hāpu‘u (Cibotium spp.), as well as significant damage to 

‘a‘ali‘i (Dodonaea viscosa) and ‘ōhelo (Vaccinium spp.) 

(Conant et al. 2010). Ornamental Erythrina species were all 

but wiped out when the Erythrina gall wasp (Quadrastichus 

Erythrinae) invaded Hawai‘i in 2005 and escaped into the 

forests, killing the native Erythrina species as well. Myoporum sandwicense, which comprises nearly half of the plant 

biomass in the māmane-naio forest type, is now threatened 

by a recently introduced myoporum thrips (Klambothrips 

myopori). Although the strain of guava rust (Puccinia psidii) recently found in Hawai‘i is not significantly impacting 

native ecosystems, the threat is great that new genotypes 

of the rust will invade and threaten ‘ōhi‘a lehua, one of 

Hawai‘i’s dominant forest tree species. Koa wilt, caused 

by the fungal pathogen Fusarium oxysporum f. sp. koae, 

is of unknown origin. The wilt disease is greatly affecting 

survival, growth, and reforestation of koa (Acacia koa), a 

dominant canopy tree and important in native culture. As 

this assessment was being completed, coconut rhinoceros 

beetle (Oryctes rhinoceros) was trapped at Joint Base Pearl 

Harbor-Hickam on O‘ahu (HDOA 2014). The source of this 

introduction has not been determined, but the insect has 

been on Guam at least 6 years. Hawai‘i has a long history of 

implementing quarantines to protect key agricultural crops. 

The same level of effective quarantines is sought for native 

forest species.

In September 1995, the Chief of the U.S. Department of 

Agriculture, Forest Service (USDA FS) chartered the Wood 

Import Pest Risk Assessment and Mitigation Evaluation 

Team (WIPRAMET), made up of USDA FS employees, 

to provide a permanent source of technical assistance to 

the USDA Animal and Plant Health Inspection Service 

1

 Scientific authorities for insects, pathogens, and plants mentioned 

in chapters 1, 2, 3, and 5 are given in appendix 2. Appendices for this 

report are available online at: http://www.fs.fed.us/psw/publications/

documents/psw_gtr250/psw_gtr250_appendix.pdf.
2

GENERAL TECHNICAL REPORT PSW-GTR-250

(APHIS) in conducting pest risk assessments of exotic pests 

that may move with logs. In September 2010, the Hawai‘i 

Division of Forestry and Wildlife (DOFAW) made a request 

of the USDA FS to provide assistance in developing a 

pathway risk assessment for forest pests. They requested 

assistance in identifying high-risk pest species that are 

likely to become established in Hawai‘i upon arrival, as 

well as the pathways through which they could enter the 

state. This report is a response to that request. Because of 

the expertise within WIPRAMET, and the similarity with 

previous work, the request from DOFAW was assigned to 

this team. 

Objectives

The specific objectives of this risk assessment are to:

• Identify insect pest and pathogen species that could 

attack species of concern in Hawai‘i.

• Determine possible pathways for the introduction of 

insect pests and pathogens to selected native flora 

of Hawai‘i. 

• Provide risk assessments for selected pathway/pest 

or pathogen combinations that are determined to be 

of most risk to Hawai‘i forest ecosystems.

This information may be used to support quarantine 

protection, prioritize inspections, implement early detection 

surveys, develop rapid response plans, and educate the 

public. Alternatives from this assessment will be made 

available to regulatory personnel.

Scope of Assessment

As the native flora of Hawai‘i includes over 1,100 species 

(Eldredge and Evenhuis 2002), conducting risk analyses for 

all species is beyond the scope of this effort. For feasibility, 

the scope of this risk assessment is limited to insect and 

mite pests and disease threats to 13 plant species/genera 

(hereafter referred to as “taxa”) identified by DOFAW 

(table 1). While much attention is paid to the recovery of 

threatened and endangered species in Hawai‘i, the dominant 

forest species that provide habitat for them are vulnerable 

to pest outbreaks. The species chosen for this assessment 

include pteridophytes, woody trees and shrubs, and a monocotyledenous species, all of which make up the foundation 

of remaining Hawaiian ecosystems, and if extirpated, would 

have cascading effects on those ecosystems. Although 

there are other species that should arguably be included, to 

make the task manageable, the list was limited to these 13. 

Table 1—Species of interest identified by Hawai‘i Department of Land and Natural Resources, Division of 

Forestry and Wildlife, included in this pest risk assessment

Species of interest Family Native name Common English name

Acacia koa A. Gray Fabaceae Koa Koa

Cibotium spp. Kaulf. Cibotiaceae Hāpu‘u Hawaiian tree fern 

Dicranopteris linearis (Burm. F) Underwood Gleicheniaceae Uluhe False staghorn fern 

Diospyros sandwicensis (A. DC.) Fosberg Ebenaceae Lama Hawaiian ebony

Dodonaea viscosa (L.) Jacq. Sapindaceae ‘A‘ali‘i Hawaiian hopseed bush

Erythrina sandwicensis O. Deg. Fabaceae Wiliwili Hawaiian coral tree

Leptecophylla tameiameiae Ericaceae Pūkiawe Hawaiian heather

 (Cham. & Schltdl.) C.M. Weiller

Metrosideros polymorpha Gaud. Myrtaceae ‘Ōhi‘a lehua Ohia

Myoporum sandwicense (A. DC.) A. Gray Scrophulariaceae Naio False-sandalwood 

Pandanus tectorius Parkinson ex Zucc. Pandanaceae Hala Hawaiian screwpine

Scaevola spp. L. Goodeniaceae Naupaka kuahiwi Naupaka

Sophora chrysophylla (Salisb.) Seem. Fabaceae Māmane Mamani

Vaccinium spp. L. Ericaceae Ōhelo Ohelo
3

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

This list originated with the Natural Area Reserve System 

Commission, an independent group that advises the state on 

managing special lands that have been set aside because of 

their unique biological qualities. The list was reviewed by 

various resource managers, botanists, as well as the state 

forestry agency. By improving biosecurity for these species, 

a large portion of Hawai‘i’s remaining biodiversity will be 

better protected.

This risk assessment estimates the qualitative likelihood that exotic pests will be introduced into Hawai‘i as a 

direct result of the importation of a variety of commodities. 

Pests addressed in this report are phytophagous insects and 

plant pathogens. Major emphasis is placed on pests with the 

potential to be transported on, in, or with a variety of commodities. This assessment also estimates the economic and 

environmental impact of potentially destructive organisms 

if introduced into Hawai‘i. Our expertise does not include 

other types of pests, such as invasive plants, which are, 

therefore, not included in this assessment.

This risk assessment is developed without regard to 

available mitigation measures already in place. Once potential risks are identified, other suitable mitigation measures 

may be formulated, if needed, to reduce the likelihood that 

destructive pests will be introduced into Hawai‘i and pose a 

risk to the above 13 host taxa. The prescription of mitigation 

measures, however, is beyond the scope of this assessment 

and is the responsibility of APHIS and the Hawai‘i Department of Agriculture (HDOA).

Additional information became available and conditions changed as this report was in preparation. The authors 

attempted to keep up to date with these changes, but not all 

were timely in their receipt or our awareness and could not 

be fully incorporated.

Existing Import Regulations and Practices

The HDOA is legally mandated to protect the agricultural 

and natural resources of the state of Hawai‘i (Hawai‘i 

Revised Statutes Chapter 150A 2010). This statute provides 

HDOA with the authority to identify specific plants that 

may be detrimental or potentially harmful to agriculture, 

horticulture, the environment, or animal or public health, 

or that spread or may be likely to spread an infestation or 

infection of an insect, pest, or disease that is detrimental 

or potentially harmful to agriculture, horticulture, the 

environment, or animal or public health. All agricultural 

items, including plants, plant parts, nondomesticated 

animals, micro-organism cultures, microbial products, 

arthropods, and soil require inspection upon arrival in 

Hawai‘i. These items must be checked before the shipment 

can be released to ensure they are free of pests or will not 

become pests themselves. People arriving in Hawai‘i from 

the U.S. mainland must declare agricultural items brought 

into the state on the “Plants and Animals Declaration Form” 

and present these items for inspection to a HDOA plant 

quarantine inspector in the baggage claim area at airports 

and maritime ports. 

Commodities moving domestically from the U.S. mainland are under the rules and regulations of HDOA. Shippers 

of these domestic commodities are required to notify 

HDOA of incoming shipments that require inspection. The 

HDOA inspects cargo based on assigned risk categories; 

all cargo does not receive inspection because of staffing 

capacity. Risk categories are determined based on the type 

of commodity, records of past interceptions, and specific 

pests potentially associated with the commodity. 

General guidelines for the importation of plants from 

the U.S. mainland to Hawai‘i are as follows:

• All plants require inspection upon entry into the 

state (however, because of limited staffing, this 

is not always achieved).

• Plants must be apparently free of insects 

and diseases.

• Plants do not need to be bare-rooted, but the growing media cannot contain soil.

• Parcels brought into the state by mail or cargo must 

be clearly labeled with the words “Plant Materials” 

or “Agricultural Commodities.”

• Shipments must be accompanied by an invoice or 

packing manifest, listing the contents and quantities 

of the commodities imported.

The USDA regulates the introduction of plants and 

plant products into the United States from foreign origin 

under the authority of the Plant Protection Act of 2000 
4

GENERAL TECHNICAL REPORT PSW-GTR-250

(Plant Protection Act 2000). The Department of Homeland 

Security, Bureau of Customs and Border Protection (CBP) 

is authorized to inspect foreign travelers and nonpropagative agricultural commodities for potential harmful pests. 

Officers and specialists within CBP inspect arrivals by air 

and sea using procedures similar to the HDOA’s. The USDA 

APHIS Plant Protection and Quarantine (PPQ) performs the 

inspection of propagative plant materials. 

Previous Hawai‘i Pest Risk Assessments

In 2007, APHIS conducted a pathway risk assessment 

for Hawai‘i (Culliney et al., n.d.), focusing on invasive 

species that threaten the state’s economy and environment. 

That assessment reviewed risks associated with airline 

passengers, cargo, hitchhikers, wood packaging material, 

and the military. It listed imminent pest threats to Hawai‘i 

agriculture. Although never finalized, the draft assessment 

provides a foundation to build upon for analyzing the 

invasive pest threat to native forest species. This current 

assessment relied heavily on the draft 2008 APHIS assessment for background information and for data on Hawai‘i 

and its trade.

In addition to the APHIS assessment (Culliney et al., 

n.d.), HDOA prepared a pest risk assessment for the Kahului 

Airport in 2002 (HDOA 2002). That assessment was based 

on inspection “blitzes” conducted during 2000 and 2001, 

where HDOA inspectors and detector dogs examined 

checked and carry-on baggage, aircraft cabins and cargo 

holds, and 100 percent of all agricultural products shipped 

by air cargo. They found an average of one new invertebrate 

or plant pathogen per day arriving in agricultural cargo 

through a port that receives only 2 percent of Hawai‘i’s 

incoming goods. Although primarily focused on inspection 

of agricultural products, that 2002 assessment does provide 

critical information regarding entry pathways, interception 

rates, and commodities entering the state, some of which 

may be relevant to the current investigation. 

To address the invasive species problem in Hawai‘i, the 

origins of alien species, and the means or “pathways” by 

which they are introduced into the state, must be examined. To date, no pathway analysis has been conducted to 

assess and quantify the risks posed by invasive insect and 

pathogen species to Hawai‘i’s native forest systems. Such 

an assessment is essential to provide a sound basis for 

science-based decisionmaking. Unfortunately, we did not 

have access to sufficient data to properly do a quantitative 

analysis.

Pest Risk Assessment Process Overview

A team of USDA FS and DOFAW specialists were responsible for producing this assessment. They received input 

and assistance from HDOA and U.S. Geological Survey 

personnel. The risk assessment complies with general 

standards set by the international plant protection organizations—for example, North American Plant Protection 

Organization (RSPM 2012), and the International Plant 

Protection Convention (IPPC) of the Food and Agriculture 

Organization of the United Nations (IPPC 2007), as well 

as U.S. government regulations (7 CFR 319.40-11) (APHIS 

1998). These standards are the same as have been used for 

the most recent pest risk assessments prepared by the USDA 

FS for APHIS (Kliejunas et al. 2001, 2003; Tkacz et al. 

1998).

The general process followed can be found in appendix 4.

Outreach

To gather information pertinent to the pest risk assessment, 

WIPRAMET contacted scientists and specialists in the 

fields of forestry, forest entomology, forest pathology, and 

plant quarantine around the world, but especially in the 

Pacific (app. 1). A preliminary list of potential organisms 

of concern was compiled for the 13 hosts of concern and 

sent to individuals for review (app. 1). Suggested revisions 

to the list were incorporated into the final list prepared by 

WIPRAMET. A draft of the assessment was also sent to scientists and specialists. Over 400 comments were returned, 

evaluated, and incorporated into the final assessment where 

the team felt appropriate.
5

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Introduction

The archipelago of Hawai‘i consists of 132 islands, reefs, 

atolls, and shoals, over a distance of 2400 km, in the North 

Pacific Ocean. There are eight major islands, comprising 

more than 99 percent of the total land area, and supporting 

almost all of the human population there and forest cover 

(Loope 1998) (fig. 1). The largest of these islands is Hawai‘i. 

The other seven islands are Kaho‘olawe, Maui, Lāna‘i, 

Moloka‘i, O‘ahu, Kaua‘i, and Ni‘ihau. All of the land area 

is volcanic in origin. The main islands range in age from 

600,000 years (Hawai‘i) to about 5.5 million years (Ni‘ihau). 

The climate of Hawai‘i is varied, with significant 

changes of rainfall, solar radiation, temperature, humidity, and wind over short distances (Schnell 1998). Mean 

monthly temperature only varies about 5 °C at sea level 

over a year. The mountainous topography influences these 

temperatures because of increased cloudiness in windward 

locations and decreasing temperature with elevation. The 

rate of temperature decrease with elevation is fairly constant. Below about 1250 m, temperature drops 6.5  ̊C per 

1000 m. Above this elevation, the temperature decreases 

4 °C per 1000 m (Schnell 1998).

Hawai‘i is covered by about 707 400 ha of forest, 

which is 43 percent of the total land area (Smith et al. 2001). 

About 1,200 taxa of flora are native to the Hawai‘i Islands, 

including 1,158 that are endemic (Loope 1998). Over 

one-fourth of these are considered at some risk of becoming 

extinct. In total, 319 species of plants are listed by the U.S. 

Fish and Wildlife Service as endangered (USFWS 2012). 

The Web database maintained by the Smithsonian National 

Museum of Natural History (2012) includes over 2,400 taxa 

of flowering plants on the islands, about half of which are 

not native. 

Hawai‘i Department of Land and Natural Resources 

(DLNR) identifies four native and five introduced forest 

cover types: (1) ‘ōhi‘a/hāpu‘u; (2) koa/‘ōhi‘a, (3) māmane/

naio, (4) a mixture of species comprising the native dry 

land forest, (5) eucalyptus (Eucalyptus spp.), (6) mixed 

introduced hardwoods, (7) guava (Psidium cattleianum), 

(8) kiawe/Leucaena, and (9) mixed-conifer plantations 

Chapter 2: Forest Resources of Hawai‘i

Figure 1—The major islands of the Hawaiian Archipelago.
6

GENERAL TECHNICAL REPORT PSW-GTR-250

(DLNR 2001). These communities were first identified and 

mapped by Little and Skolmen (1989) (fig. 2).

Hawai‘i recently completed an assessment of the state’s 

forest resources to meet requirements of the 2008 Farm 

Bill (Cannarella 2010). In that document, the state‘s forest 

resources, the benefits they provide, and the threats that 

they face were identified. Consult that document for more 

details on forests, their benefits and threats.

Description of Taxa Analyzed

While much attention is paid to the recovery of threatened 

and endangered species in Hawai‘i, the dominant forest 

species that provide habitat for them are vulnerable to 

pest outbreaks. Recent incursions have spurred resource 

managers to seek improvements of the biosecurity system 

to prevent an ecosystem instability or collapse that would 

occur if such important species were eliminated from 

the landscape. The species chosen for this assessment 

include pteridophytes, woody trees and shrubs, and a 

monocotyledonous species, all of which make up the 

foundation of remaining Hawai‘i ecosystems, and if 

extirpated, would have cascading effects on them. 

Although there are other species that could arguably be 

included, the list was limited to 13 species/genera to make 

the task manageable. This list originated with the Natural 

Area Reserve System Commission, an independent group 

that advises the state on managing special lands that have 

been set aside because of their unique biological qualities. 

The list was reviewed by various resource managers, botanists, and the state forestry agency (Hawai‘i Department of 

Forestry and Wildlife [DOFAW]). By improving biosecurity 

for these species, a large portion of Hawai‘i’s remaining 

biodiversity will be better protected.

Because of the broad distribution of these 13 species/

genera across the islands and their importance to native 

ecosystems, we refer to them on the whole as taxa. What 

follows is more detailed information on each of the 13 

species/species groups analyzed in this report, including 

geographic distribution, ecology, uses, and known pests 

in Hawaiʽi. 

1. Acacia koa Gray; Fabaceae (Bean family)

Common name—koa

Distribution in Hawai‘i—Hawai‘i, Kaua‘i, Lāna‘i, Maui, 

Moloka‘i, and O‘ahu. The potential range has been identified across most of each of these islands except at the 

highest elevations and along much of the coast (Grünwald et 

al. 2012). 

Distribution worldwide—The species is endemic to the 

Hawai‘i Islands. The genus Acacia previously contained 

roughly 1,300 species, about 960 of them native to Australia, with the remainder spread around the tropical to 

warm-temperate regions of both hemispheres, including 

Europe, Africa, southern Asia, and the Americas. In 2005, 

the genus was divided into five separate genera; instead of 

the name Acacia being retained for the majority of the Australian species and a few in tropical Asia, Madagascar, and 

the Pacific Islands. Koa’s closest relatives may be Acacia

species on Rénuion and Mauritius in the Indian Ocean, or 

A. melanoxylon in Australia.

Ecology—Koa is a large, nitrogen-fixing, shade-intolerant 

tree, typically attaining a height of 15 to 25 m and a spread 

of 6 to 12 m. Height and spread are greater in deep volcanic 

ash. The tree is capable of reaching 6 to 9 m in height in 

5 years on a good site. The species grows at elevations 

of 100 to 2300 m on acidic to neutral soils, and requires 

850 to 5000 mm of annual rainfall. Koa and ‘ōhi‘a lehua 

dominate the canopy of mixed mesic forests. Koa is second 

in abundance to ‘ōhi‘a lehua in native Hawai‘i forests, and 

frequently grows co-dominantly with it. Koa provides 

important habitat to native birds and invertebrates, and is 

regenerated for restoration, both by scarifying areas where 

a seed bank persists, and by outplanting seedlings (Baker et 

al. 2009).

Human uses—Ancient Hawaiians used koa for voyaging 

canoes and surf boards. The resurgence in Hawaiian 

culture, and specifically traditional navigation, has created 

an interest in growing koa for canoe building; however, 

few canoe-sized trees exist today. Koa wood is valuable 

for high-quality wood carvings and furniture making, 
7

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Figure 2—Generalized forest types mapped on the eight major islands of Hawai‘i (Little and Skolmen 1989).
8

GENERAL TECHNICAL REPORT PSW-GTR-250

especially if the piece being worked has strongly expressed 

curly grain. There are several small koa mills, mainly on the 

island of Hawai‘i.

Because of the high value of koa wood, and the general 

acceptance of this tree as an important part of Hawaiian 

culture, there is considerable interest in growing koa in 

plantations. Although the species produces large amounts of 

seed that germinate easily, and grows quickly on some sites, 

it has problems as a plantation tree. It does not stand up well 

in competition, especially from itself, so mortality rates 

tend to be high (greater than 60 percent) 

2. Cibotium spp. Kaulf.; Cibotiaceae 

(Dicksoniaceae) (Tree fern family)

Common names—hāpu‘u, tree fern

Distribution in Hawai‘i—four species are endemic to the 

Hawai‘i Islands—

C. chamissoi; Hawai‘i, Lāna‘i, Maui, Moloka‘i, O‘ahu. 

The potential range of C. chamissoi is primarily coastal and 

mid elevations (Grünwald et al. 2012).

C. glaucum; Hawai‘i, Kaua‘i, Lāna‘i, Maui, Moloka‘i, 

O‘ahu. The potential range of C. glaucum is primarily 

coastal and mid elevations (Grünwald et al. 2012).

C. menziesii; Hawai‘i, Kaua‘i, Lāna‘i, Maui Moloka‘i, 

Oʽahu. The potential range of C. menziesii is primarily 

coastal and lower elevations (Grünwald et al. 2012).

C. nealiae; Kaua‘i. The potential range of C. nealiae is 

primarily coastal and mid elevations (Grünwald et al. 2012).

Distribution worldwide—The genus Cibotium is endemic 

to northeast India, southern China, Taiwan, Malaysia, 

Indonesia, New Guinea, the Ryukyu Islands (Japan), the 

islands of the Pacific (including Hawai‘i), El Salvador, 

Guatemala, Honduras, and southern Mexico (Chiapas, 

Oaxaca, and Veracruz).

Ecology—The genus consists of 11 species of large tree 

ferns (plus a naturally occuring hybrid, Cibotium x heleniae [C. chamissoi x C. menziesii]). Some species have 

tall trunks and may reach a height of 8 m with a crown of 

spreading fronds up to 6 m in length. Others have a prostrate habit. 

Cibotium chamissoi (Chamisso’s manfern) is a large, 

upright tree fern found in mesic to wet forests from 150 to 

1200 m on all major islands except Kaua‘i. It is common 

on O‘ahu and uncommon and scattered on Moloka‘i, Maui, 

Lāna‘i, and Hawai‘i (Palmer 2003).

Cibotium glaucum (Hāpu‘u pulu) is a large tree fern 

with leathery fronds. Although the trunk usually does not 

surpass 3.7 m in height, the arching fronds can reach a great 

length. It is abundant in mesic to wet forests, from 300 to 

1700 m on all major islands. This species is usually found 

at higher elevations than the other Hawai‘i species (Palmer 

2003). Hapu‘u pulu is one of the most commonly used of 

Hawai‘i’s native tree ferns in landscape plantings and is 

an excellent understory plant to help control erosion. The 

species can occasionally be found for sale in California. 

Cibotium menziesii (Hāpu‘u ‘i‘i) can grow up to 11 m 

tall, but is typically 2.1 to 7.6 m in height with a diameter of 

nearly 0.91 m, making it Hawai‘i’s largest tree fern. Cibotium menziesii is locally abundant on the windward portions 

of the main Hawai‘i Islands. It is found in rainforests, 

occasionally in mesic forests, at elevations of 305 to 1830 m, 

and can grow on the ground or on trees as an epiphyte. 

Cibotium nealiae (Neal’s manfern) is a 1-m-tall dwarf 

variety, restricted to the island of Kaua‘i between 135 and 

1300 m. It is never seen in the horticultural trade.

The three large Cibotium species, locally important as 

ecosystem dominants, are also important for biodiversity 

preservation in Hawai`i, as their trunks serve as substrates 

for epiphytic growth of many other ferns and flowering 

plant species. In forest areas where feral pig damage is moderate, allowing hāpu‘u to persist, many native herbaceous 

species survive pig rooting by growing epiphytically on the 

fern, out of reach of pigs, and can recolonize the forest floor 

if pigs are controlled.

Human uses—The starchy core is an important food 

source for feral pigs (Anderson 1994). Parts of C. menziesii 

have been used in traditional medicine to treat a variety of 

illnesses and ailments. The fibers are used in handcrafted 

pillows that are sold as souvenirs on the islands. The trunk 

was hollowed out by native Hawaiians and used as a planter 

for uhi (Dioscorea alata); this practice continues today.
9

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

3. Dicranopteris linearis (Burm. F.) Underwood; 

Gleicheniaceae (Forked fern family)

A form of D. linearis, D. linearis (Burm.) Underw. forma 

emarginata, is endemic to Hawai‘i.

Common names—uluhe, old world forked fern, false 

staghorn fern

Distribution in Hawai‘i—Indigenous to Hawai‘i, Kaua‘i, 

Lāna‘i, Maui, Moloka‘i, and O‘ahu. The potential range of 

D. linearis has been identified on all of the major islands 

from the coast to mid elevations, including near Hilo and 

Līhu‘e (Grünwald et al. 2012).

Distribution worldwide—The genus Dicranopteris

contains about 22 species of terrestrial ferns. Dicranopteris 

linearis is pantropical, widely distributed throughout wetter 

parts of the Old World tropics and subtropics, including all 

of Polynesia.

Ecology—Uluhe is a very common terrestrial fern in mesic 

to wet forests, often covering steep slopes, near sea level 

to above 2000 m, on all major islands. It is intolerant of 

drought, shade, and frost and is an early invader on disturbed sites. It is an important soil-binding pioneer species 

that volunteers after a landslide or other erosion (Follett et 

al. 2003). Uluhe forms dense thickets, often more than 3 m 

deep, over large areas of wet Hawai‘i rainforests. Rhizomes, 

which aid in its spread, can climb other vegetation up to 

several meters. 

After establishment, this fern can persist for an 

extended period but is eventually shaded out by overstory 

trees. It plays a large role in structuring plant communities 

in many habitats of Hawai‘i. In typical succession on new 

lava or cinder surfaces, uluhe mats eventually give way 

in succession to Metrosideros forest (Follett et al. 2003, 

Mueller-Dombois 2000). 

Human uses—Dicranopteris linearis has numerous uses 

around the world. It has been used medicinally for asthma, 

women’s sterility, and as an antihelmintic (Perumal 2010). 

Hawaiians drank an infusion brewed from the fronds as 

a laxative (Palmer 2003). The aqueous extract from D. 

linearis fronds was shown to have antinociceptive, anti-inflammatory, and antipyretic properties in experimental 

animals (Zakaria et al. 2008). It has been used for erosion 

control and for building materials. Fiber from the plant is 

used in the production of various domestic and personal 

items. It can be formed into ropes for lashing posts. It is also 

used for the construction of leis.

4. Diospyros sandwicensis (A. DC.) Fosberg; 

Ebenaceae (Ebony family)

Common names—lama, ēlama

Distribution in Hawai‘i—Hawai‘i, Kaua‘i, Lāna‘i, Maui, 

Moloka‘i, O‘ahu. The range of this species is primarily 

coastal and low elevations. It can grow near Hilo, Honolulu, 

Kawaihae, and Kona (Grünwald et al. 2012).

Distribution worldwide—The species is endemic 

to Hawai‘i.

Ecology—Diospyros is a genus of about 450 to 500 species 

of deciduous and evergreen trees. The majority are native 

to the tropics, with only a few species extending into 

temperate regions. They are commonly known as ebony 

or persimmon trees. Diospyros sandwicensis is a small, 

slow-growing tree generally not more than 15 m tall and 3 

m wide. It occurs, sometimes as a dominant plant, in dry 

to moist forests and occasionally in wet forests. Lama was 

once a primary component of Hawai‘i dry forests, but habitat degradation owing to wildfire and grazing by cattle and 

goats have drastically reduced the extent of dry forests and 

the abundance of lama. It grows at elevations ranging from 

almost sea level to 1220 m (Wagner et al. 1990). Currently, 

the Hawai‘i species is treated as endemic, but the closeness 

to other Pacific species should be recognized. 

Human uses—Lama is considered sacred in Hawaiian 

culture. It is not a primary medicinal plant but can be found 

as a secondary ingredient in many remedies. The berries 

are edible.
10

GENERAL TECHNICAL REPORT PSW-GTR-250

5. Dodonaea viscosa (L.) Jacq.; Sapindaceae 

(Soapberry family)

Common names—‘a‘ali ‘i, ‘a‘ali‘i ku makani, ‘a‘ali‘ ku ma 

kua, kumakani, hopbush.

Distribution in Hawai‘i—Hawai‘i, Kaho‘olawe, Kaua‘i, 

Lāna‘i, Maui, Moloka‘i, Ni‘ihau, and Oʽahu. This species 

can be found almost anywhere on all of the islands except 

the highest elevations of the island of Hawai‘i (Grünwald et 

al. 2012).

Distribution worldwide—The species is indigenous 

and widespread throughout the tropics and subtropics, 

particularly in the Southern Hemisphere, including 

Australia, New Zealand, Southeast Asia, Pacific Islands, 

India, Africa, Southern United States, Mexico, Caribbean, 

Central and South America. It has been introduced to 

Israel. The evolutionary origin of the genus is Australia; 59 

of the 61 species of Dodonaea are restricted to Australia. 

In Australia, D. viscosa has seven subspecies that are 

geographically distinct.

Ecology—The species is found in almost every habitat from 

near sea level to 2347 m. Tree-sized plants are mostly in the 

upper elevation forests of Hawai‘i and Maui, but are also 

observed occasionally in the Wai‘anae and Ko‘olau Ranges 

on O‘ahu. It is often found in open locations, such as ridges, 

and is an early colonizer of lava fields and pastures.

Human uses—Dodonaea viscosa is used extensively in 

dry forest restoration in Hawai‘i. The flowers of D. vicosa

are unspectacular, but its winged fruits can become red 

and purple as they mature, making it an attractive garden 

plant in the tropics and subtropics. One cultivated variety 

develops purple leaves when grown in direct light and is 

a popular ornamental. Fruits and seeds were traditionally 

used for dye. The dense, hard, and durable wood is used 

for specialty products, lumber, and fuel wood by native 

cultures. The plants have medicinal properties that have 

been used by native populations throughout the world.

6. Erythrina sandwicensis O. Deg.; Fabaceae 

(Bean family)

Common names—wiliwili, Hawaiian erythrina, Hawaiian 

coral tree

Distribution in Hawai‘i—Hawai‘i, Kaho‘olawe, Kaua‘i, 

Lāna‘i, Maui, Moloka‘i, Ni‘ihau, and O‘ahu. This species 

principally occupies coastal and very low elevations. It may 

be found near Kawaihae, Kona, Honolulu, and Kahului 

(Grünwald et al. 2012). 

Distribution worldwide—The wiliwili tree is endemic 

to Hawai‘i. About 115 species of Erythrina have been 

described, with centers of distribution in South and Central 

America, and Africa. Two native Erythrina exist on the 

U.S. mainland—E. herbacea and E. flabelliformis. Erythrina herbacea (redcardinal) is widespread throughout the 

Southeastern United States, and E. flabelliformis (coralbean) 

is found in arid environments in Arizona and New Mexico. 

The Neotropics are a center of endemism for Erythrina; 24 

species are native to Mexico. 

Ecology—Erythrina sandwicensis is a small deciduous tree 

characterized by short spines, leaves with three broadly 

triangular leaflets, and showy orange, yellow, salmon, 

greenish or whitish flowers when leafless. Trees are 4.5 to 

9 m tall, with a short, stout, crooked or gnarled trunk 0.3 to 

0.9 m in diameter, stiff spreading branches, and broad thin 

crown becoming wider than high. Wiliwili was once an 

abundant endemic tree in the now much-reduced dry forests 

at low elevations of 152 to 610 m on the lee side of the 

Hawai‘i Islands. It is locally common in dry forests up to 

600 m on leeward slopes of all main islands (Wagner 1990). 

At present, native dry forests have been largely replaced by 

kiawe (Prosopis pallida), but wiliwili may still be seen in 

the dry gullies on the leeward side of all islands (Little and 

Skolmen 1989). Wiliwili is used as a restoration species in 

dry forests, especially following the success of a biological 

control release to control the Erythrina gall wasp. 
11

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Human uses—Erythrina spp. are important to native 

cultures and are keystone species in many tropical and 

subtropical ecosystems. The bright reddish-orange seeds 

are used in leis. On Moloka‘i, trees produce an especially 

treasured yellow seed. Coral trees are cultivated for their 

showy flowers, and countless numbers exist as high-value 

ornamentals. Some Erythrina spp. are used widely in the 

tropics and subtropics as street and park trees, especially 

in drier areas. 

7. Leptecophylla tameiameiae (Cham. & Schltdl.) 

C.M. Weiller; Ericaceae (Heath family)

Common name—pūkiawe

Distribution in Hawai‘i—Hawai‘i, Kaua‘i, Lāna‘i, Maui, 

Moloka‘i, and O‘ahu. Leptecophylla tameiameiae occurs 

over much of the islands except for the driest sites (Grünwald et al. 2012).

Distribution worldwide—Indigenous to Hawai‘i and 

Marquesas Islands (Nuku Hiva)

Ecology—Now in the Ericaceae, pūkiawe was formerly 

known as Styphelia tameiameiae and placed in the Family 

Epacridaceae (Wagner et al. 1990). Pūkiawe, or Hawaiian 

heather, is a common indigenous shrub that is often the 

principal vegetation component in mixed mesic forests, 

wet forests, bogs, and alpine shrublands. It occurs, from 

15 to 3200 m elevation, on all the main Hawai‘i Islands 

except Ni‘ihau and Kaho‘olawe. Pūkiawe is an exceedingly 

variable species, both morphologically and ecologically. 

The largest wild specimens of pūkiawe, generally in wet 

forest situations, grow to 3 m in height and have a spread of 

about 2 m. The species is found in areas where the annual 

precipitation ranges from 12 to 250 cm or more. 

Human uses—The entire pūkiawe plant was highly 

esteemed by early Hawaiians. Second-stage kapa beaters, 

called kua kala, were made from several native woods 

including pūkiawe. The leaves were used medicinally for 

cold or headaches. The new leaves (liko) and berries were 

used by lei makers, and the boiled and mashed berries were 

used as a dye for coloring kapa cloth. 

8. Metrosideros polymorpha Gaud.; Myrtaceae 

(Myrtle family)

Common names—‘ōhi‘a lehua, ‘ōhi‘a

Distribution in Hawai‘i—Hawai‘i, Kaua‘i, Lāna‘i, Maui, 

Moloka‘i, and O‘ahu. Metrosideros polymorpha occurs over 

much of the islands except for the driest sites (Grünwald et 

al. 2012).

Distribution worldwide—Metrosideros polymorpha is 

endemic to the Hawai‘i Islands.The genus Metrosideros has 

about 50 species of trees, shrubs, and vines; native to the 

islands of the Pacific Ocean, from the Philippines to New 

Zealand, and including the Bonin Islands, Polynesia, and 

Melanesia, with an anomalous outlier in South Africa.

Ecology—‘Ōhi‘a lehua is the most common of Hawai‘i 

trees, and makes up about 80 percent of the remaining 

native Hawai‘i forest (Friday and Herbert 2006). The 

species exhibits tremendous morphological variation and 

occurs over a wide range of habitats. The tree typically 

reaches 20 to 24 m in height. It grows over a wide elevation 

range, from sea level to 2500 m, and over a wide range of 

precipitation, from 40 to 1000 cm. The largest components 

of ‘ōhi‘a are in lowland and montane wet and mesic forests, 

dry forests, subalpine shrublands, and new lava flows. Past 

land use practices have resulted in the reduction of ‘ōhi‘a’s 

range. It tends to be slow growing and shade intolerant. It 

does not regenerate in its own shade or under other tree 

canopy, but regenerates rapidly and prolifically from windblown seeds after site disturbance. The species is a critical 

food source to endemic nectivorous and insectivorous birds 

(Berger 1981, Smith et al. 1995) and critical specific habitat 

to endemic Achatinella and Partulina tree snail species 

(Hadfield and Miller 1989, Hadfield and Mountain 1980). 

Human uses—There are many ancient and modern uses for 

the flowers, leaves, and wood of ‘ōhi‘a lehua. Ōhi‘a lehua is 

an important landscape tree and provides shade and wind 

protection. The flowers provide nectar for honey production. 

The wood is very hard and dense. The most common uses 

of the wood include wood strip flooring, decking, decorative 

posts, and round wood construction. 
12

GENERAL TECHNICAL REPORT PSW-GTR-250

9. Myoporum sandwicense (A. DC.) A. Gray; 

Scrophulariaceae (Figwort family)

Common names—naio, false sandalwood

Distribution in Hawai‘i—Indigenous to Hawai‘i (endemic 

to Hawai‘i and Mangaia, a small island in the Cook Islands). 

In Hawai‘i, naio is found on Hawai‘i, Kaua‘i, Lāna‘i, Maui, 

Moloka‘i, Ni‘ihau, and O‘ahu. This species can be found 

almost anywhere on all of the islands except the highest 

elevations of the island of Hawai‘i (Grünwald et al. 2012).

Distribution worldwide—Myoporum is a genus of 

flowering plants in the Scrophulariaceae (formerly placed 

in Myoporaceae). There are about 32 species in the genus, 

which is found from Mauritius, across Australasia to the 

Pacific Islands, and north to China. Myoporum spp. are 

widely planted as ornamentals. 

Ecology—Naio is common in dry upland forest and shrublands and near sea level. It is uncommon in many areas it 

formerly occupied because of site disturbance. On Hawai‘i 

and Maui, trees, some large, occur in mesic and dry forests, 

whereas on the other islands it is mostly a shrub. Along with 

mamane (Sophora chrysophylla), naio is an integral part of 

palila (an endangered honeycreeper) habitat on Mauna Kea. 

Naio is planted as an ornamental shrub. 

Human uses—Timber of this species was among those preferred for frames of Hawaiian homes. It was also used for 

fishing torches because of its good burning characteristics. 

Naio is considered good firewood by most upland ranchers. 

The lumber cut from large trees in recent years has been 

used for flooring, furniture, and craftwood items. 

10. Pandanus tectorius Parkinson ex Zucc.; 

Pandanaceae (Screwpine family)

Common names—hala, pū hala

Distribution in Hawai‘i—Hawai‘i, Kaua‘i, Lāna‘i, Maui, 

Moloka‘i, Ni‘ihau, and O‘ahu. This species principally occupies coastal and very low elevations. It may be found near 

Hilo, Kawaihae, Kona, Honolulu, and Kahului (Grünwald et 

al. 2012). 

Distribution worldwide—The genus Pandanus contains 

about 600 species of palm-like monocots native to the Old 

World tropics and subtropics. Pandanus tectorius naturally 

occurs in strandline and near coastal forests in Southeast 

Asia, including the Philippines and Indonesia, extending 

eastward through Papua New Guinea and northern Australia, and throughout the Pacific islands, including Melanesia 

(Solomon Islands, Vanuatu, New Caledonia, and Fiji), 

Micronesia (Palau, Northern Marianas, Guam, Federated 

States of Micronesia, Marshall Islands, Kiribati, Tuvalu, 

and Nauru), and Polynesia (Wallis and Futuna, Tokelau, 

Samoa, American Samoa, Tonga, Niue, Cook Islands, 

French Polynesia, and Hawai‘i).

Ecology—Hala is common to abundant in many Hawai‘i 

coastal ecosystems. Hala was generally believed to have 

been first introduced to Hawai‘i by the Polynesians (Abbot 

1992), but in 1993, was proved to be native to the Hawai‘i 

Islands when a rockslide uncovered a 1-million year-old 

fossilized impression on a Kaua‘i beach (TenBruggencate 

1993). Polynesians undoubtedly brought selected cultivars 

with them, increasing the variation of this species in 

Hawai‘i (Staples and Herbst 2005).

Pandanus tectorius grows in maritime (usually less 

than 20 m above sea level), tropical, humid and subhumid 

climates. Pandanus mainly occurs in localities with 1500 

to 4000 mm annual rainfall, and with no or a short dry 

season (i.e., no or a few months receiving less than 40 mm 

on average). In its native habitats, temperatures are warm 

to hot throughout the year and show little variation, both 

seasonally and diurnally. It is adapted to an extraordinarily 

wide range of light to heavy-textured soil types, including 

brackish/saline soils, light-colored, infertile coralline atoll 

sands, alkaline sands, thin soils over limestone, and peaty 

swamps. In Hawai‘i, it is an important component of the 

few remaining intact lowland wet forests on the islands of 

Hawai‘i and Kaua‘i.

Human uses—Hala is an extremely important cultural 

plant species for native Hawaiians, who traditionally used it 

for cordage, thatching, healing, decoration, and other uses 

(Abbot 1992, Thompson et al. 2006). The plant is prominent 
13

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

in Pacific culture and tradition, including local medicine. 

Hundreds of cultivated varieties, collectively recognized in 

the Pacific, but specific to numerous independent cultural 

traditions, are known by their local names and characteristics of fruits, branches, and leaves. All parts are used, from 

the nutritious fruits of edible varieties, to the poles and 

branches used in construction, to the leaves for weaving 

and garlands. 

11. Scaevola sp. L.; Goodeniaceae 

(Goodenia family)

Common name—naupaka

Distribution in Hawai‘i—The species of Scaevola and 

their distribution in the Hawai‘i Islands are listed in table 2:

Distribution worldwide—Goodeniaceae consists of more 

than 130 tropical species, with the center of diversity being 

Australia and Polynesia, including Hawai‘i. Scaevola 

taccada is the only Hawai‘i species that is found outside of 

the Hawai‘i Islands. It is widely distributed throughout the 

tropical and subtropical Pacific and Indian Oceans. It is an 

introduced species in Florida and certain Caribbean islands, 

including the Cayman Islands and the Bahamas. Many species of Scaevola, and all other genera of the Goodeniaceae, 

are limited to Australia where they are herbaceous and have 

little commercial value. 

Ecology—The Hawai‘i Islands are home to nine endemic 

Scaevola species, most of which are short shrubs. The 

mountain naupaka, S. gaudichaudiana, is a small tree 

that grows up to 4.9 m tall and 7.6 cm in diameter. Beach 

Table 2—Scaevola spp. and their distribution in the Hawai‘i Islands

Common name/

Botanical name Hawai‘i name Hawai‘i distribution (when known)

Scaevola chamissoniana Naupaka kuahiwi Hawai‘i, Lāna‘i, Maui, Moloka‘i 

 Gaudich. endemic

Scaevola coriacea Dwarf naupaka Maui, Moloka‘i (Mokuho‘oniki Islet); 

 Nutt. endemic historically on five additional 

 islands. Endangered species.

Scaevola gaudichaudiana Mountain naupaka, Kaua‘i, O‘ahu 

 Cham. endemic Naupaka kuahiwi

Scaevola gaudichaudii Ridgetop naupaka; Hawai‘i, Kaua‘i, Lāna‘i, Maui, 

 Hook. & Arn. endemic Naupaka kuahiwi Moloka‘i, O‘ahu

Scaevola glabra Hook. ‘Ohe naupaka Kaua‘i, O‘ahu

 & Arn. endemic

Scaevola kilaueae O. Huahekili uka, Hawaiʽi (Ocean View Estates, 

 Deg. endemic Papa’ahekili; Ka‘u District; Kilauea). Rare.

 Naupaka kuahiw’i

Scaevola mollis Hook. & Naupaka, Kaua‘i, Moloka‘i (rare), O‘ahu

 Arn. endemic Naupaka kuahiwi

Scaevola procera Forest naupaka, Kaua‘i, Moloka‘i 

 Hillebr. endemic Naupaka kuahiwi

Scaevola taccada (Gaertn.) Beach naupaka, Kure atoll, Midway atoll, Pearl and 

 Roxb. indigenous Naupaka kahakai, Hermes atoll, Lisianski Island, 

 Aupaka, Huahekili Laysan Island, French Frigate 

 Shoals, Hawaiʽi
14

GENERAL TECHNICAL REPORT PSW-GTR-250

naupaka, S. sericea (= S. taccada), is a densely branched, 

woody shrub that can grow more than 3 m tall. Hybridization occurs among some of the nine species. 

Human uses—Species of Scaevola are abundantly planted 

in Hawai‘i as landscape trees and shrubs, with different 

species being suited for different habitats—from arid 

wastelands to wet areas. The flowers of Scaevola are valued 

owing to traditional folklore tales, and flowers and seeds are 

used in lei making. Fabric dyes can be made from fruits.

12. Sophora chrysophylla (Salisb.) Seem.; 

Fabaceae (Bean family)

Common names—māmane, māmani

Distribution in Hawai‘i—Hawai‘i, Kaua‘i, Lāna‘i 

(extinct?), Maui, Moloka‘i, and O‘ahu; it is rare on Kaua‘i, 

Moloka‘i, and O‘ahu but common at higher elevations on 

Maui and Hawai‘i. It primarily may be found at lower to 

mid elevations on the islands (Grünwald 2012).

Distribution worldwide—The species is endemic to 

Hawai‘i. Sophora is a genus of about 45 species of small 

trees and shrubs. The species are native to Southern Asia, 

Australasia, the islands of the Pacific Ocean, western South 

America, and southeast Europe. One species, S. tomentosa

(necklace pod), has a native distribution in coastal areas of 

subtropical and tropical climates around the world—Americas, Africa, Australia, Japan, and other Pacific islands.

Ecology—Māmane is a large shrub or medium-sized tree 

up to 15 m tall. This species is one of the most widely 

distributed trees in Hawai‘i and is a dominant species 

in subalpine forest types on east Maui and Hawai‘i. It is 

common mainly in dry mountain forests at 1219 to 2438 

m elevation, ranging down almost to 30 m and up to 2896 

m at the treeline on the highest mountains of the island of 

Hawai‘i (Mauna Kea, Mauna Loa, and Hualalai). It reaches 

its best development as a tree on the higher slopes of Mauna 

Kea and Mauna Loa. Elsewhere, except for portions of 

Haleakala on Maui, it grows predominantly as a shrub.

Māmane is essential for the endangered palila bird, a 

Hawai‘i honeycreeper that feeds almost exclusively on the 

plants’ immature seeds when these are in season and nests 

in māmane branches. Caterpillars of Cydia moths eat the 

māmane’s seeds, and, in turn, are eaten by the palila.

Human uses—The flowers were used as an astringent. 

The hard, durable wood was used by the native Hawaiians 

for house-building material, digging sticks, sled runners, 

tools, firewood, and fence posts. The wood was also used in 

religious rituals to ward off evil.

13. Vaccinium calycinum Sm., V. dentatum Sm., V. 

reticulatum Sm.; Ericaceae (Heath family)

Common names—‘ōhelo, tree ohelo

Distribution in Hawai‘i—Endemic to Hawai‘i. The potential ranges of V. calycinum and V. dentatum are mainly at 

low elevations. Vaccinium reticulatum extends elevationally 

to near the highest points of the island of Hawai‘i (Grünwald et al. 2012).

Vaccinium calycinum—Hawai‘i, Kaua‘i, Lāna‘i, Maui, 

Moloka‘i, O‘ahu

Vaccinium dentatum—Hawai‘i, Kaua‘i, Lāna‘i, Maui, 

Moloka‘i, O‘ahu 

Vaccinium reticulatum—Hawai‘i, Kaua‘i, Maui, 

Moloka‘i, O‘ahu 

Ecology—About 450 species of Vaccinium are found in 

north temperate, tropical, and subtropical regions around 

the world. Numerous species are grown for fruit production 

and as ornamentals. Vaccinium calycinum is a woody 

shrub or small tree that is slow growing and long lived. 

It ranges from 500 to 1800 m elevation in wet forests and 

bogs in its natural habitat. Vaccinium dentatum is a small, 

sprawling shrub. Vaccinium reticulatum is a small shrub 

that is long lived and grows on disturbed sites from 640 to 

3700 m elevation. It is rare on Kaua‘i, O‘ahu, and Moloka‘i 

but common on Maui and Hawai‘i. The berries provide an 

important food source for the endangered nēnē or Hawaiian 

goose (Branta sandvicensis), Hawai‘i’s state bird.
15

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Human uses—The early Hawaiians believed that the ‘ōhelo 

was sacred to Pele, the goddess of fire. Various parts of 

‘ōhelo have been used for their medicinal properties. The 

flowers and fruit were (and are to this day) used in lei making. The berries produced are similar to other Vaccinium 

species and are edible. They are used to make jams, jellies, 

and pie filling. Research on production of ornamental ‘ōhelo 

has been done to provide an agricultural source of berries 

and lessen the impact of extensive berry harvesting on 

native populations. 

Known Insect and Disease Pests 

in Hawai‘i

Numerous insects and pathogens have been identified on 

these 13 taxa, some of which are native and others introduced to Hawai‘i. These are of obvious interest in our analysis because of their presence already in the state. We did an 

extensive literature search and consulted with local forest 

health specialists to identify known insects and pathogens. 

The known insects and pathogens are listed in tables 5-1 

and 5-2 (app. 5)1, including the species they attack, whether 

they are native or introduced, the part of the plant on which 

they are found, and which islands they inhabit. 

Previous Interceptions of Quarantine 

Organisms

A search of the APHIS Pest-ID database was made for 

pests identified at Hawai‘i ports of entry from 1984 to 2010 

(APHIS 2007a). This does not include military ports of 

entry. The search included insects and pathogens on all 

plant hosts and other means of entry. Over 10,000 items 

were reported at least once transporting a pest (table 6-1, 

app. 6). More than 9,800 pests were intercepted on these 

commodities during this period (table 6-2, app. 6). The 

majority of the pests were insects and often not identified 

to species. The severity of the infestation is not reported. A 

difficulty in interpreting these data is that foreign shipments undergo inspection at the first port of U.S. entry. If 

a shipment first makes entry at a U.S. mainland port then 

is shipped to Hawai‘i, the port of entry for the interception 

is the mainland port, not the final destination port. Any 

associated pest is then recorded associated with the commodity at the mainland port and not with any Hawai‘i port. 

Much of the international trade destined for Hawai‘i occurs 

through U.S. mainland ports and is, therefore, not included 

in this pest data. 

Most of the interceptions were in Honolulu, either at the 

airport or seaport. A very small number were intercepted 

at the Kailua and Kahului airports and harbors. Most of the 

pests were intercepted in baggage at the Honolulu International Airport. The second largest source of interceptions 

was with cargo. Citrus sp. and Alyxia sp. had the largest 

number of interceptions of all commodities. Most of these 

were either fruit and leaves of Citrus and leaves of Alyxia. 

This is most likely because of the volume of these materials 

imported. Figure 3 identifies the commodities with more 

than 100 interceptions each. Several of this assessment’s 

species of concern had related host species with interceptions reported, including Acacia, Diospyros, Erythrina, 

Pandanus, and Vaccinium. The imported commodity for 

Acacia was cut flowers and seed. The two interceptions on 

Erythrina were on plants. Interceptions on the remaining 

three species concerned fruit. Most intercepted pests came 

from countries in the Asia-Pacific region. The largest source 

was the Phillipines (1,540), followed by Japan (1,032), and 

Thailand (1,002). The majority of these interceptions were 

insects (7,580), followed by pathogens (1,637), mites (76), 

and nematodes (4). This supports the idea that most inspections more readily find and identify easily visible pests.

1

 Appendices for this report are available online at: http://www.fs.fed.

us/psw/publications/documents/psw_gtr250/ psw_gtr250_appendix.

pdf.
16

GENERAL TECHNICAL REPORT PSW-GTR-250

In addition to surveying the APHIS database, HDOA 

performed a risk assessment for Kahului Airport in 2000 

to 2001 (HDOA 2002). Intensive inspections of baggage, 

aircraft, and air cargo from the continental United States 

and foreign areas were done. During this time period, 

nearly 2,200 insects were intercepted in all ports across 

the state. Over 1,400 insects were intercepted in air cargo 

at Kahului Airport. The family Aphididae was the most 

commonly recovered, although most of these were species 

already established in Hawai‘i. Most of the insects that were 

intercepted that were not established in Hawai‘i included 

members of Aphididae, Lygaeidae, Staphylinidae, Gracillariidae, Chrysomelidae, and Cicadellidae. A total of 156 

plant pathogenic organisms were intercepted during these 

same inspections. The most common interceptions were 

avocado scab disease (caused by the fungus Sphaceloma 

perseae) and Cercosporidium sequoiae, cause of needle 

blight of Leyland cypress and related conifers, neither of 

which was established in Hawai‘i.

A previous pathway risk analysis for Hawai‘i by 

APHIS listed intercepted pests on agricultural commodities between 2004 and 2006. The data source was the 

Agricultural Quarantine Activity System (Culliney et 

al., n.d.). An unidentified pest on Erythrina was reported 

in an air shipment of cut flowers from South Africa, and 

on plant material from South Africa at a port inspection 

station. An unidentified pest on Pandanus was discovered 

in 129 air shipments of cut flowers and several shipments 

of plant material from Thailand. Unidentified pests were 

intercepted on Scaevola plant material from Micronesia. No 

interceptions were reported on any of the other hosts being 

evaluated in this assessment (Culliney et al., n.d.).

Figure 3—Number of pest interceptions on commodities arriving in Hawai‘i, 1984–2010.

0

200

400

600

800

1,000

1,200

1,400

1,600

N

u

m

b

er of interc

eptio

n

s

Host genus
17

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Pathways

The principal pathways considered for this assessment 

follow. Other pathways are likely, but we believe the ones 

listed are sufficiently inclusive to cover other, unidentified 

pathways. 

• Plant material

• Seeds for sowing and consumption

• Nursery stock

• Cut flowers

• Fruits and vegetables

• Living plant material

• Christmas trees 

• Cut foliage 

• Dried plant material

• Tissue culture

• Wood products

• Unmanufactured wood products

• Manufactured wood products 

• Jewelry and handcrafts

• Pallets, crating, dunnage

• Hitchhikers

• Privately owned vehicles

• Maritime ship superstructures

• Aircraft

• Containers

• Potting media/compost/soil

Several pathways may exist for a single organism. 

We developed a means to identify pathways based on the 

location on the host plant where the pest can occur. Table 3 

identifies likely relationships between the parts of the host 

that are affected and probable commodity pathways. This 

simplified and streamlined the analysis, as many of the 

pathways for specific organisms are difficult to predict.

Significant Pathways for Potential 

Pest Entry

Wood Packing Material

A significant source of potential pest entry is on solid 

wood packaging material (SWPM). This includes dunnage, 

crating, pallets, packing blocks, drums, cases, and skids. 

The origin of this material is not necessarily the same 

as that of the shipment it accompanies, as it is routinely 

reused and reconditioned. It is also not reported on shipping manifests, so it cannot be tracked and quantified. On 

September 16, 2005, the United States started enforcing 

the International Plant Protection Convention’s standard 

ISPM No.15, “Guidelines for Regulating Wood Packaging 

Material in International Trade” (IPPC 2009). The standard 

requires fumigation or heat treatment for all wood packaging material entering the United States.

Chapter 3: Pathways and Commodities for Pest Entry

Table 3—Location of pest on host and potential 

pathways of pest entry

Location of pest on host Pathway

Seeds Seeds for sowing

Seeds Hitchhikers

Roots Nursery stock

Roots Live plant material 

Roots Potting media

Foliage/other Nursery stock

Foliage/other Cut flowers 

Foliage/other Cut foliage 

Foliage/other Live plant material 

Foliage/other Propagative plant cuttings

Foliage/other Fruit 

Foliage/other Christmas trees 

Foliage/other Hitchhikers 

Foliage/other Decorative dried plant material

Foliage/other Jewelry and handicrafts

Bark/cambium Nursery stock 

Bark/cambium Cut flowers 

Bark/cambium Live plant material 

Bark/cambium Propagative plant cuttings

Bark/cambium Christmas trees 

Bark/cambium Hitchhikers 

Bark/cambium Unmanufactured wood products 

Bark/cambium Wood packing material 

Bark/cambium Manufactured wood products 

Bark/cambium Decorative dried plant material

Bark/cambium Jewelry and handicrafts

Sapwood Christmas trees

Sapwood Unmanufactured wood products 

Sapwood Wood packing material 

Sapwood Manufactured wood products 

Heartwood Unmanufactured wood products 

Heartwood Wood packing material 

Heartwood Manufactured wood products 
18

GENERAL TECHNICAL REPORT PSW-GTR-250

Culliney et al. (n.d.) estimated that between 3 and 11 

percent (95 percent binomial confidence interval) of all 

shipments with SWPM arriving at the port of Honolulu 

are infested with live pests based on an evaluation of 

Agricultural Quarantine Inspection Monitoring (AQIM) 

data records for the period between October 2005 and April 

2007 (APHIS 2011a).

Airline Passengers

Airline passengers are another major source for potential 

pest entry. The total number of visitors arriving by air in 

Hawai‘i from 2007 to 2011 was over 34 million (fig. 4). 

Over 70 percent were from the mainland United States. The 

principal country of origin for foreign arrivals was Japan, 

followed by Canada (fig. 5) (HDBDET 2013). From 1984 

through 2010, The U.S. Department of Agriculture Animal 

and Plant Health Inspection Service (APHIS) intercepted 

over 9,800 reportable pests of foreign origin at Hawai‘i 

ports of entry. Almost 7,400 of these interceptions were 

associated with airports (APHIS 2007a). 

Live Plant Material

Annual imports—

Plants for horticultural use are continually arriving in 

Hawai‘i from foreign and domestic locations. Many of these 

have become invasive and are affecting native ecosystems. 

In addition, they may be carriers for invasive insects 

and pathogens. Figure 6 provides information on recent 

foreign imports of live plant material into Hawai‘i. The 

majority consists of live trees, shrubs, and plants without 

soil attached to roots. The quantity imported has remained 

stable during the past 5 years. The primary and most 

consistent exporting countries for this material are Australia and the Netherlands (U.S. Department of Commerce 

Census Bureau 2013). Data on interstate movement of live 

plant material from the continental United States were not 

available for comparison.

Restrictions on importation of plants and plant parts—

The importation of plants and plant parts is regulated by 

APHIS and Hawai‘i Department of Agriculture (HDOA), 

depending on the place of origin. APHIS has a plant 

inspection station at the Honolulu International Airport 

where plants and seeds are inspected for plant pests and 

diseases. Plants known to be invasive, or known to carry 

unwanted insects or pathogens, may be restricted entry 

or require quarantine prior to release. However, these 

restrictions are established based on known issues and do 

not cover unknown or unexpected insects and pathogens. 

Current regulations (7 CFR part 319.37) prohibit or restrict 

the importation of certain plants and plant products into the 

United States (APHIS 2013a). Those allowed entry must 

be accompanied by a phytosanitary certificate of inspection issued by the national plant protection service of the 

exporting country.

Plants and plant parts in the following genera and 

families related to species covered by this risk assessment 

are either prohibited from importation into the United 

States (7 CFR 319.37-2), require specific treatment prior 

to importation (7 CFR 319.37-6), or have a postentry 

quarantine requirement (7 CFR 319.37-7). Although they 

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

8,000,000

2007 2008 2009 2010 2011

Number of visitors

All others

Canada

Japan

Continental U.S.

Year

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

2011 2010 2009 2008 2007

Total seats

Other

Oceania

Other Asia

Canada

Japan

Year

Figure 4—Number of airline passenger arrivals to Hawai‘i by 

air from 2007 to 2011. Source: Hawai‘i Department of Business, 

Economic Development and Tourism 2011.

Figure 5—Total passenger seats to Hawai‘i by international air 

travel, 2007 to 2011 . Source: Hawai‘i Department of Business, 

Economic Development and Tourism 2013.
19

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

are not the species of interest in this pest risk assessment, 

their close relationship indicates the potential for harboring 

insects and pathogens that could attack the 13 taxa. Any 

species not listed must have a phytosanitary certificate and 

be inspected at the port of entry, but is then released if no 

pests are identified.

Species, genus, or family of plants with restrictions on 

importation of plants or plant parts into the United 

States from foreign countries—

• Prohibited from importation 

• Acacia from Australia and Oceania

• Eucalyptus spp. from Europe, Sri Lanka, and 

Uruguay

• Herbaceous species in Fabaceae (=Leguminosae) 

from all countries except Canada

• Vaccinium spp. from Canada not meeting the 

conditions for importation in §319.37–5(t) 

• Specific treatment required

• Lathyrus (Fabaceae) from all countries except 

North and Central America

• Lens (Fabaceae) from all countries except North 

and Central America

• Vicia (Fabaceae) from all countries except 

North and Central America

• Restricted postentry quarantine

• Acacia spp. from all countries except Australia, 

Canada, and Oceania

• Blighia sapida (Sapindaceae) from all countries 

except Canada, Cote d’Ivoire, and Nigeria

• Eucalyptus spp. (Myrtaceae) from all countries except Canada, Europe, Sri Lanka, and 

Uruguay

• Fruit and nut articles and other propagules of:

• Ceratonia (Fabaceae)

• Diospyros (Ebenaceae)

• Euphoria (Sapindaceae)

• Eugenia (Myrtaceae)

• Feijoa (Myrtaceae)

• Litchi (Sapindaceae)

• Melicoccus (Sapindaceae)

• Nephelium (Sapindaceae)

• Psidium (Myrtaceae)

• Rhodomyrtus (Myrtaceae)

• Syzygium (Myrtaceae)

• Vaccinium (Ericaceae)

50,000

100,000

150,000

200,000

250,000

300,000

2007

2008200920102011200720082009201020112007200820092010201120072008200920102011200720082009

20102011

A

n

nual Im

ports

of li

v

e

plant material (kg)

Thailand

Taiwan

Netherlands

Indonesia

Hong Kong

China

Canada

Australia

Herbaceous

perennials

without soil

Trees and

shrubs

with soil

sttached

to roots

Plants,

live, with

soil

attached

Trees and

shrubs

live

without

soil

attached

Plants,

live,

without

soil

attached

to roots

Live plant material

Figure 6—Annual import of live plant material from foreign countries to Hawai‘i, 2007 to 2011.
20

GENERAL TECHNICAL REPORT PSW-GTR-250

In 2011, APHIS established new regulations (7 CFR 

319.37-2a) on importation of plants for planting (APHIS 

2011c). In addition to the existing categories of prohibited 

and restricted plants, a third category called Not Authorized 

Pending Pest Risk Analysis (NAPPRA) was established. 

This category identifies plants for which scientific evidence 

indicates they are quarantine pests or hosts of quarantine 

pests and pose a risk to the United States. The current 

NAPPRA list contains 107 genera of hosts of quarantine 

pests that are not allowed entry into the United States from 

certain countries. Plants on this list are prohibited entry 

pending pest risk analysis. Three genera, Acacia, Sophora, 

and Vaccinium, which are part of this analysis, are included 

in this list. In addition, the following genera are in the same 

families of some of the 13 species being assessed in this 

pest risk assessment and are in the NAPPRA list: Albizia

(Fabaceae), Cajanus (Fabaceae), Cercis (Fabaceae), Litchi 

(Sapindaceae), Maackia (Fabaceae), Psidium (Myrtaceae), 

Rhododendron (Ericaceae), Robinia (Fabaceae). Although 

these are not the same species as those being analyzed, 

some pests do occur on multiple species, often of the 

same family. 

Commodities Entering Hawai‘i

Hawai‘i receives all of its commodities and visitors either 

by ship or aircraft. Six principal maritime ports (Honolulu, 

Hilo, Barbers Point, Kahului, Kawaihae, and Nawiliwili) 

receive most of the foreign and continental U.S. shipments. 

Excluding interisland service, Hawai‘i has five principal 

commercial airports (Hilo, Honolulu, Kahului, Kona, 

Lihue); most overseas visitors arrive through the Honolulu 

International Airport. In addition to these commercial ports 

of entry, military ports, both air and sea, are significant 

places for commodity imports.

Maritime cargo—

In 2010, maritime ports in Hawai‘i received 8 million 

metric tons of cargo on over 600 vessels from foreign 

points of origin. They also received 8 million metric tons 

on more than 7,000 vessels from domestic sources, which 

include mainland United States, Alaska, Puerto Rico and 

the Virgin Islands, Guam, American Samoa, Wake Island, 

and the United States Trust Territories (U.S. Army Corps 

of Engineers 2010). This includes military cargo shipped 

as ordinary commercial cargo but does not include what is 

shipped on Department of Defense vessels. A breakdown 

by harbor illustrates the volume of cargo arriving by ship at 

each port in 2010 (table 4).

The arrival of cargo on commercial maritime vessels 

was about equally split between domestic and foreign 

sources in 2010 when considering the quantity of goods 

(table 4). The number of vessels was considerably higher 

from domestic ports. However, this is somewhat misleading 

as the majority of foreign cargo is not shipped directly 

Table 4—Foreign and domestic commercial traffic arriving at Hawai‘i maritime ports in 2010a

 

Total

 

Number of

vessels

 

Total cargo vessels inboundb

inbound

Cargo (short tons)c

Harbor Foreign Domestic Foreign Domestic (short tons)

Barbers Point, O‘ahu 127 772 899 7,336,838 307,614 7,644,452

Hilo, Hawai‘i 64 673 737 26,322 833,309 859,631

Honolulu, O‘ahu 398 3,010 3,408 836,902 5,010,833 5,847,735

Kahului, Maui 19 968 987 94,218 1,243,508 1,337,726

Kawaihae, Hawai‘i 1 643 644 28,175 604,613 632,788

Nawiliwili, Kaua‘i 37 542 579 10,475 586,135 596,610

 Total 646 6,608 7,254 8,332,930 8,586,012 16,918,942

a

 Data source: U.S. Army Corps of Engineers 2010. http://www.navigationdatacenter.us/index.htm. 

b

 Inbound self-propelled and non-self-propelled vessels, which includes dry cargo, tanker, and tow or tug vessels ranging in draft.

c

 Cargo includes agricultural and nonagricultural freight. Short ton = 2,000 lbs. (907.18474 kg).
21

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

to Hawai‘i, but arrives at the U.S. mainland and is then 

shipped as domestic cargo. This results in different phytosanitary inspections upon arrival in Hawai‘i. All foreign 

imports are cleared by the U.S. Department of Homeland 

Security, Bureau of Customs and Border Protection (CBP), 

whereas domestic shipments (including shipments of 

foreign origin arriving from the U.S. mainland) are cleared 

by HDOA at the port of arrival (Culliney et al., n.d.).

Much of this cargo is nonagricultural and would only 

carry insects and pathogens as hitchhikers or in material 

used for packing, crating, and dunnage. Data on categories 

of commodities of direct interest to our analysis are not 

available, but volumes of some likely commodities of interest are reported. Honolulu Harbor received all of the forest 

product type commodities from foreign sources in 2010. 

This included fuel wood (28 short tons), rough wood (218 

short tons), lumber, (2,652 short tons), and forest products 

not classified elsewhere (576 short tons) (U.S. Army Corps 

of Engineers 2010). Even there, the quantity is a small 

proportion of the total maritime cargo received. Most of this 

was identified as lumber. Regardless of form, this material 

needs to meet APHIS importation requirements (7 CFR 

319.40), which restrict certain types of lumber from importation and require mitigation measures (kiln dried, heat 

treated, or fumigated) for the remainder (APHIS 2013b).

During the past several decades, the amount of foreign 

imports into Hawai‘i has been on a general increase, but 

the recent economic downturn has seen this trend reversed. 

There was stabilization in maritime importation in 2010 

(fig. 7), and this foreign importation will likely continue and 

increase as economic conditions improve. 

Air cargo—

Hawai‘i is a resort destination and receives most visitors by 

air. Preliminary estimates for 2011 indicate over 7,284,000 

visitor arrivals to Hawai‘i, with about 98 percent arriving by 

air (USDOT BTS 2011). Table 5 displays data for 2011 on 

air traffic into Hawai‘i. Most foreign passengers and cargo 

arrive through Honolulu International Airport. 

Foreign cargo arriving by air has had a similar trend as 

foreign cargo arriving by sea. As with maritime importation 

of foreign goods, there was stabilization in air importation 

Figure 7—Foreign cargo arriving in Hawai‘i via maritime vessels 

between 1992 and 2012. Source: Hawai‘i Department of Business, 

Economic Development and Tourism 2010, 2012.

Figure 8—Foreign cargo arriving in Hawai‘i via aircraft between 

1992 and 2012. Source: Hawai‘i Department of Business, Economic Development and Tourism 2010 and 2012.

0.00

1,000.00

2,000.00

3,000.00

4,000.00

5,000.00

6,000.00

7,000.00

8,000.00

9,000.00

10,000.00

19921993199419951996

1997

199819992000200120022003200420052006

2007

20082009201020112012

Shipping weight (mil. kgs.)

Year

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

199219931994199519961997199819992000200120022003200420052006

2007

20082009201020112012

Shipping weight (mil. kgs.)

Year

in 2010 (fig. 8), and this foreign air importation is expected 

to continue to increase as economic conditions improve. 

Inspection of international arrivals is the responsibility 

of the U.S. Customs and Border Patrol (CBP). Officers with 

CBP meet arriving foreign transports and inspect a percentage of passengers, crew, luggage, and cargo to prevent 

entry of agricultural pests and diseases. Domestic travelers, 

including those from the U.S. mainland, are the responsibility of HDOA for inspection. Interception data from HDOA 

quarantine inspections of passenger carry-on baggage identified over 300 pest interceptions between 1995 and 2006 in 

domestic travelers (HDOA 2007). Currently, HDOA does 

not have a program in place to routinely inspect passenger 

carry-on baggage.
22

GENERAL TECHNICAL REPORT PSW-GTR-250

Potential Origins of Pests

The above information on potential pathways provides an 

idea of the quantity of importation, but not the origin. The 

origin of foreign trade by all means of transportation to 

Hawai‘i is tracked by the U.S. Department of Commerce 

Census Bureau. During the period 2008 to 2010, the top 

countries exporting to Hawai‘i based on value of exports 

have been identified. The top 14 are shown in figure 9. The 

cumulative 3-year total is valued at over $14.7 billion from 

these countries (USDC CB 2013). Eight of the top 10 are in 

the Asia-Pacific region. Using commodity value may not 

be the best measure to evaluate potential origins of pests 

but are the only data readily available. Measures of volume 

or shipments could provide a better measure, but were not 

available to the authors.

In 2010, over 8.3 million tons of cargo arrived at 

Hawai‘i ports on marine vessels from foreign sources (U.S. 

Army Corps of Engineers 2010). About 95 percent of that 

arrived from 11 countries, primarily in Asia or the Pacific. 

This includes Australia, China, Indonesia, Japan, Russia, 

South Korea, Thailand, and Vietnam (fig. 10). 

Figure 9—Top countries exporting to Hawai‘i based on 3-year average, 2008 to 2010, dollar value. Source: 

USDC CB 2013.

Indonesia, 13.4%

Vietnam, 11.6%

Saudi Arabia, 11.8%

Russia, 10.2%

Thailand, 9.3%

China, 7.2%

Japan, 5.5%

Australia, 3.6%

South Korea, 3.7% France, 3.9%

Canada, 2.5% New Zealand, 1.0% United Kingdom,

0.8%

Taiwan, 0.9%

Table 5—Number of aircraft, passengers, cargo, and mail arriving at Hawai‘i airports from January through 

August 2011a

Number of aircraft Number of passengers Cargo (short tons) Mail (short tons)

Foreign Domestic Foreign Domestic Foreign Domestic Foreign Domestic

Airport origin origin origin originb origin originb origin origin

Hilo 0 4,692 1 12,643 0 70 0 0

Honolulu 5,882 42,113 1,296,599 414,778 56,494,828 14,185,243 277,002 2,207,421

Kahului 592 19,127 102,416 937,175 7,114 10,261,229 0 196

Kona 53 11,431 8,178 354,401 32,234 9,563,835 0 80,703

Lihue 35 8,806 4,758 306,900 0 657,765 0 2,797

 Total 7,042 86,169 1,411,952 2,025,897 56,534,176 34,668,142 277,002 2,291,117

a Data Source: U.S. Department of Transportation, Bureau of Transportation Statistics 2011. www.transtats.bts.gov.

b

 Interisland traffic excluded.
23

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Figure 10—Origin of foreign freight arriving by sea to Hawai‘i in 2010. Source: U.S Army Corps of 

Engineers 2010.

Argentina

4% Australia

8% Canada

3%

China

3%

Indonesia

27%

Japan

2%

Russia

8%

Saudi Arabia

10%

South Korea

17%

Thailand

10%

Vietnam

8%

The Bureau of Transportation Statistics collects data on 

movement of trade by aircraft in the United States. In 2010, 

Japan was the major exporter by air to Hawai‘i, with about 

75 percent of the total cargo. Almost all of the remaining 

25 percent arrived from sources in the Pacific and Asia 

(fig. 11). A total of over 50,200 tons arrived by air from 

foreign sources in 2010 (USDOT RITA 2010). In addition 

to foreign sources, a considerable amount of freight arrives 

by air from the U. S. mainland. In 2011, over 239,300 tons 

of freight was shipped by air to Hawai‘i from the continental United States and its territories (USDOT BTS 2011). 

The majority of the domestic freight arrived through the 

Honolulu International Airport (fig. 12). Of this, 1,830 tons 

were shipped from Guam, American Samoa, and Saipan. 

Material from these three territories may present particular 

concern because of their similar environment to Hawai‘i 

and the increased potential of exotic pests to find habitable 

conditions in Hawai‘i. 

Known Pests at Potential Origins

A principal means of determining potential pests for 

introduction is the evaluation of the host plant and its pests 

in other geographic areas. Of the 13 host taxa in this assessment, nine are endemic to the Hawai‘i Islands. Exposure 

to foreign pests only occurs where these plants have been 

introduced to foreign environments. Most of these have not 

been planted in other locations and have not been exposed 

to potential insect pests and pathogens. To better assess 

what pest organisms might be a threat, we went beyond 

the species level and looked at the genus and family to 

provide a list of potential pests around the world. In some 

cases this was a daunting task. For example, Diospyros and 

Vaccinium are genera with members that produce agricultural commodities. Because of the economic value of these 

crop plants, extensive lists of pests have been identified 

and evaluated. These crops have also been planted in many 

areas around the world. The list of insects and pathogens for 

these species is considerably longer and more complete than 

those lists of species with more limited host distribution. 
24

GENERAL TECHNICAL REPORT PSW-GTR-250

Figure 12—Destination of air freight arriving in Hawai‘i from the continental United States and its 

territories, 2011. Source: USDT BTS 2011.

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

Hilo Honolulu Kahului Kaneohe Kona Lihue

Freig

ht (th

o

usa

n

d to

ns)

Freight airports in Hawai‘i

Figure 11—Origin of foreign freight arriving by air to Hawai‘i in 2010. Source: USDT BTS 2011.

Australia

Canada

Federated States

of Micronesia

Japan

Malaysia

Marshall Islands

New Zealand

PhilippinesSouth Korea

Taiwan
25

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Introduction

The probability of pest introduction is determined by 

several related factors, including the likelihood of a pest 

traveling with and surviving on a shipment from the place 

of origin, a pest colonizing suitable hosts at the point of 

entry and during transport to processing sites, and subsequent pest spread to adjacent territories. Many insects and 

pathogens could be introduced on various commodities into 

Hawai‘i from any origin in the world. Because it would be 

impractical to analyze the risk of all of them, some form 

of selection was necessary. Selection was based on the 

likelihood of the pest being on or in a commodity, and on 

potential risk the pest poses to resources in Hawai‘i. The 

pest risk assessment team compiled and assessed pertinent 

data using the methodology outlined in “Pest Risk Assessment Process” in appendix 4,1 and as used in previous pest 

risk assessments (Kliejunas et al. 2001, 2003; Tkacz et al. 

1998; USDA FS 1991, 1992, 1993).

Analysis Process

The general analysis process used is explained in appendix 

4. For this risk assessment, information was collected from 

an array of sources on the organisms associated with or 

considered a risk to any of the 13 taxa identified as hosts 

of concern in Hawai‘i. Lists of insects and pathogens that 

have been reported to inhabit these species or closely 

related species outside of Hawai‘i were compiled from the 

literature, information provided by Hawaiian entomologists 

and plant pathologists, information received from reviewers 

of a preliminary list prepared by the team, and information 

described in appendix 4. These organisms were catalogued 

in one of the categories of quarantine pests defined in the 

log import regulations. The team broadened some of the 

categories to include a broader definition of genetic variation (table 6). The part of the plant the organisms affect was 

also noted: seeds, roots, on foliage or bark, in or under the 

bark, in sapwood, or in heartwood. From these lists, organisms were selected for further analysis. Organisms were 

selected from each of the plant parts affected. Organisms 

were selected based on the amount of damage they may 

cause in Hawai‘i, the availability of information available 

on the organism, and the pathway the organism represents. 

For each organism selected, a thorough individual pest 

risk assessment (IPRA) was developed as described in 

appendix 4. 

Potential Insects and Pathogens of Concern

The species of insects and pathogens associated with the 

13 taxa in Hawai‘i and identified as potential pests of 

concern are presented in appendix 7 (tables 7-1 and 7-2). 

The organisms listed are not meant to be all-definitive or 

Chapter 4: Insects and Pathogens Posing Risk

Table 6—Pest categories and descriptions

Category Description

1 Nonindigenous plant pest not present in Hawai‘i

2 Nonindigenous plant pest present in Hawai‘i and capable of further dissemination in Hawai‘i 

2a Native plant pest of limited distribution in Hawai‘i, but capable of further dissemination in Hawai‘i

3 Nonindigenous plant pest present in Hawai‘i that has reached probable limits of its ecological range 

but differs genetically from the plant pest in Hawai‘i in a way that demonstrates a potential for greater 

damage potential in Hawai‘i

4 Native species of Hawai‘i that has reached probable limits of its ecological range, but differs genetically 

from the plant pest in Hawai‘i in a way that demonstrates a potential for greater damage potential 

4a Native pest organisms that may differ in their capacity for causing damage, based on genetic variation 

exhibited by the species

5 Nonindigenous or native plant pest that may be able to vector another plant pest that meets one of the 

above criteria

1

 Appendices for this report are available online at: http://www.fs.fed.

us/psw/publications/documents/psw_gtr250/ psw_gtr250_appendix.pdf.
26

GENERAL TECHNICAL REPORT PSW-GTR-250

all-inclusive lists but are a result of literature searches and 

information provided by colleagues. For an organism to be 

listed in table 7-1 or in table 7-1, it must have been identified with one of the 13 Hawai‘i host species or a closely 

related species, either in the literature or by communication 

amougst other entomologists or plant pathologists. That host 

is listed in the tables, as are any additional hosts known to 

harbor the insect or pathogen. Bold type is used in the tables 

to highlight the insects or pathogens treated in IPRAS. The 

tables represent a list of potential pests of concern, and 

do not represent, or judge, quarantine status of any of the

organisms listed. 

Individual Pest Risk Assessments

Twenty-four IPRAS were prepared, 12 dealing with insects 

and 12 with pathogens. The objective was to include in the 

IPRAS representative examples of insects and pathogens 

found on seeds, roots, bark, sapwood, and heartwood that 

would have the greatest potential risk to forests and other 

tree resources of Hawai‘i. The team recognized that these 

might not be the only organisms associated with these 

hosts in Hawai‘i. They, however, are representative of the 

diversity of insects and pathogens that might inhabit the 

hosts of concern. By necessity, the IPRAS focus on those 

insects and pathogens for which biological information is 

available. The assessments of risks associated with known 

organisms that inhabit a variety of niches can be used by the 

Animal Protection and Health Inspection Service (APHIS) 

and Hawai‘i Department of Agriculture (HDOA) to identify 

effective mitigation measures to eliminate both the known 

organisms and any similar heretofore unrecognized organisms that inhabit the same niches. A summary table 

(table 11) of the IPRA results can be found in chapter 5.

Insect IPRAs

Apple Stem Borer

Assessor: Andris Eglitis

Scientific name of pest: Aeolesthes holosericea 

(Fabricius) (Coleoptera: Cerambycidae)

Scientific names of hosts: Acacia nilotica, A. arabica, 

Aegle marmelos, Alnus nitida, Anogeissus latifolia, 

Bauhinia acuminata, Bauhinia retusa, B. variegata, 

Bombax malabaricum, Bridalia retusa, Butea frondosa, 

Careya arborea, Cedrela toona, Chloroxylon swietenia, 

Cynometra ramiflora, Duabanga sonneratioides, Eucalyptus robusta, Excaecaria agallocha, Ficus bengalensis, 

Grewia oppositifolia, Hardwickia binata, Juglans regia, 

Kydia calycina, Lannea grandis, Largerstraemia parviflora, 

Mallotus philippinensis, Malus domestica, Mangifera 

indica, Miliusa velutina, Morus alba, Myristica andamanica, Ougenia dalbergioides, Pentacme suavis, Pinus 

longifolia, Prunus armeniaca, P. avium, P. communis, 

P. domestica, P. persica, Psidium guajava, Pterocarpus 

marsupium, Pyrus baccata, P. communis, Quercus incana, 

Shorea robusta, Tamarix articulata, Tectona grandis, 

Terminalia balerica, T. myriocarpa, T. tomentosa, Sapium 

sebiferum, Shorea assamica, Soymida febrifuga (Rahman 

and Khan 1942).

Distribution: India

Summary of natural history and basic biology of 

the pest: The apple stem borer, also known as the cherry 

stem borer, is widely distributed throughout forested 

areas in India (Rahman and Kahn 1942, Tara et al. 2008). 

The insect has a very wide host range that includes many 

important fruit trees such as apple (Malus sp.), and several 

Prunus species, including cherry, apricot, plum, and 

peach (Rahman and Kahn 1942). The apple stem borer is 

considered to be one of the most destructive borers of apple 

plantations in India (Tara et al. 2008). Larval feeding progressively weakens trees, initially causing branch dieback, 

and eventually tree death (Gupta and Tara 2013). As many 

as 70 larvae may be found within infested branches (Tara 

et al. 2008). Rahman and Kahn (1942) reported that a single 

larva could kill a young apple tree. Infested trees are easily 

recognized because of the continuous sap flow from the 

openings of larval feeding galleries and from the frass plugs 

on the trunk and branches (Gupta and Tara 2013). 

Adult beetles are large and stout, measuring from 38 

to 45 mm in length and 10 to 13 mm wide (Gupta and Tara 

2013). Males are distinctly smaller than females and have 

antennae considerably longer than their body. The insects 

are dark brown or reddish brown and covered by dense 

golden brown pubescence, giving them a silky appearance 

(Gupta and Tara 2013). 
27

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

In the field, adult beetles begin emerging from infested 

material in March or April (spring) and emergence continues well into the summer or fall, depending on the area and 

the affected host (Gupta and Tara 2013). For oviposition, 

females select crevices or injured areas on the bark, where 

eggs are laid singly or in groups of two to five. The egg-laying period can occur between May and October (spring and 

fall) (Rahman and Kahn 1942). Under laboratory conditions, each female is capable of producing 45 to 80 eggs 

(Gupta and Tara 2013). The eggs hatch within 2 weeks and 

young larvae immediately begin feeding on the phloem and 

cambium. As the larvae grow, the later instars move into 

the heartwood where they create branched galleries. These 

“sub-tunnels” are open to the exterior of the tree, allowing 

the insects to expel their excreta as they feed (Gupta and 

Tara 2013). The gallery openings are typically plugged with 

frass and oozing sap (Gupta and Tara 2013). Gupta and 

Tara (2013) reported that the period of larval development 

is extremely variable on fruit trees, ranging from 9 to 32 

months. Mature larvae widen the main feeding tunnel to 

form a pupal chamber that is located near the outer surface 

of the infested tree (Gupta and Tara 2013). Pupation takes 

place between September and October (fall), and the insects 

spend the winter in the pupal stage (Gupta and Tara 2013). 

The entire life cycle can range from 2 to 3 years (Rahman 

and Kahn 1942).

Specific information relating to risk elements (elements 

defined in table 7):

A. Likelihood of introduction (untreated wood pathway)

1. Pest with host-commodity at origin potential: High

(VC) (Applicable rating criteria, from app. 

4: c, e, f, g, h) 

The insect has a broad host range and is widely distributed throughout India. All of the life stages of wood-boring 

beetles are well-protected beneath the bark or in the wood of 

host material, and survival during shipment of at least a few 

individuals would be expected. Cerambycids are very adept 

at finding freshly cut or otherwise suitable host material and 

once inside their host, are not easily dislodged. 

2. Entry potential: High (VC) (Applicable rating criteria, from app. 4: b, c, d) 

Life stages of the wood borer would be well-protected 

within untreated raw wood and could be difficult to detect 

in packing material made of that wood. Wood-boring 

insects have been highly successful in gaining entry 

into new environments via the solid wood packing 

material pathway. 

3. Colonization potential: High (RC) (Applicable 

rating criteria, from app. 4: b, d, e) 

Hawai‘i occupies the same latitudinal band as parts of 

India. Within India, the apple stem borer ranges in elevation 

from 1067 to 2438 m and has nearly 40 host plants (Rahman 

and Kahn 1942). Aeolesthes holosericea has a high reproductive potential, with each female capable of laying up to 

80 eggs (Gupta and Tara 2013).

4. Spread potential: High (RC) (Applicable rating 

criteria, from app. 4: a, c, d, e, f, g)

The apple stem borer has a very broad host range 

including plant genera that occur in Hawai‘i (e.g., Acacia,

Bauhinia, Eucalyptus, Mangifera, Morus, Psidium, Pterocarpus, Prunus, Pyrus, Tectona, Terminalia). As evidenced 

by introductions of cerambycids in other parts of the world, 

infestations often go undetected for many years. Typically, 

the lengthy period of time between detection of infestations 

and response means that eradication is not possible. 

B. Consequences of introduction

5. Economic damage potential: High (RC) (Applicable 

rating criteria, from app. 4: a, b, c, d) 

The apple stem borer infests a wide variety of fruit 

trees and is capable of weakening and killing many of its 

hosts through repeated infestation (Gupta and Tara 203). 

6. Environmental damage potential: High (RC) 

(Applicable rating criteria, from app. 4: d, e) 

This insect is being evaluated because it has hosts in 

the genus Acacia, which could include the Hawai‘i species 

A. koa. Given its wide host range, cryptic nature, and ability 

to attack economically important plants, the apple stem 

borer might affect species with limited ranges and could 

require aggressive controls once established. 
28

GENERAL TECHNICAL REPORT PSW-GTR-250

7. Social and political considerations: Moderate (RU) 

(Applicable rating criteria, from app. 4: a)

Public concerns could be likely if another economically 

important pest were introduced into Hawai‘i.

C. Pest risk potential:

High (Likelihood of introduction = high; Consequences of introduction = high) 

Selected bibliography:

Gupta, R.; Tara, J.S. 2013. First record on the biology 

of Aeolesthes holosericea Fabricius, 1787 (Coleoptera: 

Cerambycidae), an important pest on apple plantations 

(Malus domestica Borkh.) in India. Munis Entomology 

and Zoology. 8(1): 243–251. 

Rahman, K.A.; Khan, A.W. 1942. Bionomics and control 

of Aeolesthes holosericea F. (Coleoptera: Cerambycidae). 

Proceedings of the Indian Academy of Sciences, Sec. B. 

15: 181–185. 

Tara, J.S.; Gupta, R.; Chhetry, M. 2008. A study on 

Aeolesthes holosericea Fabricius, an important pest of 

apple plantations (Malus domestica Borkh.) in Jammu 

region. The Asian Journal of Animal Science. 3(2): 

222–224. 

Reviewers’ comments: None received.

Botany Bay Diamond Weevil 

Assessor: Andris Eglitis

Scientific name of pest: Chrysolopus spectabilis Fabricius 

(Coleoptera: Curculionidae)

Scientific names of hosts: Acacia decurrens, A. mearnsii; 

nearly 30 other Acacia spp.

Distribution: Australia (Queensland, New South Wales, 

Victoria, South Australia)

Summary of natural history and basic biology of 

the pest: Hawkeswood (1991) summarized the biology 

of the Botany Bay weevil as described by several Australian 

authors and added his personal observations. The adult 

weevil feeds on at least 28 species of Acacia (wattles), 10 of 

which have bipinnately compound leaves, and 18 of which 

are phyllodinous species. The bipinnate host species occur 

in the more heavily timbered habitats such as the dry sclerophyll forests, and the phyllodinous Acacia species are in the 

coastal heathland and open woodland habitats (southeastern 

Queensland and northern New South Wales, Australia) 

(Hawkeswood 1991). The wattles preferred by C. spectabilis

are usually thick-stemmed, large, shrubby species with 

mucilaginous bark (Hawkeswood 1991). 

Adults are typically observed on their hosts during 

the summer (November, December, January), when they 

feed and mate on stems, branches, and foliage. Hunt et al. 

(1996) described damage caused by this insect in young 

plantations of Acacia mearnsii in southeastern Australia. 

The weevils removed the leading shoots from saplings and 

hindered the development of a single stem in the affected 

hosts. For egg-laying purposes, the female weevil typically 

attacks the main stem just above the ground line, where she 

gnaws the bark into small roughened spots and deposits an 

egg under each spot (Hawkeswood 1991). Some trees may 

have as many as 20 eggs laid in this fashion (Hawkeswood 

1991). After the eggs hatch, the small larvae bore down into 

the main roots, which are eventually completely hollowed 

out. Host trees can sometimes be killed by this larval 

feeding (Hawkeswood 1991). The life cycle is believed to be 

completed in 1 year (Hawkeswood 1991). The adult weevils 

are bronze-black to black with three bright green bands on 

the pronotum of those emerging early, and metallic blue on 

weevils that emerge later in the season (Hawkeswood 1991). 

The elytra are irregularly mottled with metallic green to 

blue and covered with dense scales on the underside of 

the body. 

Hawkeswood (1991) points out that even though C. 

spectabilis is considered one of the most distinctive and 

common weevils in Australia, there is relatively little 

known about larval food plants and biology of the insect. 

Only six larval hosts have been recorded, although all of 

them are also adult hosts and Hawkeswood (1991) speculated that further research would probably expand the list of 

larval hosts, perhaps to include most of the Acacia species 

utilized by the adults. 
29

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Specific information relating to risk elements:

A. Likelihood of introduction (wood or plant material 

pathway)

1. Pest with host-commodity at origin potential: 

Moderate (MC) (Applicable rating criteria, from 

app. 4: c, e, g, h)

The larval stage could be harbored within stems 

of Acacia, if infested wood were to be transported. 

Hawkeswood (1991) describes adult behavior, noting that 

sometimes the weevils firmly grasp the foliage of their hosts 

and can be very difficult to dislodge. 

2. Entry potential: High (MU) (Applicable rating criteria, from app. 4: b, c, d)

Although C. spectabilis has not often been intercepted, 

other curculionids with similar habits are commonly found 

during port inspections. Criterion “d” would only apply to 

larvae within the wood; adults on foliage would likely be 

conspicuous. 

3. Colonization potential: Moderate (MU) (Applicable 

rating criteria, from app. 4: b)

Chrysolopus spectabilis occurs in Queensland, Australia, which is at latitudes similar to those of the Hawai‘i 

Islands. Acacia koa is a potential host in Hawai‘i and occurs 

between the latitudes of 19 and 22 degrees N. Acacia koa 

belongs in the Acacia subgroup that includes phyllodinous 

and bipinnate species, which are the only Acacia hosts for 

the Botany Bay diamond weevil. 

4. Spread potential: Moderate (MU) (Applicable rating 

criteria, from app. 4: d, e)

If A. koa proves to be an acceptable host for C. spectabilis, then criterion “d” would apply. Infestations would not 

likely be detected in the short term.

B. Consequences of introduction

5. Economic damage potential: Moderate (MU) 

(Applicable rating criteria, from app. 4: a, b, e)

Hunt et al. (1996) reported that the Botany Bay weevil 

was capable of affecting the growth patterns of young trees 

by killing the leaders through adult feeding. In addition, 

Hawkeswood (1991) observed that larval feeding could kill 

host trees. 

6. Environmental damage potential: Moderate (MU) 

(Applicable rating criteria, from app. 4: e)

The chemical controls necessary to eradicate this 

weevil could have negative environmental effects. 

7. Social and political considerations: Low (MU) 

(Applicable rating criteria, from app. 4: none of the 

rating criteria apply)

C. Pest risk potential: 

Moderate (Likelihood of introduction = moderate; 

Consequences of introduction = moderate) 

Selected bibliography:

Elliott, H.J.; Ohmart, C.P.; Wylie, F.R. 1998. Insect 

pests of Australian forests: ecology and management. 

Melbourne, Sydney, Singapore: Inkata Press. 214 p.

Hawkeswood, T.J. 1991. Review of the history, biology 

and host plants of the Australian weevil Chrysolopus 

spectabilis (Fabricius) (Coleoptera: Curculionidae: 

Aterpinae). Spixiana. 14(1): 17–25.

Hunt, A.J.; Gullan, P.J.; Reid, C.A.M. 1996.

Chrysomelidae (Coleoptera) and other phytophagous 

insects in a plantation of black wattle, Acacia mearnsii

De Wild., in southeastern Australia. Australian Journal 

of Entomology. 35: 85–92. 

Reviewers’ comments: None received.

Coconut Rhinoceros Beetle

Assessor: Sheri Smith

Scientific name of pest: Oryctes rhinoceros Linnaeus 

(Coleoptera: Scarabaeidae)

Scientific names of hosts: Cocos nucifera, Elaeis guineensis, Areca catechu, Phoenix dactylifera, Wodyetia bifurcata, 

Pandanus tectorius, Colocasia esculenta, Ananas comosus, 

Musa spp., Saccharum spp., Corypha spp; a variety of other 

ornamental palms
30

GENERAL TECHNICAL REPORT PSW-GTR-250

Distribution: Pakistan, India, Maldive Islands, Hainan, 

Taiwan, Hong Kong, Thailand, Vietnam, Malay Peninsula, 

islands of Java, Sumatra, Bali, Lombok, Kalimantan, Celebes, Ceram and Amboina in Indonesia, Philippine Islands, 

Sri Lanka, Upolu, Western Samoa, American Samoa, 

Tonga, Palau Islands, New Britain, West Irian, New Ireland, 

Pak Island and Manus Island (New Guinea), Fiji, Cocos 

(Keeling) Islands, Mauritius, Reunion, and Guam.

2014 update: One adult coconut rhinoceros beetle (CRB) 

was found in baggage claim at the Honolulu Airport on 

O‘ahu in November 2013; an additional adult beetle was 

detected in a trap in the same vicinity in December 2013. 

Breeding sites (piles of green waste) were subsequently 

found on the Joint Base Pearl Harbor-Hickam military 

facility. It is not known exactly how the beetles arrived 

in Hawai‘i. As of June 2014, 423 adults, 531 larvae, and 

16 pupae have been found in the established buffer zone 

(HDOA 2014).

Summary of natural history and basic biology of the 

pest: Coconut rhinoceros beetle is a major pest of coconut 

palm in its Asian homeland, and on the south and western 

Pacific Islands it has invaded. Adult beetles attack several 

species of endemic and ornamental palms and Pandanus, 

banana, taro, and pineapple. The CRB likely entered 

Malaysia about 1895 and worked its way throughout the 

coconut growing areas of lower Burma over the following 

15 years (McKenna and Shroff 1911). In the early part of 

the 20th century, the major economic activity for most 

Pacific Islands was production of copra from coconuts in 

natural and managed plantations. The CRB is believed 

to have entered the Pacific concealed in rubber seedling 

potted plants from Ceylon in 1909 (Catley 1969). The insect 

established rapidly in Samoa and subsequently spread to 

Tonga and to multiple other locations by the mid-1960s. 

The CRB was first reported from Fiji in 1953, and despite 

intensive attempts to implement quarantine procedures, 

had spread through most of the Fiji Island group by 1971 

(Bedford 1976). Initial outbreaks of CRB have been 

devestating; when it invaded Palau in 1942, coconut palms 

were completely eradicated from some islands, and overall 

tree mortality was about 50 percent (Gressitt 1953). Since 

its invasion of Guam in 2007, CRB has spread to most parts 

of the island (Aubrey Moore, entomologist, University of 

Guam, personal communication). Typhoons produced an 

abundance of dead coconut material suitable for breeding 

sites, and larval food and coconut palms killed by adult 

feeding are adding to the supply of larval food, further 

facilitating population growth. In addition, CRB seems to 

be free of control by natural enemies on Guam. Over 6,000 

beetles have been trapped and over 11,000 larvae found. 

Sixty dead or dying coconut palms have been felled and 

destroyed. An aggressive eradication program was implemented on Guam but has failed and is now transitioning to 

a management program. The most likely method of CRB 

introduction onto Guam was as a hitchhiker with construction material from the Philippines (Berringer 2007). 

Floating logs can also contain larvae and serve as transporters to new or already infested locations. 

Adults are the injurious stage of the insect. They feed 

and aggregate in the crowns of palm trees. They are generally night-time fliers, and when they alight on a host, they 

enter the axil and bore into unfurled tissue at the meristem 

to feed on sap. Each feeding visit can cause petiole or leaflet 

injury to three to four fronds (Hinckley 1966). Male beetles 

produce an aggregation pheromone, attractive to both sexes, 

which results in patchy distribution of beetles within stands 

of palms. Beetle presence is evident through notching, 

fanning, and breaking of emergent palm fronds. V-shaped 

cuts in the fronds and holes through the midrib are visible 

when the leaves grow out and unfold. If the growing tip is 

injured, the palm will have severe loss of leaf tissue and 

decreased nut set. High feeding pressure results in mortality 

of the growing tip, leaving a dead standing stump. Feeding 

wounds may also serve as an infection pathway for pathogens or other pests. The effects of adult boring may be more 

severe on younger palms where spears are narrower. 

Almost any log or heap of material soft enough for burrowing, yet firm enough to provide compacted frass, may be 

utilized for oviposition. Large numbers of CRB larvae may 

develop in the tops of dead standing coconut palms, coconut 

stumps, and in logs on the ground. High numbers of palms 

injured or killed in typhoons have served to initiate outbreaks in many locations. Gressitt (1953), Cumber (1957), 
31

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

and Paine (1967) all emphasized the correlation between 

abundance of larval food and damage by adults to palms. 

Based on recent information from Guam, CRB is able 

to complete the entire life cycle in the crowns of palms, 

negating the need for down material (Aubrey Moore, entomologist, University of Guam, personal communication), 

which would likely increase the establishment potential 

in Hawai‘i. The CRB is most likely to be of economic 

importance whenever and wherever suitable breeding sites 

are numerous. On Guam and in other locations, the beetle 

is also known to breed in compost piles and shredded 

palm material. Decaying Pandanus trunks have served as 

breeding sites on Palau (Gressitt 1953), and other breeding 

sites such as cattle dung, decaying cocoa pod shells, and 

decaying matter of other host species have been noted.

Hinckley (1973) described the life cycle of O. rhinoceros from Western Samoa, which agreed closely with the 

description made by Gressitt (1953) from Palau. Under 

favorable conditions, one generation, egg to egg, can be as 

short as 20 weeks. The female beetle makes a serpentine 

burrow, laying eggs one by one and compressing the chewed 

material behind her. Clutch size averages about 27 eggs 

but can be as many as 62, with more being laid by larger 

females. About 11 days are required for development in the 

egg stage. It is not known how many clutches are laid by 

each female but numerous (e.g., five) may be possible. Gressitt (1953) estimated between three or four, totaling 90 to 

120 eggs per female. First instar larvae feed on the burrow 

frass and develop rapidly under favorable conditions. About 

3 weeks each are spent as first and second instars, and 5 

to 9 weeks as third instars. The late third instar burrows 

into a firm portion of material prior to pupation, creates a 

pupal chamber and goes through a nonfeeding stage lasting 

about 1 week (Gressitt 1953). High mortality rates of larval 

instars are common, particularly in the first and third instar. 

Teneral adults are found in chambers after about 3 weeks. 

After the teneral period, the adult beetle chews out of the 

pupal chamber and emerges. 

Adult feeding visits are multiple, and burrowing depths 

into host crowns vary greatly. Deep burrows on young 

palms are often fatal, either by destruction of the growing 

tip or from secondary infections by pathogens. The normal 

interval between feedings is probably more than 10 days 

and less than 20 days. Dispersal, mating, and oviposition 

occur within 2 weeks of emergence, and adults can survive 

up to 12 more weeks. A female beetle can lay viable eggs 

for several months after one mating. The lifespan of individuals reaching maturity is 4 to 9 months (Bedford 1980). 

Specific information relating to risk elements:

A. Likelihood of introduction (hitchhiker)

1. Pest with host-commodity at origin potential:

Plant material/pots/detritus—High (MC) (Applicable 

risk criteria from app. 4: b, c, d, e, f, g)

Hitchhiker in shipping containers/military equipment—High (RC) (Applicable risk criteria from app. 4: b, c, 

d, e, f, g)

A number of risk criteria apply for this element when 

movement of plants, detritus, and shipping containers/

military equipment are considered. The CRB is widely 

distributed in the Western and Southern Pacific and Asia. 

Building populations on Guam are also of great concern, 

particularly now that eradication has failed and adult beetles 

are likely to be numerous, increasing the likelihood of 

accidental transport to other islands in Micronesia, Hawai‘i, 

and beyond. Guam has more than 13 million coconut palms 

(Donnegan et al. 2004), so host supply is readily available 

for continued population increase. The most likely method 

of introduction onto Guam was by adult beetle(s) hitchhiking in a shipping container from Asia. There is evidence 

that Guam and other Micronesian islands have been the 

source of several major insect pests invading Hawai‘i. Oriental fruit fly is a prime example (Swezey 1942). Accidental 

transport of other scarab beetles from Guam to Hawai‘i is 

well documented (Moore 2007). 

2. Entry potential:

Plant material/pots/detritus: High (MC) (Applicable 

risk criteria from app. 4: b, c, d)

Hitchhiker in shipping containers/military equipment: 

high (VC) (Applicable risk criteria from app. 4: a, b, c, d)
32

GENERAL TECHNICAL REPORT PSW-GTR-250

The adult stage is most likely to be transported as a 

hitchhiker in shipping containers or with military equipment. Five adult beetles were detected in maritime shipments, originating in Indonesia, at the Kahului seaport on 

Maui during two different time periods in 2003, confirming 

that previous entries have occurred. Dependent upon the 

amount of plant material transported from CRB-infested 

locations to Hawai‘i, this could also be a mode of entry for 

adults, but less likely than in containers. The most likely 

method of introduction onto Guam was by adult beetle(s) 

hitchhiking in a shipping container from Asia. Invasion 

of CRB into Palau in 1942 has been linked to transport of 

military equipment/supplies. Adult survival during transport would be higher than for other life stages, but it seems 

plausible that other life stages could be transported as well. 

Adults can live for several months, and several days can 

lapse between sap feeding visits. 

3. Colonization potential: High (VC) (Applicable risk 

criteria, from app. 4: a, b, c, d, e)

The CRB has already invaded and successfully 

colonized several western and southern Pacific Islands with 

similar climates and hosts as those that exist in Hawai‘i. 

Proximity of hosts to ports of entry would greatly increase 

the likelihood of successful colonization. As has occurred 

with other invasive insects in Hawai‘i, nonnative ornamental plantings served as initial hosts to facilitate colonization, 

and then populations expanded into more distant native 

hosts; this could easily be the case with CRB as well, with 

numerous ornamental palms available in proximity to ports 

of entry. In addition to palms, Pandanus tectorius, pineapple, and other hosts exist on several Hawai‘i islands. Pandanus tectorius is thought to be much more common in some 

parts of Honolulu and on other islands today, and fan palms 

could also serve as hosts. Any type of outbreak can expand 

and become self-perpetuating if attacks by adult beetles 

become frequent enough to kill mature palms. Given that 

females lay an average of 90 eggs, CRB generation time is 4 

months, and a one to one sex ratio. Gressitt (1953) estimated 

that a single gravid female could theoretically produce a 

progeny, assuming no mortality, of 16,995,293,890 by the 

end of 2 years. 

4. Spread potential: High (VC) (Applicable risk criteria, from app. 4: a, b, c, d, e, f) 

Based on laboratory data from tethered adult CRBs, 

flight duration after feeding was between 2 and 3 hours, 

and distances travelled were between 2 to 4 km; so ability 

to disperse is high (Hinckley 1973). However, it may be 

somewhat lessened by potentially poor fitness of beetles 

upon arrival. The organism does have high reproductive 

potential but is also susceptible to high levels of mortality in 

the larval stages. Based on beetle distribution and numbers 

found initially on Guam in 2007, we estimate that it was 

present there 1 to 2 years (three to six generations) before 

detection, which could potentially be the case as well in 

Hawai‘i. A single CRB was caught in a seaport warehouse 

on Saipan, 241 km to the north of Guam, in September 

2006. Infestations can be contained, suppressed, and eradicated by removing larval breeding sites and mass trapping 

adults. The CRB was exterminated from the 36 km2 of 

Niuatoputapu Island, between Samoa and Tonga, using 

these methods (Gressitt 1953). However, mass trapping 

coupled with sanitation during 1971 through 1974 failed to 

eradicate CRB on two islands in Fiji, and eradication has 

failed recently on Guam. 

B. Consequences of introduction

5. Economic damage potential: Moderate (RC) 

(Applicable risk criteria, from app. 4: b, c, d)

The CRB killed over 50 percent of the coconut palms 

on Palau after it was introduced in 1942 (Gressitt 1953). In 

1968, CRB caused over $1 million in damage to palms in 

South Pacific countries (Bedford 1980). The damage and 

losses to resort, park, and residential and ornamental plants 

in Hawai‘i will affect the aesthetic appeal of important 

properties and tourist areas. Some losses in recreational use 

and revenue owing to diminished scenic appeal are likely. 

Costs associated with hazard tree removal, tree replacement, and regulatory actions are expected to increase. Current cost of replacing a mature ornamental palm on Guam is 

$1,000. A permanent infestation could lead to interstate and 

international quarantine restrictions, affecting Hawai‘i, its 

trade partners, and other U.S. states. 
33

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

6. Environmental damage potential: Moderate (MC) 

(Applicable risk criteria, from app. 4: d)

Outbreaks of CRB can expand and become self-perpetuating if attacks by the adult beetles become frequent 

enough to kill mature palms and other hosts. Based on 

CRB’s invasiveness, injury to native host plants is expected 

to be substantial if populations are left untended. Movement of wood, debris, or infested host plants would likely 

increase the rate of spread into native forests. Extensive 

mortality of cultivated and wild hosts should be expected. 

The consequent changes in composition and age structure 

of palms and P. tectorius could have long-term ecological 

effects. 

7. Social and political considerations: Moderate (MC) 

(Applicable risk criteria, from app. 4: a, b, c)

The successful introduction of CRB would likely 

result in public concerns regarding the aesthetics of damaged palms in urban plantings. In addition, P. tectorius is 

prominent in Pacific culture and tradition, including local 

medicine. All parts are used, from the nutritious fruits of 

edible varieties, to the poles and branches in construction, 

to the leaves for weaving and garlands. 

A permanent infestation could lead to interstate and 

international quarantine restrictions, affecting Hawai‘i, its 

trade partners, and other U.S. states. 

C. Pest risk potential (plant material/pots/detritus): 

High (Likelihood of introduction = high;

Consequences of introduction = moderate)

(Hitchhiker in shipping containers/military equipment): 

High (Likelihood of introduction = high; Consequences of 

introduction = moderate)

Selected bibliography:

Bedford, G.O. 1976. Use of a virus against the coconut 

palm rhinoceros beetle in Fiji. Pest Articles and News 

Summaries (PANS). 22: 11–25. 

Bedford, G.O. 1980. Biology, ecology, and control of palm 

rhinoceros beetles. Annual Review of Entomology. 25: 

309–339.

Berringer, D. 2007. Coconut rhinoceros beetle eradication 

program. Environmental Assessment. Tamuning, 

Guam: U.S. Department of Agriculture, Animal and 

Plant Health Inspection Service, Plant Protection and 

Quarantine. 23 p.

Catley, A. 1969. The coconut rhinoceros beetle Oryctes 

rhinoceros (L.). PANS. 15: 18–30.

Cumber, R.A. 1957. Ecological studies of rhinoceros 

beetle, Oryctes rhinoceros (L.), in Western Samoa. 

South Pacific Commission Tech. Pap. 107. Nouméa, New 

Caledonia: South Pacific Commission. 32 p.

Donnegan, J.A.; Butler, S.L.; Grabowiecki, W.; 

Hiserote, B.A.; Limtiaco, D. 2004. Guam’s forest 

resources, 2002. Resour. Bull. PNW-RB-243. Portland 

OR: U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Research Station. 32 p.

Gressitt, J.L. 1953. The coconut rhinoceros beetle (Oryctes 

rhinoceros) with particular reference to the Palau Islands. 

Bulletin 212. Honolulu, HI: Bernice P. Bishop Museum. 

157 p.

Hawai‘i Department of Agriculture. 2014. Coconut 

rhinoceros beetle information. Hawai‘i Department of 

Agriculture. http://hdoa.hawaii.gov/pi/main/crb/. (June 

2014).

Hinckley, A.D. 1966. Damage by coconut rhinoceros 

beetle, Oryctes rhinoceros (L.) to Pacific Island palms. 

South Pacific Bulletin. 16(4): 51–52.

Hinckley, A.D. 1973. Ecology of the coconut rhinoceros 

beetle, Oryctes rhinoceros (L.) (Coleoptera: Dynastidae). 

Biotropica. 5(2): 111–116.

McKenna, J.; Shroff, K.D. 1911. The rhinoceros beetle 

(Oryctes rhinoceros Linn.) and its ravages in Burma. 

Bull. No. 4. Rangoon: Burma Department of 

Agriculture. 6 p.

Moore, A. 2007. Assessment of the rhinoceros beetle 

infestation on Guam. http://guaminsects.net/uogces/

kbwiki/index.php?title=Oryctes_rhinoceros. 

(4 May 2013).
34

GENERAL TECHNICAL REPORT PSW-GTR-250

Paine, R.W. 1967. A search for parasites and predators 

of Oryctes and related dynastids in the Southeast Asia 

region. Unpublished report. On file with: Noumea, New 

Caldonia: South Pacific Commission. 71 p.

Smith, S.L.; Moore, A. 2008. Early detection pest risk 

assessment–coconut rhinoceros beetle. R5-FHP-2008-01. 

Susanville, CA: U.S. Department of Agriculture, Forest 

Service, Pacific Southwest Region, Forest Health 

Protection. 6 p.

Swezey, O.H. 1942. Insects of Guam-1. Bull. 172. Honolulu: 

Bernice P. Bishop Museum. 1-218.

Reviewers’ comments: The economic rating of moderate; 

that seems underestimated. An overhaul of the landscaping 

in Waikīkī, and other tourist areas seems significant as 

well as the removal of the iconic swaying palms when 50 

percent are gone. Hawai‘i imports substantial amounts of 

taro from the Pacific. It is important if commercial trade 

in taro corms are likely to harbor CRB. More information 

on where we would expect to find CRB in taro, the signs 

for inspectors and field extension agents would be helpful. 

Hawai‘i is active in preserving taro varieties as an important cultural crop.

Response to comments: The economic damage potential 

rating of moderate is an estimate based on the rating 

criteria determined to be appropriate by the author of this 

assessment. There is no disagreement that economic losses 

could be quite high with the loss of high numbers of ornamental palms. The CRB is likely to arrive as an adult and 

as a hitchhiker “at large,” not correlated with any particular 

commodity. The adults are attracted to bright lights and like 

to hide out in dark places during the day, so they are likely 

to enter the hold of a ship or aircraft at a loading dock.

2014 update—Coconut rhinoceros beetle was not established in Hawai‘i when this pest risk assessment effort was 

initiated, although five adult beetles had been detected in 

2003 at the Kahului seaport on Maui. Coconut rhinoceros 

beetle was included as a pest for further evaluation in the 

risk assessment process primarily owing to the building 

CRB populations on Guam where eradication has failed 

and adult beetles are numerous, increasing the likelihood of 

accidental transport to other islands.

Since the 2013 CRB detection on O‘ahu, a joint effort 

between the U.S. Department of Agriculture, the University of Hawai‘i at Manoa, the U.S. Navy, the Hawai‘i 

Department of Agriculture, USDA Forest Service, and 

other partners have mobilized surveying, trapping and 

control efforts in the area where the beetles were initially 

found. An Incident Command System has been established 

to help manage the various agencies and activities needed 

to efficiently respond to this pest (for more information see 

emergencyhttp://hdoa.hawaii.gov/pi/main/crb/). Breeding 

sites have been located at several locations on the Joint Base 

Pearl Harbor-Hickam military facility. As of June 2014, 423 

adults, 531 larvae, and 16 pupae have been found within the 

established buffer zone. Based on the high number of all life 

stages found at the base compost sites and in traps, CRB 

has likely been on O‘ahu for at least 2 to 3 years. Based on 

visual surveys, 103 palms have injury indicative of CRB 

attack; over 66,000 palms have been surveyed (HDOA 

2014). 

Coconut Stick Insect

Assessor: Andris Eglitis

Scientific name of pest: Graeffea crouanii (LeGuillou) 

(Orthoptera: Phasmatidae) 

Scientific names of hosts: Mainly coconut palm (Cocos 

nucifera); Sago palm (Cycas revoluta), Miscanthus japonicus, Pandanus tectorius, Pandanus spp.

Distribution: Australia, Solomon Islands, Caroline Islands, 

Cook Islands, Fiji, American Samoa, Western Samoa, 

Society Islands, Marquesas, Mangareva, Tokelau, Tonga, 

French Polynesia, New Caledonia, Niue, Tuvalu 

Summary of natural history and basic biology of the 

pest: Graeffea crouanii is considered a pest of significance 

on coconut palms in Tuvalu (Hardy et al. 2009), Fiji (Swamy 

and Deesh 2012), and other islands in Oceania (Hinckley 

1967). The coconut stick insect is one of the most widespread species of walkingsticks in Oceania (Nakata 1961). 

Bedford (1978, citing Swaine 1969), described outbreaks 

in the Pacific, noting that the most serious damage occurs 
35

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

in palms 24.4 m or more in height, although defoliation 

and fall-off in crop production can occur in younger palms 

as well. Outbreaks develop from small areas or pockets of 

infestation and gradually spread outwards if conditions 

remain suitable. The buildup and spread of damaging 

populations is slow, and a severe outbreak may last a year 

or more before it gradually subsides (Swaine 1969, cited by 

Bedford 1978). Control of outbreaks in Fiji using chemicals 

has been effective, but is expensive, and some biological 

control approaches have been attempted instead, with 

limited success thus far (Paine 1968). 

Female stick insects lay up to 100 eggs, many of which 

fall to the ground (MAF Biosecurity New Zealand 2009) 

while others are trapped in the axils of fronds of coconut 

palms (Bedford 1978). The eggs are enclosed in a very 

hard protective shell that is resistant to adverse weather 

conditions (Nakata 1961). There is a lengthy development 

time before the eggs hatch (Nakata 1961), sometimes up 

to 100 days (Hardy et al. 2009). Although the eggs are 

well-protected and resist salt water, they are sensitive to 

high temperature and desiccation (Rapp 1995). Thus, pest 

populations are maintained at higher levels when undergrowth beneath palms is high, and decline dramatically 

when cover is removed (Rapp 1995). Nymphs are highly 

mobile and can climb from the ground into the fronds of 

palms (Hardy et al. 2009). Feeding by the stick insects strips 

the palm fronds, leaving only the midribs and branch veins 

(Bedford 1978). Female nymphs pass through six instars 

(males through five) that collectively last for over 100 days 

(Hardy et al. 2009). Adults are also long lived (167 days for 

males, 115 for females [Hardy et al. 2009]) and are more 

susceptible to adverse environmental conditions than the 

egg stage (Nakata 1961). The males grow to 65 to 70 mm 

in length and females to 116 mm (Swamy and Deesh 2012). 

The males disperse through flight, while the females do not 

(Bedford 1978). 

Specific information relating to risk elements:

A. Likelihood of introduction (plant material pathway)

1. Pest with host-commodity at origin potential: 

Moderate (RU) (Applicable rating criteria, from 

app. 4: c, e)

The coconut walkingstick is widely distributed 

throughout the Pacific Islands (Nakata 1961). Dharmaraju 

(1980) reported that in Tuvalu, G. crouanii was strongly 

associated with green Pandanus fronds that are very widely 

used for handicrafts. 

2. Entry potential: Moderate (MC) (Applicable rating 

criteria, from app. 4: b)

The egg stage of G. crouanii is long lived and very 

resistant to adverse conditions (Nakata 1961), and if 

associated with palm or Pandanus fronds being transported 

for use in crafts, could gain entry into a new environment. 

Nakata (1961) points out that phasmatids, as a rule, have 

limited powers of dispersal, and probably depend on the egg 

as the stage most likely to be transported to a new environment. He stated that the possible spread of the widely 

distributed G. crouanii may have occurred through “rafting” where eggs were attached to fronds and transported by 

ocean currents to new locations (Nakata 1961). 

3. Colonization potential: Moderate (MC) (Applicable 

rating criteria, from app. 4: b)

The climatic conditions in Hawai‘i should be suitable 

for the stick insect, which is widespread throughout many 

islands in the Pacific. 

4. Spread potential: Low (MC) (Applicable rating criteria, from app. 4: d)

Pandanus tectorius is widely distributed in Hawai‘i and 

has been identified as a host for G. crouanii (Hardy et al. 

2009). Phasmatids have limited powers of dispersal unless 

assisted by human transport (Nakata 1961). 

B. Consequences of introduction

5. Economic damage potential: Low (MC) (Applicable 

rating criteria, from app. 4: c)

Criterion “c” would likely apply if the walkingstick 

were to become established, as mitigation costs for protecting Pandanus would increase. 

6. Environmental damage potential: Low (MC) 

(Applicable rating criteria, from app. 4: none)

None of the rating criteria would apply.
36

GENERAL TECHNICAL REPORT PSW-GTR-250

7. Social and political considerations: Moderate (MC) 

(Applicable rating criteria, from app. 4: a)

Public concerns could be elevated by the presence of a 

damaging insect on P. tectorius.

C. Pest risk potential: 

Moderate (Likelihood of introduction = low; Consequences of introduction = moderate) 

Selected bibliography:

Bedford, G.O. 1978. Biology and ecology of the 

Phasmatodea. Annual Review of Entomology. 

23: 125–149. 

Dharmaraju, E. 1980. Pest problems of crops in Tuvalu. 

Alafua Agricultural Bulletin. 5(4): 7–9. 

Hardy, C.; Anthony, D.; Sathyapala, S. 2009. Import risk 

analysis: fresh coconut (Cocos nucifera) from Tuvalu. 

Wellington, NZ: MAF Biosecurity, New Zealand. 138 p.

Hinckley, A.D. 1967. Associates of the coconut rhinoceros 

beetle in Western Samoa. Pacific Insects. 9(3): 505–511. 

Nakata, S. 1961. Some notes on the occurrence of 

Phasmatodea in Oceania. Pacific Insects Monograph. 

2: 107–121.

Paine, R.W. 1968. Investigations for the biological control 

in Fiji of the coconut stick-insect Graeffea crouanii

(Le Guillou). Bulletin of Entomological Research. 

57: 567–604. 

Rapp, I.G. 1995. Eggs of the stick insect Graeffea crouanii

Le Guillou (Orthoptera: Phasmidae). Mortality after 

exposure to natural enemies and high temperature. 

Journal of Applied Entomology. 119: 89–91. 

Swaine, G. 1969. The coconut stick insect Graeffea crouani

Le Guillon. Oleagineux. 24: 75–77. 

Swamy, B.N.; Deesh, A.D. 2012. Management of coconut 

stick insect—Graeffea crouanii (LeGuillou) in Fiji. Tech. 

Bull. Issue No. 1. Raiwaqa, Fiji: Ministry of Primary 

Industries. 3 p. 

Reviewers’ comments: None received.

Erythrina Scale

Assessor: Sheri Smith

Scientific name of pest: Toumeyella erythrinae Kondo and 

Williams (Hemiptera: Coccoidea: Coccidae)

Scientific name of host: Erythrina coralloides

Distribution: Mexico

Summary of natural history and basic biology of 

the pest: Erythrina scale was newly described by Kondo 

and Williams (2003) after being observed on twigs and 

branches of Erythrina coralloides in Mexico in 1991. 

According to the scale insects database ScaleNet (Ben-Dov 

et al. 2010), currently there are 14 species of soft scale 

insects in the Toumeyella genus, which are distributed in 

Brazil, Cuba, Mexico, and the United States. Toumeyella

species also are reported on erythrina in Guatemala (T. 

sallei is reported on E. corallodendron, and collections of 

presumed Toumeyella spp. have been made from E. berteroana and other Erythrina spp.) and in Colombia. Fifty-one 

species of scale insects have been recorded from Erythrina 

spp. worldwide (Ben-Dov et al. 2010).

The biology and injury caused by the erythrina scale 

were described by Kondo and Williams (2003). The scale is 

ovoviviparous and has one generation per year. It is a large 

(up to 2.1 cm long and 2.0 cm wide), bisexual species with 

males developing alongside the leaf veins on the underside 

of leaves. Infestation results in localized chlorosis on leaves, 

defoliation, branch dieback, and often death of the host 

plant. In some localities in Mexico, it has caused serious 

injury and plant death; infestation levels have reached 91 

percent and mortality 56 percent.

About 115 Erythrina spp. have been described. They 

are globally traded for medicinal and cultural uses and as 

ornamentals plantings, owing to their conspicuous and 

beautiful flowers.

Specific information relating to risk elements:

A. Likelihood of introduction (plants for planting).

1. Pest with host-commodity at origin potential (plants 

for planting): Moderate (MC) (Applicable risk criteria from app. 4: b, e, h) 
37

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Scale insects can have large increases in populations, 

particularly in the absence of parasites and predators. 

Erythrina scale could likely survive and be transported on 

leaves of live erythrina plants.

2. Entry potential (plants for planting): High (MC) 

(Applicable risk criteria from app. 4: b, c,) 

If live erythrina plants are imported, they could easily 

harbor scale insects. 

3. Colonization potential: Low (RU) (Applicable risk 

criteria, from app. 4: b)

It is unknown if erythrina scale would attack Erythrina species in Hawai‘i, in particular the native Erythrina 

sandwicensis. Many of the nonnative Erythrina spp. in 

Hawai‘i were killed by the invasive erythrina gall wasp 

(Quadrastichus erythrinae) over the past decade. Remaining ornamentals could serve as potential hosts for scale 

insects and, depending on distribution, could serve as a 

pathway to the more remote native trees. Coccids have 

limited inherent powers of dispersal, and thus, once introduced, expansion would most likely be facilitated by people 

moving infested material. 

4. Spread potential: Moderate (RU) (Applicable risk 

criteria, from app. 4: c, f) 

Likelihood of spread beyond any colonized area would 

depend on host availability and human-assisted transport. 

Control techniques have been developed for some scale 

insects; however, eradication would be infeasible in a 

natural environment.

B. Consequences of introduction

5. Economic damage potential: Moderate (RC) 

(Applicable risk criteria, from app. 4: b, c)

Infestation results in localized chlorosis on leaves, 

defoliation, branch dieback, and often death of the host 

plant. In some localities in Mexico, the scale insect has 

caused serious injury and plant death; infestation levels 

have reached 91 percent and mortality 56 percent (Kondo 

and Williams 2003).

6. Environmental damage potential: Moderate (RU) 

(Applicable risk criteria, from app. 4: d)

If attacks and subsequent plant injury or mortality of 

Erythrina sandwicensis were to occur, impacts could be 

high, as this species has limited distribution and has already 

experienced high mortality rates owing to the invasive 

erythrina gall wasp (Quadrastichus erythrinae) and 

reduced seed viability owing to an invasive bruchid beetle 

(Specularius impressithorax). 

7. Social and political considerations: Moderate (MC) 

(Applicable risk criteria, from app. 4: a, d)

Public concerns could result if moderate to high levels 

of tree injury or mortality occur, particularly for native 

species. Control with pesticides would likely have limited 

acceptance or be prohibited as a result of potential secondary impacts to other insect species.

C. Pest risk potential:

Moderate (Likelihood of introduction = low; Consequences of introduction = moderate)

Selected bibliography:

Ben-Dov, Y.; Miller, D.R.; Gibson, G.A.P. 2010. ScaleNet: 

a database of the scale insects of the world. http://www.

sel.barc.usda.gov/scalenet/scalenet.htm. (6 May 2013).

Kondo, T.; Williams, M.L. 2003. A new species of 

Toumeyella (Hemiptera: Coccoidea: Coccidae) on 

Erythrina in Mexico. Revista Especializada en Ciencias 

Quimico-Biologicas. 6(1): 11–15.

Reviewers’ comments: None received.

Eugenia Psyllid 

Assessor: Andris Eglitis

Scientific name of pest: Trioza eugeniae Froggatt (Hemiptera: Psyllide)

Scientific names of hosts: Syzygium paniculatum (= 

Eugenia myrtifolia), Metrosideros excelsa

Distribution: Native to southeastern Australia; introduced 

into California (1988) and Florida (1993)

Summary of natural history and basic biology of 

the pest: The eugenia psyllid, Trioza eugeniae, attacks 

the new growth of Syzygium paniculatum, a common 
38

GENERAL TECHNICAL REPORT PSW-GTR-250

ornamental tree in California (Dahlsten et al. 1999). Young 

(2003) determined that T. eugeniae could also complete its 

development on seven other species of trees belonging to 

three allied genera in the Myrtaceae. The Eugenia psyllid 

completes three to five generations per year, determined in 

part by temperature and the physiological state of the host 

(Dahlsten et al. 1999). The adult psyllid is chocolate brown, 

2 mm long, and membranous-winged (Mead 1994). Mature 

nymphs are completely ringed with white waxy filaments, 

a characteristic typical of the Triozinae (Mead 1994). After 

mating, the females lay yellow football-shaped eggs (more 

than 100 per female) partially inserted into the edges of 

new terminal leaves of host plants (Dahlsten et al. 1999). 

Small mobile nymphs hatch from the eggs and settle on 

newly expanding leaves, primarily on the underside, where 

they feed and develop in a cup-shaped pit or gall formed 

by the plant’s response to the psyllid feeding (Dahlsten 

et al. 1999). The feeding of the psyllids produces a sticky 

substance called honeydew, which is eventually covered by 

a black sooty mold. High densities of psyllids produce acute 

plant damage that includes shoot deformation, distortion of 

foliage and stems, and inhibition of new shoot formation 

(Dahlsten et al. 1999). The long-term effects of sustained 

high infestation include severe weakening of plants, poor 

growth, and reduced economic value (Dahlsten et al. 1999). 

Dahlsten et al. (1999) noted that in California, some native 

natural enemies had been found feeding on the eugenia 

psyllid, but their effects as control agents were negligible. 

In its native Australia, T. eugeniae attracts little 

attention and is not considered a problem (Mead 1994). 

Mead (1994) describes the host range of the eugenia psyllid 

as extremely narrow.

The eugenia psyllid is sensitive to both frost and heat. 

In California, population densities drop off when temperatures exceed 32.2 °C. The psyllid does much better in the 

cool, mild weather of fall through spring and does best in a 

cool coastal climate (Mead 1994). In southern California, 

the eugenia psyllids reproduce the year around (Downer et 

al. 1991).

Starr et al. (2007) identify Trioza eugeniae as a 

potential pest of ‘ōhi‘a lehua. Several other psyllids have 

been introduced into the continental United States through 

the movement of plant material. Two of these psyllids have 

also been introduced into Hawai‘i (Starr et al. 2007). Trioza 

eugeniae first appeared in California in 1988 and has been 

moved via nursery stock to several new counties within the 

state (Dahlsten et al. 1999). 

Specific information relating to risk elements:

A. Likelihood of introduction (nursery stock pathway)

1. Pest with host-commodity at origin potential: 

Moderate (MC) (Applicable rating criteria, from 

app. 4: b, d, e, h)

Female eugenia psyllids produce over 100 eggs per 

female and can complete several generations per year 

(Downer et al. 1991). In the past, survival on plant material 

has been sufficient to allow this insect to be transported into 

new environments (Dahlsten et al. 1999, Starr et al. 2007). 

2. Entry potential: High (MC) (Applicable rating criteria, from app. 4: b, c, d)

Light infestations would be difficult to detect, and 

insects survive in transit, as evidenced by their successful 

introduction into new environments and further redistribution within California. 

3. Colonization potential: High (MC) (Applicable rating criteria, from app. 4: a, b, e) 

Trioza eugeniae has become established in Florida and 

California despite having a narrow host range (Mead 1994). 

There is some disagreement in the literature as to this 

psyllid’s adaptability to new hosts. Although the host range 

may be narrow, it is important to note that T. eugeniae was 

raised to maturity on seven myrtaceous hosts in three genera (Young 2003), and that a species of Metrosideros is an 

observed host (Dreistadt and Dahlsten 2001). For Hawai‘i, 

M. polymorpha is considered a potential host of concern. 

4. Spread potential: Moderate (MC) (Applicable rating 

criteria, from app. 4: b, c, e)

A high reproductive potential combined with a cryptic 

nature have allowed this insect to be spread widely within 

California, when moved with infested plant material. 

Metrosideros polymorpha, the key host of concern is widely 

distributed in the Hawai‘i Islands.
39

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

B. Consequences of introduction

5. Economic damage potential: Moderate (MC) 

(Applicable rating criteria, from app. 4: c, d)

If M. polymorpha proves to be a suitable host for T. 

eugeniae, feeding damage could lower the value of ‘ōhi‘a 

lehua or increase the costs of managing the pest. The 

presence of a quarantine pest is always a factor in trade 

involving potentially infested species. 

6. Environmental damage potential: Moderate (RC) 

(Applicable rating criteria, from app. 4: e)

The most effective controls for psyllids have proven 

to be biological agents (parasitic wasps). No plants with 

limited distribution are expected to be hosts for T. eugeniae. 

7. Social and political considerations: Moderate (MC) 

(Applicable rating criteria, from app. 4: a)

‘Ōhi‘a lehua is an important plant species in Hawai‘i, 

and additional pests on this plant would be cause for 

concern from the public. 

C. Pest risk potential: 

Moderate (Likelihood of introduction = moderate; 

Consequences of introduction = moderate) 

Selected bibliography:

Dahlsten, D.L.; Rowney, D.L.; Copper, W.A. 1999. 

Eugenia psyllid biological control. University of 

California at Berkeley, Center for Biological Control. 4 

p. http://www.cnr.berkeley.edu/biocon/dahlsten/eugenia/

eug-web.htm. (4 August 2013).

Dahlsten, D.L.; Rowney, D.L.; Robb, K.L.; Downer, 

J.A.; Shaw, D.A.; Kabashima, J.H. 2002. Biological 

control of introduced psyllids on Eucalyptus. 

Proceedings of the 1st international symposium on 

biological control of arthropods. FHTET-03-05. Fort 

Collins, CO: U.S. Department of Agriculture, Forest 

Service: 356–361. http://www.fs.fed.us/foresthealth/

technology/webpubs/FHTET-2003-05/day5/dahlsten.pdf. 

(12 May 2013).

Downer, A.J.; Koehler, C.S.; Paine, T.D. 1991. Biology 

and management of the Eugenia psyllid (Trioza eugeniae

Froggatt). Journal of Environmental Horticulture. 9(3): 

137–141.

Dreistadt, S.H.; Dahlsten, D.L. 2001. Psyllids. Pest Notes. 

Publication 7423. Davis, CA: University of California, 

Davis, Agriculture and Natural Resources. http://www.

ipm.ucdavis.edu/PDF/PESTNOTES/pnpsyllids.pdf. (13 

May 2013)

Mead, F.W. 1994. Eugenia psyllid, Trioza eugeniae

Froggatt (Homoptera: Psyllidae). Entomology Circular 

No. 367. Gainsville, FL: Florida Department of 

Agriculture and Consumer Services. 3 p.

Starr, F.; Starr, K.; Loope, L.L. 2007. Potential pests of 

ohia (Metrosideros polymorpha) and other Myrtaceae. 

Hawaiian Ecosystems at Risk Project. Draft report. 85 p.

Young, G.R. 2003. Life history, biology, host plants 

and natural enemies of the lilly pilly psyllid, Trioza 

eugeniae Froggatt (Hemiptera: Triozidae). Australian 

Entomologist. 30 (1): 31–38.

Reviewers’ comments: In response to a comment under 

“Environmental damage potential” stating “parasitic wasps 

... would not be expected to have adverse environmental 

effects” a reviewer stated: “is home to several endemic 

Trioza species. Introduced biological control agents could 

devastate populations of these, so there very well could be 

detrimental environmental effects.” (Culliney)

Response to comments: The comment was removed, rating 

criterion “e” was added, and the rating for “Environmental 

damage potential” was changed from “low” to “moderate.” The overall Pest Risk Potential for T. eugeniae was 

unchanged and remains “moderate.”

Keyhole Ambrosia Beetle 

Assessor: Andris Eglitis

Scientific name of pest: Amasa truncata (Erichson) (Coleoptera: Curculionidae)
40

GENERAL TECHNICAL REPORT PSW-GTR-250

Scientific names of hosts: Acacia spp., Albizia distachya, 

Eucalyptus spp., Knightia excelsa, Kunzea ericoides, Leptospermum scoparium, Metrosideros spp., Pinus radiata, 

Pseudotsuga menziesii, Podocarpus spicatus, Weinmannia 

racemosa

Distribution: Australia, New Zealand, Brazil 

Summary of natural history and basic biology of 

the pest: In Australia, the keyhole ambrosia beetle is mainly 

associated with species of Eucalyptus and closely related 

species within the Myrtaceae, and only in live standing 

trees (Flechtmann and Cognato 2011). Froggatt (1926) listed 

saplings of Eucalyptus saligna and E. rostrata as the key 

hosts in Australia. Flechtmann and Cognato (2011) summarized the host records reported by other Australian authors 

and added several species of eucalypts to the host list. The 

ambrosia beetle has been in New Zealand since 1930, where 

it appears to have acquired additional hosts beyond those 

found in Australia. In New Zealand, A. truncata has been 

found breeding in Albizia lophanta, Acacia verticillata, A. 

decurrens, Leptospermum ericoides, L. scoparium, Knightia excelsa, Metrosideros robusta, M. excelsa, Weinmannia

racemosa, and several species of Eucalyptus including 

E. botryoides, E. globulus, E. obliqua, E. ovata, and E. 

viminalis (Zondag 1977). Several other hosts including 

Pinus radiata have also been attacked, but no broods were 

produced in them (Zondag 1977). Zondag (1977) reported 

that the only living trees to be attacked by A. truncata are 

eucalypts, especially E. globulus, in which severe branch 

dieback can occur. However, Flechtmann and Cognato 

(2011) report that New Zealand literature also identifies 

other live myrtaceous hosts for A. truncata. Attacks on live 

trees by the keyhole ambrosia beetle are followed by rapid 

wilting of the foliage, leading to the conclusion that an 

associated fungus other than the ambrosia fungus may be 

responsible for killing the sapwood (Zondag 1977). Despite 

this capability of producing branch dieback and infesting 

numerous hosts, A. truncata is considered of little economic 

importance in New Zealand (Zondag 1977).

Flechtmann and Cognato (2011) reported that A. truncata has recently been introduced into Brazil, with several 

individuals trapped in a young plantation of Eucalyptus 

grandis in 2006 and 2007. They speculate that the pathway 

may have been through solid wood packing material in 

trade from New Zealand or Australia. They estimate that 

the ambrosia beetle arrived and became established in 

Brazil around 1996 (Flechtmann and Cognato 2011).

The keyhole ambrosia beetle is thought to have a life 

cycle of less than 1 year and may complete two generations 

in a year (Zondag 1977). The adult female of A. truncata

bores an entry tunnel into the wood to a depth of about 30 

mm. There may be one or two short additional tunnels that 

branch from the main tunnel (Zondag 1977). Eggs are laid 

in the far end of the tunnel and small larvae make a small 

excavation called a “keyhole chamber” where they feed and 

develop. Eggs are apparently laid over a long period of time, 

because larvae of all sizes, pupae and young adults can all 

be found in the gallery at the same time (Zondag 1977). 

Most of the larvae develop into females, which emerge in 

the spring and summer (Zondag 1977). Froggatt (1926) 

reported that feeding is typically near damaged areas on the 

tree, but later Moore (1959) found that healthy trees may 

also be attacked. 

Specific information relating to risk elements:

A. Likelihood of introduction (untreated wood pathway)

1. Pest with host-commodity at origin potential: High 

(VC) (Applicable rating criteria, from app. 

4: a, d, e, f, g, h)

Ambrosia beetles possess a strong ability to locate 

and colonize hosts, be they standing trees or freshly cut 

material, and if log moisture remains suitable, they can 

survive in this material for a sufficient amount of time to 

be transported to a new environment. Ambrosia beetles are 

always common on lists of interception records (Brockerhoff et al. 2006, Haack 2001). 

2. Entry potential: High (VC) (Applicable rating criteria, from app. 4: a, b, c, d)

Amasa truncata has demonstrated its ability to survive 

in transit, as it has become established in at least two new 

environments, New Zealand and Brazil (Brockerhoff et al. 

2003, Flechtmann and Cognato 2011). 
41

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

3. Colonization potential: High (RC) (Applicable rating criteria, from app. 4: a, b, c, d)

The keyhole ambrosia beetle has become successfully 

established in at least two new environments (Brockerhoff 

et al. 2003, Flechtmann and Cognato 2011) and has taken 

on new hosts in those settings. Because members of the 

Mimosaceae (Acacia spp.) and Myrtaceae (Metrosideros 

spp.) are among the known hosts for A. truncata (Flechtmann and Cognato 2011), it is believed the ambrosia beetle 

could encounter suitable hosts in Hawai‘i. 

4. Spread potential: High (MC) (Applicable rating criteria, from app. 4: b, d, e, f, g, h)

Redistribution (criterion b) of A. truncata has occurred 

by virtue of its successful introduction into two new 

countries. Its host list has become broader than it was in 

its native environment. The cryptic nature of A. truncata 

would likely ensure that it could become well-established 

before being detected, and thus, would be difficult to eradicate once found. There is possible reason for concern that 

the insect has an associated fungus, which may be involved 

in its ability to kill debilitated hosts.

B. Consequences of introduction

5. Economic damage potential: Moderate (MC) 

(Applicable rating criteria, from app. 4: b, c, d)

In New Zealand, A. truncata is not considered economically important (Withers 2001, Zondag 1977). In 

Australia, however, the ambrosia beetle has been linked to 

the death of healthy trees and others that were debilitated by 

psyllids (Moore 1959). There could be reason for concern 

about the potential for increased virulence of the associated 

Ceratocystis fungus in a new setting, and the fact that the 

insect appears to have a broad host range that becomes even 

broader as it becomes established in new environments. In 

Hawai‘i, the species of greatest concern as a potential host 

is ‘ōhi‘a lehua (Metrosideros polymorpha).

6. Environmental damage potential: Low (RU) 

(Applicable rating criteria, from app. 4: none)

7. Social and political considerations: Moderate (RU) 

(Applicable rating criteria, from app. 4: a)

Public concerns could arise from the introduction 

of another invasive insect if it were to cause damage to 

important native or other aesthetically significant plants 

that are not presently being damaged.

C. Pest risk potential: 

High (Likelihood of introduction = high; Consequences of introduction = moderate) 

Selected bibliography:

Brockerhoff, E.G.; Bain, J.; Kimberley, M.; Knizek, M. 

2006. Interception frequency of exotic bark and ambrosia 

beetles (Coleoptera: Scolytinae) and relationship with 

establishment in New Zealand and worldwide. Canadian 

Journal of Forest Research. 36: 289–298. 

Brockerhoff, E.G.; Knizek, M.; Bain, J. 2003. Checklist 

of indigenous and adventive bark and ambrosia beetles 

(Curculionidae: Scolytinae and Platypodinae) of New 

Zealand and interceptions of exotic species (1952–2000). 

New Zealand Entomologist. 26: 29–44. 

Flechtmann, C.A.H.; Cognato, A.I. 2011. First report of 

Amasa truncata (Erichson) (Coleoptera: Curculionidae: 

Scolytinae) in Brazil. The Coleopterists Bulletin. 65(4): 

417–421. 

Froggatt, W.W. 1926. The ridge-tailed borer, Amasa 

truncata, Erickson. The Australian Forestry Journal. 

9: 144–146.

Haack, R.A. 2001. Intercepted Scolytidae (Coleoptera) 

at U.S. ports of entry: 1985-2000. Integrated Pest 

Management Reviews. 6: 253–282. 

Moore, K.M. 1959. Observations on some Australian 

forest insects. 4. Xyleborus truncatus Erichson 

1842 (Coleoptera: Scolytidae) associated with dying 

Eucalyptus saligna Smith (Sydney blue-gum). 

Proceedings of the Linnean Society of New South Wales. 

84(2): 186–193.

Withers, T.M. 2001. Colonization of eucalypts in New 

Zealand by Australian insects. Austral Ecology. 26: 

467–476. 
42

GENERAL TECHNICAL REPORT PSW-GTR-250

Zondag, R. 1977. Xyleborus truncatus Erichson 

(Coleoptera: Scolytidae). Forest and Timber Insects in 

New Zealand 21. Rotorua, New Zealand: New Zealand 

Forest Service, Forest Research Institute.

Reviewers’ comments: “To clarify why a moderate economic damage potential is concluded, it would be good to 

mention an example of a host species of economic importance which would be affected.” (Martin–GCAPS)

“If the species has demonstrated a capacity to acquire 

new hosts in regions into which it has been introduced, 

wouldn’t criterion “f” apply? It’s hard to believe that there 

would be no environmental consequences should it become 

established in Hawaii.” (Culliney) 

“I suspect this is a tricky species to assess and this may 

be why I wasn’t entirely convinced of its risk potential. I 

think it would be helpful to explain a few things a bit more. 

As a reader I was trying to work things out rather than 

seeing it clearly laid out. For instance, if the only living 

trees it attacks are Eucalypts, is it likely A. truncata will 

attack other genera of living trees? Is the non-eucalypt host 

range living or fallen or decayed trees? Are there congeners 

that might provide some insight into the behaviour of this 

species? If there is no information to support or explain 

aspects of the assessment, I think it is worth commenting on 

that and on areas of uncertainty so the reader understands 

what has been considered.”

Response to comments: The “moderate” rating for economic damage potential is derived from the fact that three 

of the rating criteria apply for that element. A statement 

was added to the text, identifying Metrosideros polymorpha

(ohia) as a potential host of economic importance. 

Perhaps taking on new hosts can be considered the 

same as developing higher virulence or more damaging 

biotypes (criterion “f”). However, even if this criterion 

were added and environmental damage potential changed 

from low to moderate, the overall pest risk potential would 

remain “high.”

Flechtmann and Cognato (2011) point out that in New 

Zealand, Amasa truncata has been reported from other live 

myrtaceous hosts besides Eucalyptus. Metrosideros excelsa

is one of those hosts. On this basis, we believe the “high”

pest risk potential (with M. polymorpha as a potential host) 

is warranted.

Lemon Tree Borer

Assessor: Sheri Smith

Scientific name of pest: Oemona hirta Fabricius (Coleoptera: Cerambycidae)

Scientific names of hosts: Acacia spp., Acer pseudoplantanus, Aeculus hippocastanum, Albizia spp., Aleurites 

spp., Alectryon excelsus, Alnus glutinosa, Amygdalus spp., 

Aristotelia spp., Asparagus spp., Avicennia spp., Brachyglottis spp., Betula spp., Callistemon spp., Casimiroa spp., 

Cassinia spp., Chaenomeles spp., Choisya spp., Chrysanthemoides spp., Citrus limon, C. reticulata, C. sinensis, 

Clerodendrum spp., Corylus spp., Coprosma robusta, 

Corynocarpus laevigatus, Crateagus spp., Cyphormandra 

spp., Cytisusm spp., Dahlia spp., Diospyros spp., Eucalyptus spp., Euonymus spp., Ficus spp., Hebe salicifolia, 

Hibiscus spp., Hoheria spp., Juglans spp., Koelreuteria spp., 

Kunzea ericoides, Leptospermum scoparium, Macadamia 

spp., Malus sylvestris, Melicytus spp., Metrosideros spp., 

Myoporum laetum, Oleana spp., Ozothamnus leptophyllus, 

Pennantia corymbosa, Persea americana, Phyllostachys 

spp., Pinus radiata, Pittosporum crassifolium, P. eugenioides, P. tenuifolium, Platanus spp., Populus spp., Prunus 

avium, P. cerasus, P. domestica, P. dulcis, P. persica, 

Punicia spp., Pyrus communis, Quercus spp., Rhus spp., 

Ribes grosularia, Rosa spp., Salix spp., Solanum beteceum, 

Syzygium spp., Tamarix spp., Telopea spp., Ulex europaeus, 

Ulmus spp., Vaccinium spp., Vitex spp., Vitis vinifera, 

Wisteria spp.

Distribution: New Zealand, Malaysia

Summary of natural history and basic biology of 

the pest: Lemon tree borer, Oemona hirta, is a longhorned 

beetle native to and found throughout New Zealand, where 

it is considered to be one of the most common insects. It 

was first recognized as a major pest of citrus trees by Cottier (1938). It is now also reported to be present in Malaysia 

(APPPC 1987). It is not regarded as established or transient 

in the United Kingdom; however, a single larva was intercepted in a Wisteria sp. plant in 1983 and in a number of 
43

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Wisteria sp. rootstocks in June 2010 and again in a Wisteria

sp. plant in July 2010 (Ostojá-Starzewski et al. 2010). 

Infested plants were destroyed; however, it is not known if 

some infested hosts went undetected so there is a chance 

that O. hirta could have escaped and become established, at 

least in the north of England (FERA 2010).

Lemon tree borer is highly polyphagous, feeding on 

many tree, shrub, and vine species. Over 130 host genera 

are listed in New Zealand. The larvae bore into wood of 

branches and stems, causing serious damage (Wang et 

al. 1998); adult beetles feed on pollen and nectar. In New 

Zealand, the native mahoe (Melicytus spp.) is suggested 

to be its principal native host. Lemon tree borer is of great 

economic importance because it attacks many species of 

fruit, nut, and vine crops, but also shelter belt trees such as 

poplar. Such a wide range of hosts is unusual for a longicorn 

borer that attacks living hosts (Wang 1995). Oemona hirta

is a species of quarantine importance because it may attack 

tree and vine crops overseas if introduced accidently (Wang 

et al. 2002). It is on the European and Mediterranean Plant 

Protection Organization’s Alert List of Quarantine Pests 

(EPPO 2013). 

In New Zealand, the life cycle takes 2 years to complete. Adults are active from the beginning of October 

through the first week of January, and during this period, 

they mate and females lay eggs. Eggs are laid singly in leaf/

stem junctions, bark crevices, or in fresh pruning scars with 

each female capable of producing about 82 eggs (Wang et 

al. 1998), of which 62 percent were oviposited. On hatching, 

the larvae bore directly into the sapwood and heartwood 

of hosts and construct long galleries, with periodic (every 

few centimeters) side branches to the surface to eject frass. 

The larval stage takes >1 year and can be found year-round; 

when fully mature (between mid-June and mid-October), 

they form a cell within the host to pupate (May to early 

November). Newly formed adults remain within the pupal 

cell until their integument has hardened, after which they 

emerge. They do not become sexually mature until 4 days 

postemergence. Adults live for about 2 months and are good 

fliers. Feeding and reproductive activities take place mostly 

at night (Wang and Davis 1998). Female beetles are brown 

and range from 14 to 31 mm in body length. They are larger 

than males and have proportionally shorter antennae.

The lines of frass ejection holes are one indication of 

the presence of live larvae, but their feeding also can cause 

small twigs to wilt and die, resulting in clusters of dead 

leaves. Major damage by larger larvae can weaken branches 

to the point that they break under wind pressure or fruit 

load or can even be girdled and die.

Specific information relating to risk elements:

A. Likelihood of introduction

1. Pest with host-commodity at origin potential (root 

stock, live plants): Moderate (RC) (Applicable risk 

criteria from app. 4: d, e, g, h)

Entry of lemon tree borer into Hawai‘i would most 

likely be facilitated via trade of infested host plants for 

planting, as occurred in the United Kingdom in 1983 and 

2010. Likelihood of introduction would increase dependent 

on how often host plants are imported into Hawai‘i from 

New Zealand. Oemona hirta larvae have an extended 

colonization period of over a year in host tissue, so could 

easily be transported in that life stage. Over 130 host genera 

are listed in New Zealand.

2. Entry potential (root stock, live plants): Moderate

(MC) (Applicable risk criteria from app. 4: b, c, d)

The larval or pupal stage would be the most likely stage 

to be transported in plant material. Both stages would be 

protected within the host material and would be difficult to 

detect. Adults could potentially be hitchhikers in containers 

or shipping materials, but survival would be less likely.

3. Colonization potential: High (MC) (Applicable risk 

criteria, from app. 4: b, c, e)

Lemon tree borer appears to be reported in Malaysia, 

but establishment cannot be confirmed based on available 

information; so criterion (a) is considered not applicable.

Likelihood of colonization will be largely determined 

by availability of host plants and climate. Several genera of 

host plants exist in Hawai‘i, and the climate is presumed to 

be suitable. The organism has a broad host range and has 

demonstrated the ability to utilize new hosts. Assuming 
44

GENERAL TECHNICAL REPORT PSW-GTR-250

both sexes would be transported in the same material, there 

is some likelihood of reproduction after entry. 

4. Spread potential: Moderate (MC) (Applicable risk 

criteria, from app. 4: b, e, f, g)

The rate of spread of cerambycids through natural 

dispersal varies according to the host within which larvae 

develop (Hanks 1999). Natural spread could be in the order 

of a few kilometers per year. If transported within infested 

plants, the eggs, larvae or pupae of O. hirta could be spread 

to many parts of the Hawai‘i Islands within days. Control 

of this pest is considered very difficult (Wang and Davis 

2005). According to Wang and Shi (1999), once the larvae 

enter branches and trunks, chemical control becomes 

impractical, which severely limits options for treatments 

and clearly puts the emphasis on destruction of any infested 

host plants. Some of the newer systemic pesticides may be 

efficacious, but this in unknown.

B. Consequences of introduction

5. Economic damage potential: Moderate (RU) 

(Applicable risk criteria, from app. 4: a, b, d)

There is limited commercial citrus production in 

Hawai‘i that might be affected by O. hirta. However, for nut 

production, Macadamia is listed as a host in New Zealand, 

and Hawai‘i produced over 49 million pounds of macadamia 

nuts in the 2011 to 2012 season, valued at over $38 million 

(NASS 2012). For host species of concern for this risk 

assessment, Acacia koa would likely be the only one with 

commercial value. Infestations in ornamental nurseries 

could also cause some economic loss.

6. Environmental damage potential: Moderate (RU) 

(Applicable risk criteria, from app. 4: d)

Extent of injury or mortality of hosts of concern for 

Hawai‘i is unknown. Acacia, Metrosideros, Vaccinium spp., 

and Myoporum laetum are listed as hosts in New Zealand; 

so if O. hirta established, it is presumed that plant injury or 

mortality may occur. Just one, or a few larvae, can kill or 

severely weaken branches of trees or vines (FERA 2010).

7. Social and political considerations: Low (RU) 

(Applicable risk criteria, from app. 4: none)

No criteria were selected based on the likelihood of 

relatively small social concern and the uncertainty of trade 

implications. High mortality rates of one of the host species 

of concern for Hawai‘i could have social implications, but 

the uncertainty of level of plant injury limits the ability 

to predict public concern. A permanent infestation could 

possibly lead to interstate and international quarantine 

restrictions, but this is likely to be more applicable to 

agricultural commodities. 

C. Pest risk potential: 

Moderate (Likelihood of introduction = moderate; 

Consequences of introduction = moderate)

Selected bibliography:

Asia and Pacific Plant Protection Commission [APPPC]. 

1987. Insect pests of economic significance affecting 

major crops of the countries in Asia and Pacific region. 

Tech. Doc. 135. Bangkok, Thailand: Regional FAO 

Office for Asia and the Pacific. 56 p.

Cottier, W. 1938. Citrus pests: (2) The citrus borer. New 

Zealand Journal of Agriculture. 57 : 28–29.

European and Mediterranean Plant Protection 

Organization [EPPO]. 2013a. EPPO alert list. http://

www.eppo.int/QUARANTINE/Alert_List/alert_list.htm. 

(4 August 2013).

Food and Environment Research Agency [FERA]. 2010. 

Rapid assessment of the need for a detailed pest risk 

analysis for Oemona hirta, the lemon-tree borer. Version 

4. The Food and Environmental Research Agency. 7 p.

Hanks, L.M. 1999. Influence of the larval host on 

reproductive strategies of cerambycid beetles. Annual 

Review of Entomology. 44: 483–505.

National Agricultural Statistics Service [NASS]. 2012. 

Hawai‘i macadamia nuts: final season estimates. 

Honolulu: U.S. Department of Agriculture, Hawai‘i Field 

Office. 8 p. 

Ostojá-Starzewski, J.; MacLeod, A.; Eyre, D. 2010. 

Lemon tree borer, Oemona hirta, plant pest fact sheet. 

York, United Kingdom: The Food and Environmental 

Research Agency. 6 p. 
45

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Wang, Q. 1995. Australian longicorn beetles plague our 

eucalypts. Australian Horticulture. 93: 34–37.

Wang, Q.; Davis, L.K. 2005. Mating behavior of Oemona 

hirta (F.) (Coleoptera: Cerambycidae) in laboratory 

conditions. Journal of Insect Behavior. 18: 187–191.

Wang, Q.; Shi, G. 1999. Parasitic natural enemies of 

lemon tree borer. In: O’Callagan, M., ed. Proceedings 

of the New Zealand 52nd plant protection conference. 

Auckland, NZ: New Zealand Plant Protection Society 

(Inc.): 60–64.

Wang, Q.; Shi, G.; Davis, L.K. 1998. Reproductive 

potential and daily reproductive rhythms of Oemona 

hirta (Coleoptera: Cerambycidae). Journal of Economic 

Entomology. 91(6): 1360–1365.

Wang, Q.; Shi, G.; Song, D.; Rogers, D.J.; Davis, L.K.; 

Chen, X. 2002. Development, survival, body weight, 

longevity, and reproductive potential of Oemena hirta

(Coleoptera: Cerambycidae) under different rearing 

conditions. Journal of Economic Entomology. 95(3): 

563–569.

Reviewers’ comments: None received.

Platypodid Ambrosia Beetle

Assessor: Sheri Smith

Scientific name of pest: Megaplatypus mutatus 

(= Platypus mutatus Chapuis) (Coleoptera: 

Curculionidae: Platypodinae)

Scientific names of hosts: Acacia spp., Acer negundo, 

Ailanthus altissima, Balfourodendron riedelianum, Casuarina cunninghamiana, Caesalpinia echinata, Cedrela 

tubiflora, Citrus spp., Calophyllum brasiliense, Erythrina

crista-galli, Eucalyptus camaldulensis, E. dunni, E. europhylla, E. robusta, E. tereticornis, Eucalyptus spp., Fraxinus spp., F. excelsior, Grevillea robusta, Oleaceae, Laurus 

nobilis, Ligustrum lucidum, Liquidambar styraciflua, 

Luehea divaricata, Magnolia grandiflora, Magnoliacea, 

Malus sylvestris, Melia azedarach, Pinus spp., Platanus x

acerifolia, Populus alba, P. deltoids, Populus spp., Populus 

x euroamericana, Pyrus communis, Quercus borealis, 

Q. palustris, Q. robur, Robinia pseudo-acacia, Salix 

alba, S. babylonica, S. nigra, Sebastiana commersoniana, 

Taxodium distichum, Tilia moltkei, Ulmus pumila, Ulmus 

spp., Vitex megapotamica

Distribution: Native to South America, more specifically 

Argentina, Bolivia, Brazil, French Guiana, Paraguay, Peru, 

Uruguay, and Venezuela, and introduced in Italy.

Summary of natural history and basic biology of the 

pest: Megaplatypus mutatus is a polyphagous ambrosia 

beetle native to the subtropical and tropical areas of South 

America. Ambrosia beetles are an important insect group in 

forest ecosystems. They usually attack felled or weakened 

trees, where they bore galleries into the wood. The common 

name “ambrosia beetle” is derived from the symbiotic 

fungus, which beetles introduce into their galleries and on 

which the larvae feed. Megaplatypus mutatus is different 

from more typical ambrosia beetles in that it is considered 

a primary pest; it affects only live trees and does not attack 

cut wood. It attacks the main stems of trees and bores 

internal tunnels in the xylem, which weakens the stem and 

causes breakage during wind events. In addition, the dark 

staining associated with the ambrosial mycelia reduces 

wood quality, making it unsuitable for some markets. New 

hosts continue to be added to an already large list for this 

insect; the endangered brazilwood, Caesalpinia echinata,

which is highly resistant to wood decay caused by termites 

and rot fungi, was recorded as a host of M. mutatus in 

Brazil, and 13 new hosts were confirmed in Argentina in 

2003. In addition, Zanuncio et al. (2010) were the first to 

observe M. mutatus in clonal Eucalyptus plantations used 

for sawlogs in Brazil.

Megaplatypus mutatus is particularly prevalent in 

Argentina. It is a serious problem in commercial plantations 

of a number of broad leaf trees but is especially damaging 

to poplars. The beetle’s continuing damage to hybrid poplar 

plantations in Argentina, its wide distribution in South 

America, and the more recent introduction into Italy have 

raised concerns regarding its potential for becoming a 

globally invasive pest of Populus species. The discovery 

of an established population in 2000 in Italy in a poplar 

plantation demonstrated that this insect can be transported 

long distances between countries and therefore presents 

a threat worldwide (Alfaro et al. 2007). It was probably 
46

GENERAL TECHNICAL REPORT PSW-GTR-250

introduced with a single trial consignment of roundwood of 

poplar with bark, imported in 2000 from Argentina (EPPO 

2009). Megaplatypus mutatus was added to the European 

and Mediterranean Plant Protection Organization’s A2 alert 

list of quarantine pests in March 2007. 

The biology of M. mutatus is summarized in EPPO 

(2009). It is univoltine in South America and Italy. It 

overwinters mainly as mature larvae or teneral adults. 

Adults appear in the field in late spring to early summer 

(November-December in South America and May-June in 

Italy). Males start emerging a few days before females and 

fly to tree trunks >15 cm in diameter, in which they bore a 

radial gallery directed toward the center of the trunk, and 

attract females by releasing a specific pheromone. After 

mating, the two adults bore new galleries inside the trunk, 

in which the female lays 100 to 200 eggs over a period of 

2 to 3 months. Adult beetles inoculate the galleries with 

Raphaelea santoroi, a symbiotic fungus cultivated for 

larval feeding. The first and second instar larvae feed on 

the mycelium; as they grow larger, they feed on the wood. 

Larvae generally reach maturity in 5 months, although 

Funes et al. (2011) reported development into pupae in 2 to 

3 months.

Specific information relating to risk elements:

A. Likelihood of introduction

1. Pest with host-commodity at origin potential (plants 

for planting, wood and wood products): 

Moderate (MC) (Applicable risk criteria from app. 

4: e, f, g, h) 

The main pathways for introduction (EPPO 2009) are 

plants for planting with trunks >15 cm diameter, round 

wood of host plants >15 cm diameter, sawn wood, and wood 

packaging material. Megaplatypus mutatus does not attack 

declining trees or cut wood and will only be present in them 

as a result of earlier primary attack. Based on the criteria 

in app. 4, the rating is moderate (owing to meeting four 

criteria); however, the likelihood for M. mutatus reaching 

Hawai‘i via live plants would be fairly low, unless importation of plants >15 cm in diameter occurs. Wood packaging 

material or other wood products may present the highest 

risk, but insect survival may be severely limited as live host 

material is required to complete development. It should be 

noted, however, that it was probably introduced into Italy 

with a single trial consignment of roundwood of poplar 

with bark, imported in 2000 from Argentina (EPPO 2009). 

Its distribution throughout South America provides many 

source populations for potential global transportation. Five 

adult beetles were detected in wood products at Kahului in 

2003 arriving from Indonesia (APHIS foreign reportable 

raw data).

2. Entry potential (plants for planting, wood and wood 

products): High (MC) (Applicable risk criteria from 

app. 4: b, c, d) 

Criteria b, c, and d are applicable. Alfaro and others 

(2007) concluded that M. mutatus is of concern to California, Oregon, and Washington, where significant plantations 

of hybrid poplars and a large fruit industry occur and 

the temperature regimes are favorable. Detection can be 

difficult, as this insect predominantly resides in the wood 

tissue throughout its life cycle. 

3. Colonization potential: High (MC) (Applicable risk 

criteria, from app. 4: a, b, c)

Megaplatypus mutatus has successfully established in 

Italy, over 11 000 m from Argentina, where it is presumed 

to have come. (EPPO 2009). New hosts continue to be 

added to an already large list; 13 new hosts were confirmed 

in Argentina in 2003. Megaplatypus mutatus attacks Eucalyptus plantations used for sawlogs in Brazil. Colonization 

potential in Hawai‘i would increase with amount of host 

material available; many ornamental eucalypts occur 

in Hawai‘i.

4. Spread potential: High (MC) (Applicable risk criteria, from app. 4: a, b, c, d, e, f, g) 

The polyphagous nature of this insect and its dispersal 

capability could aid in spread potential once introduced into 

a new environment. Its distribution in Italy increased from 

130 km2 in 2000 to over 587 km2 by 2007 (Allegro and 

Griffo 2008). 

B. Consequences of introduction
47

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

5. Economic damage potential: Moderate (MC) 

(Applicable risk criteria, from app. 4: b, c, d)

Megaplatypus mutatus development in plant tissue 

weakens trees, reducing yield and causing breakage by 

wind, and even killing highly stressed trees. The galleries 

and staining disqualify the wood from standards required 

by the plywood industry, thus dramatically lowering its 

value. Some poplar producers in South Africa have lost 

their high-quality wood market (EPPO 2009) owing to M. 

mutatus. A permanent infestation could lead to interstate 

and international quarantine restrictions, affecting Hawai‘i, 

its trade partners, and other U.S. states. It is unknown if M. 

mutatus would attack Acacia koa in Hawai‘i; it is reported 

to attack A. meanmsii in Brazil (Girardi et al. 2006).

6. Environmental damage potential: Moderate (MC) 

(Applicable risk criteria, from app. 4: d, e)

Erythrina crista-galli is listed as a host in South America. It is unknown if M. mutatus would attack or be successful in other Erythrina species. If attacks and subsequent 

plant injury or mortality of E. sandwicensis were to occur, 

impacts could be high as this species has limited distribution and has already experienced high mortality rates 

owing to the invasive erythrina gall wasp (Quadrastichus 

erythrinae) and reduced seed viability owing to an invasive 

bruchid beetle (Specularius impressithorax). Control with 

pesticides has been highly effective (EPPO 2009); however, 

treatments are costly and could be potentially harmful to 

the environment.

7. Social and political considerations: Moderate (MC) 

(Applicable risk criteria, from app. 4: a, c, d)

Public concerns likely would result if moderate to high 

levels of tree injury or mortality occur, particularly for 

native species. Megaplatypus mutatus is on the quarantine 

pest list for several countries (EPPO 2009). A permanent 

infestation could lead to interstate and international 

quarantine restrictions, affecting Hawai‘i, its trade partners, 

and other U.S. states. Control with pesticides would likely 

have limited acceptance or be prohibited owing to potential 

secondary impacts on other insect species.

C. Pest risk potential: 

Moderate (Likelihood of introduction = moderate; 

Consequences of introduction = moderate)

Selected bibliography:

Alfaro, R.I.; Humble, L.M.; Gonzalez, P.; Villaverde, 

R.; Allegro, G. 2007. The threat of the ambrosia beetle 

Megaplatypus mutatus (Chapuis) (= Platypus mutatus

Chapuis) to world poplar resources. Forestry (Oxford). 

80(4): 471–479.

Allegro, G.; Griffo, R. 2008. Risks of spread of 

Megaplatypus mutatus. Edizioni I’Informatore Agrario 

Srl. Verona, Italy: Informatore Agrario. 64(13): 73–76.

European and Mediterranean Plant Protection 

Organization [EPP0]. 2009. Megaplatypus mutatus.

Data sheets on pests recommended for regulation. 

European and Mediterranean Plant Protection 

Organization. Bulletin 39: 55–58.

Funes, H.; Griffo, R.; Zerba, E.; Gonzalez-Audino, 

P. 2011. Mating disruption of the ambrosia beetle 

Megaplatypus mutatus in poplar and hazelnut plantations 

using reservoir systems for pheromones. Entomologia 

Experimentalis et Applicata. 139: 226–234.

Gimenez, R.; Etiennot, A. 2003. Host range of Platypus 

mutatus (Chapuis, 1865) (Coleoptera: Platypodidae). 

Entomotropica. 18(2): 89–94.

Girardi, G.; Giménez, R.; Braga, M. 2006. Occurrence 

of Platypus mutatus (Chapuis, 1865) (Coleoptera: 

Platypodidae) in a brazilwood experimental plantation 

in southeastern Brazil. Neotropical Entomology. 35(6): 

864–867.

Zanuncio, A.; Pastori, P.; Lino-Neto, L.; Serrão, J.; 

Zanuncio, J. 2010. Megaplatypus mutatus (Chapuis) 

(Coleoptera: Curculionidae: Platypodinae) attacks hybrid 

Eucalyptus L’Héritier De Brutelle clones in southern 

Espírito Santo, Brazil. The Coleopterists Bulletin. 64(1): 

8–183.

Reviewers’ comments: None received.
48

GENERAL TECHNICAL REPORT PSW-GTR-250

Summer Fruit Tortrix Moth

Assessor: Andris Eglitis

Scientific name of pest: Adoxophyes orana (Fischer von 

Roslerstamm, 1834) (Lepidoptera: Tortricidae) 

Scientific names of hosts: Vaccinium spp.; wide 

host range with over 50 species in several families, 

especially Rosaceae

Distribution: Throughout Europe and Asia; successfully 

introduced into England and Greece (Davis et al. 2005b).

Summary of natural history and basic biology of the 

pest: Adoxophyes orana is a multivoltine species that 

is distributed from Asia throughout northern Europe. It 

is considered the most damaging leaf roller in Europe 

(Kamminga and Maguylo 2011). The summer fruit tortrix 

moth is a major pest of fruit crops, particularly apple and 

pear, in temperate regions (Davis et al. 2005b). The insect 

is polyphagous with a host range that includes some forest 

tree species (Davis et al. 2005b). Adoxophyes orana occurs 

in warm, humid climates and could be closely associated 

with biomes characterized as tropical and subtropical moist 

broadleaf forests and temperate broadleaf and mixed forests 

(Davis et al. 2005b). Since the 1980s, the insect has spread 

throughout southern Europe and has become a serious pest 

in many fruit orchards, primarily cherries, peaches, and 

apples (Milonas and Savopoulou-Soultani 1999). The summer fruit tortrix feeds primarily on host foliage, but when 

populations are high, the larvae may feed on fruits as well 

(Milonas and Savopoulou-Soultani 2006). High populations 

can defoliate host trees (Dickler 1991, cited by Kamminga 

and Maguylo 2011). The fruit damage of the first summer 

generation is different from that of the second summer 

generation. For the first, the damage of the fruits consists 

of large deep holes. In the second generation, the insects 

make very superficial and small holes of less than 5 mm in 

diameter. Usually, several of these holes are adjacent to each 

other (CPC Report 2011). Damage to the fruit is greatest 

by fall, coinciding with the time of harvest (Milonas and 

Savopoulou-Soultani 2006). Crop losses attributed to the 

summer fruit tortrix range up to 20 percent (Whittle 1985, 

cited by Kamminga and Maguylo 2011). Most of the important damage that this insect causes is directly to the fruits 

that it feeds upon, and the additional feeding on foliage may 

not be very important to plant growth (Davis et al. 2005b). 

Davis et al. (2005b) pointed out, however, that the impact of 

A. orana on forest productivity has not been well-studied.

Milonas and Savopoulou-Soultani (2006) described 

the biology of the insect in northern Greece where A. orana

completes three generations in 1 year. Overwintering larvae 

become active in early spring and complete their development by the end of April (Milonas and Savopoulou-Soultani 

2006). There are three distinct moth flights, with the first 

occurring in early May and others in July and late August. 

The females lay eggs in groups (up to 300 eggs per female) 

on host foliage, branches, and sometimes the bole of the tree 

(CPC Report 2011). The eggs hatch within 8 to 14 days, and 

young larvae immediately begin feeding on host leaves and 

shoots (CPC Report 2011). The larvae pass quickly through 

five instars and eventually spin pupal shelters under the 

leaves that have been damaged and stuck together by the 

larvae (CPC Report 2011). 

Adoxophyes orana is not currently found in the United 

States. However, the insect has established populations in 

geographic areas with climates closely following the USDA 

Plant Hardiness Zones 4 to 11 (Kamminga and Maguylo 

2011). On this basis, the majority of the United States has a 

climate that would support the summer fruit tortrix moth. 

Within the continental United States, Davis et al. (2005b) 

predicted a potential distribution that would range from 

Maine to Louisiana and Texas. The similarity of certain climates in the continental United States with those of Hawai‘i 

is implied by the fact that many continental U.S. pests have 

been successfully introduced into Hawai‘i in recent years 

(HDOA 2002). 

Davis et al. (2005b) noted that A. orana has moved 

through commerce, and introductions of larvae onto trees 

and shrubs have been particularly problematic in some 

areas. 

Specific information relating to risk elements:

A. Likelihood of introduction (plant material pathway) 

1. Pest with host-commodity at origin potential: 

High (RC) (Applicable rating criteria, from app. 

4: a, c, d, g, h)
49

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Although A. orana has not specifically been intercepted 

on very many occasions, note that for Hawai‘i, the tortricid 

leaf rollers as a group are very commonly intercepted in 

ports. As such, we apply criterion “a.” A wide host range, 

broad distribution, and multiple generations all increase 

the likelihood that A. orana could be associated with fruits, 

foliage, or planting stock. 

2. Entry potential: High (MC) (Applicable rating 

criteria, from app. 4: a, b, c)

Adoxophyes orana has not often specifically been 

intercepted in U.S. ports. However, it has been introduced 

into Greece and England, probably via infested plant 

material or fruit (Davis et al. 2005b). Interception records 

for Hawai‘i from 1985 to 2004 show that members from the 

family Tortricidae are very commonly intercepted (at least 

400 times in the past two decades). Within a 20-year period, 

unidentified tortricids were intercepted in the continental 

United States over 10,000 times (Davis et al. 2005b). 

The most common pathways for these interceptions were 

international airline baggage (44 percent) and permit cargo 

(41 percent) (Davis et al. 2005b). There was not a strong 

association with a particular plant product, as over 100 plant 

taxa were involved (Davis et al. 2005b). 

3. Colonization potential: High (MC) (Applicable rating criteria, from app. 4: a, b, e) 

As part of its broad geographical range, A. orana

occurs in tropical and subtropical moist broadleaf forests. 

The summer fruit tortrix has successfully expanded its 

range into the Mediterranean region. A broad host range 

and high biotic potential increase the chances for successful 

colonization by A. orana. 

4. Spread potential: High (MC) (Applicable rating 

criteria, from app. 4: b, c, d, e, g)

The summer fruit tortrix moth has poor capacity for 

dispersal (Kamminga and Maguylo 2011). Adult flights are 

typically of a short distance, and some larval movement 

may occur when larvae drop from silken threads and are 

carried by the wind. Most of the movement into new areas 

has been via infested plant material (Davis et al. 2005b). A 

high reproductive potential, broad host range, and somewhat cryptic nature are all factors that could facilitate the 

movement of this insect if introduced into Hawai‘i.

B. Consequences of introduction

5. Economic damage potential: Moderate (MC) 

(Applicable rating criteria, from app. 4: c, d)

Although the host range includes several forest species, 

the summer fruit tortrix moth is documented as causing 

economic damage primarily to apples, pears, and other 

rosaceous hosts (Kamminga and Maguylo 2011). Where 

fruit is involved, damage from A. orana can be very significant. As leafrollers, these insects use foliage for shelter 

while feeding on the outer surface of fruit. The larval 

feeding creates a misshapen appearance and can lead to 

losses of 10 to 50 percent in fruit-growing regions (Davis et 

al. 2005b). Because this insect is considered a regulated pest 

in some countries, its presence in Hawai‘i could result in 

international quarantines or mitigating treatments affecting 

trade. The effects of A. orana on Vaccinium spp. are not 

likely to be as important as they would be on major fruit 

crops such as those attacked in Europe. 

6. Environmental damage potential: High (MC) 

(Applicable rating criteria, from app. 4: c, d, e)

Adoxophyes orana may have the potential to affect forest composition or reduce biodiversity because of its ability 

to utilize many hosts. There might be indirect environmental effects if pest-mitigating actions were invoked. There 

are at least 27 endangered species from six plant families 

(Urtiaceae, Solonaceae, Rosaceae, Malvaceae, Fabaceae, 

and Convulvulaceae) in Hawai‘i that may be hosts for the 

summer fruit tortrix (Kamminga and Maguylo 2011). 

7. Social and political considerations: Moderate (MC) 

(Applicable rating criteria, from app. 4: b)

Because this insect is considered a regulated pest in 

some countries, its presence in Hawai‘i could result in 

international quarantines or mitigating treatments affecting 

trade.

C. Pest risk potential: 

High (Likelihood of introduction = high; Consequences of introduction = high) 
50

GENERAL TECHNICAL REPORT PSW-GTR-250

Selected bibliography:

Crop Protection Compendium Report. 2011. Adoxophyes 

orana (summer fruit tortrix). http://caps.ceris.purdue.

edu/webfm_send/1441. (2 May 2013).

Davis, E.E.; French, S.; Venette, R.C. 2005b. Mini risk 

assessment. Summer fruit tortrix moth, Adoxophyes 

orana (Fischer von Roslerstamm, 1934) [Lepidoptera: 

Tortricidae]. Cooperative Agricultural Pest Survey 

(CAPS) Pest Risk Assessment. 48 p.

Hawai‘i Department of Agriculture [HDOA]. 2002.

Kahului airport pest risk assessment. Honolulu: Hawai‘i 

Department of Agriculture Plant Quarantine Branch. 

41 p. 

Kamminga, K.; Maguylo, K. 2011. New pest response 

guidelines: summer fruit tortrix moth (Adoxophyes 

orana). Riverdale, MD: U.S. Department of Agriculture, 

Animal Plant Health Inspection Service, Plant Protection 

and Quarantine. http://www.aphis.usda.gov/import_

export/plants/manuals/online_manuals.shtml.

(2 May 2013).

Milonas, P.G.; Savopoulou-Soultani, M. 1999. Cold 

hardiness in diapause and non-diapause larvae of the 

summer fruit tortrix, Adoxophyes orana (Lepidoptera: 

Tortricidae). European Journal of Entomology. 

96: 183–187.

Milonas, P.G.; Savopoulou-Soultani, M. 2006. Seasonal 

abundance and population dynamics of Adoxophyes 

orana (Lepidoptera: Tortricidae) in northern Greece. 

International Journal of Pest Management. 52(1): 45–51. 

Ministry of Agriculture and Forestry, Biosecurity 

New Zealand. 2009. Import risk analysis: pears (Pyrus 

bretschneideri, Pyrus pyrifolia, and Pyrus sp. nr. 

communis) fresh fruit from China. Wellington, New 

Zealand. 454 p. 

Reviewers’ comments: “This assessment reads well with 

clear rationale” (D. Anthony)

Response to comments: None needed.

West Indian Sugarcane Borer Weevil 

Assessor: Andris Eglitis

Scientific name of pest: Diaprepes abbreviatus (Linnaeus) 

(Coleoptera: Curculionidae) 

Scientific names of hosts: Diospyros spp., Citrus spp., 

Acacia spp., Erythrina spp.; many others 

Distribution: West Indies, Central and South America, 

California, Florida, Texas 

Summary of natural history and basic biology of 

the pest: The West Indian sugarcane borer weevil is originally from the Caribbean, where it is known principally as 

a pest of sugarcane, citrus, and other crops (Stansly 2011). 

The weevil was introduced into Florida in 1964 and was 

commonly collected 4 years later (Woodruff 1968). Since 

then, it has become a very serious pest to the citrus industry 

in Florida (Simpson et al. 2011). In 2000, the weevil also 

became established in a mature citrus grove in Texas (Grafton-Cardwell et al. 2004). Since 1974, D. abbreviatus was 

intercepted numerous times in California (Grafton-Cardwell 

et al. 2004) and eventually became established in that state 

in 2008 after eradication attempts were ended owing to a 

lack of funding (Jetter and Godfrey 2009). 

Diaprepes abbreviatus is a large, colorful weevil, 

measuring 10 to 19 mm in length with numerous color 

forms ranging from gray to yellow to orange and black 

(Grafton-Cardwell et al. 2004). Adult weevils can live up to 

4 months (Jetter and Godfrey 2009), during which time they 

can lay up to 5,000 eggs per female (Griffith 1975, Simpson 

et al.1996). Eggs are laid in masses of around 40, placed 

between two leaves that are glued together by the female 

(Griffith 1975). The eggs normally hatch within a week, and 

the young larvae drop to the ground and work their way into 

the soil to begin feeding on plant roots (Griffith 1975). The 

youngest larvae feed on the finest roots, moving to larger 

roots as they develop (Jetter and Godfrey 2009). The larvae 

can remain in the soil for a prolonged period, ranging from 

2 months to as long as 2 years before maturing into the adult 

stage (Griffith 1975). The larvae pass through 11 instars, 

with instars 3 through 9 being the most destructive feeders 
51

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

(Grafton-Cardwell et al. 2004). Late-instar larvae construct 

a chamber where they transform into pupae. The pupal stage 

lasts for 2 to 3 weeks, and in Puerto Rico, the pupal stage 

can be found in any month of the year (Woodruff 1968). 

Young adults may remain in the pupal chamber for an 

extended period of time before emerging (Woodruff 1968). 

The adult weevils “typically” emerge from the ground in 

late spring and early summer (Stansly 2011, citing Wolcott 

1936), although in Florida, emergence has been found to be 

quite variable with adults present nearly year-round (Stansly 

2011). Adults are sometimes difficult to find because they 

feed during the early morning and late afternoon, hiding in 

the foliage during the day (Grafton-Cardwell et al. 2004). 

Adult feeding is typically limited to leaf edges, producing 

irregular and semicircular notches (Jetter and Godfrey 

2009). Young and tender leaves are preferred. It is important 

to locate the actual weevil doing the damage because the 

feeding of D. abbreviatus is similar to that of other weevils 

(Grafton-Cardwell et al. 2004). The most significant losses 

come from larval feeding, which occurs in the roots. Young 

trees may be killed outright by larval girdling, while larger 

trees decline rapidly and fall over or become exposed to root 

diseases (Jetter and Godfrey 2009). Many citrus trees do not 

show symptoms of decline until extensive damage has been 

done to the root system (Grafton-Cardwell et al. 2004).

Although the sugarcane borer weevil is most commonly 

associated with citrus and other important crops, it has an 

extremely broad host range that encompasses nearly 300 

plant species in 59 families (Simpson et al. 1996). Among 

those hosts are plants from three genera of concern to this 

pest risk assessment (Acacia, Diospyros, and Erythrina). 

Most of these host plants are ones where adults have been 

collected and larval feeding has not yet been documented. 

Nearly 50 of the species have been verified as larval hosts, 

and many others have been associated with adult feeding or 

egg laying (Simpson et al. 1996).

Specific information relating to risk elements:

A. Likelihood of introduction (plant material pathway)

1. Pest with host-commodity at origin potential: High

(MC) (Applicable rating criteria, from app. 4: a, b, c, 

d, e, g)

Diaprepes abbreviatus has been successfully transported into at least three new locations via plant material 

containing life stages. A very broad host range and overlapping life stages increase the likelihood that the insect will 

be associated with transported plant material.

2. Entry potential: High (RC) (Applicable rating criteria, from app. 4: a, b, d)

The West Indian weevil was intercepted many times 

in California before it became established. Even though the 

weevils are strong fliers, they are probably most effectively 

moved as “hitchhikers,” attached to plants or transported 

through infested nursery containers (Jetter and Godfrey 

2009). Successful entry has been gained into Florida, Texas, 

and California. 

3. Colonization potential: High (RC) (Applicable rating criteria, from app. 4: a, b, e)

Diaprepes abbreviatus has been introduced into 

Florida, Texas, and California. A very broad host range 

and a high reproductive potential (up to 5,000 eggs per 

female) increase the chances of successful colonization in a 

new environment. The weevil has hosts within three of the 

genera of concern for this risk assessment. 

4. Spread potential: High (RC) (Applicable rating criteria, from app. 4: b, c, d, e, f, g)

Although the West Indian weevil has strong dispersal 

capability on its own, it has most likely been aided in its 

spread by human transport. A broad host range, a high 

reproductive potential, and somewhat cryptic nature have 

allowed it to spread beyond quarantine areas in Florida 

(Griffith 1975). Simpson et al. (1996) believe that the 

weevil could be well established in an area before being 

detected. Aggressive but unsuccessful attempts were made 

at eradication in both Florida and California once the insect 

was detected. 

B. Consequences of introduction

5. Economic damage potential: High (MC) (Applicable 

rating criteria, from app. 4: a, b, c, d, f)

Most of the evaluations of damage by this insect have 

been associated with the citrus industry, where the economic impacts have been devastating (Hall 1995, Simpson 
52

GENERAL TECHNICAL REPORT PSW-GTR-250

et al. 2011). Three of the Hawai‘i genera of concern in this 

assessment contain plants that are hosts to the West Indian 

weevil. If damage in these hosts approached the levels that 

the weevil has inflicted on citrus, then the impacts would 

be severe. Criterion “f” is applied because of the experience 

with the first introduction of the weevil into the United 

States. When D. abbreviatus was discovered in Florida, 

very aggressive efforts were undertaken to limit the expansion of its range. These efforts involved aerial spraying with 

assorted insecticides but were not successful and the weevil 

spread far beyond the quarantine areas (Griffith 1975). 

6. Environmental damage potential: High (MC) 

(Applicable rating criteria, from app. 4: d, e)

Given a broad host range, it is possible that D. abbreviatus could affect hosts with limited distributions. Thus 

far, eradication programs have been ineffective and could 

create their own environmental problems.

7. Social and political considerations: Moderate (MC) 

(Applicable rating criteria, from app. 4: b)

Simpson et al. (1996) stated that, given the high reproductive potential (5,000 eggs per female), a fairly long life 

cycle, and hidden eggs and larvae, D. abbreviatus would 

probably be well-established before it is detected. The 

presence of the weevil could lead to quarantine restrictions 

on trade from Hawai‘i.

C. Pest risk potential: 

High (Likelihood of introduction = high; 

Consequences of introduction = high) 

Selected bibliography:

Grafton-Cardwell, E.E.; Godfrey, K.E.; Peña, J.E.; 

McCoy, C.W.; Luck, R.F. 2004. Diaprepes root 

weevil. IPM Publication 8131. Davis, CA: University 

of California, Division of Agriculture and Natural 

Resources. 7 p.

Griffith, R.J. 1975. The West Indian sugarcane rootstalk 

borer weevil in Florida. Proceedings of the Florida State 

Horticultural Society. 88: 87–90.

Hall, D.G. 1995. A revision to the bibliography of the 

sugarcane rootstalk borer weevil, Diaprepes abbreviatus 

(Coleoptera: Curculionidae). Florida Entomologist. 78 

(2): 365–377. 

Jetter, K.M.; Godfrey, K. 2009. Diaprepes root weevil, 

a new California pest, will raise costs for pest control 

and trigger quarantines. California Agriculture. 63(3): 

121–126.

Simpson, S.E.; Nigg, H.N.; Coile, N.C.; Adair, R.A. 1996. 

Diaprepes abbreviatus (Coleoptera: Curculionidae) host 

plant associations. Environmental Entomology. 25(2): 

333–349. 

Simpson, S.E.; Nigg, H.N.; Knapp, J.L. 2011. Host plants 

of Diaprepes root weevil and their implications to the 

regulatory process. University of Florida, Florida Citrus 

Resources. 15 p. http://irrec.ifas.ufl.edu/flcitrus/short_

course_and_workshop/diaprepes/host_plants.shtml. (4 

August 2013).

Stansly, P.A. 2011. Biology of Diaprepes abbreviatus in 

the laboratory and field. Fort Pierce, FL: University of 

Florida, Indian River Research and Education Center. 

6 p. http://irrec.ifas.ufl.edu/flcitrus/short_course_and_

workshop/diaprepes/biology_of_diaprepes_abbreviatus.

shtml. (4 August 2013).

Wolcott, G.N. 1936. The life history of Diaprepes 

abbreviatus at Rio Piedras, Puerto Rico. Journal of 

Agriculture, University of Puerto Rico. 20: 883–914.

Woodruff, R.E. 1968. The present status of a West 

Indian weevil (Diaprepes abbreviata (L.)) in Florida. 

Entomology Circular No. 77. Gainsville, FL: Florida 

Department of Agriculture, Division of Plant 

Industry. 4 p. 

Reviewers’ comments: In response to High rating for “Pest 

with host-commodity at origin potential”] “I find this a 

bit surprising—the adults are large and often colourful, 

therefore one would expect they would be readily detectable 

during routine inspections, (allowing for very low numbers 

in large consignments being harder to detect). Are they 

likely to move or fly when disturbed? I would expect eggs 
53

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

to be the most likely lifestage to be accidentally imported 

on whole plants, though, depending on the plant, I would 

think leaves stuck together might arouse some curiosity and 

masses are more obvious than single or few eggs. If plants 

are supposed to come in without soil, wouldn’t this reduce 

the likelihood of larvae and pupae entering?” (D. Anthony)

Response to comments: Although adults are large and colorful and should be easily detected (as should plant leaves 

glued together), the West Indian weevil has been moved into 

several new environments. Several other criteria also apply, 

leading to the “high” rating for that risk element.

White Wax Scale 

Assessor: Andris Eglitis

Scientific names of pest: Ceroplastes destructor Newstead 

(Hemiptera: Coccidae) 

Scientific names of hosts: Citrus spp., Diospyros spp., 

Acacia spp., Dodonaea spp.; over 150 others 

Distribution: Africa, Australasia, Oceania 

Summary of natural history and basic biology of 

the pest: Ceroplastes destructor utilizes several species 

of Citrus as primary hosts (Sullivan and Molet 2011) and 

has a long list of secondary hosts including some species 

in the genera Acacia, Diospyros, and Dodonaea that have 

representatives in Hawai‘i. The white wax scale was once 

considered a serious pest of Citrus spp. in several states of 

Australia until highly successful biological control agents 

were introduced from Africa (Sullivan and Molet 2011). 

These natural enemies also limit the pest importance of the 

white wax scale in its native range of Africa (Sullivan and 

Molet 2011). 

The white wax scale has three nymphal instars. The 

early stages are morphologically difficult to distinguish 

from other Ceroplastes species (Sullivan and Molet 2011). 

Adult females are oval, sometimes with some marginal 

indentation, and measure from 2.5 to 6.4 mm in length (Sullivan and Molet 2011). The females are immobile and are 

covered with a white waxy layer. Adult males are unknown. 

Sullivan and Molet (2011) described the life cycle of the 

white wax scale in Australia, Africa, and New Zealand. 

In Australia, C. destructor is univoltine and occasionally 

produces a partial second generation in the warmer areas 

of citrus growing regions. In Africa, adults are found from 

March to September, and females oviposit from September 

to mid-January (Sullivan and Molet 2011). During their 

lifetime, females will lay an average of over 1,700 eggs 

(Davis et al. 2005a). Nymphal instars can be found from 

mid-November to late March, and overwintering can occur 

in the third instar or adult stage (Sullivan and Molet 2011). 

In New Zealand, females begin to lay eggs in November, 

and crawlers emerge in December (Sullivan and Molet 

2011). The first instar nymphs initially settle on leaves; later 

instars move to twigs where they secrete a waxy covering 

(Davis et al. 2005a). The nymphal feeding reduces the vigor 

and growth of host plants (Sullivan and Molet 2011). Sooty 

mold growing on honeydew produced by the feeding instars 

may inhibit photosynthesis (Davis et al. 2005a). Developmental rate of the scale is dependent on host species, 

temperature, and water availability (Davis et al. 2005a).

Specific information relating to risk elements:

A. Likelihood of introduction (plant material pathway)

1. Pest with host-commodity at origin potential: High

(RC) (Applicable rating criteria, from app. 4: b, c, e, 

f, g, h)

Although Ceroplastes destructor has not been intercepted in Hawai‘i or the conterminous United States, the 

third most commonly intercepted insect in Hawai‘i ports 

between 1984 and 2010 was a related scale insect, C. rubens

(red wax scale) (AQIM Database). Ceroplastes rubens has a 

wider geographical distribution (including Hawai‘i) than C. 

destructor, but an equally broad host range (Dekle 2001).

2. Entry potential: High (RC) (Applicable rating criteria, from app. 4: a, b, c) 

Although C. destructor has not been intercepted in port 

inspections, it has become established in three new environments, demonstrating that interceptions are only loosely 

tied to establishments. Many Ceroplastes interceptions are 

associated with materials for consumption in passenger 

baggage (Sullivan and Molet 2011).

3. Colonization potential: High (RC) (Applicable rating criteria, from app. 4: a, b)
54

GENERAL TECHNICAL REPORT PSW-GTR-250

C. destructor has been successfully introduced into 

Australia, New Zealand, and other South Pacific Islands 

(Sullivan and Molet 2011). The climate in Hawai‘i would 

be similar to many locations where the scale now occurs. 

In addition, C. destructor has hosts in four of the Hawai‘i 

genera of concern for this risk assessment (Davis et al. 

2005a), increasing the likelihood of successful establishment in Hawai‘i.

4. Spread potential: High (MC) (Applicable rating criteria, from app. 4: b, c, d, f, g)

The white wax scale has a very broad host range such 

that elements “d” and “g” could apply. In addition, C. 

destructor has a very high reproductive potential (1,700 

eggs per female) (Davis et al. 2005a). Inherent powers 

of dispersal are limited, mainly involving transport 

of crawlers.

B. Consequences of introduction

5. Economic damage potential: High (RC) (Applicable 

rating criteria, from app. 4: a, b, c, d)

With a broad host range, economically important host 

plants could likely be affected by C. destructor. The white 

wax scale has been a major pest of Citrus in South Africa 

(Davis et al. 2005a). Feeding by scales weakens host plants 

and may predispose them to mortality agents. 

6. Environmental damage potential: High (MC) 

(Applicable rating criteria, from app. 4: b, c, d, 

possibly e) 

In their mini risk assessment for the continental United 

States, Davis et al. (2005a) rated the environmental damage 

potential of C. destructor as “high” owing to the potential 

for degrading ecosystems, reducing biodiversity, and 

jeopardizing endangered or threatened species. They also 

pointed out that new pest introductions typically result in 

greater use of chemical measures to combat infestations or 

attempt eradication.

7. Social and political considerations: Moderate (RC) 

(Applicable rating criteria, from app. 4: a)

Damage by the white wax scale could lead to increased 

public concerns. In addition, increases in pesticide use are 

often met with public resistance. 

C. Pest risk potential: 

High (Likelihood of introduction = high; Consequences of introduction = high) 

Selected bibliography:

Davis, E.E.; French, S.; Venette, R.C. 2005a. Mini risk 

assessment. Soft wax scale, Ceroplastes destructor

Newstead (Hemiptera: Coccidae). Cooperative 

Agricultural Pest Survey (CAPS) Pest Risk 

Assessment. 35 p.

Dekle, G.W. 2001. Red wax scale (Ceroplastes rubens

Maskell). Entomology Circular 15. Gainesville, FL: 

Florida Department of Agriculture and Consumer 

Services, Division of Plant Industry. 2 p.

Sullivan, M.; Molet, T. 2011. CPHST Pest Datasheet for 

Ceroplastes destructor. Raleigh, NC: U.S. Department 

of Agriculture-APHIS-PPQ-CPHST. http://caps.ceris.

purdue.edu/webfm_send/1553. (4 August 2013).

Reviewers’ comments: “Criteria “a” states the organism 

has been intercepted at ports of entry not that an 

organism/related organism is intercepted. So is it valid to 

state that criterion “a” applies in this case?” (Martin)

Response to comments: The reviewer makes a valid point. 

Criterion “a” was dropped from the “Pest with host 

commodity potential.” Because numerous other criteria 

apply, the rating for that element remains “high.”

Pathogen IPRAs

Acacia Gall Rust

Assessor: Phil Cannon

Scientific names of pest: Uromycladium tepperianum 

(Sacc.) McAlpine

Scientific names of hosts: Species of Acacia, Albizia, and 

Racosperma (Fabaceae). The pathogen is known to attack 

more than 100 species of Acacia in Australia (Wood 2012), 

as well as Falcataria moluccana (Molucca albizia) and 

Paraserianthes falcataria (syn. Adenanthera falcataria) 

(albizia). The African species of Acacia are not susceptible 

to this fungus (Morris 1987).
55

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Distribution: Uromycladium tepperianum is native to Australia. It has spread through much of the Philippines, Sabah 

in Malaysia, and Java in Indonesia (Rahayu et al. 2010). It 

is also found in New Zealand, Papua New Guinea, and New 

Caledonia (Morris 1987). It was introduced to South Africa 

as a biological control agent for the invasive Acacia saligna

(Wood 2012).

Summary of natural history and basic biology of 

the pests: Uromycladium tepperianum is a microcyclic 

rust, producing only teliospores (Morris 1987). It does not 

produce urediniospores or aeciospores (Rahayu et al. 2010). 

Teliospores, composed of a cluster of three probasidial 

cells at top of a single pedicel, are depressed globose to 

globose, cinnamon brown, thickly vertically striate, margin 

crenulate, wall 2 to 3 μm, at apex up to 5 μm thick, 14 to 22 

μm high, 18 to 25 μm wide, one apical germ pore; pedicel 

hyaline, septate, deciduous (Systematic Mycology and 

Microbiology Laboratory 2007). 

Acacia pycnantha, cultivated in Australia for its bark, 

is severely affected by U. tepperianum; infection causes significant yield losses and eventually host death (Gathe 1971). 

This rust has potential as a biocontrol agent for weedy 

acacias outside of Australia; it has been highly effective 

against A. saligna in South Africa (Morris 1991, 1997, 1999; 

Wood and Morris 2007).

The most characteristic symptom of infection is the 

formation of reddish brown, globose or irregularly shaped 

galls at least several centimeters in diameter, on stems and 

shoots. Witches’ brooms of different shapes and sizes can 

develop. Flowers, phyllodes, and shoot tips can also be 

infected, causing gross malformation (Gothe 1971). Older 

galls may turn dark brown and become invaded by tunneling insects (Old et al. 2002). Infected trees can have several 

galls per stem, which can lead to girdling, death of the stem 

and repeated branching. Severely infected trees die.

Fresh galls are covered with powdery, cinnamon-colored masses of teliospores. Telia develop on galls on leaves, 

branches, inflorescences, and fruits. The teliospores from 

the gall are wind blown, can travel great distances, and can 

infect virtually any part of a susceptible plant except the 

thick bark.

During the infection process, the teliospore germinates 

to produce a basidiospore on the host surface. Under favorable conditions (relative humidity > 90 percent), the basidiospore forms a penetration peg, which penetrates the host 

cells directly through the epidermis (Rahayu et al. 2010). 

After penetration, the mycelia of the rust spread inter- and 

intracellularly. As a result, the periderm and phloem cells 

become misshapen while the xylem cells become twisted or 

die. Pycnia are formed after about 7 days; they are the small 

brown pustules that eventually erupt under the epidermis. 

Often, no urediniospores are found (Rahayu et al. 2010).

Galls can persist for several years. However, because 

the rust is an obligate parasite, the rust will die when the 

cells of the host plant die. 

Specific information relating to risk elements:

A. Likelihood of introduction

1. Pest with host-commodity at origin potential: High

(VC) (Applicable rating criteria, from app. 4: b, c, d, 

e, g, h)

The rust can colonize basically any aerial unlignified 

part of a host plant, and a large number of large, spore-bearing galls form on these tissues and persist as the seedling 

or tree grows larger. If seedlings of F. moluccana, which 

had been produced in a nursery near an infected mature 

tree were to be brought to Hawai‘i, the likelihood of these 

seedlings being infected with this rust would be high. However, Hawai‘i already has numerous Albizia growing on its 

islands, so this should significantly lessen the motivation of 

bringing in such seedlings from abroad. Presumably, spores 

of this rust could also be introduced with seed or on wood 

products coming from an infested area, although this would 

be purely casual and the likelihood of spores brought in by 

this manner, and also infecting a susceptible host and leading to the formation of galls, seems quite low. The spores 

of this rust are fairly durable and should be wind dispersed 

for fairly long distances. Although the possibilities of this 

rust making it on the wind all the way to Hawai‘i from 

someplace like Asia seem remote (and have not happened, 

to date), once in Hawai‘i, wind dispersal would become 

important in local spread.
56

GENERAL TECHNICAL REPORT PSW-GTR-250

2. Entry potential: High (VC) (Applicable rating criteria, from app. 4: b, c, d)

Uromycladium tepperianum can colonize all aerial nonwoody parts of a plant, so it could be brought into Hawai‘i 

on any infected plant. Presumably spores of this fungus 

could also be introduced with seed, although this would be 

purely casual; it should not be a risk on wood products.

3. Colonization potential: High (VC) (Applicable rating criteria, from app. 4: a, b, c, e)

There is a fair amount of Albizia on all of the Hawai‘i 

Islands (Dave Bakke, regional pesticide coordinator, USDA 

Forest Service, personal communication), so presumably 

U. tepperanium could rapidly build up inoculum levels 

and also very quickly colonize entire stands of these trees 

as well.

The ability of this fungus to infect and colonize A. koa, 

or any other leguminous trees in Hawai‘i, has not yet been 

evaluated. More than 100 species of Acacia in Australia are 

at least somewhat susceptible to this fungus; Acacia saligna

has proven to be exceptionally vulnerable to this rust 

(Wood 2012).

4. Spread potential: High (RC) (Applicable rating criteria, from app. 4: a, b, c, d, e, f, g)

Spread in stands of Albizia could be expected to be 

exceptionally high. Spread in locations where this species 

was absent would probably be much lower.

B. Consequences of introduction

5. Economic damage potential: Moderate (RC) 

(Applicable rating criteria, from app. 4: c, d, f)

Locally, where there are well-established stands of 

Albizia, the economic damage could be considerable, as 

many of these trees in these stands are huge (50 to 100 cm 

dbh and 35 m in height). As many of these Albizia trees 

are in semiurban settings, infected trees would become 

hazard trees as the rust galls will make their branches more 

malformed and weaker. 

The potential for economic damage to native Hawai‘i 

Acacia species is not known. Pathogenicity tests to 

determine whether A. koa is susceptible would be 

worth conducting.

6. Environmental damage potential: Low (MC) 

(Applicable rating criteria, from app. 4: none)

Locally, where there are well-established stands of A. 

falcataria (= Falcataria moluccana), the environmental 

damage could be considerable as many of these trees in 

these stands are huge (50 to 100 cm dbh and 35 m in height). 

The potential for environmental damage to native Hawai‘i 

acacia species is not yet known.

7. Social and political considerations: Low (MC) 

(Applicable rating criteria, from app. 4: none)

The social and political impact of having U. tepperanium become established in Albizia in the state would be 

a mixed bag. One segment of the Hawaiian population 

would probably applaud any damage to Albizia because 

it is an invasive species. On the other hand, the impact 

that this fungus has on Albizia is to make it an incredibly 

ugly tree with an even higher than usual propensity for 

branch breakage.

The segment of the Hawaiian population that does not 

object to Albizia, and basically all visitors who are unaware 

that this is not a native species, would probably be appalled 

at the disfiguration that this rust would be causing to both 

individual trees and stands of Albizia.

As it is not yet known how this rust might affect koa 

or other leguminous trees currently found on the Hawai‘i 

islands, it is premature to speculate on the social or political 

impacts that the introduction of this rust fungus might have 

in Hawai‘i.

C. Pest risk potential:

High (Likelihood of introduction = high; Consequences of introduction = moderate) 

Selected bibliography:

Burges, A. 1934. Studies in the genus Uromycladium

(Uredinaceae) I. Proceedings of the Linnean Society of 

New South Wales. 59: 212–228.

Dick, M. 1985. Uromycladium rusts of Acacia. Forest 

Pathology in New Zealand, No. 15. Rotorua, New 

Zealand: New Zealand Forest Service. 8 p.
57

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Gathe, J. 1971. Host range and symptoms in Western 

Australia of gall rust, Uromycladium tepperianum. 

Journal of the Royal Society of Western Australia. 

54: 114–118.

Lee, S.S. 2004. Diseases and potential threats to Acacia 

mangium plantations in Malaysia. Unasylva. 217: 31–35.

McAlpine, D. 1906. The rusts of Australia: their structure, 

nature and classification. Melbourne, Australia: Brain, 

Department of Agriculture, Victoria. 349 p.

Morris, M.J. 1987. Biology of the Acacia gall rust, 

Uromycladium tepperianum. Plant Pathology. 36: 

100–106.

Morris, M.J. 1991. The use of plant pathogens for 

biological weed control in South Africa. Agriculture, 

Ecosystems and Environment. 37: 239–255.

Morris, M.J. 1997. Impact of the gall-forming rust fungus 

Uromycladium tepperianum on the invasive tree Acacia 

saligna in South Africa. Biological Control. 10: 75–82.

Morris, M.J. 1999. The contribution of the gall-forming 

rust fungus Uromycladium tepperianum (Sacc.) McAlp. 

to the biological control of Acacia saligna (Labill.) 

Wendl. (Fabaceae) in South Africa. African Entomology 

Memoir No. 1: 125–128.

Old, K.M.; Vercoe, T.K.; Floyd, R.B.; Wingfield, 

M.J.; Roux, J.; Neser, S. 2002. FAO/IPGRI Technical 

Guidelines for the Safe Movement of Germplasm No. 20. 

Acacia spp. Rome: Food and Agriculture Organization 

of the United Nations, International Plant Genetic 

Resources Institute. 88 p.

Rahayu, S.; Lee, S.S.; Shukor, N.A.A. 2010.

Uromycladium tepperianum, the gall rust fungus from 

Falcataria moluccana in Malaysia and Indonesia. 

Mycoscience. 51: 149–153.

Savile, D.B.O. 1971. Generic disposition and pycnium type 

in Uredinales. Mycologia. 63: 1089–1091.

Systematic Mycology and Microbiology Laboratory.

2007. Invasive fungi. Uromycladium tepperianum

on Acacia spp. U.S. Department of Agriculture, 

Agricultural Research Service. http://nt.ars-grin.

gov/taxadescriptions/factsheets/pdfPrintFile.

cfm?thisApp=Uromycladiumtepperianum. (8 May 2013).

Wood, A.R. 2012. Uromycladium tepperianium (a gall 

forming rust fungus) cause a sustained epidemic on the 

weed Acacia saligna in South Africa. Australasian Plant 

Pathology. 41: 255–261.

Wood, A.R.; Morris, M.J. 2007. Impact of the gallforming rust fungus Uromycladium tepperianum on the 

invasive tree Acacia saligna in South Africa: 15 years of 

monitoring. Biological Control. 41: 68–77.

Reviewers’ comments: ”Wind dispersal is another means 

of introduction but this depends on the prevailing wind 

directions.” (Su See Lee)

“Don’t think there are any studies or reports of this rust 

on other Albizias—perhaps it may not attack other Albizias? It has been found on some acacias but not on others. 

In Malaysia, it is present on F. moluccana but absent on 

adjacent Acacia mangium.” (Su See Lee)

“In Sabah (Malaysia) and the Philippines infection is 

much more serious in areas of higher elevation (400 m asl) 

with persistent early morning fog, low wind speed, and high 

relative humidity (>90 percent). It is absent in low lying and 

open areas. So it may not be a threat in semiurban setting.” 

(Su See Lee)

Response to comments: Comments by the reviewer were 

incorporated.

Aecidium Rusts

Assessor: Gregg DeNitto

Scientific names of pests: see table 7

Scientific names of hosts: see table 7

Distribution: see table 7

Summary of natural history and basic biology of 

the pests: Species of Aecidium are rust fungi that infect 

primarily foliage of deciduous hosts. The species identified 

in this analysis likewise affect host foliage, but some species 
58

GENERAL TECHNICAL REPORT PSW-GTR-250

Table 7—Hosts, country of origin and citations for Aecidium spp. on Diospyros and Myoporum species

Pathogen Host(s) Country of origin Citation

Aecidium atrocrustaceum Syd. & P. 

Sydow (Pucciniales: 

Incertae sedis)

Diospyros discolor Philippines Watson 1971

Aecidium calosporum Juel 

(Pucciniales: Incertae sedis)

Diospyros sp., Diospyros 

hispida, Diospyros 

liriosmoides

Brazil Hennen et al. 2005

Aecidium carbonaceum W.T. Dale 

(Pucciniales: Incertae sedis)

Diospyros inconstans South Africa, Trinidad & 

Tobago

Dale 1955, Hennen et al. 2005

Aecidium diospyri A.L. Sm. 

(Pucciniales: Incertae sedis)

Diospyros mespiliformis Angola, South Africa Watson 1971

Aecidium mabae Diospyros piscatorial,

Mabea abyssinica

Ivory Coast, 

Ethiopia

Watson 1971

Aecidium melaenum Syd. & P. Syd. 

(Pucciniales: Incertae sedis)

Diospyros sp. India, Philippines Bagyanarayana and Ramesh 

1995, Watson 1971

Aecidium muelleri Thurst. 

(Pucciniales: Incertae sedis)

Diospyros sp. Brazil Hennen et al. 2005

Aecidium miliare Berk. & Broome 

(Pucciniales: Incertae sedis)

Diospyros embryopteris, D. 

ovalifolia, 

D. xanthochlamys,

India, Ivory Coast, Sri 

Lanka

De 2000, Watson 1971

Aecidium myopori G. Cunn. 

(Pucciniales: Incertae sedis)

Myoporum acuminatum, M. 

laetum, 

M. parvifolium, 

M. tetrandrum

Australia, New Zealand Birch 1938, Cunningham 1924, 

McKenzie 1998

Aecidium ramosii Syd. & P. Syd. 

(Pucciniales: Incertae sedis) 

Diospyros sp. Philippines Watson 1971

Aecidium reyesii Syd. & P. Syd. 

(Pucciniales: Incertae sedis)

Diospyros discolor Philippines Watson 1971

Aecidium rhytismoideum Berk. 

& Broome (Pucciniales: 

Incertae sedis)

Diospyros sp., D. discolor, 

D. embryopteris, D. 

malabaricus, 

D. melanoxylon, 

D. mespiliformis, 

D. ovalifolia, 

D. paniculata, 

D. tomentosa

Eritrea, Ethiopia, India, 

Ivory Coast, Java, 

Philippines, South 

Africa, Sri Lanka

Hosagoudar 1985, 2006; 

Watson 1971

Aecidium royenae Cooke & Massee 

(Pucciniales: 

Incertae sedis)

Diospyros pallens, 

Diospyros sp.

South Africa Farr and Rossman, n.d.

Aecidium ulei Henn. 

(Pucciniales: Incertae sedis)

Diospyros sp. Brazil Hennen et al. 2005, Watson 

1971

Aecidium yapoense Vienn. Bourg. 

(Pucciniales: Incertae sedis)

Diospyros gabonensis Ivory Coast Watson 1971
59

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

also infect branches, trunks, petioles, inflorescences, and 

drupes. Some cause the formation of branch swellings and 

witches’ brooms. For the most part, they are limited to 

species of Diospyros or Myoporum as hosts. In Malaysia, 

species of Aecidium have been recorded on various hosts, 

but not Diospyros or Myoporum (Lee et al. 2012). There are 

few known rust fungi on the 13 species of concern in this 

risk assessment in Hawai‘i. Three species of Atelocauda, 

two species of Endoraecium, and one species of Uromyces

have been reported on Acacia koa (Gardner 1994). Pucciniastrum vaccinii has been reported on Vaccinium spp. 

(Gardner and Hodges 1989) and Uredo myopori on Myoporum sandwicense (Gardner 1994). 

The aecia produced by Aecidium are cupulate with a 

defined peridium. This form-genus houses anamorphs of 

members of the Order Pucciniales. The associated teleomorph has not been identified for the species in table 7, 

and the life cycle is not known. Most of the above species 

have been identified and reported in the literature, but no 

further information or examination has been completed. 

There is little biological information published on the species identified in the above table, so much of the following is 

based on what is known about other Aecidium species.

The only consistent reproductive body identified in 

most Aecidium species is the aeciospore. These are produced in cup-like structures, usually on the underside of 

the leaf. Transmission of A. mori to new hosts is mainly 

by aeciospore transport through the air or by rain splash 

(Mordue 1991). Infection by aeciospores of A. mori from 

tree to tree has been demonstrated (Mordue 1991) and they 

are considered to function as an uredinial stage (Hernández 

2005).

Specific information relating to risk elements:

A. Likelihood of introduction

1. Pest with host-commodity at origin potential: 

Moderate (MC) (Applicable rating criteria, from 

app. 4: b, d, e, h)

Aecidium species are somewhat common on host plants 

in their native ranges. Diospyros are used by humans for 

their fruit, timber, or ornamental purposes, depending on 

the species. There does not appear to currently be a trade in 

this genus, other than for persimmons and ebony. Neither of 

these commodities would likely transport Aecidium species. 

Some Diospyros species are suggested for use in ornamental plantings, especially as producers of food for wildlife. 

Myoporum has potential uses for ornamental plantings 

(Richmond and Ghisalberti 1995) and ground covers. Plants 

for planting could become traded commodities with either 

of these genera and, would provide a means of transport of 

Aecidium to Hawai‘i. 

2. Entry potential: High (MC) (Applicable rating criteria, from app. 4: b, c, d) 

Aecidium could readily survive transport on live host 

tissue, and reproductive structures, aeciospores, could survive on dead tissue. Commodities such as plants for planting 

could certainly contain and carry fruiting structures of 

Aecidium. Although aecia of these fungi could be visible 

because of their color, they likely would not be readily 

visible in the mass of foliage that would be in transport. 

Witches’ brooms that may be present with the infection 

could be detected upon arrival at the port.

3. Colonization potential: Moderate (MC) (Applicable 

rating criteria, from app. 4: b, e)

The Aecidium species evaluated occur in tropical or 

subtropical climates similar to that of Hawai‘i. Environmental conditions upon arrival would likely be conducive to 

fungal survival and spread. A limiting factor is the amount 

of host material near maritime ports. Diospyros sandwicensis does occur down to basically sea level. Also, species of 

Aecidium are somewhat host specific, and native hosts of 

Hawai‘i may not be as susceptible as the rust’s native hosts.

4. Spread potential: High (RC) (Applicable rating criteria, from app. 4: a, c, d, e, f)

Diospyros sandwicensis and Myoporum sandwicense 

occur on all of the islands with significant maritime ports 

that deal with imports. Diospyros hillebrandii only occurs 

on Kaua‘i and O‘ahu, both having maritime ports. Because 
60

GENERAL TECHNICAL REPORT PSW-GTR-250

of the moderate temperatures, it is expected that infection 

in Hawai‘i can occur year-round, and available moisture 

can accelerate spread. Airborne spread of fungal spores 

seems to be the primary means for spread of the fungus, so 

overland movement may be substantial and wide-ranging. 

Because these fungi do not usually cause host mortality, 

recognition of their presence could be delayed numerous 

years from introduction. 

B. Consequences of introduction

5. Economic damage potential: Low (RU) (Applicable 

rating criteria, from app. 4: f)

Diospyros species are grown as native plants in some 

Hawai‘i nurseries. Their slow growth rate may limit their 

production by these nurseries and their outplanting. Nonnative species that grow faster could become more desirable 

to the Hawaiian population if planting of Diospyros as an 

ornamental came to be in greater demand. Other economic 

uses of either Diospyros or Myoporum are very limited.

6. Environmental damage potential: Moderate (MC) 

(Applicable rating criteria, from app. 4: d)

Diospyros sandwicensis can be a principal or minor 

part of the dry and mesic forests of Hawai‘i. It once covered 

large portions of the lowlands on several islands as part of 

the dry forest community. It can also be found growing in 

wet forests and open lava fields. Myoporum sandwicense

grows in mesic to wet forests on all of the major islands. It 

is a dominant tree species with both cultural and ecological 

significance. Impacts on either of these species could 

have significant ecological effects on already altered and 

degraded ecosystems.

7. Social and political considerations: Low (MC) 

(Applicable rating criteria, from app. 4: none)

The introduction of any Aecidium species that infects 

Diospyros or Myoporum would likely not have significant 

social or political impacts. Myoporum sandwicense is 

currently being affected by an introduced thrips species that 

will likely cause more damage than a species of Aecidium. 

Therefore, introduction of Aecidium likely will not increase 

the current concern. Because a foliar and branch pathogen 

like Aecidium will not cause tree mortality or other highly 

visible symptoms, the likelihood of public response is 

considered low.

C. Pest risk potential: 

Moderate (Likelihood of introduction = moderate; 

Consequences of introduction = moderate) 

Selected bibliography:

Bagyanarayana, G.; Ramesh, P. 1995. Notes on rust fungi 

from Andhra Pradesh. Journal of the Indian Botanical 

Society. 74: 227–230.

Birch, T.T.C. 1938. Synopsis of forest fungi of significance 

in New Zealand. New Zealand Journal of Forestry. 

4: 109–125.

Cunningham, G.H. 1924. The Uredinales, or rust-fungi, 

of New Zealand: Supplement to Part 1; and Part 2. 

Transactions and Proceedings of the New Zealand 

Institute. 55: 1–58. 

Dale, W.T. 1955. New species of Uredinales from Trinidad. 

Mycological Papers. 59: 1–11.

De, A.B. 2000. Parasitic fungi of Ramna forest (Burdwan, 

West Bengal). Annals Forestry. 8: 270–273.

Farr, D.F.; Rossman, A.Y. [N.d.]. Systematic mycology 

and microbiology [Database]. http://nt.ars-grin.gov/

fungaldatabases/. (13 March 2012).

Gardner, D.E. 1994. The native rust fungi of Hawaii. 

Canadian Journal of Botany. 72: 976–989.

Gardner, D.W.; Hodges, C.S., Jr. 1989. The rust fungi 

(Uredinales) of Hawai‘i. Pacific Science. 43: 41–55.

Hennen, J.F.; Figueiredo, M.B.; deCarvalho, A.A., 

Jr.; Hennen, P.G. 2005. Catalogue of the species 

of plant rust fungi (Uredinales) of Brazil. 490 p. 

http://200.20.168.5/publica/livros_pdf/catalogue.pdf. 

(13 August 2013).

Hernández, J.R. 2005. Systematic Mycology and 

Microbiology Laboratory, ARS, USDA. 31 March 

2005. Invasive fungi. Mulberry rust—Aecidium mori. 

http://nt.ars-grin.gov/taxadescriptions/factsheets/index.

cfm?thisapp=Aecidiummori. (26 March 2013).
61

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Hosagoudar, V.B. 1985. Teliomycetes of South India. 

Indian Phytopathology. 38: 278–281.

Hosagoudar, V.B. 2006. Additions to the fungi of Kerala. 

Zoo’s Print Journal. 21: 2322–2330.

Lee, S.S.; Alias, S.A.; Jones, E.G.B.; Zainuddin, N.; 

Chan, H.T. 2012. Checklist of fungi of Malaysia. Forest 

Research Institute of Malaysia Research Phamphlet No. 

132. Kepong, Malaysia: Swan Printing. 556 p. 

McKenzie, E.H.C. 1998. Rust fungi of New Zealand—an 

introduction, and list of recorded species. New Zealand 

Journal of Botany. 36: 233–271.

Mordue, J.E.M. 1991. Aecidium mori. IMI descriptions 

of fungi and bacteria No. 1031. Mycopathologia. 114: 

45–46.

Richmond, G.S.; Ghisalberti, E.L. 1995. Cultural, food, 

medicinal uses and potential applications of Myoporum

species (Myoporaceae). Economic Botany. 49: 276–285. 

Watson, A.J. 1971. Foreign bacterial and fungus diseases 

of food, forage, and fiber crops: An annotated list. Agric.

Handb. 418. Washington, DC: U.S. Department of 

Agriculture. 111 p.

Reviewers’ comments: The rationale was clear and easy 

to follow.

Response to comments: No response needed.

Armillaria Root Disease

Assessors: Helen Maffei and Jessie A. Glaeser

Scientific names of pests: Armillaria luteobubalina Watling & Kile; A. tabescens (Scop.) Emel; A. limonea G. Stev.;

Armillaria novae-zelandiae G. Stev. (Agaricales: Physalacriaceae); Armillaria sp., a currently unnamed species from 

Mexico (Elías-Román et al. 2013). Phylogenetic studies are 

clarifying species relationships within the genus (Klopfenstein et al. 2012, Maphosa et al. 2006, Pildain et al. 2010, 

Ross-Davis et al. 2012, Tsykun et al. 2013) and resolving 

cryptic species (Baumgartner et al. 2011, Elías-Román et 

al. 2013). Species identifications and distributions in older 

literature are highly suspect. 

Scientific names of hosts: Species of Armillaria have broad 

host ranges and can often colonize both hardwoods and 

conifers (table 8). Genera of Hawai‘i native plants at particular risk to Armillaria root rots are Diospyros, Acacia, 

Dodonaea, Vaccinium, Metrosideros, and Erythrina.

Summary of natural history and basic biology of 

the pests: The genus Armillaria contains both primary, 

virulent pathogens and secondary, facultative pathogens. 

Armillaria luteobubalina and A. tabescens are generally 

considered primary pathogens, but the amount of disease 

that occurs may be influenced by the nature of the host and 

the environment of the fungus. Armillaria limonea and A. 

novae-zelandiae are often secondary pathogens but can 

also cause significant disease and damage, either alone or in 

combination with other agents when the host is stressed by 

factors such as soil compaction, injury, nutrient deficiency 

or imbalances, drought, wind damage, and other unfavorable environmental conditions. All species of Armillaria

are facultative necrotrophs that can colonize living roots, 

kill root tissue, and then use the dead tissue as a source of 

nutrition, persisting as saprotrophic white rot decay fungi 

(Baumgartner et al. 2011). 

Armillaria luteobubalina is native to Australia and is an 

agent of mortality in natural ecosystems, forest plantations, 

fruit crops, and ornamental plants (Kile 1981; Shearer et 

al. 1997, 1998). It is commonly found in drier, more open 

eucalypt forests (Guillaumin and Legrand 2013, Kile and 

Watling 1981, Podger et al. 1978) and is thought to be the 

most pathogenic and most widespread Armillaria species 

native to Australia (Guillaumin and Legrand 2013, Kile and 

Watling 1981, Smith and Kile 1981). Stressors, including 

drought or flooding, can also predispose trees to infection. 

The fungus is a primary cause of Eucalyptus spp. death 

and forest dieback. Rainfall appears to govern the pathogenicity of A. luteobubalina. In intermediate and lower 

rainfall zones of Australian jarrah forest, the fungus is an 

aggressive pathogen but causes only minor disease on the 

same hosts in the wetter, western coastal forests. Armillaria 

luteobubalina has also been reported from southern South 

America, in Argentina, Chile, and southern Brazil (Guillaumin and Legrand 2013, Pildain et al. 2009). A 2003 study 

of the molecular phylogenetics and pattern of its distribution 
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GENERAL TECHNICAL REPORT PSW-GTR-250

Table 8 —Armillaria species of concern, their hosts and distribution

Species Hosts

Hosts from genera 

of concern Distribution Citation

Armillaria 

limonea

Wide host range of hardwoods 

and conifers from multiple 

families, including species 

of Acacia, Chamaecyparis, 

Citrus, Cryptomeria, 

Cupressus, Eucalyptus, 

Larix, Malus, Metrosideros, 

Nothofagus, Pinus, 

Pseudotsuga, Podocarpus, 

Pyrus, Salix, Tsuga

Acacia melanoxylon; 

Metrosideros robusta

New Zealand Farr and Rossman, 

n.d.; Hodges and 

Hildebrand 2005a; 

McKenzie et al. 1999 

Armillaria luteobubalina

Wide and poorly defined. At 

least 50 families, primarily 

hardwoods. Includes species 

of Acacia, Banksia, Cassinia,

Cedrus, Eucalyptus, Malas,

Melaleuca, Nothofagus, 

Pinus, Prunus, Pyrus,

Vaccinum, Vitis

Acacia browniana, A. 

cyclops, A. dealbata, A. 

extensa, A. howittii, A. 

longifolia, A. mearnsii, 

A. melanoxylon, A. 

mucronata, A. pulchella, 

A. saligna, A. urophylla, 

A. verticillata; Dodonaea 

amblyophylla, D. 

viscosa; Scaevola nitida; 

Vaccinium ashei, V. 

corymbosum

Australia, 

Argentina, 

Chile

CABI 2011a; CIPM 

2012a; Falk and 

Parbery 1995; Farr and 

Rossman, n.d.; Shaw 

and Kile 1991; Shearer 

et al. 1998

Armillaria 

novaezelandiae

Wide host range from multiple 

families of hardwoods and 

conifers. Includes species 

of Acacia, Chamaecyparis, 

Cedrus, Citrus, Cryptomeria, 

Cupressus, Eucalyptus, 

Larix, Malus, Metrosideros, 

Nothofagus, Pinus, 

Podocarpus, Prunus, 

Pseudotsuga, Pyrus, Salix, 

Tsuga, Vitis

Acacia mangium, 

A. melanoxylon; 

Metroosideros 

kermadecensis 

Widespread, 

especially 

Oceania 

(Australia, 

New Zealand, 

Malaysia), 

South 

America

Farr and Rossman, 

n.d.; Hodges and 

Hildebrand 2005b; 

Shearer et al. 1998 

Armillaria 

tabescens

Wide host range from 

multiple families; 

primarily hardwoods but 

some conifers. Includes 

species of Acacia, Acer, 

Cedrus, Citrus, Cupressus, 

Diospyros, Erythrina, 

Eucalyptus, Malus, 

Melaleuca, Metrosideros, 

Pinus, Podocarpus, Prunus, 

Pyrus, Quercus, Salix, 

Thuja, Vitis

Acacia farnesiana; 

Diospyros sp., D. 

kaki var. domestica; 

Erythrina sp., E. cristagalli, E. subumbrans, E. 

variegata 

United States 

(primarily 

South, 

Central, and 

South East), 

Mexico, 

India, 

Malaysia, 

Tanzania, 

Trinidad 

and Tobago, 

Europe, 

China

Farr and Rossman, n.d.; 

Lenné 1990; Lushaj 

et al. 2010
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

in South America and Australia indicate that A. luteobubalina is an ancient species, originating before the separation 

of the precursor supercontinent Gondwana (Coetzee et 

al. 2003). At least four distinct polymorphic groups exist 

within the species, which may eventually be separated into 

different taxa (Dunne et al. 2002). 

Armillaria tabescens is widely distributed (North 

America, the Caribbean, Europe, India, Africa, Japan, 

and Malaysia) with a very broad host range. It can act as a 

primary, aggressive pathogen on highly susceptible hosts or 

be an opportunistic pathogen on those trees with more resistance. It can persist for many years on dead roots, infecting 

and colonizing adjacent healthy roots as they grow through 

the soil. It grows rapidly in a new host if colonization begins 

in root tissue already dying or recently dead. Symptoms in 

woody ornamentals are often observed 3 to 4 years after 

transplant, indicating that wounded roots may be the source 

of infection. Vigorous plants with undamaged roots often 

avoid attack. The fungus is favored by higher temperatures. 

The disease was previously known as “Clitocybe root 

disease” or “mushroom root rot” (Sinclair and Lyon 2005, 

Tainter and Baker 1996). 

Armillaria limonea is restricted to New Zealand 

(Coetzee et al. 2001, Hood et al. 1992, McKenzie et al. 

1999). It occurs in wet, indigenous podocarpus-hardwood 

and Nothofagus forests where it colonizes stumps, logs, 

and dead trees and causes a butt rot in living trees (Hood 

1989). Armillaria limonea often occurs together with A. 

novae-zelandiae on Pinus radiata (Shaw et al. 1981). Both 

fungi are most prevalent on sites once occupied by native 

forests and can cause losses of up to 30 percent in the first 

5 years of P. radiata plantations grown on land cleared of 

indigenous forests, with additional losses in subsequent 

rotations (Hood et al. 1991). 

Armillaria novae-zelandiae is indigenous to Australia, 

New Zealand, and the higher elevations of Papua-New 

Guinea. It causes root and butt rot of many native species. It 

has also been reported from Chile, although differences in 

internal transcribed spacer sequences suggest that the fungi 

have been separated for a long period, as observed for A. 

luteobubalina (Coetzee et al. 2003). A study of P. radiata

colonized by A. novae-zelandiae showed that trees younger 

than 5 years old usually died upon infection and colonization. Colonization in older trees was restricted to bark so 

that the cambium and living inner phloem were left largely 

intact, allowing tree survival. Small areas of the cambium 

were penetrated during the dormant season, but the tree’s 

defenses were able to compartmentalize the area with callus 

tissue. These trees survived until harvest with a small loss 

of growth. The stumps of infected trees can serve as a 

source of inoculum for the succeeding plantation, resulting 

in the death of young trees (van der Kamp and Hood 2002). 

In other hosts, the fungus most commonly occurs as a secondary pathogen characterized by epiphytic rhizomorphs 

or root lesions (Kile et al. 1983). When a large foodbase 

becomes available through logging or wildfire, massive root 

and stump infection can result, but little mortality occurs 

in the regenerating stands of eucalypts and other species. 

Disease is restricted to the footprint of the preexisting stand 

(Kile 1980).

Armillaria sp. is a new, currently unnamed species of 

Armillaria that has recently been associated with high incidence of root disease mortality in peach (Prunus persica) 

and other woody species in south-central Mexico (ElíasRomán et al. 2013). This species is genetically distinct from 

other North American species of Armillaria and could 

represent a serious threat to Hawai‘i and other regions of the 

world (Klopfenstein 2014, personal communication). Little 

is known about its distribution or host specificity.

The infection biology and epidemiology of Armillaria 

root disease has been reviewed by Guillaumin and Legrand 

(2013). Wood, primarily tree roots, provides the major 

source of inoculum for all species of Armillaria. The fungi 

can survive for long periods of time saprotrophically in old 

stumps and other woody debris (Kile 1980, Rishbeth 1972, 

Shaw 1975). Infection usually occurs via the roots from 

contact with infected roots or colonized woody debris in the 

soil. These fungi also form hard, melanized rhizomorphs 

that facilitate movement between food sources while 

preventing desiccation. Although rhizomorphs are seldom 
64

GENERAL TECHNICAL REPORT PSW-GTR-250

observed for A. tabescens, Mihail et al. (2002) demonstrated that they can form under conditions of high oxygen 

availability and moisture near saturation and are capable of 

establishing new infection centers. Most pathogenic species 

produce limited rhizomorphs (CABI 2011a), primarily 

spreading to a new hosts through infected roots/stumps or 

contaminated wood or mulch (Baumgartner et al. 2011). 

Several studies have shown that the spread of Armillaria

root rot in eucalypt forests is associated with infected 

stumps that remain after an area has been logged (Edgar et 

al. 1976, Kellas et al. 1987, Pearce et al. 1986). Armillaria 

luteobubalina can persist on these stumps, using them as 

a source of food, for up to 25 or more years (Kile 1981). In 

one case reported in Ovens, Victoria, the disease spread to 

blueberry plants (Vaccinium spp.) via buried fragments of 

infected Eucalyptus that remained following preparation 

of the previously forested site for planting (Falk and 

Parbery 1995).

The potential importance of basidiospore infection in 

the spread and establishment of Armillaria root disease is 

circumstantial. Infection rates in the relatively dry forest 

of western North America and the dry sclerophyll eucalypt forest appear to be low, possibly because of limited 

infection courts. Conversely, spore establishment may be 

more common in wetter forests where moisture conditions 

are more favorable for frequent and abundant mushroom 

production and the basidiospore survival on stumps and 

other infection courts (Kile 1986). Basidiospores may be 

responsible for long-distance spread and are effective at 

establishing disease in natural stands that lack competitors 

(Guillaumin and Legrand 2013). Localized spread is usually 

vegetative, by contact of healthy roots with infected wood 

debris and by the spread of infected roots and rhizomorphs. 

This is particularly common when plantation stands are 

planted in previously colonized forest soils (Baumgartner 

et al. 2011, Kliejunas et al. 2001). Variations in virulence 

among species of Armillaria have been observed among 

isolates of A. solidipes from coastal and interior British 

Columbia (Morrison and Pellow 2002), as well as with A. 

limonea and A. novae-zelandiae on Pinus radiata in New 

Zealand (Shaw et al. 1981).

Although species of Armillaria are found all over the 

world, their natural distribution reflects the Holartic or 

non-Holarctic floral kingdoms that have relatively uniform 

compositions of plant species. Thus, species from the Holarctic region (North America, Europe, China, and Japan) 

form one cluster; species from Australia, South America, 

and New Zealand form a second grouping, and species from 

Africa represent a third group. Introductions have become 

established in new areas. North American strains of A. mellea are present on planted hosts in South Africa, probably 

arising from European stock. The spread of these strains 

is restricted, however, spreading to neighboring plants in 

urban gardens but not becoming widespread. Similarly, 

other strains of A. mellea in Africa originated in Asia; these 

could have spread from a single infection center as far as 

4000 km, probably by basidiospore dispersal (Baumgartner 

et al. 2011).

Some species of Armillaria already occur in Hawai‘i. 

Past surveys have noted A. mellea sensu lato and A. 

nabsnona on numerous hosts in Hawai‘i, including Sophora 

chrysophylla (māmane) (Burgan and Nelson 1972, Hodges 

et al. 1986). Kim et al. (2010b) identified A. gallica in 

Hawai‘i, where it was found on Sophora chrysophylla

(māmane), Pinus radiata, P. taeda, and Prunus salicina

(Methley plum). Recent studies (Brazee and Wick 2009, 

Klopfenstein et al 2014, Nelson et al 2013) suggest that A. 

gallica can be highly pathogenic and may be an important 

component of forest decline, especially under increasing 

stressors such as climate change. The isolation of A. gallica 

from declining stands on both introduced and endemic 

hosts under drought conditions suggests this pathogen is a 

contributing factor to forest decline on the island of Hawai‘i. 

Specific information relating to risk elements:

Pest risk assessments have been done previously for A. 

limonea (Hodges and Hildebrand 2005a), A. novae-zelandiae (Hodges and Hildebrand 2005b), and for the genus as a 

whole (Kliejunas et al. 2001, 2003). 

A. Likelihood of introduction

1. Pest with host-commodity at origin potential: 

High (VC) (Applicable rating criteria, from app. 

4: c, d, e, g, h) 
65

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Species of Armillaria have broad host ranges and can 

survive in both living and dead wood for extensive periods 

of time. They can colonize the roots, cambium, and lower 

boles of host material and can be present in logs, solid wood 

packing material, chips and mulch, and living nursery 

stock. Incipient infections are unlikely to be detected. 

2. Entry potential: High (VC) (Applicable rating criteria, from app. 4: b, c, d)

The vegetative forms of the fungi, living as saprotrophs, can survive harvest and transport and could 

continue to grow under conditions of high humidity during 

transport. Rhizomorphs and mycelia can survive beneath 

the bark on poorly debarked material and in living plants.

3. Establishment potential: High (MC) (Applicable 

rating criteria, from app. 4: a, b, c, d, f)

Genetic research in Africa has shown that species of 

Armillaria from both Europe and Asia have become established after introduction, probably from contaminated nursery material (Baumgartner et al. 2011). Suitable climate and 

host species are found at ports of entry in Hawai‘i. The wide 

host range of these fungi and their ability to utilize new 

hosts increases the probability of establishment. Infection 

centers may arise either from contact with infected roots 

from live plants or from contaminated woody material. 

4. Spread potential: High (VU) (Applicable rating criteria, from app. 4: a, b, c, d, e, f, g)

Although the role of basidiospores in the spread of 

Armillaria species is debated, most studies have concluded 

that they are responsible for long-distance spread once 

the fungus becomes established. This likely occurred in 

spreading Asian isolates of A. mellea throughout Africa 

from infected planting materials (Baumgartner et al. 2011). 

Newly established infections are likely to go undetected for 

many years as other agents, including drought and other soil 

fungi, are thought responsible for forest declines (Hodges et 

al. 1986).

B. Consequences of introduction 

5. Economic damage potential: High (VU) (Applicable 

rating criteria, from app. 4: a, b, c, e, f)

Tree decline and mortality over a broad host range 

could severely affect forest and agricultural hosts, 

especially those stressed by other factors. Economic 

impact might be slow to develop unless basidiospore 

dispersal results in long-distance establishment of 

numerous infection centers.

6. Environmental damage potential: High (VU) 

(Applicable rating criteria, from app. 4: c, d)

Armillaria species may have indirect impacts on threatened and endangered species by disrupting sensitive and 

critical habitat owing to decline and death of native forests, 

although spread might be slow from a single infection site. 

The broad host ranges of these fungi endanger native hosts 

with limited distribution. Variations in virulence have been 

noted in A. limonea, A. novae-zelandiae, and other species 

of Armillaria, so the ability to evolve more virulent strains 

is always possible.

7. Social and political considerations: High (VU) 

(Applicable rating criteria, from app. 4: a, c, d)

 Damage from Armillaria species and subsequent 

death or decline of native Hawai‘i tree species would result 

in public concerns about aesthetics and recreation as well 

as urban plantings. Removal of affected trees would have 

limited acceptance by the public. Armillaria luteobubalina, 

a serious pathogen in Australia, is not yet present in North 

America, and its broad host range includes many important 

ornamental species. Introduction of the fungus to Hawai‘i 

would interfere with domestic interstate commerce, trade, 

and traffic.

C. Pest risk potential:

High (Likelihood of introduction = high; Consequences of introduction = high) 

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Pearce, M.H.; Malajczuk, N.; Kile, G.A. 1986. The 

occurrence and effects of Armillaria luteobubalina in 

the karri (Eucalyptus diversicolor F. Muell.) forests 

of Western Australia. Australian Forest Research. 

16: 243–259.

Pildain, M.B.; Coetzee, M.P.A.; Rajchenberg, R.H.; 

Petersen, R.H.; Wingfield, M.J.; Wingfield, B.D. 2009. 

Molecular phylogeny of Armillaria from the Patagonian 

Andes. Mycological Progress. 8: 181–194.

Pildain, M.B.; Coetzee, M.P.A.; Wingfield, M.J.; 

Wingfield, B.D.; Rajchenberg, R.H. 2010. Taxonomy 

of Armillaria in the Patagonian forests of Argentina. 

Mycologia. 102: 392–403.

Podger, F.D.; Kile, G.A.; Watling, R.; Fryer, J. 1978.

Spread and effects of Armillaria luteobubalina sp. 

nov. in an Australian Eucalyptus regnans plantation. 

Transactions of the British Mycological Society. 71: 

77–87.

Rishbeth, J. 1972. The production of rhizomorphs by 

Armillaria mellea from stumps. European Journal of 

Forest Pathology. 2: 193–205.

Ross-Davis, A.L.; Hanna, J.W.; Kim, M.S.; 

Klopfenstein, N.B. 2012. Advances toward DNAbased identification and phylogeny of North American 

Armillaria species using elongation factor-1 alpha gene. 

Mycoscience. 53: 161–165.

Shaw, C.G., III. 1975. Epidemiological insights into 

Armillaria mellea root rot in a managed ponderosa 

pine forest. Corvallis, OR: Oregon State University. 

201 p. Ph.D. thesis.

Shaw, C.G.; Kile, G.A., eds. 1991. Armillaria root disease. 

Agric. Handb. 691. Washington, DC: U.S. Department of 

Agriculture, Forest Service. 233 p.

Shaw, C.G., III.; MacKenzie, M.; Toes, E.H.A.; Hood, 

I.A. 1981. Cultural characteristics and pathogenicity to 

Pinus radiata of Armillaria novae-zelandiae and 

A. limonea. New Zealand Journal of Forestry Science. 

11: 65–70.

Shearer, B.L.; Crane, C.E.; Fairman, R.G.; Grant, 

M.J. 1997. Occurrence of Armillaria luteobubalina and 

pathogen-mediated changes in coastal dune vegetation of 

south-western Australia. Australian Journal of Botany. 

45: 905–917.

Shearer, B.L.; Crane, C.E.; Fairman, R.G.; Grant, 

M.J. 1998. Susceptibility of plant species in coastal 

dune vegetation of South-western Australia to killing by 

Armillaria luteobubalina. Australian Journal of Botany. 

46: 321–334.

Sinclair, W.A.; Lyon, H.H. 2005. Diseases of trees and 

shrubs. Ithaca, NY: Comstock Publishing Associates. 

660 p.
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Smith, L.; Kile, G.A. 1981. Distribution and hosts of 

Armillaria root rot in Melbourne suburban gardens. 

Australasian Plant Pathology. 10: 41–42.

Tainter, F.H.; Baker, F.A. 1996. Principles of forest 

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Tsykun, T.; Rigling, D.; Prospero, S. 2013. A new 

multilocus approach for a reliable DNA-based 

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32: 103–115.

Reviewers’ comments: No comments received except 

corrections of citations.

Response to comments: Citations corrected.

Calonectria morganii

Assessor: Phil Cannon

Scientific names of pest: Calonectria morganii Crous, 

Alfenas & M.J. Wingf. (anamorph = Cylindrocladium 

scoparium Morgan (imperfect form)). In most locations, 

it is much more common to find this fungus in the 

imperfect state. 

Scientific names of hosts: The pathogen occurs on a 

number of hosts but has been particularly common on 

Eucalyptus spp. and Rhododendron spp. Other host genera 

include Dodonaea, Magnolia, Juniperus, Mangifera, Pistacia, Melaleuca, Trifolia, Ilex, Pinus, Callistemon, Cuphea,

Picea, Juglans, Liriodendron, Liquidambar, Anacardium, 

Quercus, Cornus, Cercis, Erica, Arachis, Azalea, Solanum, 

Glycine, Beta, Fragaria, Cucumis, Mahonia bealei, Calluna 

vulgaris, Metrosideros spp., and Leucotheae catesbaei.

Distribution: Based on phylogenetic studies, Calonectria 

(Ca.) morganii has been reported in Brazil, Europe, and 

the United States (Crous et al. 1993, Overmeyer et al. 1996, 

Schoch et al. 2000). Cylindrocladium (Cy.) scoparium is 

especially prevalent in the Eastern United States, Canada, 

and Brazil. It has also been recorded in the United Kingdom, Poland, Italy, Panama, Brunei, New Zealand, Tunisia 

(Lombard et al. 2010a), Malaysia (Lee and Manap 1983), 

and India (Old et al. 2000).

Summary of natural history and basic biology of the 

pest: To understand Ca. morganii, a cursory understanding 

of the whole genus is useful. Fungi in the genus Calonectria

were initially regarded as saprobes, as no disease symptoms 

could be induced by inoculating a suspected host (Graves 

1915). The first proof of pathogenicity of these fungi was 

provided by Massey (1917), and subsequently by Anderson 

(1919), who proved pathogenicity of Ca. morganii (as Cy. 

scoparium). Subsequently, Calonectria spp. have been 

reported worldwide from agricultural and forestry nurseries 

(Crous 2002; Crous et al. 1991; Lombard et al. 2009, 2010a, 

b, c), whereas in Europe, they have only been reported from 

commercial ornamental nurseries (Crous 2002; Henricot 

and Culham 2002; Lombard et al. 2010a; Polizzi 2000; 

Polizzi and Crous 1999; Polizzi et al. 2007a, 2007b; 2009; 

Vitale and Polizzi 2008). At present, 52 Cylindrocladium

spp. and 37 Calonectria spp. are recognized based on sexual 

compatibility, morphology, and phylogenetic inference 

(Lombard et al. 2010a). 

Calonectria morganii and Ca. pauciramosa are the 

most common Calonectria spp. found in ornamental nurseries in the Northern Hemisphere (Polizzi 2000; Polizzi and 

Catara 2001; Polizzi and Crous 1999; Polizzi et al. 2006a, 

2006b, 2007a, 2007b) and of these two, C. pauciramosa has 

wider global distribution and is adapted to a wider array of 

different environmental conditions (Chen et al. 2011, Crous 

2002, Lombard et al. 2010b). Calonectria pauciramosa

was also regarded as the dominant pathogen in nurseries 

in Australia and South Africa (Crous 2002, Lombard et al. 

2010b, Schoch et al. 2001).

Species of Calonectria are common pathogens of a 

wide range of plant hosts cultivated through seedings or 

vegetative propagation in nurseries (Crous 2002, Lombard 

et al. 2010a). Nursery disease symptoms associated with 

these fungi include crown, collar and root rot, leaf spots, 

and cutting rot (Crous 2002, Lombard et al. 2010a, Polizzi et 

al. 2009, Vitale and Polizzi 2008). Infection causes damping-off, root rot and blight, stem lesions, stem canker, stem 

dieback, stunting, leaf spots, wilted leaves, defoliation, and 

fruit rot (Alfenas et al. 2004, Cordell and Rowen 1975).
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GENERAL TECHNICAL REPORT PSW-GTR-250

In the past, several authors have indicated that Calonectria species cause one or more of these kinds of disease 

symptoms on plants residing in about 30 plant families 

(Booth and Gibson 1973, Peerally 1991). Upon closer 

inspection, the number of susceptible plant families is actually closer to 100, and includes about 335 plant host species 

(Crous 2002). The plant hosts include important forestry, 

agricultural, and horticultural crops, and the impact of these 

plant pathogens has likely been underestimated.

Perithecia and ascospores, indicative of the perfect state 

of Ca. morganii, may occasionally be produced, but they are 

rare. Far more common are the imperfect spore stages of Cy. 

scoparium, which in addition to microsclerotia, include the 

fairly long, uniquely-shaped conidia, which have a single 

septation. Both of these spore types are much more likely to 

be produced under conditions of high humidity and rainfall 

and can be spread by wind and rain.

Cylindrocladium spp. can also survive drought and 

cold as microsclerotia for up to several years in infected 

and dead plant tissues and in infested soil (Overmeyer et al. 

1996). When seedling roots come in contact with the microsclerotia, the microsclerotia germinate and infection occurs. 

Inadvertent transport of microsclerotia is the main means 

by which this fungus is distributed to new environments.

Hodges and May (1972) first identified Ca. morganii in 

Brazil, although at that time, they called it by its imperfect 

name Cy. scoparium. In 1993, Crous et al. (1993) found 

the teleomorph and gave it the name Calonectria morganii

(to honor Dr. Morgan). Since 1973, it has received a lot 

of attention in the forest nurseries of Brazil but has never 

been so intensively studied as in recent years. Alfenas et 

al. (2013) published a report on Ca. metrosideri, which was 

given that name because it was an exceptionally aggressive 

pathogen growing on and occasionally killing some ‘ōhi‘a 

lehua seedlings growing in a nursery in Vicosa. Subsequent 

work has shown that there are at least another 24 new species in the Ca. morganii complex of phylogenetic species, 

and most of these are expected to be highly pathogenic on 

the Myrtaceae (A. Alfenas, Univesidade Federal de Viçosa, 

Viçosa Brazil, personal communication).

At present, the only key to disease control is the use 

of healthy cuttings, seedlings, and plants. One way to deal 

with Calonectria populations in a nursery is to swap nursery locations (Thies and Patton 1966) or to simply insist that 

soil substrates used in beds or for potting media are free of 

the microsclerotial propagules. Although these microsclerotia are resistant to many common fungicides, good control 

has been achieved by using tabuconazole, epoxyconozole, 

tetraconazole, triamendol, and a mix of epoxyconozole and 

pyraclostrobin (Alfenas et al. 2004).

Specific information relating to risk elements:

A. Likelihood of introduction

1. Pest with host-commodity at origin potential: 

High (VC) (Applicable rating criteria, from app. 

4: b, c, d, e, g, h)

The transportability of Ca. morganii has been clearly 

demonstrated by the fact that it can colonize basically any 

part of a small host plant. It is capable of infecting a broad 

range of host plants, several of which are brought to Hawai‘i 

as cut plants and some as whole plants. Its highly viable 

microsclerotia can survive in a dormant state for years in 

organic matter or soil; so potentially this pathogen could be 

introduced into Hawai‘i in infested soil, as well as through a 

broad range of plants.

2. Entry potential: High (VC) (Applicable rating criteria, from app. 4: b, c, d) 

Calonectria morganii can colonize any part of a plant, 

so it could be brought into Hawai‘i on any infected plant. 

Also, its ability to form microsclerotia, which can survive 

in infested soil for long periods of time and endure great 

drought, and its tolerance of a wide range of pH make it 

hard to sanitize with many fungicides.

3. Colonization potential: High (VC) (Applicable rating criteria, from app. 4: a, b, c, e)

The capacity of this fungus to colonize host plants will 

vary by the species of plant being infected, the physiological 

condition of that plant, and the environmental conditions 

that are prevailing at the time that infection is taking place. 

Some susceptible tree species are found in abundance in 

Hawai‘i nurseries where the environmental conditions will 

be optimal for infection by this pathogen.
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

The exact colonization potential cannot be known, but 

the fact that natural Hawai‘i forests are largely populated 

with species in genera that have been shown to be highly 

vulnerable to fungi in the Ca. morganii complex suggest 

that the colonization potential might be fairly high. 

The greatest opportunity for colonizing wide areas of 

Hawai‘i would come through the infestation of nurseries. 

Nurseries, with their millions of young susceptible plants 

per acre and high soil and air humidities, provide the perfect 

conditions for a rapid buildup of this pathogen and the 

formation of large numbers of microsclerotia.

4. Spread potential: High (RC) (Applicable rating 

criteria, from app. 4: b, c, d, e, f)

Spread under natural forest circumstances in most parts 

of Hawai‘i would not be especially high because air conditions are not near the point of saturation much of the time. 

However, Hawai‘i nurseries are producing fairly large numbers of seedlings of tree species that are susceptible to Ca. 

morganii, and if several crops of infected seedlings were to 

be produced, the subsequent distribution of these seedlings 

might quickly hasten the distribution of this fungus around 

the islands. This spread potential could easily be reduced to 

moderate by using nursery practices that would limit the 

buildup and distribution of the microscletrotia.

B. Consequences of introduction

5. Economic damage potential: Moderate (RC) 

(Applicable rating criteria, from app. 4: b, d, f)

Loss of flower production and wood for timber could 

have some economic impact in Hawai‘i. Damage to landscape trees around the islands may have more significant 

impacts. Because of the wide host range of Ca. morganii, 

introduction to Hawai‘i could result in quarantines put in 

place by a number of countries of potential export goods.

6. Environmental damage potential: Moderate (MC) 

(Applicable rating criteria, from app. 4: d)

The capacity that this fungus has to destroy seedlings 

of eucalypts is quite substantial (Alfenas et al. 2013). 

However, this is under nursery conditions, which are 

conducive to the development of this fungus. If introduced 

into Hawai‘i, impacts on native forests could be significant. 

If ‘ōhi‘a lehua were to be a host of Ca. morganii, damage to 

native forests across the islands could affect water quantity 

and quality, as well as wildlife habitat.

7. Social and political considerations: Low (MC) 

(Applicable rating criteria, from app. 4: none)

Although it is not known if M. polymorpha may be a 

host of Ca. morganii, if the pathogen was introduced and 

infected M. polymorpha, some public concern could be 

raised similar to that raised during the 1960s and 1970s 

when M. polymorpha underwent dramatic diebacks. 

Impacts to D. viscosa may receive somewhat less public 

concern because of its more limited distribution across the 

islands.

C. Pest risk potential 

High (Likelihood of introduction = high; Consequences of introduction = moderate) 

Although this brief pest risk analysis has focused on 

Ca. morganii, there are two other closely related species of 

Calonectria that might also present a tremendous problem 

for Hawai‘i. One of these is Ca. metrosideri, which was 

found vigorously attacking (and commonly killing) a large 

proportion of ‘ōhi‘a lehua seedlings in a nursery in Viçosa, 

Brazil (Alfenas et al. 2013). This fungus was slightly less 

pathogenic on Metrosideros tremuloides. The other is Ca. 

pauciramosa, which has an even more global distribution 

than Ca. morganii, and which has been a dominant pathogen in nurseries of South Africa and Australia (Crous 2002, 

Lombard et al. 2010a).

Selected bibliography:

Alfenas, A.C.; Zauza, E.A.V.; Mafia, R.G.; de Assis, 

T.F. 2004. Clonagem e doencas do eucalipto. Viçosa: 

Universidade Federal do Viçosa. 442 p.

Alfenas, R.F.; Pereira, O.L.; Ferreira, M.A.; Jorge, 

V.L.; Crous, P.W.; Alfenas, A.C. 2013. Calonectria 

metrosideri, a highly aggressive pathogen causing leaf 

blight, root rot, and wilt of Metrosideros spp. in Brazil. 

Forest Pathology. doi:10.1111/efp.12035.
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GENERAL TECHNICAL REPORT PSW-GTR-250

Anderson, P.J. 1919. Rose canker and its control. Bulletin 

of the Massachusetts Agricultural Experiment Station. 

183: 11–46.

Barnard, E.L. 1984. Occurrence, impact, and 

fungicidal control of girdling stem cankers caused by 

Cylindrocladium scoparium on eucalyptus seedlings in a 

south Florida nursery. Plant Disease. 68: 471–473.

Booth, C.; Gibson, I.A.S. 1973. Cylindrocladium 

scoparium. CMI descriptions of pathogenic fungi 

and bacteria No. 362. Kew, Surrey: Commonwealth 

Mycological Institute.

Chen, S.F.; Lombard, L.; Roux. J.; Xie, Y.J.; Wingfield, 

M.J.; Zhou, X.D. 2011. Novel species of Calonectria

associated with Eucalyptus leaf blight in Southeast 

China. Persoonia. 26: 1–12.

Cordell, C.E.; Rowan, S.J. 1975. Cylindrocladium 

scoparium infection in a natural sweetgum stand. 

Plant Disease Reporter. 59: 775–776.

Crous, P.W. 2002. Taxonomy and pathology of 

Cylindrocladium (Calonectria) and allied genera. St. 

Paul, MN: American Phytopathological Society. APS 

Press. 294 p.

Crous, P.W.; Alfenas, A.C.; Wingfield, M.J. 1993.

Calonectria scoparia and Calonectria morganii sp. nov. 

and variation among isolates of their Cylindrocladium

anomorphs. Mycological Research. 97(6): 701–708.

Crous, P.W.; Phillips, A.J.L.; Wingfield, M.J. 1991. The 

genera Cylindrocladium and Cylindrocladiella in South 

Africa, with special reference to forest nurseries. South 

African Forestry Journal. 157: 69–89.

Graves, A.H. 1915. Root rot of coniferous seedlings. 

Phytopathology. 5: 213–217.

Henricot, B.; Culham, A. 2002. Cylindrocladium 

buxicola, a new species affecting Buxus spp., and its 

phylogenetic status. Mycologia. 94: 980–997.

Hodges, C.S.; May, L.C. 1972. A root disease of 

pine, Araucaria and Eucalyptus in Brazil caused by 

a new species of Cylindrocladium. Phytopathology. 

62: 898–901.

Lee, S.S.; Manap, A.A. 1983. Seed-borne fungi of 

some Malaysian forest tree species. In: Guzman, 

E.D.; Nuhamara, S.T., eds. Forest pests and diseases 

in Southeast Asia. BIOTROP Special Publication No. 

20. Bogor, Indonesia: [Publisher unknown]: 117–128.

Lombard, L.; Rodas, C.A.; Crous, P.W.; Wingfield, B.D.; 

Wingfield, M.J. 2009. Calonectria (Cylindrocladium) 

species associated with dying Pinus cuttings. Persoonia. 

23: 41–47.

Lombard, L.; Crous, P.W.; Wingfield, B.D.; Wingfield, 

M.J. 2010a. Species concepts in Calonectria. Studies in 

Mycology. 66: 1–13.

Lombard, L.; Crous, P.W.; Wingfield, B.D.; Wingfield, 

M.J. 2010b. Multigene phylogeny and mating tests 

reveal three cryptic species related to Calonectria 

pauciramosa. Studies in Mycology. 66: 15–30.

Lombard, L.; Crous, P.W.; Wingfield, B.D.; Wingfield, 

M.J. 2010c. Phylogeny and systematics of the genus 

Calonectria. Studies in Mycology. 66: 31–69.

Lombard, L.; Polizzi, G.; Guamaccia, V.; Vitale, A.; 

Crous, P. 2011. Calonectria spp. causing leaf spot, 

crown and root rot of ornamental plants in Tunisia. 

Persoonia. 27: 73–79. 

Massey, L.M. 1917. The crown canker disease of rose. 

Phytopathology. 7: 408–417.

Old, K.M.; Wingfield, M.J.; Yuan, Z.Q. 2003. A manual 

of diseases of eucalypts in South-East Asia. Bogor, 

Indonesia: Center for International Forestry Research. 

98 p.
73

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Overmeyer, C.; Lunnemann, S.; von Wallbrunn, 

C.; Meinhardt, F. 1996. Genetic variability among 

isolates and sexual offspring of the plant pathogenic 

fungus Calonectria morganii on the basis of random 

amplification of polymorphic DNA (RAPD) and 

restricted fragment length polymorphism (RFLP). 

Current Microbiology. 33: 249–255.

Peerally, A. 1991. The classification and phytopathology of 

Cylindrocladium species. Mycotaxon. 40: 323–366.

Polizzi, G. 2000. Prime esperience di lotta chimica 

nei confrontidel marciume del colletto e delle radici 

di Polygala myrtifolia causato da Cylindrocladium 

pauciramosum. Informatore Fitopatologico. 11: 39–47.

Polizzi, G.; Catara, V. 2001. First report of leaf spot 

caused by Cylindrocladium pauciramosum on Acacia 

retinodes, Arbutus unedo, Feijoa sellowiana and 

Dodonaea viscosa in southern Italy. Plant Disease. 

85: 803.

Polizzi, G.; Crous, P.W. 1999. Root and collar of milkwort 

caused by Cylindrocladium pauciromosum, a new 

record for Europe. European Journal of Plant Pathology. 

105: 407–411.

Polizzi, G.; Grasso, F.M.; Vitale, A.; Aiello, D. 2007a. 

First occurrence of Calonectria leaf spot on mexican blue 

palm in Italy. Plant Disease. 91: 1057.

Polizzi, G.; Vitale, A.; Aiello, D.; Castello, I.; 

Guarnaccia, V.; Parlavecchio, G. 2009. First record 

of crown and root rot caused by Cylindrocladium 

pauciramosum on brush cherry in Italy. Plant Disease. 

93: 547.

Polizzi, G.; Vitale, A.; Aiello, D.; Dimartino, M.A.; 

Parlavecchio, G. 2007b. First report of damping-off 

and leaf spot caused by Cylindrocladium scoparium on 

different accessions of bottlebrush cuttings in Italy. Plant 

Disease. 91: 769.

Polizzi, G.; Vitale, A.; Aiello, D.; Parlavecchio, G. 

2006a. First record of crown and root rot caused by 

Cylindrocladium pauciramosum on California lilac in 

Italy. Plant Disease. 90: 1459.

Polizzi, G.; Vitale, A.; Castello, I.; Groenewald, J.Z.; 

Crous, P.W. 2006b. Cylindrocladium leaf spot, blight 

and crown rot, new diseases of mastic tree seedlings 

caused by Cylindrocladium scoparium. Plant Disease. 

90: 1110.

Schoch, C.L.; Crous, P.W.; Wingfield, B.D.; Wingfield, 

M.J. 2001. Phylogeny of Calonectria based on 

comparisons of β-tubulin DNA sequences. Mycological 

Research. 105: 1045–1052.

Schoch, C.L.; Crous, P.W.; Witthuhn, R.C.; Cronwright, 

G.; El-Gholl, N.E.; Wingfield, B.D. 2000.

Recombination in Calonectria morganii and phylogeny 

with other heterothallic small-spored Calonectria

species. Mycologia. 92: 665–673.

Thies, W.G.; Patton, R.F. 1966. Spot-plate technique 

for the bioassay of Cylindrocladium scoparium. 

Phytopathology. 56: 1116–1117. 

Thu, P.Q.; Griffiths, M.W.; Pegg, G.S.; McDonald, 

J.M.; Wylie, F.R.; King, J.; Lawson, S.A. 2010. 

Healthy plantations: a field guide to pests and 

pathogens of Acacia, Eucalyptus, and Pinus in 

Vietnam. Queensland Austrailia: Agri-Science 

Queensland, Department of Employment, Economic 

Development and Innovation. 124 p.

Vitale, A.; Polizzi, G. 2008. First record of leaf spots 

and stem lesions on Pistacia lentiscus caused by 

Cylindrocladium pauciramosum and C. scoparium in 

Italy. Plant Pathology. 57: 384.

Von Walbrunn, C.; Luftmann, H.; Bergander, K.; 

Meinhardt, F. 2001. Phytotoxic chaetoglobosins are 

produced by the plant pathogen Calonectria morganii

(anamorph Cylindrocladium scoparium). Journal of 

General and Applied Microbiology. 47(1): 33–38.

Reviewers’ comments: “In Malaysia, on seeds of Maesopsis eminii and Shorea roxburghii” (Su See Lee)

“Cy. reteaudii is a major foliar pathogen of eucalypts in 

areas of high humidity and frequent rainfall in SE Asia, particularly in Vietnam. Old KM, Wingfield MJ & Yuan ZQ. 

2003. A Manual of Diseases of Eucalyptus in South East 
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GENERAL TECHNICAL REPORT PSW-GTR-250

Asia. CIFOR, Bogor, Indonesia; Thu PQ et al. 2010. Healthy 

plantations. A field guide to pests and pathogens of Acacia, 

Eucalyptus and Pinus in Vietnam. DEEDI, Queensland, 

Australia.” (Su See Lee)

Response to comments: References for report on seeds 

in Malaysia added to text and bibliography. Reference 

for Cy. reteaudii on Acacia, Eucalyptus, and Pinus in 

Vietnam added.

Fomitiporia spp.

Assessor: Jessie A. Glaeser

Scientific names of pests: Fomitiporia australiensis M. 

Fisch., J. Edwards, Cunningt. & Pascoe, F. mediterranea

M. Fisch., F. punctata (Pilát) Murrill–species complex, F. 

robusta (P. Karst.) Fiasson & Niemelä–species complex, F. 

sonorae (Gilb.) Y.C. Dai.

F. australiensis, F. punctata, and F. robusta make 

up a cluster of sibling species with F. mediterranea that 

are genetically distinct but cannot be distinguished using 

traditional characters, including fruiting body macro- or 

microscopic morphology (Fischer 2000, Fischer et al. 2005). 

The taxonomy of Fomitiporia is largely unresolved with 

many new species being described by phylogenetic analysis 

from what used to be the F. punctata and F. robusta species 

complexes (Amalfi and Decock 2013, 2014; Amalfi et al. 

2012; Brazee 2013; Campos-Santana et al. 2013; Decock et 

al. 2005, 2007; Fischer 2006; Ota et al. 2014; Pollastro et al. 

2000; Terashima 2013; Vlasák and Kout 2011). Fomitiporia 

sonorae is a member of the F. robusta complex (Gilbertson 

and Ryvarden 1987). Because of this taxonomic uncertainty, 

the host lists and geographical distributions reported in the 

older literature are highly suspect. Three of these “species”—F. mediterranea, F. australiensis, and F. punctata—

have been associated with the white heart rot associated 

with esca disease of grapes (Vitis vinifera), in Australia and 

Europe. A pest risk assessment has been prepared for esca 

disease by the Centre for Agricultural Bioscience International (CABI 2011c). 

Scientific names of hosts: The genus Fomitiporia is 

widespread on conifers and hardwoods worldwide. Hosts 

that have been associated with F. australiensis and the F. 

punctata and F. robusta species complexes include:

Acacia spp. (wattle), Acer negudo (box elder), Actinidia 

chinensis (Chinese gooseberry), A. deliciosa (kiwi fruit), 

Celtis spp., Cornus mas (Cornelian cherry), Corylus spp., 

Dodonaea viscosa (hop bush), Eucalyptus spp., Fraxinus 

excelsior (European ash), Juniperus phoenicea (Phoenician 

juniper), Lagerstroemia indica (Indian crepe myrtle), 

Laurus nobilis (sweet bay), Ligustrum spp. (privet), Myoporum acuminatum (waterbush), Olea europaea (olive), Pinus 

halepensis (aleppo pine), Quercus spp. (oak), Rhamnus 

cathartica (common buckthorn), Robinia spp., Salix spp. 

(willow), Sorbus aucuparia (European mountain ash), Syringea vulgaris (lilac), Vitis vinifera (grapevine), Ulex spp. 

(gorse) (CABI 2011c, Decock et al. 2007, Farr and Rossman, 

n.d.; Fischer 2002, Fischer et al. 2005)

Distribution: Fomitiporia australiensis is limited to 

Australia and has been reported only on V. vinifera and 

Dodonaea viscosa (Fischer et al. 2005). Fomitiporia 

mediterranea is found on numerous hardwood hosts in 

Italy and southern Europe, but seems to be confined to V. 

vinifera throughout the rest of Europe. The F. punctata and 

F. robusta species complexes are widespread in tropical, 

semitropical, and temperate climates, and are polyphyletic, 

consisting of many undescribed and newly described 

species. Fomitiporia sonorae, reported as a possible root rot 

pathogen on D. viscosa in Arizona, is part of the F. robusta

species complex (Gilbertson and Ryvarden 1987). Fomitiporia punctata has been reported on Acacia in Portugal

and is cosmopolitan on Myoporum accuminatum (Farr and 

Rossman, n.d.). 

Summary of natural history and basic biology of 

the pests: These species of Fomitiporia, including those 

in the F. robusta and F. punctata species complexes, are 

strong white-rot fungi of both living and dead hardwoods. 

Fomitiporia sonorae is associated specifically with dead 
75

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

and dying D. viscosa and fruits at the base of dead and 

dying plants, suggesting that it could be a root rot pathogen 

(Gilbertson and Ryvarden 1987). Esca disease of grapes is 

the most economically important disease associated with 

Fomitiporia and has been the focus of most research on the 

basic biology of the pathogen (Fischer 2000). The fruiting 

bodies of Fomitiporia species are perennial and long lived 

(Fischer 2002). In Central Europe, spore production by F. 

mediterranea occurs throughout the year with maximum 

spore production occurring when average daily temperatures are above 10 °C. Fruiting body formation is preceded 

by a vegetative phase, where the fungus grows within the 

host for several years. Dispersal of the fungus is believed 

to be airborne, through the production of basidiospores. 

Genetic testing through the use of random amplified polymorphic DNA (RAPD) markers and somatic incompatibility 

types have revealed a large degree of genetic diversity of F. 

mediterranea within Italian vineyards, indicative of sexual 

reproduction, even when fruiting bodies were not observed 

in large numbers within the vineyard. That amount of 

genetic diversity did not indicate that the pathogen was 

spread by root grafts or pruning utensils. It is thought that 

other hosts outside of the vineyards could be the source of 

airborne spores (Cortesi et al. 2000, Fischer 2002) as these 

fungi have a broad host range. Basidiospores enter the tree 

through wounds. Decay is evident in the trunk and in the 

main branches and is usually associated with older plants. 

Mycelium and basidiospores may also survive in the soil 

(CABI 2011c). Fruiting bodies are resupinate (crust-like) and 

difficult to observe. They form on standing, mostly dead, 

plants or plant parts, and can persist on dead standing or 

fallen trees, stumps, or branches (Fischer 2002, Fischer and 

Kassemeyer 2003). Fomitiporia mediterranea is able to act 

as a primary pathogen. Artificial inoculations have resulted 

in white rot formation within 2 years at the infection site 

(Sparapano et al. 2000). The fungus can survive and be 

transmitted in the bark, stems, sapwood and heartwood of 

infected hosts, as well as infested soil (CABI 2011c).

Specific information relating to risk elements:

Pest risk assessments for root-, sapwood- and heart-rots 

(Kliejunas et al. 2001) and for esca disease (CABI 2011c) are 

available in the literature and were consulted in assessing 

risk elements.

A. Likelihood of introduction 

1. Pest with host-commodity at origin potential: High

(VC) (Applicable rating criteria, from app. 4: b, c, d, 

e, g, h) 

Root- and stem-rot fungi have a good chance of being 

present in the heartwood or sapwood when logs are harvested and could survive drying if kiln temperatures are 

not uniform during the drying process. They could also 

survive saprotrophically in wood chips and noncomposted 

mulch. Most stem decays are associated with older plants, 

so “Plants for Planting” seedlings are probably not an issue, 

although esca disease seems to be spreading throughout the 

world with the establishment of viticulture. Mycelium and 

spores could be present in soil.

2. Entry potential: High (VC) (Applicable rating criteria, from app. 4: b, c, d)

These fungi are capable of surviving saprotrophically 

and would remain viable during transport. They would 

be difficult to detect, especially if being transported in 

the mycelial stage within wood. Fruiting bodies are dark, 

resupinate, and difficult to observe.

3. Colonization potential: High (VC) (Applicable rating criteria, from app. 4: a, b, c)

To become established, the pathogen would have to 

fruit, and wind-dispersed basidiospores would need to find 

susceptible hosts. Many Fomitiporia species are distributed 

throughout tropical and subtropical areas and have broad 

host ranges, so conditions in Hawai‘i would favor fruiting 

and spore release from infected material.

4. Spread potential: High (VC) (Applicable rating criteria, from app. 4: a, b, c, d, f, g) 
76

GENERAL TECHNICAL REPORT PSW-GTR-250

Wind dispersal of spores is the common means of 

spread for most basidiomycete decay fungi. This has 

been demonstrated for Fomitiporia through genetic 

testing, which has shown that esca disease of grapes is 

spread by air dispersal of basidiospores rather than by 

root grafts or infected pruning tools. The disease has 

followed the establishment of viticulture throughout 

most countries where wine is produced. Eradication efforts 

are difficult, as the disease takes many years to become 

established and is often confused with other declines and 

saprotrophic wound decays.

B. Consequences of introduction

5. Economic damage potential: Moderate (VC) 

(Applicable rating criteria, from app. 4: a, b, c) 

These Fomitiporia species would threaten Hawai‘i 

native plants, including Dodonaea, Acacia, and Myoporum, 

which are important components of the native forest and 

also landscape trees. These fungi would also threaten the 

small Hawai‘i viticulture industry.

6. Environmental damage potential: High (VC) 

(Applicable rating criteria, from app. 4: b, c, d) 

The danger towards native Hawai‘i plant species is 

significant, resulting in direct impacts on those species 

(Acacia, Dodonaea, and Myoporum). These fungi have 

broad host ranges and could affect other trees in native 

forests and landscapes, thus indirectly affecting the health 

of native species. 

7. Social and political considerations: High (VC) 

(Applicable rating criteria, from app. 4: a, d) 

Damage from the organisms and subsequent death 

or decline of native Hawai‘i tree species would result 

in public concerns in aesthetics and recreation, as 

well as in urban plantings. Removal of affected trees 

would have limited acceptance by the public.

C. Pest risk potential: 

High (Likelihood of introduction = high; Consequences of introduction = high) 

Selected bibliography:

Amalfi, M.; Decock, C. 2013. Fomitiporia castilloi sp. nov. 

and multiple clades around F. apiahyna and F. texana

in Meso- and South America evidenced by multiloci 

phylogenetic inferences. Mycologia. 105: 873–887.

Amalfi, M.; Decock, C. 2014. Fomitiporia expansa, an 

undescribed species of French Guiana. Cryptogamie, 

Mycologie. 35: 73–85.

Amalfi, M.; Raymundo, T.; Valenzuela, R.; Decock, C. 

2012. Fomitiporia cupressicola sp. nov., a parasite on 

Cupressus arizonica, and additional unnamed clades 

in the southern USA and northern Mexico, determined 

by multilocus phylogenetic analyses. Mycologia. 104: 

880–893.

Brazee, N. 2013. Phylogenetic and differentiation analysis 

of the trunk rot pathogen Fomitiporia tsugina in North 

America. Forest Pathology. 43: 407–414.

Campos-Santana, M.; Amalfi, M.; Robledo, G.; Borges 

da Silveira, Decock, C. 2013. Fomitiporia neotropica, 

a new species from South America evidenced by 

multilocus phylogenetic analysis. Mycological Progress. 

doi:10.1007/s11557-013-0943–1.

Centre for Agricultural Bioscience International 

[CABI]. 2011c. Crop protection compendium: 

Fomitiporia mediterranea (esca disease). Wallingford, 

United Kingdom: CAB International. http://www.cabi.

org/cpc. (27 March 2013).

Cortesi, P.; Fischer, M.; Milgroom, M.G. 2000.

Identification and spread of Fomitiporia punctata

associated with wood decay of grapevine showing 

symptoms of esca. Phytopathology. 90: 967–972.
77

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Decock, C.; Bitew, A.; Castillo, G. 2005. Fomitiporia 

tenuis and Fomitiporia aethiopica (Basidiomycetes, 

Hymenochaetales), two undescribed species from 

the Ethiopian highlands: taxonomy and phylogeny. 

Mycologia. 97: 121–129.

Decock, C.; Figueroa, S.H.; Robledo, G.; Castillo, 

G. 2007. Fomitiporia punctata (Basidiomycota, 

Hymenochaetales) and its presumed taxonomic 

synonyms in America: taxonomy and phylogeny 

of some species from tropical/subtropical areas. 

Mycologia. 99: 733–752.

Farr, D.F.; Rossman, A.Y. [N.d.]. Systematic mycology 

and microbiology [Database]. http://nt.ars-grin.gov/

fungaldatabases/. (19 June 2014).

Fischer, M. 2000. Grapevine wood decay and lignicolous 

basidiomycetes. Phytopathologia Mediterranea. 39: 

100–106.

Fischer, M. 2002. A new wood-decaying basdiomycete 

species associated with esca of grapevine: Fomitiporia

mediterranea (Hymenochaetales). Mycological Progress. 

1: 315–324.

Fischer, M. 2006. Biodiversity and geographic distribution 

of basidiomycetes causing esca-associated white rot in 

grapevine: a worldwide perspective. Phytopathologia 

Mediterranea. 45: S30–S42.

Fischer, M.; Edwards, J.; Cunnington, J.H.; Pascoe, 

I.G. 2005. Basidiomycetous pathogens on grapevine: a 

new species from Australia—Fomitiporia australiensis. 

Mycotaxon. 92: 85–96.

Fischer, M.; Kassemeyer, H.H. 2003. Fungi associated 

with esca disease of grapevine in Germany. Vitis. 42: 

109–116.

Gilbertson, R.L.; Ryvarden, L. 1987. North American 

polypores. Oslo: Fungiflora. 885 p. Vol. 2

Kliejunas, J.T.; Tkacz, B.M.; Burdsall, H.H., Jr.; 

DeNitto, G.A.; Eglitis, A.; Haugen, D.A.; Wallner, 

W.E. 2001. Pest risk assessment of the importation 

into the United States of unprocessed Eucalyptus logs 

and chips from South America. Gen. Tech. Rep. FPLGTR-124. Madison, WI: U.S. Department of Agriculture, 

Forest Service, Forest Products Laboratory. 134 p.

Ota, Y.; Hattori, T.; Nakamura, H.; Terashima, Y.; 

Lee, S.; Miyuki, Y.; Sotome, K. 2014. Taxonomy and 

phylogenetic position of Fomitiporia torreyae, a causal 

agent of trunk rot on Sanbu-sugi, a cultivar of Japanese 

cedar (Cryptomeria japonica) in Japan. Mycologia. 106: 

66–76.

Pollastro, S.; Abbatecola, A.; Dongiovanni, C.; Faretra, 

F. 2000. Use of molecular markers (PCR-RAPD) for 

studying genetic variability in Phellinus (Fomitiporia) 

sp. Phytopathologia Mediterranea. 39: 107–111.

Sparapano, L.; Bruno, G.; Ciccarone, C.; Graniti, A. 

2000. Infection of grapevines by some fungi associated 

with esca. I. Fomitiporia punctata as a wood-rot inducer. 

Phytopathologia Mediterranea. 39: 46–52.

Terashima, U. 2013. Influence of stem rot pathogen 

Fomitiporia sp. on “Sanbu-sugi” cultivar of the Japanese 

cedar Cryptomeria japonica. Journal of Wood Science. 

59: 80–87.

Vlasák, J.; Kout, J. 2011. Pileate Fomitiporia species in 

the USA. New combinations Fomitiporia calkinsii and F. 

bakeri. Mycological Progress. 10: 445–452.

Reviewers’ comments: “The table presentation (as used 

in tables [10] and [11]) showing distribution and reference 

attached per species is helpful.” (DJE338).

Response to comments: The description of distribution and 

hosts of Fomitiporia species was kept in a textual format. 

Many of the described species are actually polyphyletic 

species complexes that will be changing as more research is 

conducted on this genus.
78

GENERAL TECHNICAL REPORT PSW-GTR-250

Guava Rust/Eucalyptus Rust

Assessor: Phil Cannon

Scientific names of pest: Puccinia psidii Winter (anamorph 

= Uredo psidii)

Synonyms/ variants of the P. psidii sensu lato complex: 

Aecidium glaziovii P. Henn., Bullaria psidii G. Winter 

(Arthur & Mains), Caeoma eugeniarum Link, Puccina 

grumixamae Rangel, P. rochaei Putt., P. actinostemonis

H.S. Jackson & Holway, P. barbacensis Rangel, P. brittoi

Rangel, P. camargoi Putt., P. cambucae Putt., P. eugeniae

Rangel, P. jambolana Rangel, P. jambosae P. Henn., P. 

neurophila Speg., Uredo cambucae P. Henn., U. eugeniarum P. Henn., U. flavidula Wint., U. goeldiana P. Henn., 

U. myrciae Mayor, U. myrtacearum Paz., U. neurophila

Speg., U. puttemansii P. Henn., U. rangelii J.A. Simpson, 

K. Thomas & C.A. Grgurinovic, U. rochaei Putt., U. seclua

H.S. Jackson & Holway

Scientific names of hosts: About 130 species in 45 genera 

of the family Myrtaceae (including the former Heteropyxidaceae) are hosts for P. psidii (Carnegie and Lidbetter 2012, 

Clark 2011, Simpson et al. 2006). All genera in the family 

are potentially susceptible (Old et al. 2003). Some economically or environmentally important genera with species 

affected by the rust include Eucalyptus (eucalypts), Eugenia 

(Surinam cherry; others, including the endangered Eugenia 

koolauensis), Melaleuca (paperbark tree), Metrosideros

(‘ōhi‘a lehua), Myrciaria (jaboticaba), Pimenta (allspice), 

Psidium (guava), Syzygium (rose apple).

Distribution: First reported in 1884 on guava in Brazil 

(Winter 1884), the rust has since been detected in other 

South America countries (Argentina, Colombia, Paraguay, 

Uruguay (Telachea et al. 2003), Venezuela); Central 

America (Costa Rica and Panama); the Caribbean (Cuba, 

Dominica, Dominican Republic, Jamaica [MacLachan 

1938] Puerto Rico, Trinidad and Tobago, Virgin Islands); 

Mexico (Gallegos and Cummins 1981); the United States 

including Florida [Marlatt and Kimbrough 1979], California 

[Zambino and Nolan 2011], and Hawai‘i [Uchida et al. 

2006]); and most recently Australia (Carnegie et al. 2010), 

Japan (Kawanishi et al. 2009), and South Africa (Roux et 

al. 2013). It has been reported once in Taiwan (Wang 1992) 

but has not been found there since. Very recently it has been 

found in New Caledonia (Giblin 2013).

Summary of natural history and basic biology of 

the pests: Puccinia psidii is an autoecious, macrocyclic 

rust fungus that infects plants of the family Myrtaceae. 

Evidence of host specialization exists within the pathogen, 

so isolates from one host genus may or may not infect other 

genera within Myrtaceae (Old et al. 2003). Many variants 

have been recognized and collectively are known as the P. 

psidii sensu lato (s.l.) complex (Carnegie et al 2010). The 

complex includes the newly described taxon Uredo rangelii, 

which was detected in Australia in April 2010. 

Under natural conditions, P. psidii produces abundant 

urediniospores, with teliospores and basidiospores being 

relatively rare. Aecia and aeciospores are morphologically 

identical to the uredinia and urediniospores (Glen et al. 

2007). The dominant phase of the life cycle is the production of uredinia and urediniospores, with the urediniospores 

being responsible for aerial spread and infection. The 

urediniospores infect young tissues of new leaves, fruits, 

flowers, shoots, and succulent twigs. Infection first appears 

as chlorotic specks that develop into uredinial pustules, 

which produce yellow masses of urediniospores. The 

uredial pustules—pale yellow to yellow-orange dusty spots, 

0.1 to 0.5 mm in diameter—often coalesce, and parts of the 

plant can be completely covered with pustules (Liberato et 

al. 2006). Uredinia occur mostly on the underside of leaves, 

on stems, and on flowers and fruit. Urediniospores are 

globose and ellipsoid to ovoid in shape, measuring 19 to 27 

by 15 to 26 μm. The spore cell walls are echinulate, hyaline 

to yellowish in color, and 1.5 to 2.5 μm thick with germ 

pores obscure (Hernández 2006).

Urediniospore germination and infection are affected 

by temperature, leaf wetness, light intensity, and photoperiod (Ruiz et al. 1989). Temperatures in the range of 15 to 25 

°C favor infection (Carvalho et al. 1994, Ruiz et al. 1989). 

High humidity or leaf wetness and low light for a minimum 

of 6 hours following inoculation are necessary for successful germination and infection (Piza and Ribeiro 1988, Ruiz 

et al. 1989). 
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

The rust pathogen causes deformation of leaves, defoliation of branches, dieback, stunted growth, and sometimes 

death. Puccinia psidii s.l. has caused severe damage in some 

years on Pimenta dioica (allspice) in Jamaica (MacLachlan 

1938), Eucalyptus grandis (Junghans et al. 2003) and Psidium guajava (guava) in Brazil (Ribeiro and Pommer 2004), 

Syzygium jambos (rose apple) in Hawai‘i (Uchida and Loope 

2009), and Melaleuca quinquenervia in Florida (Rayachhetry et al. 1997). Several races or biotypes of P. psidii

exist, differing in host specificity, environmental tolerances, 

characteristics of sporulation and spore survival, and 

virulence (Glen et al. 2007, MacLachlan 1938, Marlatt and 

Kimbrough 1979). Studies by Costa da Silva et al. (2014) 

have demonstrated that these different strains of P. psidii

can have remarkably different levels of pathogenicity on a 

given host species such as Metrosideros polymorpha. Based 

on analysis of microsatellite markers, P. psidii populations 

from South America are distinct from the rust populations 

that became established in California and Hawai‘i, suggesting that the Hawai‘i and California isolates did not come 

directly from South America (Graça et al. 2011b).

Quarantine restrictions are the most effective means 

of preventing introductions of potentially virulent strains 

of Puccinia psidii (Loope and La Rosa 2008). In 2007, the 

Hawai‘i State Board of Agriculture passed an interim rule, 

which banned any plant or plant products of the Myrtaceae 

family from California, Florida, and South America that 

could be disease hosts; the ban expired, however, 1 year 

later (Loope 2010). A long-term rule is in development. 

The ban includes any plants of the Myrtaceae family (GISD 

2010b).

Specific information relating to risk elements:

A. Likelihood of introduction

1. Pest with host-commodity at origin potential: High 

(VC) (Applicable rating criteria, from app. 4: a, b, c, 

d, e, g, h)

The rust has a wide host range, and can infect basically 

any part of the aerial parts of a myrtaceous plant, including 

succulent tissue in leaves, flowers, and small-diameter 

branches. It does not colonize seed, but it can infect 

capsules; seed produced on eucalypts may have chance 

contamination with infections that might be taking place on 

the same or neighboring trees from where the seed collections take place.

2. Entry potential: High (VC) (Applicable rating criteria, from app. 4: a, b, c, d) 

Recent introductions of the rust to Australia, California, Florida, Hawai‘i, and Japan are evidence that the biological characteristics of P. psidii make it a pathogen easily 

moved to new environments. The most dangerous pathway 

for spread of the pathogen to a new region is by germplasm, 

including rooted cuttings and other vegetatively propagated 

trees, seed, and pollen (Old et al. 2003). In 2007, P. psidii 

arrived in Japan, on Metrosideros polymorpha cuttings 

imported from Hawai‘i. The likelihood of this fungus being 

introduced on a living seedling of the family Myrtaceae or a 

recently cut branch or flower would be high.

3. Colonization potential: High (VC) (Applicable rating criteria, from app. 4: a, b, c, e)

The potential for P. psidii to colonize new hosts in 

Hawai‘i has already been demonstrated. One introduction 

of the pathogen into Honolulu resulted in spread to, and 

colonization of, hosts on all of the major islands within 6 

months (Killgore and Heu 2007). The moist tropical and 

montane tropical climate of Hawai‘i is an ideal environment 

for P. psidii infection. 

4. Spread potential: High (RC) (Applicable rating criteria, from app. 4: a, b, c, d, e, f)

The occurrence of numerous Myrtaceae in Hawai‘i, 

the rust’s known ability for natural spread, and its high 

reproductive potential would result in a high spread potential. The current strain of the rust in Hawai‘i has spread to 

all parts of the state that have a favorable environment for 

infection.

B. Consequences of introduction

5. Economic damage potential: High (RC) (Applicable 

rating criteria, from app. 4: a, c. d, e, f)
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GENERAL TECHNICAL REPORT PSW-GTR-250

Currently, only a single P. psidii genotype has been 

found in Hawai‘i; introduction of new P. psidii genotypes to 

Hawai‘i represents an additional threat to native and exotic 

myrtaceous species by potentially increasing the host range 

and the severity of the disease. 

There are many species of Myrtaceae in Hawai‘i 

(about 80) and, so far, 37 of these have shown that they are 

susceptible, at least to some degree, to the strain of P. psidii

currently in Hawai‘i. One species, Syzygium jambos, an 

invasive species that occupies tens of thousands of hectares 

in the Hawai‘i Islands, is exceptionally vulnerable to this 

strain of the rust; especially on the more humid sides of the 

Hawai‘i Islands. The endangered Eugenia koolauensis has 

also shown a high vulnerability to this strain of the rust. 

Fortunately, most other Myrtaceous species—including 

Metrosideros polymorpha, which is very widely distributed 

in Hawai‘i and comprises about 80 percent of the native 

forests—have shown only a slight susceptibility to this 

strain of the rust.

This situation could change substantially if other 

strains of the rust were introduced into Hawai‘i. Costa da 

Silva et al. (2014) have shown that some of these strains can 

be especially virulent on M. polymorpha under environmental conditions favorable for the development of the fungus.

There is probably very little financial loss that would 

occur directly as a result of having less lumber being 

produced from ‘ōhi‘a lehua trees; this species is not used 

significantly for wood products, in part because only a very 

small percentage of its trees reach merchantable dimensions; however, a massive loss of ‘ōhi‘a lehua trees, which 

currently comprise about 80 percent of all trees in Hawai‘i’s 

native forests, could have some very unfortunate environmental consequences (see next section), and some of these 

could be costly. 

6. Environmental damage potential: High (MC) 

(Applicable rating criteria, from app. 4: a, b, c, f)

Eucalyptus rust threatens to disrupt ecosystems by 

causing damage to dominant forest trees, such as the ‘ōhi‘a 

lehua in Hawai‘i. The ‘ōhi‘a lehua tree is a cornerstone species in the natural forests of Hawai‘i and most of the islands 

native fauna have evolved to live in these ‘ōhi‘a lehua 

forests. Outbreaks of P. psidii, which affect these dominant 

trees could result in significant changes to the structure, 

composition, and potentially, the function, of forests on a 

landscape level. This would likely affect the biodiversity of 

other flora and fauna in these ecosystems (Loope and La 

Rosa 2008).

7. Social and political considerations: High (MC) 

(Applicable rating criteria, from app. 4: a, b, c)

Presence of the current strain of P. psidii in Hawai‘i has 

affected export of hosts to countries where the rust is not 

yet present. Occurrence of additional strains would increase 

public concern and export restrictions.

C. Pest risk potential:

High (Likelihood of introduction = high; Consequences of introduction = high) 

Selected bibliography:

Booth, T.H.; Old, K.M.; Jovanovic, T. 2000. A 

preliminary assessment of high risk areas for Puccinia 

psidii (Eucalyptus rust) in the Neotropics and Australia. 

Agriculture, Ecosystems and Environment. 82: 295–301.

Cannon, P.G.; Alfenas, A.C.; Britton, K.O. 2009.

Understanding the potential of guava rust (Puccinia 

psidii) to destroy a myrtaceous tree, ohia (Metrosideros 

polymorpha), in Hawaii. Bulletin No. 233. Rotorua, 

New Zealand: New Zealand Forest Research Institute: 

213–214.

Carnegie, A.J.; Cooper, K. 2011. Emergency response to 

the incursion of an exotic myrtaceous rust in Australia. 

Australasian Plant Pathology. 40: 346–359.

Carnegie, A.J.; Lidbetter, J.R. 2012. Rapidly expanding 

host range for Puccinia psidii sensu lato in Australia. 

Ausralasian Plant Pathology. 41: 13–29. 

Carnegie, A.J.; Lidbetter, J.R.; Walker, J.; Horwood, 

M.A.; Tesoriero, L.; Glen, M.; Priest, M.J. 2010.

Uredo rangelii, a taxon in the guava rust complex, newly 

recorded on Myrtaceae in Australia. Australasian Plant 

Pathology. 39: 463–466.
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Carvalho, A.O.; Alfenas, A.C.; Maffia, L.A.; Carmo, 

M.G.F. 1994. Avaliação do progresso da ferrugem 

(Puccinia psidii) em brotações de Eucalyptus cloeziana

no sudeste da Bahia, de 1987 a 1989. Revista Árvore. 

18: 265–274.

Clark, S. 2011. Risk analysis of the Puccinia psidii/guava 

rust fungal complex (including Uredo rangelii/myrtle 

rust) on nursery stock. Wellington, New Zealand: 

Ministry of Agriculture and Forestry, Biosecurity Risk 

Analysis Group. 60 p. http://www.biosecurity.govt.nz/

files/regs/imports/risk/puccinia-psidii-on-nursery-stockra.pdf. (13 August 2013).

Costa da Silva, A.; Magno Teixeira de Andrade, P.; 

Costa da Silva, A.; Alfenas, A.C.; Graça, R.N.; 

Cannon, P.; Hauff, R.; Ferreira, D.C.; Mori, S. 2014. 

Virulence and impact of Brazilian strains of Puccinia 

psidii on Hawaiian ‘ohia (Metrosideros polymorpha). 

Pacific Science. 68: 47–56.

Coutinho, T.A.; Wingfield, M.J.; Alfenas, A.C.; Crous, 

P.W 1998. Eucalyptus rust: a disease with the potential 

for serious international implications. Plant Disease. 82: 

819–825.

Gallegos, M.L.; Cummins, G.B. 1981. Uredinales (royas) 

de Mexico. Instituto Nacional de Investigaciones 

Agrícoles. Culiacan, Sinaloa, Mexico. 400 p. Vol. 2.

Giblin, F. 2013. Myrtle rust report: New Caledonia. 

Assessment of myrtle rust situation in New Caledonia. 

Maroochydore, Queensland, Australia: University of the 

Sunshine Coast. 18 p.

Glen, M.; Alfenas, A.C.; Zauza, E.A.V.; Wingfield, 

M.J.; Mohammed, C. 2007. Puccinia psidii: a threat 

to the Australian environment and economy—a review. 

Australasian Plant Pathology. 36: 1–16.

Global Invasive Species Database [GISD]. 2010b. 

Puccinia psidii (fungus). http://www.issg.org/database/

species/ecology.asp?si=1538&fr=1&sts=&lang=EN. (18 

December 2013).

Graça, R.N.; Alfenas, A.C.; Ross-Davis, A.L.; 

Klopfenstein, N.B.; Kim, M.S.; Peever, T.L.; Cannon, 

P.G.; Uchida, J.Y.; Kadooka, C.Y.; Hauff, R.D. 2011a. 

Multilocus genotypes indicate differentiation among 

Puccinia psidii populations from South America and 

Hawaii. In: Fairweather, M.L.; Palacios, P., comps. 

Proceedings of the 58th western international forest 

disease work conference. Flagstaff, AZ: U.S. Department 

of Agriculture, Forest Service, Forest Health Protection. 

Graça, R.N.; Ross-Davis, A.; Klopfenstein, N.; Kim, 

M.; Peever, T.; Cannon, P.; Uchida, J.; Alfenas, 

A.C. 2011b. Tracking down worldwide Puccinia psidii

dispersal. BMC Proceedings. 5(Suppl. 7): 14.

Hernández, J.R. 2006. Invasive fungi. Puccinia psidii. 

Belstville, MD: U.S. Department of Agriculture, 

Agricultural Research Service, Systematic 

Mycology and Microbiology Laboratory. http://

nt.ars-grin.gov/taxadescriptions/factsheets/index.

cfm?thisapp=Pucciniapsidii. (26 March 2013).

Junghans, D.T.; Alfenas, A.C.; Brommonschenkel, S.H.; 

Oda, S.; Mello, E.J.; Grattapaglia, D. 2003. Resistance 

to rust (Puccinia psidii Winter) in eucalyptus: mode of 

inheritance and mapping of a major gene with RAPD 

markers. Theoretical Applied Genetics. 108: 175–180. 

Kadooka, C.Y. 2010. Current molecular characterization 

and disease management results for Puccinia psidii,

the ‘öhi‘a rust. In: Cram, M., ed., Proceedings of the 

7th meeting of IUFRO Working Party 7.03-04. Forest 

Health Protection Report 10-01-01. Atlanta, GA: U.S. 

Department of Agriculture, Forest Service, Southern 

Region: 48–54.

Kawanishi, T.; Uematsu, S.; Kakishima, M.; Kagiwada, 

S.; Hamamoto, H.; Horie, H.; Namba, S. 2009. First 

report of rust disease on ohia and the causal fungus, 

Puccinia psidii, in Japan. Journal of General Plant 

Pathology. 75: 428–431.

Killgore, E.M.; Heu, R.A. 2007. ‘Öhi‘a rust, Puccinia 

psidii Winter. New Pest Advisory No. 05-04. Honolulu, 

HI: Hawai‘i Department of Agriculture.
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Kim, M.S.; Alfenas, A.C.; Peever, T.L.; Cannon, P.G.; 

B. 2010a. Toward understanding genetic relationships 

among populations of guava rust (Puccinia psidii): 

an invasive pathogen of native Hawaiian forests and a 

potential threat to eucalypts world-wide [Poster]. In:

Fairweather, M.L.; Palacios, P., comps. Proceedings 

of the 58th western international forest disease work 

conference. Flagstaff, AZ: U.S. Department of 

Agriculture, Forest Service, Forest Health Protection. 

Langrell, S.R.H.; Glen, M.; Alfenas, A.C. 2008.

Molecular diagnosis of Puccinia psidii (guava rust): a 

quarantine threat to Australian eucalypt and Myrtaceae 

biodiversity. Plant Pathology. 57: 687–701.

Liberato, J.R.; Silveira, S.F.; Junghans, D.T.; Rocabado, 

J.A.; Aparecido, C.C.; Shivas, R.G. 2006. Eucalyptus 

rust (Puccinia psidii). PaDIL (Plant and Disease Image 

Library), Australian Biosecurity (updated on 8/13/2012). 

http://www.padil.gov.au/pests-and-diseases/pest/

main/136599. (4 August 2013).

Loope, L.L. 2010. A summary of information on the rust 

Puccinia psidii Winter (guava rust) with emphasis on 

means to prevent introduction of additional strains to 

Hawaii. Open-File Report 2010-1082. Reston, VA: U.S. 

Department of the Interior, Geological Survey. 31 p. 

http://pubs.usgs.gov/of/2010/1082/. (4 August 2013).

Loope, L.; La Rosa, A.M. 2008. An analysis of the risk 

of introduction of additional strains of the rust Puccinia 

psidii Winter (‘öhi‘a rust) to Hawai‘i. Open File Report 

2008-1008. Reston, VA: U.S. Department of the Interior 

Geological Survey. 11 p. 

Loope, L.; La Rosa, A.M. 2010. Protecting Hawai‘i’s 

forests from harm: an argument for strong measures to 

prevent arrival of pests of Hawai‘i’s myrtle family. In: 

Cram, M., ed., Proceedings of the 7th meeting of IUFRO 

Working Party 7.03- 04. Forest Health Protection Report 

10-01-01. Atlanta, GA: U.S. Department of Agriculture, 

Forest Service, Southern Region: 2–15.

MacLachlan, J.D. 1938. A rust of the pimento tree in 

Jamaica, BWI. Phytopathology. 28: 157–170.

Marlatt, R.B.; Kimbrough, J.W. 1979. Puccinia psidii on 

Pimenta dioica in South Florida. Plant Disease Reporter. 

63: 510–512.

Okada, C.; Loope, L.; Hauff, R. 2011. A rule 

designed to protect ‘öhi‘a forests by preventing 

new strains of Puccinia psidii from establishing 

in Hawai‘i: rationale, process, and implications. 

Hawai‘i conservation conference. http://hawaii.

conference-services.net/reports/template/

onetextabstract.xml?xsl=template/onetextabstract.

xsl&conferenceID=2468&abstractID=512332. (13 

August 2013).

Old, K.M.; Wingfield, M.J.; Yuan, Z.Q. 2003. A manual 

of diseases of eucalypts in South-East Asia. Bogor, 

Indonesia: Center for International Forestry Research. 

98 p.

Piza, S.M.; Ribeiro, I.J.A. 1988. Influence of light and 

temperature on uredospore germination of Puccinia 

psidii Winter. Bragantia. 47: 75–78.

Rangel, E. 1916. Contribucao para o estudo das Puccinias 

das Myrtaceas. Archivos do Museo Nacional do Rio de 

Janeiro. 18: 149–158.

Rayachhetry, M.B.; Elliott, M.L.; Van, T.K. 1997.

Natural epiphytotic of the rust Puccinia psidii on 

Melaleuca quinquenervia in Florida. Plant Disease. 

81: 831.

Ribeiro, I.J.A.; Pommer, C.V. 2004. Breeding guava 

(Psidium guajava) for resistance to rust caused by 

Puccinia psidii. Acta Horticulturae. 632: 75–78.

Roux, J.; Greyling, I.; Coutinho, T.A.; Verleur, M.; 

Wingfield, M.J. 2013.The myrtle rust pathogen, 

Puccinia psidii, discovered in Africa. IMA Fungus. 

4(1): 155–159.

Ruiz, R.A.R.; Alfenas, A.C.; Ferreira, F.A. 1989. Effect 

of temperature, light and inoculum source on telioscopic 

and urediniospore production of Puccinia psidii.

Fitopatologia Brasileira. 14: 7–73.
83

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Simpson, J.A.; Thomas, K.; Grgurinovic, C.A. 2006.

Uredinales species pathogenic on species of Myrtaceae. 

Australasian Plant Pathology. 35: 546–562.

Telechea, N.; Rolfo, M.; Coutinho, T.A.; Wingfield, 

M.J. 2003. Puccinia psidii on Eucalyptus globulus in 

Uruguay. Plant Pathology. 52: 26.

Uchida, J.Y.; Loope, L.L. 2009. A recurrent epiphytotic of 

guava rust on rose apple, Syzygium jambos, in Hawaii. 

Plant Disease. 93: 429.

Uchida, J.; Zhong, S.; Killgore, E. 2006. First report of 

a rust disease on ‘öhi‘a caused by Puccinia psidii in 

Hawaii. Plant Disease. 90: 524.

Wang, W.-y. 1992. Survey of Eucalyptus diseases in 

Taiwan. Bulletin of the Taiwan Forest Research Institute. 

New Series 7: 179-194. In: Keane, P.J.; Kile, G.A.; 

Podger, F.D.; Brown, B.N., eds. 2000. Diseases and 

pathogens of eucalypts. Collingwood, VT, Australia: 

CSIRO Publishing. 241 p.

Winter G. 1884. Repertorium. Rabebhorstii fungi europaei 

et extraeuropaei exsiccate cura. Dr. G. Winter, Centuria 

XXXI. Hedwigia. 23: 164–172.

Zambino, P.J.; Nolan, P.A. 2011. First report of a rust 

caused by Puccinia psidii on paperbark, Melaleuca 

quinquernervia, in California. Plant Disease. 95(10): 

1314. 

Zauza, E.A.V.; Alfenas, A.C.; Old, K.; Couto, M.M.F.; 

Graça, R.N.; Maffia, L.A. 2010. Myrtaceae species 

resistance to rust caused by Puccinia psidii. Australasian 

Plant Pathology. 39: 406–411.

Zhong, S.; Yang, B.; Alfenas, A.C. 2007. Development 

of microsatellite markers for the guava rust fungus, 

Puccinia psidii. Molecular Ecology Resources. 8: 

348–350.

Reviewers’ comments: “Most recent report is 

from Africa.”

Response to comments: The 2013 citation for report in 

South Africa was added, as was a report of the pathogen in 

New Caledonia.

Pestalotia and Pestalotiopsis

Assessor: Gregg DeNitto

Scientific names of pests: see table 9

Scientific names of hosts: see table 9

Distribution: see table 9

Summary of natural history and basic biology of 

the pests: Pestalotia and Pestalotiopsis contain numerous 

species of pathogens, endophytes, and saprophytes; however, the taxonomy of the species and of the two genera is 

poorly understood and under debate (Maharachchikumbura 

et al.2011). There is differing mycological opinion whether 

these genera are distinct (Maharachchikumbura et al. 2011). 

Pestalotiopsis is a common genus on a wide range of hosts 

in tropical and temperate climates (Maharachchikumbura et 

al. 2011, Yang et al. 2012). 

When these species occur as pathogens they commonly 

affect leaves or fruit. They cause leaf blights and spotting 

and fruit rot. Often fruit rot occurs postharvest during 

storage and transport (Kwon et al.2004). They are usually 

considered weak pathogens, often found on stressed or 

weakened host plants (Pirone 1978). 

A sexual stage for many of these species has not been 

identified. Initial infection usually occurs from conidia 

contact with the host. Secondary infections can occur and 

increase disease severity. Conidia disperse in the air and 

in rain splash. Maharachchikumbura et al. (2011) provide a 

generalize disease cycle for Pestalotiopsis. Pestalotia likely 

has a similar life cycle.

Specific information relating to risk elements:

A. Likelihood of introduction

1. Pest with host-commodity at origin potential: High 

(VC) (Applicable rating criteria, from app. 4: b, c, d, 

e, g, h) 

Many of the species of Pestalotia and Pestalotiopsis

have a wide host range and are usually found associated 

with foliage and other nonwoody green tissue. They are 

among the most commonly isolated endophytic fungi of 

tropical plants (Yang et al. 2012). These same authors state 

that, globally, Pestalotiopsis may represent one of the largest biomasses of any plant-associated endophytic fungus. 
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GENERAL TECHNICAL REPORT PSW-GTR-250

Table 9 —Hosts, country of origin, and citations, for Pestalotia and Pestalotiopsis species 

of concern (continued)

Pathogen Host(s) Country of origin Citation

Pestalotia acaciae

Thüm. (Xylariales: 

Amphispaeriaceae)

Acacia crassicarpa, A. longifolia, A. 

comosus, Chamaecyparis pisifera, 

Cucumis sativus, Diospyros kaki, 

Durio zibethinus, Musa spp., Pachira 

macrocarpa, Pinus thunbergii, 

Quercus glauca

Australia, China, Japan, 

Philippines, Portugal

Farr and Rossman, n.d.

Pestalotia angustata (Pers.) 

Arx (syn. Truncatella 

angustata (Pers.) S. 

Hughes)

Vaccinium spp. Chile Espinoza et al. 2008

Pestalotia cibotii R.P. 

White (Xylariales: 

Amphisphaeriaceae)

Cibotium schiedei, Araucaria imbricata, 

Illicium verum

United States (New 

Jersey), China, 

Scotland

White 1935

Pestalotia diospyri Syd. & P. 

Syd. (syn. Pestalatiopsis 

diospyri (Syd. & P. Syd.) 

Rib.) Souza (Xylariales: 

Amphisphaeriaceae)

Diospyros chinensis, D. kaki, D. 

kaki var. domestica, D. peregrina, 

Euonymus alatus, E. japonicus, 

E. sieboldianus, Podocarpus 

macrophyllus, Rhus javanica, R. 

javanica var. roxburghii, Smilax china

China, India, Japan, 

Korea, Spain

Blanco et al. 2008; Farr 

and Rossman, n.d.; 

Kobayashi 2007

Pestalotia dodonaea 

Canonaco (Xylariales: 

Amphisphaeriaceae)

Dodonaea viscosa Eritrea, Ethiopia Farr and Rossman, n.d. 

Pestalotia pandani

Verona (Xylariales: 

Amphisphaeriaceae)

Pandanus tectorius, P. tessellatus, P. 

pedunculatus var. stradbrookeensis, 

P. pedunculatus f. lofuensis, P. 

odoratissimus

Taiwan, Cook Islands, 

Australia, Loyalty 

Islands

Farr and Rossman, n.d.; 

McKenzie and Hyde 

1996 

Pestalotia vaccinii (Shear) 

Guba (Xylariales: 

Amphisphaeriaceae)

Vaccinium angustifolium, V. ashei, 

V. australe, V. corymbosum, V. 

macrocarpon, Vaccinium sp., V. 

stamineum

New Zealand, United 

States (Maine, 

Michigan), Latvia

Farr and Rossman, n.d.; 

Vilka et al. 2009

Pestalotiopsis

sp. (Xylariales: 

Amphisphaeriaceae)

Scaevola hainanensis Hong Kong Farr and Rossman, n.d.

Pestalotiopsis 

breviseta (Sacc.) 

Steyaert (Xylariales: 

Amphisphaeriaceae)

Vaccinium ashei, Viburnum awabuki, 

Diospyros kaki var. domestica, 

Podocarpus macrophyllus, Prunus 

tomentosa, Rhaphiolepis umbellata, 

Rhododendron ponticum, Arenga 

engleri, Celastrus orbiculatus, Cercis 

chinensis, Trochodendron aralioides

Japan, United States, 

Russia, Italy

Farr and Rossman, n.d.; 

Kobayashi 2007 
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Table 9 —Hosts, country of origin, and citations, for Pestalotia and Pestalotiopsis species 

of concern (continued)

Pathogen Host(s) Country of origin Citation

Pestalotiopsis clavispora 

G.F. Atk. (Xylariales: 

Amphisphaeriaceae)

Vaccinium spp. Chile Espinoza et al. 2008

Pestalotiopsis glandicola 

(Castagne) Steyaert (syn. 

Robillarda glandicola 

Cast.; Pestalotia 

glandicola (Castagne) 

Guba) (Xylariales: 

Amphisphaeriaceae)

Diospyros kaki, Pandanus tectorius, 

Quercus ilex, Q. acuta, Mangifera 

indica, Vaccinium oldhamii; 

numerous others

China, India, Japan, 

Bangalore

Farr and Rossman, n.d.; 

Kobayashi 2007; 

Ullasa and Rawal 

1989; Yasuda et al. 

2003 

Pestalotiopsis neglecta Vaccinium spp. Chile Espinoza et al. 2008

Pestalotiopsis 

palmarum (Cooke) 

Steyaert (Xylariales: 

Amphisphaeriaceae)

Pandanus whiteanus American Samoa Brooks 2006

Pestalotiopsis photiniae

(Thüm.) Y.X. 

Chen (Xylariales: 

Amphisphaeriaceae)

Acer palmatum, Camellia japonica, C. 

sasanqua, C. sinensis, Dendrobium 

devonianum, D. thyrsiflorum, Fragaria 

spp., Photinia glabra, P. serrulata, 

Pinus massoniana, Podocarpus 

macrophyllus, P. nagi, Roystonea 

regia, Taxus chinensis, Vaccinium 

angustifolium, Vaccinium spp.

Australia, China, Japan, 

Korea, Viet Nam

Farr and Rossman, n.d.

Pestalotiopsis theae

(Sawada) Steyaert 

(syn. Pestalotia theae

Sawada) (Xylariales: 

Amphisphaeriaceae)

Diospyros kaki, D. kaki var. domestica, 

Diospyros sp., D. samoensis, Camelia 

sinensis, Illicium religiosum, Turpinia 

ternate; numerous hosts

Asia, Australia, Europe, 

USSR, Africa, South 

America

Farr and Rossman, n.d.; 

Kobayashi 2007; 

Watson 1971 

Pestalotiopsis uvicola

(Speg.) Bisset (Xylariales: 

Amphisphaeriaceae)

Metrosideros kermadecensis Italy Grasso and Granata 

2008

Pestalotiopsis 

versicolor (Speg.) 

Steyaert (Xylariales: 

Amphisphaeriaceae)

Pandanus tectorius, Tamarindus indica, 

Acacia melanoxylon, Oryza sativa, 

Musa sp., Jatropha curcas, Mangifera 

indica; numerous hosts

Europe, Australia, South 

America, Central 

America, Asia, 

Africa, Papua New 

Guinea, Solomon 

Islands, Caribbean 

Islands

Farr and Rossman, n.d. 
86

GENERAL TECHNICAL REPORT PSW-GTR-250

It is probable that inoculum can increase rapidly through 

secondary infections when environmental conditions are 

met. Once infection occurs, these fungi can survive easily 

within host tissue; conidia can survive during harsh weather 

conditions (Maharachchikumbura et al. 2011). Likely 

pathways for introduction include cut foliage, live plants, 

fruit, and live cuttings.

2. Entry potential: High (VC) (Applicable rating criteria, from app. 4: b, c, d) 

They can readily survive transport in infected leaves 

or fruit with limited symptoms expressed. For example, P. 

longiseta was isolated from blackberry seedlings with shoot 

blight shipped from the United States to Japan (Dai et al. 

1990). Detection of leaf spots or fruit rot from these fungi 

is difficult, especially in larger shipments of foliage and 

foliage-bearing material. 

3. Colonization potential: Moderate (VC) (Applicable 

rating criteria, from app. 4: b, e) 

Most of the host plants of concern exist at or near likely 

ports of entry. Because of the wide host range of some of the 

species, it is possible other species could become infected 

around ports with subsequent spread to the host species 

of concern in this report. Weather conditions favorable for 

infection occur most of the year. Conidia of these fungi are 

known to spread through the air to cause infection. 

4. Spread potential: High (RC) (Applicable rating criteria, from app. 4: a, c, d, e, f) 

These fungi spread readily and rapidly through the air 

and in rain splash. Spread distance is not known but may be 

considerable. Spread between islands may be limited unless 

human movement of infected material occurs.

B. Consequences of introduction

5. Economic damage potential: Low (RC) (Applicable 

rating criteria, from app. 4: f) 

These fungi are generally not known as significant 

pathogens in their native range. The hosts of concern have 

limited direct economic benefit and, except for some ornamental plantings, are not commercially produced. Control 

techniques for these fungi would be limited to greenhouse 

and potted plant situations.

6. Environmental damage potential: Moderate (MC) 

(Applicable rating criteria, from app. 4: d) Damage 

from these fungi is limited and does not normally 

result in significant growth or mortality impacts. 

Some of the hosts of concern have limited distribution; therefore, if they were to become infected, 

some ecosystem damage might occur.

7. Social and political considerations: Low (MC) 

(Applicable rating criteria, from app. 4: none) 

Most damage from the presence of these fungi would 

be aesthetic. None of the hosts are currently involved in any 

trade. It is unlikely their presence in Hawai‘i would cause 

significant public response.

C. Pest risk potential: 

Moderate (Likelihood of introduction = moderate; 

Consequences of introduction = moderate) 

Selected bibliography:

Blanco, C.; Romero, F.; De los Santos, B. 2008. First 

report of Pestalotiopsis dyospiri causing calyx blight 

of sweet persinnon in Huelva Province (Southwestern 

Spain). Plant Disease. 92: 176.

Brooks, F. 2006. List of plant diseases in American Samoa. 

Land Grant Tech. Rep. No. 44. Pago Pago, AS: American 

Samoa Community College. 53 p.

Dai, K.; Kimura, S.; Gotoh, M.; Kobayashi, T. 1990. 

Shoot blight and its causal pathogen of blackberry 

seedling imported from the United States. Research 

Bulletin of the Plant Protection Service, Japan. 26: 1–6.

Espinoza, J.G.; Briceño, E.X.; Keith, L.M.; Latorre, 

B.A. 2008. Canker and twig dieback of blueberry caused 

by Pestalotiopsis spp. and a Truncatella sp. in Chile. 

Plant Disease. 92: 1407–1414.

Farr, D.F.; Rossman, A.Y. [N.d.]. Systematic mycology 

and microbiology [Database]. http://nt.ars-grin.gov/

fungaldatabases/. (13 March 2012).
87

Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Grasso, F.M.; Granata, G. 2008. First report of stem 

blight on Metrosideros kermadecensis induced 

by Pestalotiopsis uvicola in Italy. Journal of Plant 

Pathology. 90: 587.

Guangcai, Z.; Nan, L. 1995. Thirty-four species of 

Pestalotiopsis in Yunnan. Journal of Northeast Forestry 

University. 23(4): 21–33.

Kobayashi, T. 2007. Index of fungi inhabiting woody 

plants in Japan. Host, distribution and literature. Tokyo: 

Zenkoku-Noson-Kyiku Kyokai Publishing Company, 

Ltd. 1227 p.

Kwon, J.H.; Park, C.S.; Ahn, G.H. 2004. Leaf blight of 

sweet persimmon tree in the field and fruit rot in the 

storage caused by Pestalotia diospyri. Korean Journal 

of Mycology. 32: 130–133.

Maharachchikumbura, S.S.N.; Guo, L-D.; Chukeatirote, 

E.; Bahkali, A.H.; Hyde, K.D. 2011. Pestalotiopsis–

morphology, phylogeny, biochemistry and diversity. 

Fungal Diversity. 50: 167–187.

McKenzie, E.H.C.; Hyde, K.D. 1996. Index of fungi 

described from the Pandanaceae. Mycotaxon. 57: 

125–143.

Pirone, P.P. 1978. Diseases and pests of ornamental plants. 

New York: Wiley Interscience. 584 p.

Ullasa, B.A.; Rawal, R.D. 1989. Occurrence of a new 

post-harvest disease of mango due to Pestaloptiopsis 

glandicolis. Acta Horticulturae. 231: 540–543.

Vilka, L.L.; Rancane, R.L.; Eihe, M.L. 2009. Fungal 

diseases of Vaccinium macrocarpon in Latvia. 

Agronomijas vestis. 12: 125–133.

Watson, A.J. 1971. Foreign bacterial and fungus diseases 

of food, forage, and fiber crops: an annotated list. Agric. 

Handb. 418. Washington, DC: U.S. Department of 

Agriculture. 111 p.

White, R.P. 1935. Pestalotia spp. on Aucuba, Cibotium, 

and Leucothoe. Mycologia. 27: 342–346.

Yang, X.; Zhang, J.; Luo, D. 2012. The taxonomy, biology 

and chemistry of the fungal Pestalotiopsis genus. Natural 

Product Reports. 29: 622–641.

Yasuda, F.; Kobayashi, T.; Watanabe, H.; Izawa, H. 

2003. Addition of Pestalotiopsis spp. to leaf spot 

pathogens of Japanese persimmon. Journal of General 

Plant Pathology. 69: 29–32.

Reviewers’ comments: A reviewer was interested in 

pathways that these fungi might follow.

Response to comments: Likely pathways were identified in 

the IPRA.

Phellinus noxius

Assessor: Jessie A. Glaeser

Scientific name of pest: Phellinus noxius (Corner) 

G. Cunn.

Synonym: Fomes noxius Corner 

Phellinidium noxium (Corner) Bondartseva & S. Herrera 

Scientific names of hosts: More than 120 genera and nearly 

300 species of tropical forest, plantation and landscape 

trees, and woody shrubs. Economically important plantation hosts of P. noxius include the conifer genera Araucaria

and Pinus, and the hardwood genera Eucalyptus, Swietenia, 

and Acacia. Other economically important crops include 

Artocarpus altilis (bread fruit), Camellia sinensis (tea), 

Elaeis guineensis (oil palm), Heavea brasiliensis (rubber), 

and Theobroma cacao (cocoa). Host lists are available at 

the Crop Protection Compendium (CABI 2011d) and the 

Global Pest and Disease Database (CIPM 2012b). Genera 

of Hawai‘i native plants that are known to be susceptible 

include Acacia, Diospyros and Erythrina. The species 

within these genera that have been reported as hosts are A. 

aulacocarpa, A. auriculiformis, A. confusa, A. crassicarpa, 

A. decurrens, A. mangium, A. mearnsii, D. decandra, D. 

ferrea var. buxifolia, D. kaki, D. oldhamii, D. samoensis, E. 

variegata, and E. variegata var. orientalis (CIPM 2012b). 

The pathogen is nonspecialized with a very broad host 

range. Other Hawai‘i native plants may prove to be susceptible but have not yet been exposed to the pathogen.

Distribution: Phellinus noxius is pantropical and subtropical. It has been reported in east and central Africa, east and 
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GENERAL TECHNICAL REPORT PSW-GTR-250

southeast Asia, Australasia and the South Pacific, including 

many of the islands, Central America and the Caribbean, 

but not from North or South America (Hodges 2005). It 

is found on species of Acacia in Taiwan and the Solomon 

Islands, on Diospyros in Taiwan, and on Erythrina in and 

from Japan (Farr and Rossman, n.d.).

Summary of natural history and basic biology of 

the pests: Phellinus noxius causes a severe root rot in many 

different tree species throughout the tropics and subtropics. 

It occurs within native forests but is particularly damaging 

in plantations of forest trees and commercial crops, such as 

breadfruit, rubber, cocoa, and oil palm (Pegler and Waterston 1968). The fungus is a strong white rotter, although it 

is commonly referred to as “brown root rot” owing to the 

dark color of the fungal mycelium and fruiting body. Two 

forms of fruit bodies, only forming after extended periods 

of rainfall, can be produced. The resupinate form is smooth, 

flat, and grows flush with the underside of logs or roots. The 

bracket form—with a dark brown to black, rough textured, 

upper surface, and a charcoal grey undersurface—can be 

leathery or woody and hard. The most striking characteristic of the disease is the presence of a brown encrustation, 

composed of fungal mycelium and incorporated soil and 

debris, that covers the surface of colonized roots. This 

crust grows toward the root collar of the tree and may be 

visible above ground level, in some cases reaching 2 m or 

more from the root collar. It can eventually girdle the tree 

and kill the cambium and sapwood (Brooks 2002b). Dark 

lines are present in the wood resulting from the presence of 

pigmented hyphae. The fungus can colonize both sapwood 

and heartwood of most hosts. The wood eventually becomes 

light, dry, and friable and honeycombed; windthrow is 

common in trees with advanced root decay. The disease is 

often first recognized by an overall wilting of the canopy or 

a more gradual dieback owing to loss of water transport by 

the root system. The fungus can survive for up to 10 years 

in colonized roots and stumps after the death of the host but 

declines quickly in the absence of wood debris or in heavy, 

wet soils. One type of preventive control measure is to flood 

fields before the establishment of new plantations (Chang 

1996). 

The principal mode of infection among neighboring 

trees is by root-to-root contact (Hattori et al. 1996, Lewis 

and Arentz 1988). Fruiting bodies are often rare or absent, 

depending on the specific host but may form on dead and 

dying trees and stumps. Airborne basidiospores can initiate 

new infection centers on freshly cut stumps or through 

wounds on living trees, with subsequent spread to neighboring trees through root to root contact (Hattori et al. 1996). 

Although asexual conidiospores have been formed in culture, they do not appear to occur in the field (Brooks 2002a). 

Differences in virulence have been detected from within the 

same host and between different hosts (Nandris et al.1987, 

Nicole et al. 1985, Sahashi et al. 2010). The fungus does 

not seem to exhibit host specificity or physiological specialization. Cross inoculation studies with isolates from 12 

different hosts were able to uniformly colonize all 12 hosts 

(Chang 1995). Woody horticultural species vary greatly in 

their susceptibility to P. noxius (Ann et al. 1999).

Phellinus noxius is present in many isolated islands in 

the Pacific, and has likely been introduced there by human 

activities. On the island of Rota, the oldest disease center 

is located next to the airport and was likely introduced 

through imported woody material (Hodges and Tenorio 

1984). 

Phellinus noxius is also associated with a serious heart 

rot problem in young plantations of Acacia mangium in 

Malaysia (Lee and Yahya 1999, as described by Hodges 

2005). In this host, the disease manifests as a heartrot that 

may extend for several meters within the tree. Infection 

occurs from airborne basidiospores through pruning 

wounds or broken branches. Pathways for possible introduction would include seedlings grown in infested soil, soil, 

and wood products.

Specific information relating to risk elements:

Phellinus noxius is the subject of previous pest risk assessments (Hodges 2005; Kliejunas et al. 2001, 2003). Information summaries also appear in the Global Invasive Species 

Database (GISD 2006), the Crop Protection Compendium 

(CABI 2011d), and the Global Pest and Disease Database 

(CIPM 2012b). Phellinus noxius is on many different 

targeted pest lists, including the CAPS FY2012 Priority 
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Pest List–Commodity and Taxonomic Surveys List, and the 

CAPS FY2009 Pest of National Concern, and is considered 

of quarantine significance (CIPM 2012b).

A. Likelihood of introduction

1. Pest with host-commodity at origin potential: High

(VC) (Applicable rating criteria, from app. 4: b, c, d, 

e, g, h) 

Phellinus noxius can colonize roots, sapwood, and 

heartwood of affected plants, and has a good chance of 

being present when logs are harvested. It could also survive 

saprotrophically in wood chips and noncomposted mulch. 

Seedlings could transmit the pathogen if they are grown in 

infested soils. Mycelium and spores could be present in soil. 

2. Entry potential: High (VC) (Applicable rating criteria, from app. 4: b, c, d) 

The fungus is capable of surviving saprotrophically in 

wood or in soil and would remain viable during transport. 

It would be difficult to detect, especially if being transported in the mycelial stage within wood. Fruiting bodies 

are relatively conspicuous when present, but they can be 

remarkably rare or even totally absent in many cases.

3. Colonization potential: High (VC) (Applicable 

rating criteria, from app. 4: a, b, c, e) 

To become established, the pathogen would have to 

fruit and wind-dispersed basidiospores would need to 

find susceptible hosts. Conditions in Hawai‘i would favor 

fruiting and spore release from infected material, and 

the broad host range would make it likely that the fungus 

could become established. It is likely that this has already 

occurred on other Pacific islands (Hodges and Tenorio 

1984).

4. Spread potential: High (VC) (Applicable rating 

criteria, from app. 4: a, b, c, d, e, f, g)

Wind dispersal of spores is the common means of 

spread for most basidiomycete decay fungi. This has been 

demonstrated for P. noxius, where it has been shown that 

tree-to-tree spread is usually through root contact but 

that disease centers are initiated with genetically diverse 

basidiospores (Hattori et al. 1996, Lewis and Arentz 1988). 

Eradication efforts are difficult since the disease takes many 

years to become established, and the indicative brown crust 

may escape notice.

B. Consequences of introduction

5. Economic damage potential: Moderate (VC) 

(Applicable rating criteria, from app. 4: a, b, c, d, e, 

f) Phellinus noxius would threaten Hawai‘i native 

plants, including species of Acacia, Diospyros, 

Erythrina, and possibly others. These are important 

components of the native forest and also landscape 

trees. The very broad host range of P. noxius would 

make this fungus also a threat to other commodities, 

forests, and landscape plantings.

6. Environmental damage potential: High (VC) 

(Applicable rating criteria, from app. 4: a, b, c, d, e, 

f) The danger towards native Hawai‘i plant species 

is significant, resulting in direct impacts on those 

species (Acacia, Diospyros, and Erythrina). The 

fungus has a broad host range and could affect other 

trees in native forests and landscapes, thus indirectly 

affecting the health of native species. Eradication 

program would involve large-scale tree destruction and probably not be effective once the fungus 

becomes established in the soil.

7. Social and political considerations: High (VC) 

(Applicable rating criteria, from app. 4: a, b, c, d) 

Damage from P. noxius and subsequent death or 

decline of native Hawai‘i tree species would result 

in public concerns in aesthetics and recreation as 

well as in urban plantings. Removal of affected 

trees would have limited acceptance by the public. 

Phellinus noxius is not yet present in North America, 

and its broad host range includes many important 

ornamental species. Introduction of the fungus to 

Hawai‘i would interfere with domestic interstate 

commerce, trade, and traffic.

C. Pest risk potential:

High (Likelihood of introduction = high; Consequences of introduction = high)
90

GENERAL TECHNICAL REPORT PSW-GTR-250

Selected bibliography:

Ann, P.J.; Lee, H.L.; Huang, T.C. 1999. Brown root rot 

of 10 species of fruit trees caused by Phellinus noxius in 

Taiwan. Plant Disease. 83: 746–750.

Brooks, F.E. 2002a. Brown root rot. The plant health 

instructor. doi: 10.1094/PHI-I-2002-0923-01. http://www.

cals.ncsu.edu/course/pp728/Phellinus/Phellinus_noxius.

html. (6 May 2013).

Brooks, F.E. 2002b. Brown root rot disease in American 

Samoa’s tropical rain forests. Pacific Science. 56: 

377–387. http://muse.jhu.edu/journals/psc/summary/

v056/56.4brooks.html. (7 May 2013).

Center for Integrated Pest Management [CIPM]. 2012b.

Global pest and disease database: Phellinus noxius. 

https://www.gpdd.info/display.cfm?pest_id=2095. 

(12 August 2013).

Centre for Agricultural Bioscience International 

[CABI]. 2011d. Crop protection compendium: 

Phellinus noxius. Wallingford, United Kingdom: CAB 

International. http://www.cabi.org/cpc. (6 May 2013). 

Chang, T.T. 1995. Decline of nine tree species associated 

with brown root rot caused by Phellinus noxius in 

Taiwan. Plant Disease. 79: 962–965.

Chang, T.T. 1996. Survival of Phellinus noxius in soil 

and in the roots of dead host plants. Phytopathology. 

86: 272–276.

Farr, D.F.; Rossman, A.Y. [N.d.]. Systematic mycology 

and microbiology [Database]. http://nt.ars-grin.gov/

fungaldatabases/. (12 August 2013).

Global Invasive Species Database [GISD]. 2006. Phellinus 

noxius. http://www.issg.org/database/species/ecology.

asp?si=1007&fr=1&sts=&lang=EN. (6 May 2013).

Hattori, T.; Abe, Y.; Usugi, T. 1996. Distribution of clones 

of Phellinus noxius in a windbreak on Ishigaki Island. 

European Journal of Forest Pathology. 26: 69–80.

Hodges, C.S. 2005. Exotic forest pest information system 

for North America: Phellinus noxius. North American 

Forest Commission. http://spfnic.fs.fed.us/exfor/data/

pestreports.cfm?pestidval=50&langdisplay. 

(8 May 2013). 

Hodges, C.S.; Tenorio, J.A. 1984. Root disease of Delonix 

regia and associated tree species in the Mariana Islands 

caused by Phellinus noxius. Plant Disease. 68: 334–336.

Kliejunas, J.T.; Burdsall, H.H., Jr.; DeNitto, G.A.; 

Eglitis, A.; Haugen, D.A.; Haverty, M.I.; Micales, 

J.A.; Tkacz, B.M.; Powell, M.R. 2003. Pest risk 

assessment of the importation into the United States of 

unprocessed logs and chips of eighteen eucalypt species 

from Australia. Gen. Tech. Rep. FPL-137. Madison, WI: 

U.S. Department of Agriculture, Forest Service, Forest 

Products Laboratory. 206 p.

Kliejunas, J.T.; Tkacz, B.M.; Burdsall, H.H., Jr.; 

DeNitto, G.A.; Eglitis, A.; Haugen, D.A.; Wallner, 

W.E. 2001. Pest risk assessment of the importation 

into the United States of unprocessed Eucalyptus logs 

and chips from South America. Gen. Tech. Rep. FPLGTR-124. Madison, WI: U.S. Department of Agriculture, 

Forest Service, Forest Products Laboratory. 134 p.

Lee, S.S.; Yahya, N.S. 1999. Fungi associated with heart 

rot of Acacia mangium trees in Peninsular Malaysia and 

East Kalimantan. Journal of Tropical Forest Science. 11: 

240–254.

Lewis, D.J.; Arentz, F. 1988. Technical note on a computer 

intensive analysis method. Klinkii. 3: 60–61.

Nandris, D.; Nicole, M.; Geiger, J.P. 1987. Variation in 

virulence among Rigidoporus lignosus and Phellinus

noxius isolates from West Africa. European Journal of 

Forest Pathology. 17: 271–281.

Nicole, M.; Nandris, D.; Geiger, J.P.; Rio, B. 1985.

Variability among African populations of Rigidoporus 

lignosus and Phellinus noxius. European Journal of 

Forest Pathology. 15: 293–300.
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Pegler, D.N.; Waterston, J.M. 1968. Phellinus noxius. 

CMI descriptions of pathogenic fungi and bacteria. No. 

195. Kew, Surrey, United Kingdom: Commonwealth 

Mycological Institute. 2 p.

Sahashi, N.; Akiba, M.; Ishihara, M.; Mivazaki, K. 

2010. Cross inoculation tests with Phellinus noxius

isolates from nine different host plants in the Ryukyu 

Islands, southwestern Japan. Plant Disease. 94: 358–356.

Reviewers’ comments: “CABI doesn’t reference its host 

lists so is useful as a starting point but probably better to 

use referenced hosts. I would also be cautious about using 

the word ‘complete’.” (DJAE)

“I suspect this record is incorrect as current records 

state it is absent from New Zealand. Will have confirmation 

after Oct 3.” (DJAE)

“Certain fungal synonyms are incorrect.” (Yuko Ota)

“I could not find the result showing “in light, welldrained soils” in Chang’s paper.” (Yuko Ota)

“I could not find the result that there is no evidence 

of root decay and no external mycelial sheath in Acacia 

mangium in Malaysia in Lee and Yahya, 1999 or that tree 

growth was not affected.” (Yuko Ota) 

“Additional literature suggested.” (Yuko Ota)

Response to comments: The word “complete” has been 

removed in connection with the list of hosts. New Zealand 

has been removed as a geographic location of the pathogen 

pending confirmation. Fungal synonyms were rechecked 

and corrected. The reference to “light, well-drained soils” 

has been removed. It was an inference based on the authors’ 

data about decay in heavy, wet soils. This information has 

been deleted pending reexamination of the original paper. 

The reference by Sahashi et al. 2010 was added.

Pink Disease 

Assessor: Jessie A. Glaeser

Scientific names of pest: Erythricium salmonicolor

(Berk. & Broome) Burds.

Synonym: Phanerochaete salmonicolor (Berk. & 

Broome) Jülich

Aleurodiscus javanicus Henn.

Botryobasidium salmonicolor (Berk. & Broome) Venkatar.

Corticium javanicum (Henn.) Sacc. & P. Syd.

Corticium salmonicolor Berk. & Broome

Corticium zimmermannii Sacc. & P. Syd., 

Necator decretus Massee

Pellicularia salmonicolor (Berk. & Broome) Dastur

Terana salmonicolor (Berk. & Broome) Kuntze

The taxonomic position of this fungus has been 

debated; some authors still recognize Phanerochaete 

salmonicolor as the current name. Molecular biosystematic 

studies (Diederich et al. 2011, Ghobad-Nejhad et al. 2010, 

Roux and Coetzee 2005) have shown that it groups with 

other species of Erythricium in the Corticiales. Phanerochaete is now known to be in the Polyporales (Wu et al. 2010) 

so is not closely related.

Scientific names of hosts: More than 140 species in 

104 genera including those from the following families: 

Annonaceae, Apocynaceae, Aquifoliaceae, Bombacaceae, 

Buxaceae, Casuarinaceae, Euphorbiaceae, Fabaceae, 

Magnoliaceae, Malvaceae, Moraceae, Myrtaceae, Oleaceae, 

Pittosporaceae, Rosaceae, Rubiaceae, Rutaceae, Sterculiaceae, Theaceae, and Verbenaceae. Important commodity 

crops include Hevea brasilliensis (rubber), Coffea spp. 

(coffee), Camellia sinensis (tea), Theobroma cacao (cocoa); 

fruits such as Citrus spp., Malus spp., and Litchi chinensis; 

woody ornamentals such as Cercis canadensis, Gardenia

spp., and Ilex spp.; commercial forest plantations species 

such as Eucalyptus spp., Acacia spp., and Paraserianthes 

falcataria (Hodges 2004). Erythrina spp. include Erythrina 

lithosperma, E. subumbrans (India) (CABI 2012; Farr and 

Rossman, n.d. Acacia spp. include A. confusa, A. mangium,

A. auriculiformis, A. aulacocarpa, A. crassicarpa, A. 

decurrens, and A. mearnsii (Farr and Rossman, n.d.; Old 

and Davidson 2000). 

Distribution: Throughout the humid tropics of Africa, 

Southeast Asia, Australasia, Oceania, some Pacific Islands, 

Central America, South America, and North America. 

In North America, it is present in Florida, Louisiana, and 

Mississippi. It has not been reported from American Samoa, 

Guam, Hawai‘i, Northern Mariana Islands, or Puerto Rico 

(Hodges 2004).
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GENERAL TECHNICAL REPORT PSW-GTR-250

Summary of natural history and basic biology of 

the pests: Pink disease, caused by the fungus Erythricium 

salmonicolor, is widely distributed in the tropics and 

subtropics but appears to cause serious disease only in 

areas that receive over 2000 mm of rain per year (Seth et 

al. 1978). The fungus has a very wide host range and would 

be a danger to most endemic tree species. It can infect and 

colonize intact, healthy trees (Old et al. 2003) by forming 

stem and branch cankers. In general, young trees (2 to 8 

years old in rubber, 2 to 6 years old in cocoa) are affected 

more severely than older trees (Brown and Friend 1973, 

Holliday 1980). The main stem of young trees can be 

girdled entirely, causing repeated dieback and possible tree 

mortality. Nongirdling cankers are formed in older, larger 

trees, decreasing growth and increasing susceptibility to 

branch breakage and other agents of mortality. Eucalyptus

plantations in India have suffered 100 percent mortality 

from pink disease (Seth et al. 1978), although the disease is 

not that severe in other areas. In Brazil, it is estimated that 

citrus crop production is reduced 10 percent by pink disease 

(Sebastianes et al. 2007). Disease incidences of 80 percent 

or more have been reported in Albizia (Eusebio et al. 1979), 

cocoa (Schneider-Christians et al. 1986), and Eucalyptus

(Deo et al. 1986). Pink disease is considered one of the 

main threats to new timber plantations in Indonesia (Hadi 

et al. 1996).

Hyphal growth is seasonal and favored by rain. The 

fungus survives through dry periods in dormant cankers 

(Luz 1983). The fungus initially colonizes the outer bark 

surface and enters into the xylem through lenticels or 

wounds. Four different growth stages have been observed, 

termed “cobwebby,” “pustule,” “necator,” and “pink 

incrustation.” Growth appears initially as a thin layer 

of vegetative mycelium on the bark surface during wet 

weather. Pink to salmon-colored pustules and crusts, 

composed of sterile tissue, form rapidly on the bark and 

in bark cracks. Cankers develop as the fungus colonizes 

and kills the inner bark, cambial layer, and outer layers of 

xylem, leading to the death of branches and small stems. 

Fruiting occurs as host tissues are dying. Initially the 

asexual “necator” stage consists of orange sporodochia that 

form hyaline, unicellular, ellipsoid conidia (10 to 18 by 6 to 

12 μm) (Mordue and Gibson 1976). Conidia are probably 

distributed by rain splash and air currents. The importance 

of this stage varies with host (CABI 2012). Conidia were 

recorded in less than 3 percent of infected cocoa branches 

in Western Samoa (Schneider-Christians et al. 1986) but 

were considered the main means of spread, by rain splash, 

on apples in China (Leng et al. 1982). The conidia are 

viable for up to 20 days in dry weather, but high humidity 

is required for germination. The conidial stage is followed 

by the “pink incrustation” stage under conditions of high 

rainfall (Giambelluca et al. 2012). This is the sexual stage of 

the fungus; basidiospores are hyaline, ellipsoid, inamyloid, 

and measure 10 to 13 by 6 to 9 μm (Mordue and Gibson 

1976). Basidiospores are also dispersed by rain splash and 

by air currents (Ciesla et al. 1996). Release of basidiospores 

occurs after the basidioma has become thoroughly wetted, 

usually 20 to 80 minutes after heavy rainfall begins. High 

humidity or heavy dew is not sufficient to trigger spore 

release. Basidiospore release continues for up to 14 hours 

after rainfall has stopped (Schneider-Christians et al. 1986). 

Basidiospores rapidly lose viability under conditions of low 

humidity and may only be viable for 24 hours after release 

(Hodges 2004, Kliejunas et al. 2001) but are thought to be 

more important than conidia in spreading the disease in 

some crops (Almeida and Luz 1986). Relative production 

of basidial and conidial stages on infected apple trees is 

influenced by air temperature and relative humidity (Verma 

1991). Optimum air temperature for growth is 28 °C (Shamsuri et al. 1997). Vegetative propagules may also spread as 

colonized bark flakes from the tree (Seth et al. 1978), and 

the fungus can most likely survive in the soil. It can remain 

viable for lengthy periods of time when affected branches 

are removed from the tree (CABI 2012). In more temperate 

climes, the fungus overwinters as dormant mycelium and 

sterile pustules (Leng et al. 1982).

The genetic and pathogenic variability of the E. salmonicolor is not well understood. Culture filtrates from two 

different isolates of E. salmonicolor collected from different 

parts of India showed differential responses on Eucalyptus 

shoots, suggesting differences in pathogenicity (Sharma et 

al. 1988). RAPD analysis of 19 isolates of E. salmonicolor 

from different regions of Brazil, primarily from citrus but 
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

also from fig, apple, and Psidium cattleianum, revealed six 

different genetic groupings. There was no correlation of 

clades with pathogenicity, geographic region, or host. The 

same study showed that isolates from different hosts could 

undergo hyphal anastomosis, demonstrating that gene flow 

can occur between isolates from different hosts (Sebastianes 

et al. 2007). Phylogenetic analysis of ribosomal large 

subunit DNA has shown that isolates from Egypt and South 

Africa grouped closely together in a subclade, separate from 

isolates from South America and Asia, but this was with a 

limited number of isolates (Roux and Coetzee 2005).

Centre for Agricultural Bioscience International (2012) 

predicts that the plant parts most likely to carry the fungus 

in trade/transport include bark, leaves, and stems, including 

shoots, trunks, and branches. Kliejunas et al. (2001) also 

suggested that long-distance transport of logs and wood 

chips could harbor the fungus because it invades and kills 

outer layers of sapwood. 

Specific information relating to risk elements:

Pest risk assessments for E. salmonicolor are available 

in the literature (CABI 2012, Hodges 2004, Kliejunas et al. 

2001, Starr et al. 2007) and were consulted in assessing risk 

elements.

A. Likelihood of introduction

1. Pest with host-commodity at origin potential: High

(VC) (Applicable rating criteria, from app. 4: b, c, d, 

e, g, h) 

Pink disease is widespread throughout the tropics 

and subtropics on many different hosts including common 

agricultural commodities. A high incidence of disease 

only occurs in climates with very high levels of rainfall, 

but the fungus can survive in soil and sapwood under drier 

conditions. As the fungus spreads by both conidia and 

basidiospores, and because it has many potential hosts in 

forests, landscape plantings, agricultural and agroforestry, 

it has a high potential for large-scale population increases. 

Mycelia and sterile pustules can survive in cankers, cracks 

in the bark, and on the surface of both living and dead trees, 

allowing a prolonged release of numerous generations 

of spores. 

2. Entry potential: High (VC) (Applicable rating criteria, from app. 4: b, c, d)

Transit of logs, mulch, soil, or colonized rootstock will 

not affect fungus survival once it is established. The likelihood of detection by inspectors is low unless plant material 

is dead. Pustules are relatively small, although their pink 

color may attract the attention of inspectors. The fungus can 

grow through the sapwood in addition to bark and cambium 

(Subramaniam and Ramaswamy 1987). Transport of materials in sealed containers will result in humid conditions that 

are favorable for fungal fruiting and spore development.

3. Colonization potential: High (VC) (Applicable rating criteria, from app. 4: a, b, c, d, f)

Pink disease has a very wide host range with many 

hosts that are widespread throughout Hawai‘i in agriculture 

and landscape plantings. As the fungus is widespread 

throughout the tropics, it has already demonstrated the ability to become established outside of its native distribution, 

which is unknown. There is a high probability of finding 

favorable climatic conditions in Hawai‘i. The most suitable 

environment for colonization is probably on the southern 

and eastern sides of the islands where rainfall is greater than 

2000 mm per year (Giambelluca et al. 2012). Spores could 

probably spread to suitable habitat from ports in drier areas 

by westerly wind currents.

4. Spread potential: High (VC) (Applicable rating criteria, from app. 4: a, c, d, e, f, g)

Spread potential is high in the areas of the islands with 

high rainfall as spores can be spread by both rain splash 

and air currents. Host presence will not be a limiting factor 

because of the extremely large host range, providing a 

continuous distribution of host species. Newly established 

populations may go undetected for years owing to the cryptic nature of the pathogen; initial infections may only appear 

as minor dieback or a few dead branches before larger 

trunk cankers are evident. Control techniques have been 

developed for some high-value crops using fungicides, but 

widespread application of fungicides in native forests is not 

possible and would probably not be effective at eradication. 
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GENERAL TECHNICAL REPORT PSW-GTR-250

B. Consequences of introduction

5. Economic damage potential: High (VC) (Applicable 

rating criteria, from app. 4: a, b, c)

Introduction to Hawai‘i could result in significant 

damage to agricultural crops as well as native species. 

The fungus can result in tree death or predispose trees to 

mortality by other agents. The development of dead trees, 

dead branches or large stem cankers will reduce value of 

landscape plantings. Significant impact is expected in the 

floriculture industry.

6. Environmental damage potential: High (VC) 

(Applicable rating criteria, from app. 4: b, c, d)

Introduction to Hawai‘i would expose susceptible 

native plants with limited distributions to colonization 

by this fungus, resulting in severe losses in areas of high 

rainfall. Organism is expected to have direct and indirect 

impacts on species listed by federal and state agencies as 

endangered, threatened, or candidate, including death of 

hosts and disruption of sensitive or critical habitat.

7. Social and political considerations: High (VC) 

(Applicable rating criteria, from app. 4: a, d)

Damage by this organism to native plants would cause 

public concern. This concern would extend to agricultural, 

forest and landscape plantings as well as native plants. The 

widespread application of fungicides as a control measure 

would not be accepted by the public, although application to 

specific agriculture crops or certain high-value individual 

trees would be accepted. 

C. Pest risk potential: 

High (Likelihood of introduction = high; Consequences of introduction = high) 

Selected bibliography:

Almeida, L.C.C.; de Luz, E.D.M.N. 1986. Action of 

wind in disseminating pink disease of cocoa. Revista 

Theobroma. 16: 133–140.

Brown, J.F.; Friend, D. 1973. Diseases of cocoa in the 

British Solomon Islands Protectorate. Tech. Pap. 166. 

Noumea, New Caledonia: South Pacific Commission. 

38 p.

Centre for Agricultural Bioscience International 

[CABI]. 2012c. Crop protection compendium: Corticium

salmonicolor. Wallingford, United Kingdom: CAB 

International. http://www.cabi.org/cpc. (20 March 2013).

Ciesla, W.M.; Dickmann, M.; Putter, C.A.J. 1996. FAO/

IPGRI Technical guidelines for the safe movement 

of germplasm. No. 17. Eucalyptus spp. Food and 

Agriculture Organization of the United Nations, Rome/

International Plant Genetic Resources Institute, Rome. 

http://www.bioversityinternational.org/publications/

Pdf/406.pdf. (21 March 2013).

Deo, A.D.; Nair, J.M.; Nair, T.J.C.; Dinesh, K.; 

Ramaswarmy, V.; Sharma, J.K.; Nair, C.T.S.; 

Kedharnath, S.; Kondas, S. 1986. Provenance trials 

of Eucalyptus grandis in Kerala. In: Sharma, J.K.; Nair, 

C.T.S.; Kedharnath, S., eds. Eucalyptus in India: past, 

present and future. Proceedings of the national seminar 

held at Kerala Forest Research Institute. Kerala, India: 

Kerala Forest Research Institute: 285–289.

Diederich, P.; Lawrey, J.D.; Sikaroodi, M.; Gillevet, 

P.M. 2011. A new lichenicolous teleomorph is related 

to plant pathogens in Laetisaria and Limonomyces

(Basidiomycota, Corticiales). Mycologia. 103: 525–533.

Eusebio, M.A.; Quimo, M.J., Jr.; Ilagan, F.P. 1979.

Canker of Mollucan Sau (Albizia falcataria) in Bislig. 

Sylvatrop. 4: 191–214.

Farr, D.F.; Rossman, A.Y. [N.d.]. Systematic mycology 

and microbiology [Database]. http://nt.ars-grin.gov/

fungaldatabases/. (13 March 2012).

Ghobad-Nejhad, M.; Nilsson, R.H.; Halleberg, N. 2010.

Phylogeny and taxonomy of the genus Vuilleminia

(Basidiomycota) based on molecular and morphological 

evidence, with new insights into Corticiales. Taxon. 59: 

1519–1534.

Giambelluca, T.W.; Chen, Q.; Frazier, A.G.; Price, J.P.; 

Chen, Y.-L.; Chu, P.-S.; Eischeid, J.K.; Delparte, 

D.M. 2012. Online rainfall atlas of Hawai‘i. Bulletin 

of the American Meteorological Society. doi: 10.1175/

BAMS-D-11-00228.1. http://rainfall.geography.hawaii.

edu/. (21 March 2013).
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Hadi, S.; Nuhamara, S.T.; Santoso, E.; Nair, K.S.S. 

1996. Disease problems associated with the large scale 

establishment of timber estates in Indonesia. In: Sharma, 

J.K.; Nair, C.T.S.; Kedharnath, S., eds. Eucalyptus

in India: past, present and future. Proceedings of the 

national seminar held at Kerala Forest Research Institute. 

Kerala, India: Kerala Forest Research Institute: 105–110.

Hodges, C.S. 2004. Exotic forest pest information 

system for North America: Erythricium salmonicolor. 

North American Forest Commission. http://spfnic.

fs.fed.us/exfor/data/pestreports.cfm?pestidval 

=51&langdisplay=english. (19 March 2012).

Holliday, P. 1980. Fungus diseases of tropical crops. 

Cambridge, United Kingdom: Cambridge University 

Press. 640 p.

Kliejunas, J.T.; Tkacz, B.M.; Burdsall, H.H., Jr.; 

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Wu, S.H.; Chen, C.T.; Yu, S.Y.; Nilsson, H.R.; 

Hallenberg, N.; Nilsson, H.R. 2010. The white-rotting 

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Reviewers’ comments: None received.

Ramorum Blight/Sudden Oak Death 

Assessor: Phil Cannon

Scientific name of pest: Phytophthora ramorum Werres, de 

Cock, & Man in’t Veld 

Scientific names of hosts: Phytophthora ramorum is a 

generalist pathogen with a broad and diverse host range. 

See APHIS (2013c) for the current list of regulated hosts 

(naturally infected by P. ramorum and Koch’s postulates 

completed) and associated hosts (found naturally infected, 

and P. ramorum has been cultured and detected using PCR, 

but Koch’s postulates have not been completed or documented and reviewed). 

Of the 13 taxa of concern in Hawai‘i, 3 have been 

identified as potential hosts of P. ramorum, namely A. koa, 

L. tameiameiae, and Vaccinium spp. (Reeser et al. 2008).

Distribution: The native distribution of P. ramorum is 

not known; it has recently been introduced, separately, to 

the United States, Canada, and Europe. Current known 

distribution includes (CABI 2014, EPPO 2014, Sansford et 

al. 2009):

Canada (British Columbia), restricted to nurseries, 

subject to official control.

Europe—under regulatory control. Belgium (nurseries, 

parks), Croatia (imported plants), Czech Republic (imported 

plants), Denmark (imported plants, garden centers), 

Estonia (imported plants, garden center, eradicated), 

Finland (imported plants, garden center), France (nurseries), Germany (nurseries, garden centers, forests, parks), 

Greece (nurseries), Ireland (nurseries, garden centers, 

parks, forests), Italy (nurseries), Latvia (imported plants, 

absent), Lithuania (nurseries), Luxembourg, Netherlands 

(nurseries, parks), Norway (imported plants, nurseries, 

gardens), Poland (imported plants, nurseries), Portugal, 

Serbia (parks), Slovenia (nurseries, garden centers), Spain 

(imported plants, nurseries), Sweden (imported plants), 

Switzerland (nurseries), and the United Kingdom (Channel 

Islands, England, Wales, Scotland) (nurseries, garden 

centers, parks, forests). In many cases, these introductions 

have stayed largely in nurseries and garden centers, but in 

Belgium, Germany, Ireland, Luxembourg, the Netherlands, 

Norway, Serbia, and the United Kingdom, these introductions have led to invasions of managed parks, gardens, or in 

some cases, forest plantations and wildlands (most notably 

in Larix kaempferi in the United Kingdom).

United States, subject to official control.

California: established in the environment and quarantined in the counties of Alameda, Contra Costa, Humboldt, 

Lake, Marin, Mendocino, Monterey, Napa, San Francisco, 

San Mateo, Santa Clara, Santa Cruz, Solano, Sonoma, and 

Trinity. Regulated in the remainder of the state.

Oregon: established in the environment and under 

quarantine in about 106 ha within Curry County. Regulated 

in the remainder of the state.

Washington: periodically detected in nurseries; 

detected in streams or ditches in seven western counties 

(Kitsap, King, Clallam, Clark, Lewis, Pierce, and Thurston) 

(Omdal and Ramsey-Koll 2013). Regulated in the state.

Infected nursery stock has been detected and destroyed 

in the following states: Alabama, Arkansas, Arizona, California, Colorado, Connecticut, Florida, Georgia, Louisiana, 

Maryland, Mississippi, New Jersey, New Mexico, New 

York, North Carolina, Oklahoma, Oregon, Pennsylvania, 

South Carolina, Tennessee, Texas, Virginia, and Washington (APHIS 2005). The number of nursery detections 

through March 31, 2014, was 543 (APHIS 2014).

Has been detected in nurseries and waterways in nine 

other states, but has been contained and under eradication: 

Alabama, Florida, Georgia, Maryland, Mississippi, New 

Jersey, North Carolina, Pennsylvania, South Carolina 

(Kliejunas 2010, Oak et al. 2013). 

Phytophthora ramorum is a member of Phytophthora

Clade 8c. Populations in North America and Europe are 

clonal and belong to four distinct lineages (NA1, NA2, EU1, 

and EU2). NA1, NA2, and EU1 have been identified in the 

United States (Van Poucke et al. 2012).
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Summary of natural history and basic biology of the 

pest: Phytophthora ramorum is a fungus-like micro-organism (Kingdom Stramenophila: Class Oomycetes), related 

to diatoms and brown algae. In culture, the pathogen is 

identified by the production of large, abundant chlamydospores and elongated, ellipsoidal, semipapillate, deciduous 

sporangia (Werres and Kaminsky 2005, Werres et al. 2001). 

Motile, asexual, zoospores are produced in the sporangia.

Phytophthora ramorum is heterothallic and has two mating 

types, A1 and A2.

The pathogen was first isolated from ornamental 

rhododendrons in Germany and the Netherlands in 1993 

(Werres and Marwitz 1997), and subsequently from dying 

Notholithocarpus densiflorus and Quercus spp. in California in 2000 (Rizzo et al. 2002). Phytophthora ramorum was 

formally described in 2001 (Werres et al. 2001). 

Symptoms produced by P. ramorum are diverse and 

depend on the host and host part infected. In general, the 

pathogen causes three different diseases with differing 

symptoms. Stem cankers are formed on oaks and tanoaks 

in native forests of the western coastal United States. Some 

of these cankers can produce bleeding lesions and may be 

lethal. Leaf blight and branch dieback symptoms develop in 

Rhododendron spp., Pieris spp., Rhamnus spp. and certain 

conifer species. Branches develop cankers with associated 

leaf lesions. Leaf spots, blotches, and scorch are produced 

in some hosts with no associated branch damages. These 

lesions often have an irregular margin. Umbellularia 

californica and Sequoia sempervirens are species that 

show these symptoms (Grünwald et al. 2008, Hansen et al. 

2002). On some hosts, notably L. kaempferi in forests and 

plantations in England and Wales, foliage infection and 

twig blight has led to extensive tree mortality (Webber et al. 

2010). The pathogen has been isolated from asymptomatic 

host tissue, including roots of tanoak seedlings (Parke et 

al. 2006), stems and roots of rhododendron (Bienapfl et al. 

2005), and leaves of rhododendron (Werres et al. 2001), 

camellia (Shishkoff 2006), holm oak (Denman et al. 2009), 

and Japanese larch (Brasier and Webber 2010). 

Phytophthora ramorum is considered a cool-temperature organism, with optimal growth between 18 and 22 °C 

(Werres et al. 2001). The pathogen produces sporangia on 

the surfaces of infected leaves and twigs of foliar hosts that 

can be splash-dispersed to neighboring hosts (Davidson et 

al. 2002, 2005), or spread longer distances by wind and rain 

(Davidson et al. 2005, Hansen 2008). Phytophthora ramorum is also spread downstream of infested areas in rivers 

and streams and can be carried in infested soil. Long-distance dispersal occurs primarily through the movement of 

infected plant material moved in trade, primarily commercial nursery trade (CABI 2014). Inoculum production occurs 

under a wide range of temperature and moisture conditions. 

In one study, zoospores were produced at a range of 

temperatures from 5 to 25 °C, with the highest numbers 

produced at 15 to 20 °C. The optimum germination range 

was 20 to 30 °C (Kliejunas 2010). 

Upon contact with a suitable host and environment, the 

sporangia germinate to produce zoospores that encyst, penetrate the host, and initiate a new infection. The presence 

of free water or high humidity favors zoospore germination 

and infection (Garbelotto et al. 2003). Chlamydospores 

are readily produced in infected plant material and can 

survive up to 12 months in potting media and soil substrate. 

(Osterbauer 2010). They may serve as resting structures in 

soil, allowing the pathogen to survive adverse conditions. 

Examination of chlamydospore production and survival in 

Umbellularia californica leaves, however, identified large 

numbers of chlamydospore production depending on site, 

but germination was not observed (Fichtner et al. 2009). 

Moisture is essential for survival and sporulation, and the 

duration, frequency, and timing of rain events plays a key 

role in inoculum production (Kliejunas 2010).

Like most Phytophthora species, P. ramorum survives 

during conditions unfavorable for growth—such as hot, dry 

summer months in California—in host tissues or in various 

nonhost substrates (such as soil, and potting media) as 

hyphae or as asexual structures (Kliejunas 2010). 

Specific information relating to risk elements

Research on sudden oak death through 2009 has been summarized (Kliejunas 2010). Previous risk assessments have 

been completed for P. ramorum in North America (Kliejunas 2003), the United States (Cave et al. 2008), the state of 

Oregon (Osterbauer 2010), Canada (CFIA 2012), the United 

Kingdom (Sansford et al. 2003), the European Union (EPPO 
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GENERAL TECHNICAL REPORT PSW-GTR-250

2013; RAPRA 2009), Norway (Sundheim et al.2009), and 

Australia (online at http://pbt.padil.gov.au). 

A. Likelihood of introduction

1. Pest with host-commodity at origin potential:

High (VC) (Applicable rating criteria, from app. 

4: a, b, c, d, e, g, h).

Phytophthora ramorum appears to have been transported globally with separate introductions at least four 

times (Grünwald et al. 2012). Plant import data from 2004 

to 2010 indicated 30,125 units of high-risk plants arrived in 

Honolulu (APHIS 2011). This was the third leading port of 

entry in the United States. Nursery stock, cut flowers and 

greenery commonly arrive in Hawai‘i from areas of California where there has been some history of P. ramorum

occurrence. The quantity of material imported into Hawai‘i 

from the regulated area was not available for this assessment. Some of this material might possibly be infected or 

might carry P. ramorum spores. Identified host species 

from quarantined areas of California and Oregon cannot 

be exported except with an APHIS-provided certificate or 

from nurseries with compliance agreements with APHIS. 

Although this material has a high chance of receiving a 

phytosanitary check upon arrival in Hawai‘i, inoculum and 

diseased material could still go undetected. Some of the 

known hosts have few if any easily identifiable symptoms 

and could be missed during inspections. 

Recent regulations by APHIS permit nurseries outside 

of regulated and quarantined areas in the United States to 

move host plants interstate unless P. ramorum has been 

detected at the nursery in the previous 3 years (on or after 

March 31, 2011) (APHIS Order DA-2014-02). Similarly, 

nurseries within regulated areas of California, Oregon, and 

Washington will be allowed to move host plants interstate 

as long as P. ramorum has not been detected in the nursery 

on or after March 31, 2011 (APHIS Order DA-2014-02). 

There is also interest in transferring conifer seedlings 

currently growing in nurseries not too far outside of P. 

ramorum-infested parts of the west coast of the mainland 

United States into Hawai‘i. Hawai‘i is interested in starting 

its own Christmas tree program using conifers from the 

west coast. This shipment would be very carefully monitored for P. ramorum and other pathogens and would come 

from nurseries outside the current P. ramorum quarantine 

zone; so the risk of this leading to the introduction of the 

pathogen into Hawai‘i should be low.

2. Entry potential: High (VC) (Applicable rating 

criteria, from app. 4: a, b, c, d) 

Phytophthora ramorum can colonize most aerial parts 

of a plant and could therefore be brought into Hawai‘i 

on any infected plant. A fair, but unknown, amount of 

movement of plant species is vulnerable to leaf infections. 

However, phytosanitary regulations for this pathogen are in 

place for west coast nurseries, and Hawai‘i regulators are 

looking for P. ramorum symptoms. Symptoms, though, may 

not be easily observed on some hosts. The possible introduction on wood products or seed should be close to nil.

3. Colonization potential: High (VC) (Applicable 

rating criteria, from app. 4: a, b, c, e)

The ability of this fungus to infect plant species in 

Hawai‘i has not been thoroughly evaluated. A small test 

with some of Hawai‘i’s more significant native species 

(including koa (Acacia koa), ohelo (Vaccinium calycinum), 

ohia (Metrosideros polymorpha), and pukiawe (Leptocophylla tameiameiae) indicated that all of these species 

could be affected by P. ramorum when inoculated with a 

heavy load of zoospores under environmental conditions 

conducive for infection. However, P. ramorum could be 

re-isolated from a few of the inoculated leaves of ohelo, koa, 

and pukiawe (Reeser et al. 2008). Of these four potential 

hosts, only L. tameiameiae, M. polymorpha, and A. koa

have ranges that coincide with known air and maritime 

ports (Price et al. 2012). 

One feature of this pathogen that would make it 

unlikely to colonize forests in Hawai‘i is that below 700 

m or above 1500 m sea level, temperatures for the growth 

and sporulation of this pathogen will be outside its optimal 

range of 18 to 22 °C. Much of Hawai‘i is too dry for this 

pathogen to likely establish. However, there are a number 

of areas on several of the islands where rainfall amounts 

are significant, exceeding 2500 mm annually and generally 

equally distributed year round. This includes the islands of 

Hawai‘i, Kauai, Maui, and O‘ahu (Giambelluca et al. 2013). 
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Areas that receive international travel and imports with 

higher levels of rainfall (>1600 mm annually) within 6.4 

km include Hilo, Honolulu, and Kahului (Giambelluca et al. 

2013). Elevations with higher levels of rainfall range from 

near sea level to over 1.2 km. There may be some areas in 

Hawai‘i that are at risk because of having both favorable 

temperatures and humidity.

4. Spread potential: High (RC) (Applicable rating 

criteria, from app. 4: a, b, c, d, e, f)

Once established around some port areas, this pathogen 

could spread into native forests in more moist areas of 

Hawai‘i. Long-distance spread of the pathogen through 

human-assisted movement has been identified based on 

genetic analysis of distant infection sites in California 

(Grünwald et al. 2012). The amount of inoculum produced 

by hosts in Hawai‘i is not known, so the spread potential 

into native forests is not known. Areas where spread could 

occur would most likely be located between 1000 and 

1400 m above sea level on the windward side of each of 

the Hawai‘i Islands. Of course, even then, the species in 

the forest would also need to be susceptible to infection 

and capable of supporting spore production as well. We 

know the susceptibility of only a few of the most common 

Hawai‘i species to P. ramorum to date, and although most 

of those that were tested were susceptible to colonization 

to some degree, the conditions used for these tests were 

extraordinarily favorable for pathogen development (Reeser 

et al. 2008). Reeser et al (2008) felt that most plant species 

would be susceptible to leaf infections with the environmental conditions that were used. Within limited localities 

of Hawai‘i where environmental conditions are conducive 

for P. ramorum infection and sporulation (approximately 

18 to 22 °C temperature and extended periods with high 

humidity), there might be small areas of Hawai‘i that meet 

the climatic requirements for this pathogen. But, even then, 

these areas would have to be composed of a number of trees 

of species that were susceptible before there was any risk as 

well, and it is likely that these areas will be fairly localized. 

Mid-elevation sites on the windward (rainy) sides of Hawai‘i 

and Kaua‘i might be among the most likely locations to be 

wary of some P. ramorum activity if there are susceptible 

species growing in these areas.

5. Economic damage potential: High (RC) (Applicable 

rating criteria, from app. 4: b, c, d, f)

In California, of the 150 species that have shown some 

susceptibility to P. ramorum, only 5 have any propensity 

at all for developing lethal cankers, the most common way 

that this pathogen can kill. Recent identification of a foliage 

blight causing mortality of L. kaempferi in the United 

Kingdom (Brasier and Webber 2010) suggests the possibility that other hosts could be affected similarly. Grünwald et 

al. (2012) noted that P. ramorum has had significant impacts 

on forests because of reductions in recreational, cultural, or 

commodity values and the costs of monitoring and eradication efforts. 

This combination of very limited environmental 

windows where P. ramorum would be favored and what will 

probably prove to be a very limited number of susceptible 

tree species suggests that the economic damage potential of 

P. ramorum in Hawai‘i might be very localized and limited. 

Also, the economic value of the possible native hosts in 

Hawai‘i is small. However, establishment of the pathogen in 

the state would affect the international and domestic movement of plants and plant products and result in restrictions 

in trade and movement. Direct costs of eradication, suppression, and prevention would be high.

6. Environmental damage potential: Moderate (MC) 

(Applicable rating criteria, from app. 4: d)

As there are likely to be only a limited number of locations in Hawai‘i and a limited number of species that might 

be vulnerable within these areas where damage might take 

place, the environmental consequences are expected to be 

limited. Furthermore, even if one species is heavily affected 

in one of these limited areas, there may well be dozens of 

other tree species that could fill into their space and thereby 

fulfill some of the other key environmental functions. Some 

of these species may not fulfill all of the functions or may 

be nondesirable invasive species.

7. Social and political considerations: High (MC) 

(Applicable rating criteria, from app. 4: a, b, c, d)

As a new exotic invasive pathogen that has killed millions of tanoaks in the San Francisco Bay Area and millions 

of Japanese larch in the United Kingdom, P. ramorum has 
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GENERAL TECHNICAL REPORT PSW-GTR-250

garnered political and social attention resulting in implementation of quarantines in over 60 countries (Sansford et 

al. 2003. It has caused a significant legislative and media 

interest in California, Oregon, and the United Kingdom 

political arenas; and has caused concern in other U.S. states 

and European nations. Thus, if even a small population of 

P. ramorum were to get started in Hawai‘i, it would almost 

certainly cause an immediate alarm amongst Hawaiians and 

trading partners. 

C. Pest risk potential 

High (Likelihood of introduction = high; Consequences of introduction = high) 

Although the pest risk potential for this pathogen is 

high, the environmental conditions optimal for infection, 

development, and sporulation by P. ramorum are limited to 

relatively small areas on any of the Hawai‘i Islands. Therefore, the risk may be limited to the wettest, mid-elevation 

sites, principally on the islands of Hawai‘i, Maui, and Oahu.

Selected bibliography:

Bienapfl, J.; Zanzot, J.; Murphy, S.; Garbelotto, 

M.; Rizzo, D. 2005. Isolation of a new lineage of 

Phytophthora ramorum from asymptomatic stems and 

roots of a commercial lot of rhododendrons in California. 

Phytopathology. 95: S9.

Brasier, C.; Webber, J. 2010. Plant pathology: sudden larch 

death. Nature. 466: 824–825.

Canadian Food Inspection Agency [CFIA]. 2012. Pest 

risk assessment summary. Ottawa, Canada: Canadian 

Food Inspection Agency. http://www.inspection.gc.ca/

plants/plant-protection/diseases/sudden-oak-death/

summary/eng/1327588394994/1327589076065. 

(May 2014).

Centre for Agricultural Bioscience International 

[CABI]. 2014. Invasive Species Compendium datasheet. 

http://www.cabi.org/isc/datasheet/40991. (May 2014).

Cave, G.L.; Randall-Schadel, B.R.; Redlin, S.C. 2008. 

Risk analysis for Phytophthora ramorum Werres, de 

Cock & In’t Veld, causal agent of phytophthora canker 

(sudden oak death), ramorum leaf blight, and ramorum 

dieback. Revision 1. Raleigh, NC: U.S. Department 

of Agriculture, Animal and Plant Health Inspection 

Service, Plant Protection and Quarantine. 88 p.

Davidson, J.M.; Rizzo, D.M.; Garbelotto, M.; Tjosvold, 

S.; Slaughter, G.W. 2002. Phytophthora ramorum and 

sudden oak death in California. II. Transmission and 

survival. In: Standiford, R.B.; McCreary, D.; Purcell, 

K.L., tech. coords. Proceedings of the fifth symposium 

on oak woodlands: oaks in California’s changing 

landscape. Gen. Tech. Rep. PSW-GTR-184. Albany, CA: 

U.S. Department of Agriculture, Forest Service, Pacific 

Southwest Research Station: 741–749.

Davidson, J.M.; Wickland, A.C.; Patterson, H.A.; Falk, 

K.R.; Rizzo, D.M. 2005. Transmission of Phytophthora 

ramorum in mixed evergreen forest in California. 

Phytopathology. 95: 587–596.

Denman, S.; Kirk, S.A.; Moralejo, E.; Webber, J.F. 2009. 

Phytophthora ramorum and Phytophthora kernoviae on 

naturally infected asymptomatic foliage. EPPO Bulletin. 

39: 105–111.

European and Mediterranean Plant Protection 

Organization [EPPO]. 2013b. Pest risk management 

for Phytophthora kernoviae and Phytophthora ramorum. 

EPPO, Paris. http://www.eppo.int/QUARANTINE/Pest_

Risk_Analysis/PRA_intro.htm. (June 2014).

European and Mediterranean Plant Protection 

Organization [EPPO]. 2014. PQR-EPPO database on 

quarantine pests. http://www.eppo.int. (June 2014).

Fichtner, E.J.; Lynch, S.C.; Rizzo, D.M. 2009. Survival, 

dispersal, and soil mediated suppression of Phytophthora 

ramorum in a California redwood-tanoak forest. 

Phytopathology. 99: 608–619.
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Garbelotto, M.; Davidson, J.M.; Ivors, K.; Maloney, 

P.E.; Hüberli, D.; Rizzo, D.M. 2003. Non-oak native 

plants are the main hosts for the sudden oak death 

pathogen in California. California Agriculture. 57(1): 

18–23.

Giambelluca, T.W.; Chen, Q.; Frazier, A.G.; Price, J.P.; 

Chen, Y.-L.; Chu, P.-S.; Eischeid, J.K.; Delparte, 

D.M. 2013. Rainfall atlas of Hawai‘i. Online. Bulletin of 

the American Meteorological Society. 94: 313–316.

Grünwald, N.J.; Goss, E.; Press, C.M. 2008.

Phytophthora ramorum: a pathogen with a remarkably 

wide host range causing sudden oak death on oaks and 

ramorum blight on woody ornamentals. Molecular Plant 

Pathology. 9(6): 729–740.

Grünwald, N.J.; Garbelotto, M.; Goss, E.M.; Heungens, 

K.; Prospero, S. 2012. Emergence of the sudden oak 

death pathogen Phytophthora ramorum. Trends in 

Microbiology. 20: 131–138.

Hansen, E. 2008. Alien forest pathogens: Phytophthora 

species are changing world forests. Boreal Environment 

Research. 13: 33–41.

Hansen, E.; Sutton, W.; Parke, J.; Linderman, R. 2002. 

Phytophthora ramorum and Oregon forest trees—

one pathogen, three diseases. In: Proceedings of the 

sudden oak death science symposium. Berkeley, CA: 

U.S. Department of Agriculture, Forest Service and 

University of California, Berkeley. http://danr.ucop.edu/

ihrmp/sodsymp/poster/poster07.html. (April 2010).

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inoculation and natural infection. Plant Disease. 

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Phytophthora ramorum in North America. Washington, 

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America. http://www.suddenoakdeath.org/pdf/

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Kliejunas, J.T. 2010. Sudden oak death and Phytophthora 

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Rep. PSW-GTR-234. Albany, CA: U.S. Department of 

Agriculture, Forest Service, Pacific Southwest Research 

Station. 181 p. 

Oak, S.; Hwang, J.; Jeffers, S. 2013. Comparison of 

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ramorum survey of waterways in the southeastern 

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Omdal, D.; Ramsey-Koll, A. 2013. Phytophthora ramorum 

detection and monitoring in western Washington 

waterways, 2013. [Poster]. U.S. Department of 

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meeting; March 24-27, 2014; Jacksonville, Florida.

Osterbauer, N.K. 2010. Phytophthora ramorum Werres, de 

Cock & Man in’t Veld pest risk assessment for Oregon. 

http://www.suddenoakdeath.org/pdf/SOD_PRA_

OR_2=04.pdf. (April 2010).
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GENERAL TECHNICAL REPORT PSW-GTR-250

Parke, J.L.; Bienapfl, J.; Oh, E.; Rizzo, D.; Hansen, E.; 

Buckles, G.; Lee, C.; Valachovic, Y. 2006. Natural 

infection of tanoak seedling roots by Phytophthora 

ramorum. Phytopathology. 96: S90.

Price, J.P.; Jacobi, J.D.; Gon, S.M., III; Matsuwaki, 

D.; Mehrhoff, L.; Wagner, W.; Lucas, M.; Rowe, B., 

2012. Mapping plant species ranges in the Hawaiian 

Islands—Developing a methodology and associated GIS 

layers: Open-File Report 2012–1192. Reston, VA: U.S. 

Department of the Interior, Geological Survey. 34 p. 1 

appendix (species table). 1,158 maps. http://pubs.usgs.

gov/of/2012/1192/. (June 2014).

Risk Analysis of Phytophora ramorum [RAPRA]. 

2009. Risk analysis of Phytophthora ramorum, a newly 

recognised pathogen threat to Europe and the cause of 

Sudden Oak Death in the USA. European Union Sixth 

Framework Project, deliverable report D28. http://rapra.

csl.gov.uk/RAPRA-PRA_26feb09.pdf.

Reeser, P.; Hansen, E.; Sutton, W.; Davidson, J.; Parke, 

J. 2008. Susceptibility of some native plant species from 

Hawai‘i to Phytophthora ramorum. In: Frankel, S.J.; 

Kliejunas, J.T.; Palmieri, K.M., tech. coords. Proceedings 

of the sudden oak death third science symposium. Gen. 

Tech. Rep. PSW-GTR-214. Albany, CA: U.S. Department 

of Agriculture, Forest Service, Pacific Southwest 

Research Station: 437–438. 

Rizzo, D.M.; Garbelotto, M.; Davidson, J.M.; Slaughter, 

G.W.; Koike, S.T. 2002. Phytophthora ramorum as 

the cause of extensive mortality of Quercus spp. and 

Lithocarpus densiflorus in California. Plant Disease. 

86: 205–214.

Rizzo, D.M.; Garbelotto, M.; Hansen, E.M. 2005.

Phytophthora ramorum: integrative research and 

management of an emerging pathogen in California 

and Oregon forests. Annual Review of Phytopathology. 

43: 309–335.

Sansford, C.E.; Woodhall, J.W. 2007. Datasheet for 

Phytophthora ramorum. PPP 11824. Sand Hutton, 

York: Central Science Laboratory, Department of 

Environment, Forestry, and Rural Affairs. 43 p. http://

www.suddenoakdeath.org/pdf/pram_PRA_UK.pdf. 

(April 2010).

Sansford, C.E.; Inman, A.J.; Baker, R.; Brasier, C.; 

Frankel, S.; de Gruyter, J.; Husson, C.; Kehlenbeck,

H.; Kessel, G.; Moralejo, E.; Steeghs, M.; Webber, 

J.; Werres, S. 2009. Report on the risk of entry, 

establishment, spread and socio-economic loss and 

environmental impact and the appropriate level of 

management for Phytophthora ramorum for the EU. 

Deliverable Report 28. Sand Hutton, York, United 

Kingdom: Forest Research, Central Science Laboratory. 

EU Sixth Framework Project, RAPRA. 310 p. http://

rapra.csl.gov.uk/RAPRAPRA_26feb09.pdf. (April 2010).

Sansford, C.E.; Jones, D.R.; Brasier, C.M. 2003. Revised 

summary pest risk analysis for Phytophthora ramorum 

for the UK. York, United Kingdom: Forest Research, 

Central Science Laboratory. 23 p.

Shishkoff, N. 2006. Susceptibility of Camellia to 

Phytophthora ramorum. Online. Plant Health Progress. 

doi:10.1094/PHP-2006-0315-01-RS.

Shishkoff, N. 2007. Persistence of Phytophthora ramorum

in soil mix and roots of nursery ornamentals. Plant 

Disease. 91: 1245–1249.

Sundheim, L.; Herrero, M.L.; Rafoss, T.; Toppe, B. 

2009. Pest risk assessment of Phytophthora ramorum 

in Norway. Opinion of the Panel on Plant Health of 

the Norwegian Scientific Committee for Food Safety, 

08/907-3 final, ISBN 978-82-8082-351-9 (Electronic 

edition). Oslo, Norway. VKM. 
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

U.S. Department of Agriculture, Animal and Plant 

Health Inspection Service [APHIS]. 2005. Program 

update for Phytophthora ramorum. U.S. Department 

of Agriculture, Animal and Plant Health Inspection 

Service, Pest Detection and Management Programs. 

January 10, 2005. http://www.aphis.usda.gov/ppq/ispm/

pramorum. (March 23, 2012).

U.S. Department of Agriculture, Animal and Plant 

Health Inspection Service [APHIS]. 2011b. APHISNational Plant Board Phytophthora ramorum regulatory 

working group reports. Gray Haun and Prakash Hebbar, 

Co-Chairs. 70 p. http://www.aphis.usda.gov/plant_health/

plant_pest_info/pram/downloads/pdf_files/

NPB-RWGR.pdf.

U.S. Department of Agriculture, Animal and Plant 

Health Inspection Service [APHIS]. 2013c. APHIS list 

of regulated hosts and plants proven or associated with 

Phytophthora ramorum. http://www.aphis.usda.gov/

plant_health/plant_pest_info/pram/downloads/pdf_files/

usdaprlist.pdf. (May 2014).

U.S. Department of Agriculture, Animal and Plant 

Health Inspection Service [APHIS]. 2014. APHIS 

Phytophthora ramorum Program 2014, 1st Quarter 

Summary; March 31st, 2014. http://www.aphis.usda.

gov/plant_health/plant_pest_info/pram/downloads/

updates/2014/1st-quarter.pdf. (June 18, 2014).

Van Poucke, K.; Franceschini, S.; Webber, J.F.; 

Vercauteren, A.; Turner, J.A.; McCracken, A.R.; 

Heugens, K.; Brasier, C.M. 2012. Discovery of a fourth 

evolutionary lineage of Phytophthora ramorum: EU2. 

Fungal Biology. 116: 1178–1191.

Webber, J.F.; Mullett, M.; Brasier, C.M. 2010. Dieback 

and mortality of plantation Japanese larch (Larix 

kaempferi) associated with infection by Phytophthora 

ramorum. New Disease Reports. 22: 19.

Werres, S.; Kaminsky, K. 2005. Characterization of 

European and North American Phytophthora ramorum

isolates due to their morphology and mating behaviour 

in vitro with heterothallic Phytophthora species. 

Mycological Research. 109: 860–871.

Werres, S.; Marwitz, R. 1997. Triebsterben an 

Rhododendron—Unbekannteb Phytophthora. Deutscher 

Gartenbau. 21: 1166–1168.

Werres, S.; Marwitz, R.; Veld, W.; De Cock, A.; 

Bonants, P.J.M.; De Weerdt, M.; Themann, K.; Ilieva, 

E.; Baayen, R.P. 2001. Phytophthora ramorum sp. 

nov., a new pathogen on Rhododendron and Viburnum. 

Mycological Research. 105: 1155–1165.

Reviewers’ comments: “This distribution list could be 

misleading since it doesn’t state if it is nursery, garden, or 

wildland.” (S. Frankel)

“Not clear what this (infested stock shipped to many 

states) refers to. What states? Add something about number 

of US nursery detections and number of states.” (S. Frankel)

“Nurseries in California, Oregon, and Washington were 

added to the regulation in 2004/5. The risk from nursery 

stock movement is not just from within the infested counties 

of California!!” (S. Frankel)

“Can you provide a map of Hawai‘i showing locations 

of forests with high rainfall and relatively cool temperatures. In all sections, there isn’t much evidence provided for 

each rating.” (S. Frankel)

“Most of your references and citations are old. There 

are many review papers (and other papers) that need to be 

included.” (S. Frankel) 

Response to comments: The first three reviewer comments were addressed by clarifying additions to the text. 

Information on types of situations where P. ramorum 

occurs in various locations was added. Maps with rainfall 

distribution were evaluated, although not included in this 

document, and information related to rainfall was added to 

the assessment. Elevation was used as a proxy for temperature distribution. Several recent review papers were added 

to the selected bibliography.
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GENERAL TECHNICAL REPORT PSW-GTR-250

Uromyces Rusts

Assessor: Gregg DeNitto

Scientific names of pests: see table 10

Scientific names of hosts: see table 10

Distribution: see table 10

Summary of natural history and basic biology of 

the pests: Rust fungi, members of the Pucciniaceae, are 

found around the world, except Antarctica, in both natural and human ecosystems. They are obligate parasites, 

with either one (autoecious) or two (heteroecious) hosts 

required for completion of their life cycle. They have been 

recognized as a group of fungi that cause serious diseases 

affecting many ornamental plants that are produced 

commercially (Wise et al. 2004). Spore stages of these fungi 

are transported naturally either by wind or rain splash. They 

can be readily moved by transport of infected host tissue, 

such as cuttings, live plants, and other tissues. 

Uromyces truncicola causes a canker of Sophora

japonica nursery seedlings in Japan (Kusano 1904, Orwa 

et al. 2009). It is an autoecious, macrocyclic rust fungus. 

Four spore stages—teliospores, sporidia, pycniospores, and 

urediospores—are produced (Zinno and Hayashi 1980). 

Pycniospores develop on cankers in late May to early July. 

Urediospores follow in early June to mid-July. Teliospores 

are produced on stem cankers from late July into the fall. 

Sporidia are produced the following spring and cause the 

primary infection on new shoots. In addition to seedling 

cankers, U. truncicola causes multiple cankers on older 

trees, causing branch dieback and eventual tree death 

(Kusano 1904). 

Uromyces sophorae-japonicae and U. scaevolae both 

affect the foliage only. Uromyces sophorae-japonicae has 

been reported to have a life cycle similar to U. truncicola

with the four spore stages (Kusano 1904). However, all of 

the spore stages of U. sophoreae-japonicae are found on the 

leaf, blade, or petiole of its host. Information on the biology 

of U. scaevolae could not be found, but it is assumed to 

have similarities to these other two species.

Sophora japonica is native to China, Japan, and Korea. 

It is grown as an ornamental species for gardens, parks, and 

road-side plantings. Several cultivars are available. Exotic 

plantings include Croatia, Italy, Spain, Thailand, United 

Kingdom, United States, and Vietnam (Orwa et al. 2009).

Specific information relating to risk elements

A. Likelihood of introduction

Table 10—Hosts, country of origin and citations for Uromyces species of concern

Pathogen Host(s) Country of origin Citation

Uromyces scaevolae G. 

Cunn. (Pucciniales: 

Pucciniaceae)

Scaevola albida, 

Scaevola sp., Scaevola 

spinescens, Selliera 

radicans

Australia, New Zealand Farr and Rossman, n.d. 

Uromyces sophoraejaponicae Dietel 

(Pucciniales: 

Pucciniaceae)

Sophora japonica Japan Kusano 1904

Uromyces truncicola

Hennings & Shirai 

(Pucciniales: 

Pucciniaceae)

Sophora japonica China, Japan, Korea Kusano 1904, Orwa et 

al. 2009
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

1. Pest with host-commodity at origin potential: 

Moderate (MC) (Applicable rating criteria, from 

app. 4: b, h) 

These rust fungi are persistent with their host as long 

as the host tissue is living. Uromyces truncicola is perennial 

because of its infecting stem tissue, so it is likely to be 

present on the host year round. The other two species may 

only be present with their host during the growing season 

when foliage is on the plant. Rust fungi generally have a 

high population increase potential, and this is expected with 

these species. Once these fungi infect their host, mycelium 

is buried within the tissue and would not be dislodged 

during any harvesting or handling.

2. Entry potential: High (MC) (Applicable rating criteria, from app. 4: b, c, d) 

The movement of either infected stems or foliage, 

depending on the fungal species, could transport these 

fungi to new areas. Mycelium within host tissue would 

likely not be a concern with entry, but infective spores that 

may be carried with the host or be produced upon arrival 

are the likely forms of subsequent infection. Like many 

fungi, cursory examination of infected hosts may not 

reveal their presence because they are microscopic and well 

concealed. The probability that a pathogen is detected at a 

port of entry is a function of visible symptoms or signs and 

the level of inspection sampling. Uromyces truncicola may 

be more apparent because of the hypertrophy of stem tissue 

that can occur.

3. Colonization potential: Moderate (MC) (Applicable 

rating criteria, from app. 4: b, e) 

Sporidia is the only fungal stage to cause new infections. Teliospores can be transported and later germinate to 

produce sporidia that can then cause new infections. Infection is dependent on the availability of viable sporidia and 

the proper temperature and humidity requirements of these 

fungi. Only Sophora have been identified as hosts, and it is 

not known if the native Hawai‘i species are susceptible. The 

occurrence of Sophora near sea level indicates that it can be 

in proximity to areas of trade.

4. Spread potential: Moderate (RC) (Applicable rating 

criteria, from app. 4: a, c, e, f)

Once infection of native Hawai‘i Sophora occurs, it is 

likely that these fungi could spread farther, at least on the 

island where they are introduced. Interisland spread is less 

likely without human assistance.

B. Consequences of introduction

5. Economic damage potential: Low (RC) (Applicable 

rating criteria, from app. 4: f) 

None of these fungi cause significant economic damage 

in their native range. If commercial propagation of Sophora

species came into existence in Hawai‘i, then it is possible 

that some economic damage could occur if these fungi were 

introduced.

6. Environmental damage potential: High (RU) 

(Applicable rating criteria, from app. 4: b, d) 

None of these fungi appear to cause significant levels 

of host mortality unless other stress factors are present. 

Impacts to other functions of these plants, such as foliage, 

flower, or seed production, do not seem significant. If 

branch cankers and dieback became significant, flower 

and seed production might be affected. This could have a 

negative effect on the endangered padilla bird.

7. Social and political considerations: Low (MC) 

(Applicable rating criteria, from app. 4: none)

The introduction of any Uromyces species that infects 

Sophora would likely not have significant social or political 

impacts. 

C. Pest risk potential: 

High (Likelihood of introduction = moderate; Consequences of introduction = high) 
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Selected bibliography:

Farr, D.F.; Rossman, A.Y. [N.d.]. Systematic mycology 

and microbiology [Database]. http://nt.ars-grin.gov/

fungaldatabases/. (13 March 2013).

Kusano, S. 1904. Notes on the Japanese fungi. I. Uredineae 

on Sophora. Botanical Magazine Tokyo. 18: 1–6.

Orwa, C.; Mutua, A.; Kindt, R.; Jamnadass, R.; 

Simons, A. 2009. Agroforestree database: a tree 

reference and selection guide version 4.0. http://

www.worldagroforestry.org/treedb2/speciesprofile.

php?Spid=18098. (13 May 2013).

Wise, K.A.; Mueller, D.S.; Buck, J.W. 2004. Quarantines 

and ornamental rusts. APSnetFeature-2004-0204. 

doi:10.1094/. (13 August 2013).

Zinno, Y.; Hayashi, H. 1980. Life history of Uromyces 

truncicola causing the canker disease of Sophora 

japonica seedlings. Transactions of the Mycological 

Society of Japan. 21: 87–95.

Reviewers’ comments: None received.

White-Thread Blight/Black Rot

Assessor: Jessie A. Glaeser

Scientific names of pest: Ceratobasidium noxium (Donk) P. 

Roberts

Synonym: Pellicularia koleroga Cooke

Corticium koleroga (Cooke) Hőhn

Botryobasidium koleroga Venkatar.

Other species of Ceratobasidium, including C. anceps, 

C. cornigerum, and two unnamed but phylogenetically 

distinct species on tea (Camillia sinensis) and persimmon 

(Diospyros kaki) from Brazil (Ceresini et al. 2012), all cause 

similar diseases, termed “white-thread blight” and “black 

rot.” Ceratobasidium anceps and C. cornigerum are associated with temperate climes (Farr and Rossman, n.d.) and 

have not been reported on genera of host plants of interest in 

this pest risk assessment.

Scientific names of hosts: Very wide host range from many 

families, including economically important crops such as 

several species of Citrus, Coffea arabica (coffee), Hevea 

brasiliensis (rubber tree), Malus domestica (apple), Mangifera indica (mango), Melia azedarach (chinaberry), Piper 

nigrum (black pepper), Theobroma cacao (cocoa), and 

Vanilla planifolia (vanilla). It is also found on many important ornamental and forest tree species; for a complete list 

see Farr and Rossman (n.d.). Two phylogenetically distinct 

species of Ceratobasidium on tea (Camillia sinensis) and 

Asian persimmon (Diospyros kaki) from Brazil (Ceresini 

et al. 2012) cause similar disease etiology and may have 

been reported as C. noxium or its synonyms in the older 

literature. Genera of Hawai‘i native plants at particular risk 

are Diospyros sp. and Erythina sp. Ceratobasidium white 

thread pathogens have been reported on D. texana in Florida, D. virginiana in Louisiana and Tennessee, D. kaki from 

Brazil, and Erythrina sp. in Florida (CABI 2011b; Ceresini 

et al. 2012; Farr and Rossman, n.d). 

Distribution: Ceratobasidium noxium is widely distributed 

in tropical and semitropical areas of Asia, Africa, the Americas, Greece, and Oceania, including American Samoa, Fiji, 

Micronesia, New Caledonia, Papua New Guinea, Samoa, 

and Vanuatu but has not been observed in Australia or 

New Zealand. In North America, it has been reported from 

Indiana but is usually associated with Southern states, 

including Florida, North Carolina, South Carolina, Louisiana, Mississippi, Texas, Tennessee, and Puerto Rico. (CABI 

2011b; Farr and Rossman, n.d.). 

Summary of natural history and basic biology of 

the pests: Ceratobasidium noxium and closely related 

species are responsible for a number of diseases on a wide 

variety of different hosts in the tropics and subtropics. 

These diseases have been termed “white-thread disease,” 

“black rot,” and “koleroga disease.” Although wide-spread, 

it is usually not an overly destructive pathogen except under 

narrowly defined environmental conditions. Humidity 
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

appears to be the most important parameter for fungal 

growth and disease development. Heavy mists, poor air 

circulation, continuous and persistent light showers, and 

cloudy skies are more conducive to disease development 

than extremely heavy rainstorms followed by sun. In India, 

the disease is observed on coffee plants in regions that 

exceed 152.4 cm of rain per year and is severe only in those 

areas that experience heavy South West Monsoon rains 

from June to September or where microclimate provides 

high humidity for extensive time periods (Mathew 1954). 

The temperature optimum of C. noxium is 22 to 25 °C 

(Matsumoto and Yamamoto 1934). Cool, humid conditions 

favor disease development. The fungus is able to infect all 

portions of the plant including young shoots, leaves, and 

berries (Mathew 1954). 

Disease is characterized by the presence of black, 

rotting leaves that continue to hang on the branches owing 

to the presence of mycelial threads that run along the twigs 

and petioles. Mycelial mats are formed on the lower surfaces of the leaves where both basidiospores and sclerotia 

are formed. The fungus penetrates the leaves through the 

stomata on the lower surface and invades the palisade 

cells and vascular system, thus spreading throughout the 

plant. Basidiospore formation on coffee is associated with 

continuous rainfall, but the fungus seems to be spread 

primarily by mycelial threads carried by wind or by contact 

from detached, infected leaves. Basidiospores lose viability 

rapidly on account of desiccation—up to 80 percent of 

spores lost the ability to germinate after 2 weeks on water 

agar—and may only be able to infect and colonize highly 

susceptible hosts in proximity to diseased plants under 

narrowly defined environmental conditions. The fungus 

appears to survive dry periods as vegetative mycelium 

within dead twigs, branches, and wood. The role of sclerotia 

in spreading the pathogen is unknown; pathogenicity testing 

using fresh and 1-year-old sclerotia as inoculum on coffee 

leaves was unsuccessful, but only a small number of plants 

were used in the experiment (Mathew 1954). 

Although the two unnamed species in Brazil are phylogenetically distinct and show host preferences for either 

tea (Camillia sinensis) or Asian persimmon (Diospyros 

kaki), they are able to cause disease on both hosts as well 

as on coffee and citrus in pathogenicity experiments. Eight 

varieties of D. kaki showed no resistance to the disease 

(Souza et al. 2009).

Specific information relating to risk elements:

Uncertainties in this assessment are due to a lack of 

literature on the biology of the fungus. Basic work on disease physiology is restricted to the fungus on coffee (Coffea 

arabica) in India (Mathew 1954) and on Asian persimmon 

and tea (Souza et al. 2009) in Brazil. 

A. Likelihood of introduction

1. Pest with host-commodity at origin potential: High

(VC) (Applicable rating criteria, from app. 4: b, c, d, 

g, h) 

The fungus has a very broad host range with a very 

wide geographic distribution in tropical and subtropical 

regions of the world. It is able to survive in soil and dried 

plant material, and can also increase its population rapidly 

under certain environmental conditions through the formation of basidiospores and sclerotia. 

2. Entry potential: High (RC) (Applicable rating criteria, from app. 4: b, c, d)

Fungus can survive within vascular tissues of the wood 

as well as in leaves and stems. It is difficult to detect as the 

mycelial threads are small and only formed during periods 

of high humidity. The presence of dead leaves could be due 

to many different causes and would not attract attention.

3. Colonization potential: High (RC) (Applicable rating criteria, from app. 4: a, b, c, e)

The worldwide distribution of the pathogen, even to 

remote Pacific islands, shows that it is capable of colonization and spread after transport. 
108

GENERAL TECHNICAL REPORT PSW-GTR-250

4. Spread potential: High (RC) (Applicable rating criteria, from app. 4: a, b, c, d, f, g) 

This pathogen has many potential hosts with overlapping ranges. Newly established populations could go 

undetected for many years as the disease often occurs at 

a low level and is limited to geographic areas and times 

of the year of extreme humidity and rainfall. The eastern, 

wetter portions of the islands would be particularly suitable 

for establishment of the fungus. The uncertainty in this 

criterion is due to the lack of information on the role of 

basidiospores and sclerotia in establishing the pathogen.

B. Consequences of introduction

5. Economic damage potential: Moderate (VC) 

(Applicable rating criteria, from app. 4: a, b, c)

The pathogen can cause plant death and decreased 

production in many different economically important host 

plants. 

6. Environmental damage potential: Moderate (RC) 

(Applicable rating criteria, from app. 4: d) 

The pathogen is active and causes leaf death and 

defoliation under conditions of extreme humidity, usually 

restricted to the monsoon or rainy season. Mortality can 

occur owing to host decline and predisposing the host to 

other mortality agents, but the fungus does not appear to be 

a primary pathogen in most situations.

7. Social and political considerations: Moderate (RC) 

(Applicable rating criteria, from app. 4: a) 

The public would become concerned with the formation of dead, rotted leaves on plants in native forests and 

landscapes. 

C. Pest risk potential 

High (Likelihood of introduction = high; Consequences of introduction = moderate) 

Selected bibliography:

Centre for Agricultural Bioscience International 

[CABI]. 2011b. Crop protection compendium: Corticium 

koleroga (thread blight). Wallingford, United Kingdom: 

CAB International. http://www.cabi.org/cpc. 

(20 May 2013).

Ceresini, P.C.; Costa-Souza, E.; Zala, M.; Furtado, E.L.; 

Souza, N.L. 2012. Evidence that the Ceratobasidiumlike white-thread blight and black rot fungal pathogens 

from persimmon and tea crops in the Brazilian Atlantic 

Forest agroecosystem are two distinct phylospecies. 

Genetics and Molecular Biology. 35: 480–497.

Farr, D.F.; Rossman, A.Y. [N.d.]. Systematic mycology 

and microbiology [Database]. http://nt.ars-grin.gov/

fungaldatabases/. (18 June 2014).

Mathew, K.T. 1954. Studies on the black rot of coffee: 

I. The disease in South India and some general 

considerations. Proceedings of the Indian Academy of 

Sciences-Section B. 39: 133–170.

Matsumoto, T.; Yamamoto, W. 1935. Hypochnus sasakii

Shirai in comparison with Corticium stevensii Burt and 

Corticium koleroga (Cooke) v. Hőhn. Transactions of the 

Natural History Society of Formosa. 25: 161–175.

Souza, E.C.; Basseto, M.A.; Boliani, A.C; Takada, 

H.M.; Ceresini, P.C. 2009. Cross pathogenicity of 

Ceratobasdium spp. from kaki (Diospyros kaki) and tea 

(Camellia sinensis) and reaction of kaki varieties to the 

pathogen. Summa Phytopathologica. 35: 9–14.

Reviewers’ comments: None received.
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Summary

Hawai‘i is unique amongst the 50 states. As noted in chapter 

2, it was formed and developed over the millennia independently of any other land mass. This has resulted in very 

unique and distinct species and ecosystems on each island. 

Because of its isolation, the state also has a rare economic 

situation, with almost all goods needing to arrive from other 

locations. This status of Hawai‘i has been a driver during 

this assessment and underlies many of the issues the state 

faces with respect to invasive species.

A major challenge of this analysis was to determine 

which of the world’s 400,000 fungal species and 900,000 

insect species known to feed on plant/plant parts are not yet 

found in Hawai‘i and pose a risk to 13 key forest tree taxa in 

the Hawaiian Islands.

The approach taken for this exercise followed protocols 

established by the international plant protection community. For each of the 13 Hawai‘i forest taxa, we examined 

the literature and determined the insects and pathogens 

recorded on them in Hawai‘i. We compiled a similar list 

of insects and pathogens world-wide and not known to 

occur in Hawai‘i and recorded in association with the taxa 

or other species of the same genera. Although this process 

may seem straightforward, the lists that were produced of 

potential pests and pathogens for each of the 13 taxa are 

considerable in length. For some species, like Acacia koa, 

this process produced lists of literally thousands of fungi 

and insect species that have been associated with Acacia

species. This is, in large measure, due to the abundance of 

land area worldwide covered by the 700 different species 

of Acacia and the fact that thousands of forest health 

personnel, mycologists, entomologists, etc. have spent large 

portions of their careers looking at the flora and fauna that 

affect species in this genus. Metrosideros polymorpha was 

another key species that had numerous fungi associated 

with it, no doubt because there are so many Metrosideros

species scattered across the Pacific. By contrast, some of 

the other species, like Sophora chrysophylla, Myoporum 

sandwicensis, and Scaevola spp. had very short lists associated with them because their genera are composed of a 

relatively small number of species, and individuals or pests 

are underreported owing to their noneconomic nature. 

We examined the lists of exotic fungal and insect 

species for those considered to have capacity to be effective 

pathogens or pests on living trees. We relied on information 

presented in the literature, when this was available, and 

also on the experience of the authors and reviewers of this 

document. This helped to narrow the list to the about 400 

insect pests and 300 pathogens shown in tables 7-1 and 7-2, 

respectively (app. 7)1. These tables represent what we consider the insect pests and pathogens with the most potential 

for damage to the taxa should they gain entry into Hawai‘i.

Besides providing lists of which insects and pathogens 

have potential to cause damage, it is also important to 

evaluate the potential for these agents to be introduced and 

become established in Hawai‘i and also the amount of damage they might cause. This evaluation is done via individual 

pest risk assessments (IPRA). We identified 12 insect pests 

and 12 pathogens to include in the IPRAs, which represent examples of insects and pathogens found on seeds, 

roots, bark, sapwood, and heartwood that would have the 

greatest potential risk to forests and other tree resources of 

Hawai‘i. They are representative of the diversity of insects 

and pathogens that might inhabit the hosts of concern. By 

necessity, the IPRAs focus on those insects and pathogens 

for which biological information was available. The location 

on the host and a summary of the risk potential for each of 

the 24 organisms is presented in table 11. 

We received over 400 comments on the draft risk 

assessment. These comments came from people in various 

agencies and countries identified in appendix 1. Our team 

is extremely grateful for the time and effort expended by 

reviewers, who clearly dedicated substantial energy to the 

review process and provided thoughtful feedback that made 

our final report much more robust.

The complexity of this project was clearly reflected in 

many of the comments that we received. Some reviewers 

felt that the scope of the risk assessment was limited and 

should be expanded (not all pathways were considered), 

while others stated that the content was overwhelming and 

made the document difficult to read. We felt that this project 

Chapter 5: Summary and Conclusions

1 Appendices for this report are available online at: http://www.fs.fed.

us/psw/publications/documents/psw_gtr250/ psw_gtr250_appendix.pdf.
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Table 11—Summary of risk potentials for pests of concern to 13 Hawai‘i forest hosts (continued)

Common name (scientific 

name)/location on host

Likelihood of introduction Consequences of introduction

Pest risk 

potential

Host 

associationEntry 

potential

Colonization 

potential

Spread 

potential

Economic 

damage

Environmental

damage

Social/

political

Insects

Apple stem borer

(Aeolesthes holosericea)/

bark/cambium, sapwood, 

heartwood

Ha H H H H H M H

Botany Bay diamond 

weevil (Chryosolopus 

spectabilis)/roots, 

foliage/other, bark/

cambium

M H M M M M L M

Coconut rhinoceros beetle

(Oryctes rhinoceros)/

foliage/other

H H H H M M M H

Coconut stick insect

(Graeffea crouanii)/

foliage/other

M M M L L L M M

Erythrina scale

(Toumeyella erythrinae)/

foliage/other, bark 

cambium

M H L M M M M M

Eugenia psyllid (Trioza 

eugeniae)/foliage/other

M H H M M M M M

Keyhole ambrosia beetle

(Amasa truncata)/bark/

cambium

H H H H M L M H

Lemon tree borer (Oemona 

hirta)/bark/cambium, 

sapwood, heartwood

M M H M M M L M

Platypodid ambrosia beetle

(Megaplatypus mutatus)/

bark/cambium

M H H H M M M M

Summer fruit tortrix moth

(Adoxophyes orana)/

foliage/other (fruit 

surface)

H H H H M H M H
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

Table 11—Summary of risk potentials for pests of concern to 13 Hawai‘i forest hosts (continued)

Common name (scientific 

name)/location on host

Likelihood of introduction Consequences of introduction

Pest risk 

potential

Host 

associationEntry 

potential

Colonization 

potential

Spread 

potential

Economic 

damage

Environmental

damage

Social/

political

West Indian sugarcane 

borer weevil (Diaprepes 

abbreviatus)/roots, 

foliage/other

H H H H H H M H

White wax scale 

(Ceroplastes destructor)/

foliage/other

H H H H H H M H

Pathogens

Acacia gall rust 

(Uromycladium 

tepperianum)/foliage/

other, bark/cambium

H H H H M M M H

Aecidium rusts (Aecidium 

atrocrustaceum, 

A. calosporum, A. 

carbonaceum, A. 

diospyri, A. mabae, 

A. melaenum, A. 

muelleri, A. myopori, 

A. ramosii, A. reyesii,

A. rhytismoideum, A. 

royenae, A. ulei, A. 

yapoense)/foliage/other, 

bark/cambium

M H M H L M L M

Armillaria root disease 

(Armillaria limonea, A. 

luteobubalina, A. novaezelandiae, A. tabescens)/

roots, bark/cambium, 

sapwood, heartwood

H H H H H H H H

Calonectria morganii/

seeds, roots, foliage/

other, bark/cambium

H H H H M M L H

Fomitiporia spp. 

(Fomitiporia 

australiensis, F. 

mediterranea, F. 

punctata, F. robusta, 

F. sonorae)/roots, bark/

cambium, sapwood, 

heartwood

H H H H M H H H
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GENERAL TECHNICAL REPORT PSW-GTR-250

Table 11—Summary of risk potentials for pests of concern to 13 Hawai‘i forest hosts (continued)

Common name (scientific 

name)/location on host

Likelihood of introduction Consequences of introduction

Pest risk 

potential

Host 

associationEntry 

potential

Colonization 

potential

Spread 

potential

Economic 

damage

Environmental

damage

Social/

political

Guava rust/eucalyptus rust

(Puccinia psidii)/foliage/

other

H H H H H H H H

Pestalotia and 

Pestalotiopsis

(Pestalotia acacia, P. 

cibotii, P. diospyri, P. 

dodonaea, P. pandani,

vaccinii; Pestalotiopsis 

sp., P. breviseta, 

P. glandicola, P. 

palmarum, P. photiniae, 

P. theae, P. uvicola, P. 

versicolor)/foliage/other

H H M H L M L M

Phellinus noxius/roots, 

bark/cambium, sapwood, 

heartwood

H H H H M H H H

Pink disease (Erythricium 

salmonicolor)/bark/

cambium

H H H H H H H H

Ramorum blight/sudden 

oak death (Phytophthora 

ramorum)/foliage/other, 

bark/cambium

H H H H H M H H

Uromyces rusts (Uromyces 

scaevolae, U. 

sophorae- japonicae, U. 

truncicola)/foliage/other

M H M M L H L H

White thread blight/black 

rot (Ceratobasidium 

noxium)/foliage/other

H H H H M M M H

a H = high, M = moderate, and L = low.
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

was very broad in scope and as such, provided a challenge 

for concise organization and documentation. 

Other comments addressed issues of document clarity 

and readability, stating that we sometimes strayed beyond 

our objectives in some of our conclusions. We gathered data 

from many sources including previous risk assessments for 

Hawai‘i and the Caribbean countries. Some reviewers felt 

that some of the data were used or interpreted incorrectly or 

were simply erroneous. We made every attempt to correct 

or clarify those mistakes. Readability was improved by 

moving the tables and other information from the body to 

appendices.

Within the tables of existing and potential insects and 

pathogens, reviewers identified a number of organisms with 

incorrect information; the appropriate edits were made by 

the team. 

Within our risk assessment process, there was some 

confusion about regulations that govern movement of 

commodities and inspection for pests. Reviewers clarified 

the roles of state and federal regulatory agencies for us in 

order to clear up confusion. 

Issues and Findings

We identified a number of issues and findings in this pest 

risk assessment. Some of them have been reported in other 

assessments (Culliney et al. [n.d.], Meissner et al. 2009) and 

were adopted by us as appropriate for Hawai‘i because they 

are integral to invasive species transport and risk around the 

world. Some are more peculiar to Hawai‘i. We present these 

findings in the following pages. We considered six findings 

most important and discuss at length. Other findings are 

more briefly mentioned. 

1. Inspection alone is not 100 percent effective in preventing introductions. In fact, some studies have shown 

that port inspections, alone, have relatively low interception efficiency (Meissner et al. 2009).

Inspection success might be improved by assessing commodities scheduled to arrive in Hawai‘i, including their 

type, source, quantity, and timing, for their potential to 

be carrying actionable pests. This could aid inspectors 

in determining where to focus their inspection efforts 

on arriving shipments and also in indicating the pest or 

pathogen that needs to be searched for in these inspections. 

The main action that needs to be considered jointly by 

Animal and Plant Health Inspection Service (APHIS), 

U.S. Customs and Border Patrol (CBP), and the Hawai‘i 

Department of Agriculture (HDOA) is whether or not some 

of the pests and pathogens in this present report should be 

put on the “actionable” lists and receive focused attention. 

The exact way of getting this to happen is beyond the 

scope of this report. However, the importance of handling 

this well is illustrated by Beardsley (1991) who estimated 

that an average of 3.5 new pest arthropods and mollusks 

establish in Hawai‘i on an annual basis. This number has 

likely increased over the past two decades despite increased 

inspections and regulatory efforts

Another way to reduce the odds of an exotic pest or 

pathogen becoming established would be to have a survey/

monitoring program in place for detecting pests and pathogens that might have recently escaped into the environs 

immediately surrounding the ports (e.g., an early detection 

system). Potentially invasive insects have often been 

trapped in such exercises using traps with species-specific 

lures.

2. The primary sources of introductions are mainland 

United States and Asia-Pacific.

Hawai‘i is located over 3218 km from the nearest continental coast, resulting in nearly absolute dependence on 

ocean surface transportation or air transport for human 

sustenance. In addition, the tropical paradise is a tourist 

destination for millions of people via aircraft or cruise 

ships. The increasing volume of goods and people coming 

into the state each year, combined with the year-round 

tropical/temperate climate, has greatly increased exotic pest 

introduction and establishment. There appears to be no end 

in sight. It is estimated that 20 to 40 new terrestrial arthropod introductions occured in Hawai‘i each year from 1937 

to 1967 (Beardsley 1979a), with about 10 percent becoming 

significant pests. At the Kahului Airport on Maui, there 

were 10.8 insect interceptions per day (of species not known 

to occur in Hawai‘i, known to be established in Hawai‘i, 

or of undetermined status) in just 130 days of inspections 

during 2000-2001 (HDOA 2002).
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GENERAL TECHNICAL REPORT PSW-GTR-250

During a good economic period, Honolulu Harbor 

accommodated more than 1 million 20-ft equivalent units 

(TEUs) per year. These were distributed on O‘ahu, to other 

islands, and shipped to overseas ports. Installation of new 

facilities could increase capacity from 950,000 to 1,500,000 

TEUs per year. In addition, in 2013, over 8.2 million people 

came to Hawai‘i either on cruise ships or airplanes (Hawai‘i 

Tourism Authority 2014). The majority of visitors came 

from the U.S. mainland (60 percent) and Japan (18 percent) 

(Hawai‘i Tourism Authority 2014). 

Increased understanding of the prevalence of pests on 

ships (including military), in cargo containers, and aboard 

aircraft (and other high-risk pathways), and their origin, can 

lead to more targeted inspections and potentially reduce the 

number of pest introductions and establishments. Eighty 

percent of all consumer goods are imported into Hawai‘i, 

98 percent of which comes through commercial harbors. 

Hawai‘i received 25.3 million metric tons (tonnes) of sea 

cargo from domestic trade and 7.6 million metric tons 

from foreign trade in 2005 (Culliney et al., n.d.: table 4-1). 

Any such numbers can be misleading though, as much of 

the domestic cargo from the U.S. mainland is foreign in 

origin and is then shipped to Hawai‘i as domestic cargo 

(Kosciuk 2007) and is subject to different phytosanitary 

inspection standards. 

Between 2004 and 2006, the majority of shipments of 

propagative material classified as foreign came from Indonesia, Canada, and Thailand. This did not include foreign 

plants shipped to the U.S. mainland and then sent to Hawai‘i 

as domestic cargo (see above). Shipments from Indonesia 

represented over 100 plant genera and two shipments of 

lumber products. Shipments from Canada and Thailand 

also contained over 100 different plant genera (Culliney et 

al., n.d.). Over 1,500 plant pests, representing 140 species 

not known to occur in Hawai‘i, were on shipments arriving 

from the U.S. mainland between 2004 and 2006. This 

includes pests intercepted on material that originated in a 

foreign country, but was classified as domestic cargo upon 

arrival in Hawai‘i (Culliney et al., n.d.). 

People can transport pests in checked and carry-on 

baggage as hitchhikers or on goods brought into the state. 

For international travelers coming into Honolulu Airport, 

an analysis of data from 2005 through 2006 shows travelers from Japan to be the source of the highest number of 

quarantine materials (primarily citrus), followed by Australia and Guam. Although no plant pest interceptions were 

recorded for the over 7,000 passenger groups sampled, 426 

pests were recorded in the PestID database (USDA 2007a) 

for the same years, potentially indicating a low interception efficiency rate. For visitors from the U.S. mainland, 

quarantine inspections by HDOA resulted in over 300 pest 

interceptions in domestic air passenger carry-on baggage 

between 1995 and 1996 (HDOA 2007), demonstrating that 

visitors entering by air from the U.S. mainland are a significant pathway for introduction of exotic pests. Pests that 

were repeatedly intercepted included scales, ants, leafminers, noctuids (owlet moths), mealybugs, and codling moths. 

Although the pest risk associated with airline passengers 

cannot be completely quantified owing to lack of data, it is 

likely significant (Culliney et al., n.d.).

Most foreign and domestic fresh agricultural shipments 

into Hawai‘i arrive by aircraft. Inspection blitzes were 

conducted between September 2000 and July 2001 at the 

Kahului Airport on Maui. Most daily flights originated from 

the U.S. mainland (81 percent), with the remainder coming 

from Canada. Each blitz lasted over a 3- to 4-week period 

during which intensive inspections were made of checked 

and carry-on baggage, aircraft cabins and cargo holds, 

and all agricultural products shipped by air cargo (HDOA 

2002). In total, 1,897 flights were inspected, 81 percent of 

which had agricultural commodities (flowers, plants, and 

produce) in the baggage or in the cabin. 

The KARA air cargo inspections involved 1,495 

shipments containing 168,351 cases of over 400 different 

agricultural commodities. Most of the shipments from 

domestic ports were from California. Foreign shipments 

primarily came from Australia, Ecuador, Guatemala, 

Holland, Mexico, and New Zealand. Pests were found in 9.8 

percent of the cases that underwent 100 percent inspection. 

Domestic shipments had a higher percentage of pests not 

known to exist in Hawai‘i (45 percent) compared to foreign 

shipments (33 percent). Foreign shipments had a higher percentage of pests already established in Hawai‘i (52 percent) 

compared to domestic shipments (37 percent). During the 
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

period 1980-2002, two-hundred sixty-six insects and other 

arthropods were recorded as new state records for Hawai‘i 

(HDOA 2002); an average of 12 new arthropods established per year. Most of these are not pests or are of minor 

significance. Some were purposely introduced to control 

other pests. Of these 266 insects and other arthropods, 46 

are considered moderate to serious pests by the HDOA. 

Twenty-five of these 46 pests are of foreign origin, and the 

other 21 pests are known to occur on the U.S. mainland. 

Although pests in Hawai‘i have come from a variety 

of origins, many have come from the U.S. mainland and 

Asia-Pacific countries and islands. The lack of ability to 

inspect everything coming into Hawai‘i (owing to the 

amount of goods and number of passengers, limited funding, lack of reliable detection methods, and other reasons), 

and knowing that a significant number of imminent pests 

have the potential to be introduced via multiple pathways, 

combined with the alarming rate of pest establishments, 

point to the need to increase inspections and improve 

targeting for pests. Having reliable and accurate data on 

pest interceptions and where pests come from can facilitate 

more informed decisions regarding where to use inspection 

resources, while having improved detection methods can 

decrease the likelihood of pest establishment. 

3. There is a strong need to make visitors aware that 

they are a significant potential source of unwanted introductions. Given what we know about plant materials as 

an important pathway of pest introduction, increased 

efforts are needed to persuade visitors to voluntarily 

stop bringing live plant material into Hawai‘i.

Hawai‘i receives a large number of visitors each year from a 

wide variety of geographic regions and cultures. The largest 

number of visitors come from the U.S. mainland and Japan 

with minor, but significant, origins including Asian Pacific 

countries like Australia, South Korea (rapidly increasing), 

and China. Most visitors arrive in the Hawai‘i Islands by 

air; although cruise ship visits also contribute large numbers 

of people. For all modes of travel, the level of phytosanitary inspection is generally insufficient to mitigate pest 

risk predominantly from live plant material (see previous 

sections). It is therefore important preemptively to persuade 

passengers not to bring live plants into Hawai‘i. In essence, 

passengers need to inspect and regulate the contents of their 

baggage. Public outreach is probably the most efficient way 

to effect this change with a majority of the visitors, most 

of whom presumably want to do the right thing. Important 

basic topics to address in any outreach should include: 

• Why live plant material brought in by visitors from 

outside Hawai‘i threatens native Hawai‘i forests. 

• What are some of “the really bad actors,” and why is 

it important to avoid introducing them. 

• What types of behavior inadvertently introduce 

pests. 

• Contact information for questions and information, 

including how visitors can help.

• Understanding why visitors bring live plants into 

Hawai‘i. While interception statistics show that 

visitors bring many potentially problematic live 

plants into Hawai‘i, there has been little available 

information on the types of motivations visitors have 

for doing so. Understanding different motives for 

live plant introduction may in turn result in better 

techniques to persuade visitors to not bring live 

plants to Hawai‘i. For example, many live plants may 

reach Hawai‘i simply because of visitor oversight, 

while others may be deliberately brought in to fill a 

need (e.g., cultural or culinary need) because they 

are thought to be (or are) unavailable in Hawai‘i. If 

this is a common situation, providing information on 

local sources of these plants might reduce the incentive to bring these plants from outside Hawai‘i.

To encourage visitors to avoid behaviors that place 

Hawai‘i’s native forests at risk, we suggest an active and 

coordinated outreach program to visitors. This outreach 

should ideally start before travelers board their plane or 

ship, reinforced during the flight or voyage, and before they 

disembark into Hawai‘i. International air or cruise ship 

travelers as well as travelers from the mainland should be 

clearly told the types of plant material that threaten’s native 

forests should they inadvertently or purposely pack them 

either in their luggage or on their person. During their stay, 

these ideas could be reinforced again at appropriate attractions that showcase native forest and species, giving visitors 

an opportunity to feel a connection with what they are being 
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GENERAL TECHNICAL REPORT PSW-GTR-250

asked to protect. Many of those who visit Hawai‘i return. 

Once the message is understood and integrated into routine 

good practices, these return visitors can be recruited to help 

spread the word to other visitors. Continue to use methods 

currently in place to obtain information from passengers 

(e.g., inspection forms required upon arrival into Hawai‘i).

Suggested specific actions that could be taken include:

Alert visitors prior to boarding: 

• Work with airlines to provide a brief online message 

to travelers warning about the dangers of introducing live plant materials from outside Hawai‘i to 

native forest and agriculture (on the boarding pass, 

reservation site, luggage tags, etc.). Provide a link 

to a website with more information about threats to 

Hawai‘i’s forests. 

• Post signs at marinas and departure gates for flights 

to Hawai‘i to educate visitors about the potential 

consequences of transporting exotic insect pests and 

pathogens on vessels. 

• Increase presence and visibility of inspectors at 

marinas and airports, mainly as a deterrent measure. 

Publicize interceptions as a warning to potential violators.

Educate travelers prior to departure and arrival about 

the potential consequences (economic, environmental, and 

personal) of transporting agricultural and other vegetative 

products. Remind travelers to consume or properly 

discard prohibited materials during travel. Implement risk 

communication strategies to educate local residents and 

business owners on the pest risks associated with trade such 

as the following:

• Informational brochures available during flight 

(include supporting statistics regarding interceptions 

of potentially harmful insects or pathogens, as well 

as several examples of serious pest introductions)

• Announcements

• Articles in in-flight magazines 

• Hand out free pens with the message about the dangers of transporting live pests for visitors who are 

filling out the declaration form. 

Reinforce the message at tourist areas when the visitor 

is actually in a position to see and experience native plants 

or forest ecosystems and develop an appreciation for them:

• Post signs at eco-tourism sites describing acceptable behavior while visiting the site. Visitors should 

be instructed to remain on marked paths and not to 

bring into or take out of the area any plants, plant 

parts, or animals. Botanical gardens that include 

native trees can also provide opportunities for interpretation and build an appreciation for the value of 

native plants. 

• Instruct visitors to clean shoes and clothing when 

entering or leaving a natural or agricultural area. 

Visitors should remove soil and plant seeds from 

shoes and clothing and inspect cuffs and Velcro® 

closures. (Where appropriate, consider the use of 

water hoses, disinfectant shoe baths, metal grates in 

ground for cleaning shoes, and other measures.)

• Work with tour guides and other staff at natural 

areas, parks, or agricultural areas to educate visitors 

on the potential environmental and economic effects 

of exotic species. Good examples of public education 

are increasingly common on the islands in important 

wildlife habitat areas and could be applied in some 

cases to raising public awareness of invasive species. 

For example, visitors kayaking to Flat Island Bird 

Sanctuary on O‘ahu are educated on proper behavior 

with respect to the birds prior to being able to rent a 

watercraft such as a kayak or paddle board. They are 

also charged a fee if they land on the islands, which 

is used to protect bird habitat. 

• Raise money by providing products such as postcards, t-shirts, calendars, or souvenirs to visitors 

who give a donation (Johnson 2006). Use the money 

towards the prevention of exotic pest introductions. 

The products themselves can be educational by 

providing information on exotic pests of concern, 

dispersal mechanisms, and possible preventative 

actions.

• Implement a user fee system for eco-tourist destinations. Funds raised through ecotourism should go to 

exotic species prevention and management (Hypolite 

et al. 2002).
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

• Conduct biodiversity impact studies for ecotourism sites to anticipate environmental and economic 

impacts of exotic species introduction.

• Limit access to very sensitive sites by restricting the 

number of visitors, access for vehicles, density of 

roads and trails, availability of accommodations, etc.

• Let visitors know they can help by spreading the 

word. 

After the visitor has returned home:

• Visitors returning from Hawai‘i may convey what 

they have learned to future visitors and become 

advocates for guarding native forest from invasives.

• Attractive souvenirs may promote discussion with 

future visitors. 

4. Plant materials, especially live plants, are by far the 

most important source of pest problems for Hawai‘i. 

Plant materials include propagative material (seeds, pods, 

seedlings, cuttings), fruits and vegetables, and cut flowers 

and plant parts for crafts or decorations. The sources and 

traffic patterns associated with the movement of plant 

materials into Hawai‘i have been thoroughly addressed in 

other risk assessments in addition to ours. The patterns are 

very complex and involve international trade and tourism, 

among other avenues. 

We examined the APHIS interception records for 

Hawai‘i ports between 1984 and 2010. During that time, 

over 10,000 pests were intercepted. Most of the sources 

of these interceptions were Asian countries, Australia and 

other countries of the Pacific. Over 20 countries were the 

sources of at least 100 interceptions each during this time 

period. Passenger baggage was listed nearly two-thirds of 

the time under the category “where intercepted.” Nearly 85 

percent of the intercepted pests were connected with plant 

materials, with “fruit” being the source of over 30 percent 

of the total records. 

Our pest risk assessment focuses on 13 taxa of native 

Hawai‘i plants and therefore, it logically follows that the 

plant pathway would be the primary source of introduction 

of potential pests. 

As noted above, a pest risk assessment for the island 

of Maui (HDOA 2002) found that between 1980 and 2002, 

two-hundred sixty-six insects and other arthropods were 

recorded as new state records for Hawai‘i. Of these 266 

introduced insects and other arthropods, 46 are considered 

moderate to serious pests by HDOA. Twenty-five of these 

46 pests are of foreign origin, and the other 21 pests are 

known to occur on the U.S. mainland. Considering the 

biology of these “moderate to serious” pests, it is likely 

that as many as 40 of the 46 species could have had a plant 

pathway as their means of entry into Hawai‘i. 

The high rate of new pest establishment in Hawai‘i 

is very disturbing and needs to be addressed in new ways 

that go beyond existing inspection measures and current 

approaches to regulation. When situations arise in the continental United States or elsewhere that involve exotic pests 

and host plants with representatives on the Hawai‘i Islands, 

an aggressive approach should be taken to ensure that 

pests do not gain entry into Hawai‘i. This approach should 

include the prohibition of movement of the affected plant 

species into Hawai‘i. A particularly disturbing example 

would be the establishment in Hawai‘i in 2008 of the highly 

damaging, newly described thrips species associated with 

Myoporum in California (Conant et al. 2009, Loope and 

LaRosa 2010).

We also believe it is important to strengthen the Pest 

Risk Committee, which deals with emerging issues involving plant pests (Culliney et al., n.d.).

5. The solid wood packing material (SWPM) pathway 

needs more scrutiny. Many pests using this pathway 

have already become established in Hawai‘i, and many 

more are on the list of potentials. Because HDOA can 

only inspect wood packing material that is associated 

with agricultural commodities, and because wood packing material is not necessarily specified as associated 

with cargo, it seems as if this is a pathway that is being 

insufficiently inspected and regulated.

Solid wood packing material, ubiquitous in international 

trade, is an important pathway for the introduction of potentially invasive species, as described in chapter 3. Because 

of international concern and the large number of bark- and 

wood-infesting insects that became established outside of 

their native ranges during the 1990s, international efforts at 

standardizing phytosanitary treatments of SWPM resulted 
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GENERAL TECHNICAL REPORT PSW-GTR-250

in the adoption of ISPM 15, a standard that requires all 

SWPM to be either heat treated for 30 minutes at 56 °C or 

fumigated with methyl bromide. In the most recent revision 

of ISPM 15 (IPPC 2009), the amount and size of residual 

bark remaining on SWPM was also restricted to patches 

less than 50 cm2 as it was determined that bark patches 

were a prime source of beetle survival and recolonization 

after treatment (Haack and Petrice 2009). As of 2011, 70 

countries require that SWPM meet the standards of ISPM 

15 (Haack and Brockerhoff 2011). 

The efficacy of treatments required by ISPM 15 has 

been questioned. Surveys of individual pieces of SWPM 

treated to ISPM 15 standards in Australia, the European 

Union, and the United States resulted in the detection of 

live beetles in 0.1 to 0.5 percent of the inspected items, 

usually in association with patches of bark (Haack and 

Brockerhoff 2011). The Australia survey examined 20,000 

pieces of SWPM in Australia from containerized sea cargo 

that resulted in a 9 percent detection rate for items of overall 

quarantine concern, including 8.5 percent bark, 5.9 percent 

fungi, 3.2 percent live insects, 2.8 percent frass, and 1.7 percent soil–these items not being mutually exclusive (Zahid et 

al. 2008). In Honolulu, a 2-year survey from 2005 to 2007 

conducted randomly by the USDA Agricultural Quarantine 

Inspection Monitoring (AQIM) program resulted in similar 

conclusions. Of 116 inspections of SWPM, four shipments 

contained live insects; single shipments were also found that 

contained soil, unidentified noxious weeds, and an “unidentified pest.” Five shipments had no ISPM 15 identifying 

marks. Only 50 percent of the wood surface was examined; 

however, and no attempt was made to determine whether 

pests were inside of the wood or whether dead pests were 

present at the bottom of the shipping containers (Culliney 

et al., n.d.]). Inspections by the New Zealand Ministry of 

Agriculture and Forestry of about 1,500 containers with 

SWPM determined that 16 percent had contaminations 

that resulted in phytosanitary action, such as fumigation or 

incineration. Organisms that were detected included fungi, 

insects, isopods, millipedes, and mites. Hitchhiking plant 

materials, spiders, mollusks, and reptiles were also found; 

these do not represent a failure of ISPM protocols (MAF 

2003). An evaluation of ISPM 15-treated SWPM in Chile 

also found important quarantine insects in or on the wood. 

These included Sinoxylon anale, S. conigerum, Monochamus alternatus (Coleoptera: Cerambycidae), Pissodes 

castaneus (Coleoptera: Curculionidae), Tomicus piniperda, 

Heterobostrychus aequalis (Coleoptera: Bostrichidae), Sirex 

noctilio (Hymenoptera: Siricidae), Ips spp. (Coleoptera: 

Curculionidae: Scolytinae), and other Pissodes spp. (Sanchez Salinas 2007). 

These are disturbing survey results. Possible reasons 

for pest survival include tolerance of certain insects to 

the mitigation treatments; recolonization after treatment 

has occurred, especially when bark is present; improper 

application of treatment owing to defective equipment or 

facilities; and outright fraud where the treatment mark is 

applied to nontreated wood (Haack and Brockerhoff 2011). 

With the exception of the Australian study, comparable 

surveys have not been done for the detection of fungi and 

other pathogens. Another concern is that SWPM is usually 

reused multiple times so it does not necessarily originate 

from the site of the commodity with which it is associated. 

Currently, there is no way to track the origin of SWPM and 

the potential pests and pathogens associated with that place 

of origin, or when and where it was treated for ISPM 15 

compliance (Haack and Brockerhoff 2011).

The current inspection system is not adequate to 

detect pests and pathogens associated with SWPM. During 

the Honolulu AQIM assessment, only about 10 percent 

of the volume was inspected, but the rate of interception 

was 10 percent higher than typically seen (HDOA 2007) 

(as reported in Culliney et al., n.d.). Inspectors from the 

HDOA cannot inspect nonagricultural shipments unless 

referred by another agency even though SWPM associated 

with nonagricultural commodities is a major risk factor. 

The AQIM data set included pests intercepted on marble 

slabs, granite and stone from China, and on furniture from 

Indonesia (Culliney et al., n.d.). Regular phytosanitary 

inspections of maritime cargo at the port of Honolulu (not 

AQIM data) by APHIS-PPQ and CBP inspectors from 

October 2005 to April 2007 resulted in 29 interceptions 

of insects on or in woody materials, all associated with 

nonagricultural commodities such as tile, granite, marble, 

and furniture (Culliney et al., n.d.). It is estimated that 
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most port inspections intercept only 30 percent or fewer of 

incoming pests (Meissner et al. 2003).

The level of training of all port inspectors is also of 

concern. Often inspectors are not well trained in detecting 

pests and pathogens associated with SWPM, which are 

difficult materials to inspect for the untrained eye. Interception rates by inspectors in the Southwestern United 

States dramatically increased for wood-boring insects after 

training in methods to detect scolytid beetles (Meissner et 

al. 2009). Targeted training for inspectors in the detection 

of pests associated with SWPM would be an inexpensive 

and cost-effective way of increasing inspection efficacy and 

could reduce additional introductions of unwanted pests. 

Many insects that have been associated with SWPM 

are already established and invasive in Hawai‘i and have 

probably arrived in the islands via this pathway, thus 

demonstrating the dangers associated with SWPM. These 

insects include the following, as compiled by Culliney et 

al., n.d.: Chlorophorus annularis, Euwallacea fornicatus, 

Hypothenemus obscurus, Xyleborus perforans, Xylosandrus 

compactus, X. crassiusculus, and X. morigerus. Many 

potential pests have not yet reached Hawai‘i but may be 

introduced by SWPM if steps are not taken to increase the 

number and efficacy of inspections. Culliney et al. (n.d.) 

listed 81 different species of insects that have the potential 

to be introduced to Hawai‘i in SWPM, with scolytid beetles 

being predominant. Other potential pests and pathogens 

associated with SWPM are assessed in the current document in individual pest risk assessments (chapter 4).

Recommendations made for the Greater Caribbean 

Region (Meissner et al. 2009) are similarly applicable to 

Hawai‘i. These recommendations include:

• Develop a strategy to ensure that SWPM in both 

agricultural and nonagricultural commodities are 

adequately inspected, preferably by random selection and thorough inspection. 

• Make the declaration of SWPM mandatory for all 

imports. (This would probably need to be done 

on a national level, however, and may be beyond 

state authority.)

• Increase regionwide inspection and identification 

expertise among inspectors. Educate inspectors 

on how to look for pests in SWPM and provide 

resources for pest identification.

• Allow entry of SWPM only if bark free. Solid wood 

products material that contains small patches of 

bark, permissible under ISPM 15, should be specifically targeted for inspection.

• Develop a communication network between HDOA, 

USDA-APHIS, and CBP inspectors to share pest 

interception data, inspection and diagnostic techniques, training materials, pest alerts, and other 

information.

6. Some pests not posing a risk to the mainland United 

States, or already present in the mainland, may be a 

potential threat to Hawai‘i. The interstate movement of 

certain plant materials from Hawai‘i to the mainland is 

restricted without treatment and certification. Similar 

restrictions on interstate movement into Hawai‘i are 

not in place. For the most part, APHIS regulations do 

not discriminate between the mainland and islands of 

Hawai‘i as far as potential threats. This includes some 

organisms that are native or commonly found on the 

mainland.

Invasive pests can be transported to Hawai‘i either from 

domestic or foreign sources. Because most materials needed 

by people of Hawai‘i are imported indicates the potential 

for unintentional introductions is substantial. Both domestic 

and foreign sources are under federal and state regulation 

and inspection. By regulation, HDOA has primary responsibility to prevent the introduction of pests that may be 

injurious to the agricultural industries and natural resources 

of the state (Hawai‘i Revised Statutes §141). This section 

was amended in HRS §150A Section 3 to provide HDOA 

the authority to prohibit entry “...into the State, from any 

or all foreign countries, or from other parts of the United 

States, (italics added) or the shipment from one island 

within the State to another island therein, or the transportation from one part of locality of any island to another part or 

locality of the same island, of any specific article, substance, 

or object or class of articles, substances or objects, among 

those enumerated above in this section, which is diseased or 

infested with insects or likely to assist in the transmission 

or dissemination of any insect or plant disease injurious, 
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GENERAL TECHNICAL REPORT PSW-GTR-250

harmful, or detrimental or likely to be injurious, harmful, 

or detrimental to the agricultural or horticultural industries, 

or the forests of the State, or which is or may be in itself 

injurious, harmful, or detrimental to the same.” 

The federal authority to regulate plant pest movement 

is within the Plant Protection Act of 2000 (Pub. L. 106–224, 

title IV, § 401, June 20, 2000, 114 Stat. 438). Specifically, 

this act states that “...no person shall import, enter, export, 

or move in interstate commerce (italics added) any plant 

pest, unless the importation, entry, exportation, or movement is authorized under general or specific permit and is 

in accordance with such regulations as the Secretary may 

issue to prevent the introduction of plant pests into the 

United States or the dissemination of plant pests within 

the United States.” 

The Plant Protection Act also states in §7756, “No 

State or political subdivision of a State may regulate in 

foreign commerce any article, means of conveyance, plant, 

biological control organism, plant pest, noxious weed, or 

plant product in order—(1) to control a plant pest or noxious 

weed; (2) to eradicate a plant pest or noxious weed; or (3) 

prevent the introduction or dissemination of a biological 

control organism, plant pest, or noxious weed.” It goes on to 

state, “No State or political subdivision of a State may regulate the movement in interstate commerce of any article, 

means of conveyance, plant, biological control organism, 

plant pest, noxious weed, or plant product in order to control 

a plant pest or noxious weed, eradicate a plant pest or noxious weed, or prevent the introduction or dissemination of a 

biological control organism, plant pest, or noxious weed, if 

the Secretary has issued a regulation or order to prevent the 

dissemination of the biological control organism, plant pest, 

or noxious weed within the United States.”

Department of Homeland Security, CBP, assumed 

foreign import inspection duties from APHIS, with the passage of the Homeland Security Act of 2002. This includes 

inspection of international passengers, luggage, cargo, 

and mail carrying nonpropagative material. Propagative 

material is still handled by APHIS. 

Apparently, when state and federal regulations and statutes conflict, federal laws take precedence. Two exceptions 

to the above restrictions on state regulations of interstate 

commerce are in the law. No exceptions are identified for 

foreign commerce. However, importation of new foreign 

commodities that may pose a risk are announced by 

APHIS with the opportunity for stakeholders, including 

states, to provide information to change, support, or cause 

the commodity not to be approved for importation into 

the United States or Hawai‘i, specifically. If the proposed 

regulations are consistent with federal regulations, “A State 

or a political subdivision of a State may impose prohibitions 

or restrictions upon the movement in interstate commerce 

of articles, means of conveyance, plants, biological control 

organisms, plant pests, noxious weeds, or plant products 

that are consistent with and do not exceed the regulations 

or orders issued by the Secretary.” If the State demonstrates 

a special need, “A State or political subdivision of a State 

may impose prohibitions or restrictions upon the movement 

in interstate commerce of articles, means of conveyance, 

plants, plant products, biological control organisms, plant 

pests, or noxious weeds that are in addition to the prohibitions or restrictions imposed by the Secretary, if the 

State or political subdivision of a State demonstrates to 

the Secretary and the Secretary finds that there is a special 

need for additional prohibitions or restrictions based on 

sound scientific data or a thorough risk assessment.” (italics 

added). 

Several recommendations are provided:

• APHIS, in collaboration with HDOA, should consider the development of quarantine regulations 

specific to Hawai‘i and their unique situation to 

limit the potential for introduction of potential pests 

from foreign and domestic sources. This should also 

include intrastate movement between islands 

of Hawai‘i.

• Manifests of goods from mainland United States to 

Hawai‘i should indicate whether they are of foreign 

or domestic origin and, if foreign, the port of origination.

• When inspecting goods on the mainland United 

States destined for Hawai‘i, CPB inspectors should 

be familiar with those pests that may pose a unique 

threat to Hawai‘i.
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

• When APHIS announces draft regulations on potential quarantines for proposed imports, HDOA should 

provide a response with specific information that 

supports the need for specific restrictions on such 

importation to Hawai‘i.

• HDOA should intensify its inspection of goods from 

mainland U.S. and foreign sources. Detailed analysis 

of the APHIS PestID (formerly Port Information 

Network 309) database and other import data 

sources may provide assistance in setting priorities. 

Unfortunately, the team was not able to access the 

PestID data and cannot provide any analysis. 

• In addition to coordinated inspections, monitoring 

for potential newly introduced pests should be initiated/continued around likely points of entry.

Additional Issues and Findings

In addition to the six priority findings discussed above, 

numerous other findings were made and are presented for 

consideration. We have attempted to group these findings 

under similar topic areas.

General

• The broad range of commodities/hosts and countries 

for potential introductions makes it extremely difficult to accurately characterize pest risk to various 

hosts of concern. 

One of the complexities of qualitative pest risk assessments is the uncertainty of which potential pests could 

be introduced to new hosts and ecosystems. This analysis 

attempted to identify pests and pathogens from other parts 

of the world that would endanger 13 species and genera of 

native Hawaiian plants. This is an impossible task to do 

completely and thoroughly; our efforts were directed at 

providing enough information and data to guide the state of 

Hawai‘i in developing acceptable regulations and restrictions to limit such introductions.

• Although an invasive insect or pathogen may exist in 

a location, it should not be considered low risk once 

established, given that strains may exist that are 

exotic with different levels of virulence (Palm and 

Rossman 2003).

Regulations are usually based on restricting the entry 

of invasive organisms at the species level. However, genetic 

diversity in fungi and other plant pathogens often results 

in the identification of strains, biovars, pathovars, form 

species, and others. These may differ in their virulence, host 

range, mating type, and infectiveness. Although species 

like Puccinia psidii are present in Hawai‘i, the potential 

for introduction of new strains that may be more damaging 

should not be ignored.

• Be aware of infestations by new species on 

the mainland.

The mainland United States is a major source of introduced pests to Hawai‘i. It is suspected that myoporum thrips 

arrived from California. Similarly, daylily rust (Puccinia 

hemerocallidis Thuem.) had been identified in the southeast 

United States several years prior to being found in Hawai‘i. 

Staying aware of new pests on the mainland can increase 

inspection effectiveness and possibly limit introductions.

• Do not attempt to develop a comprehensive list of 

pest threats to the entire state.

Most invasive pests are not considered significant 

in their home environment. Trying to identify a list of 

pest threats would be of little benefit and could provide 

a false sense of security. A more effective approach is to 

utilize data and information from accurate and up-to-date 

databases of interception records and pest surveys. Nonproprietary data need to be shared with stakeholders to better 

focus inspection efforts. This also benefits early inspection, 

rapid response, and public outreach.

• Do not base risk estimates on port interception 

data alone.

Port interception records are useful for exploring pest 

risk; however, it is erroneous to assume that a low number 

of interceptions is equivalent to low risk.

• Strive for transparency in all decisions and analyses.

Most decisions concerning safeguarding (e.g., level of 

inspection, inspection methodology, whether something 

should be considered high or low risk, and others) are made 

by some committee or group, either formally or informally. 
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GENERAL TECHNICAL REPORT PSW-GTR-250

All decisions have to be reevaluated periodically as situations change or new information becomes available. If the 

reasoning behind a decision is not clearly documented, it 

becomes impossible to evaluate the decision’s validity. For 

the sake of continuous improvement and to reduce the possibility of errors, the reasoning behind all decisions should 

be clearly explained and documented, and this information 

should be available. 

• Provide for greater transparency and sharing of pest 

interception data between all regulatory agencies 

involved in port inspections.

State and federal agencies both perform inspections 

of visitors and imported goods to identify potential pests 

and locate commodities not permitted to enter the state. 

A coordinated database of all agencies involved in these 

efforts that includes data on interceptions could increase 

everyone’s ability in identifying commodities and pathways 

to target for increased inspection efforts. Limited sharing 

or delay in sharing these data decreases the efficiency and 

efficacy of efforts by all.

Ecology

• Outdoor recreation and ecotourism in Hawai‘i 

increase the chance of introductions and spread 

of pests, especially pathogens, because of direct 

exposure from visitors. Limit access to very 

sensitive sites.

A major draw of tourists to Hawai‘i is its natural 

environment. Direct access by recreationists to natural 

areas significantly increases the risk of introducing invasive 

pests on their equipment and clothing. Educating visitors 

and guides to this potential and how they can reduce the 

risk will aid in reducing the possibility of introduction and 

spread of new and existing invasive species. Pristine natural 

areas may be considered for closure to recreational use 

because of extreme threat of exposure.

• The numerous nonnative plant species that are 

present (planted around airports, ports, and other 

areas) serve to harbor pests that can move to the 

native species. 

Some nonnative host species may be highly susceptible 

to invasive pests and provide a means for pest establishment 

and rapid population increase around ports of entry. This 

may increase the possibility of transfer and spread onto 

native species. This is a difficult balance between aesthetic 

landscaping around ports and the possible increased 

likelihood of pest establishment. Nonnative hosts could be 

useful detection sentinels if closely monitored, but could 

also become avenues of spread to native environments. 

Monitoring efforts need to be increased if these hosts are 

identified as detection sentinels.

Detection Surveys

• Get more involved with the USDA’s Cooperative 

Agriculture Pest Survey (CAPS) program to expand 

beyond agricultural pests to include 

forestry pests.

The HDOA is a participant in CAPS program designed 

for the early detection of significant plant pests: add 

Hawai‘i Division of Forestry and Wildlife as a participant to 

increase awareness of and attention to forest pests.

• Maintain current awareness of the literature for 

reports of new pests (or outbreaks or rises in pest 

populations) in other countries that could potentially 

infest/infect the 13 priority species and other native 

species. 

New invasive insects and pathogens are constantly 

identified and reported on commodities in other countries. 

Many of these pests could just as easily be transported 

to Hawai‘i. Awareness of these new identifications can 

increase vigilance for them during inspection. Maintaining 

good contacts and access to databases with other countries 

pest regulatory authorities, especially those in Asia-Pacific, 

can improve the state’s ability to intercept potential pests.

• Early detection can be increased, particularly for 

species where traps/lures have been identified. 

Early detection is emphasized as a way to limit spread 

of introduced exotics. It is often difficult to achieve, 

however, because of the lack of efficacious attractants and 

traps. When individual pests of concern are identified that 

have a high likelihood of introduction, opportunities for 
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

detection trapping should be assessed. If detection tools are 

available, they should be implemented around likely places 

of introduction, including military installations and training 

sites. Also, vegetation around ports should be monitored at 

least annually to determine if any exotic pest may have been 

introduced.

• Develop surveillance systems for the early detection 

of pests.

Surveillance programs for the early detection of exotic 

species should be implemented. Decisions will need to be 

made regarding which pests to survey for and which areas 

to survey. The USDA CAPS Program has developed a 

process for making these decisions using the analytical hierarchy process. Hobby entomologists and botanists, gardeners, nursery professionals, and others (e.g., Invasive Species 

Councils), may be important and competent contributors to 

a regional surveillance system. 

• Implement surveys to determine the distribution of 

pests commonly associated with SWPM outside of 

their native range.

Collaborate with state and federal forest management 

agencies, not-for-profit organizations (e.g., Centre for 

Agricultural Bioscience International [CABI] and the CAPS 

Program. Involve the public. Use the help of hobby biologists. Do not exclude countries that are enforcing ISPM 15 

from these survey efforts.

• Develop an effective integrated biosurveillance and 

pest information system, also to be used as a mechanism for official pest reporting

Both safeguarding against and responding to pest 

introductions depend strongly on the availability of current 

pest information. Of special importance is information 

on distribution, host range, trapping and identification 

tools, control methods, and port interception records. The 

sheer amount of pest information available throughout the 

world and the fast pace at which new information appears 

make it impossible for any individual to stay abreast of 

it. The collection, analysis, dissemination, and storage of 

pest information must occur in an efficient and organized 

manner. An on-line database is indispensable. One example 

of an existing biosurveillance system is the Exotic Pest 

Information Collection and Analysis of USDA APHIS-Plant 

Protection and Quarantine. Examples of initiatives that deal 

with pest information management are the Global Pest and 

Disease Database and the Off-Shore Pest Information Program of USDA APHIS, as well as the Hawai‘i Biodiversity 

Information Network Early Detection Network, the Global 

Invasive Species Database of the Invasive Species Specialist 

Group, and the Invasive Species Compendium of CABI. 

The potential usefulness and applicability of these and other 

projects should be evaluated and collaborations should be 

developed as appropriate. 

• Increase the use of detector dogs wherever feasible. 

Resources will never allow a thorough inspection of 

all pathways by human inspectors. Detector dogs make 

it possible to reliably scan a larger number of items than 

humans given the same amount of time. Dogs can be used 

to increase efficacy of checking incoming mail, luggage, 

and cargo.

• Develop targeting strategies for inspection of airline 

passenger baggage.

Possible targeting criteria include origin of passenger, 

seasonality, and holidays. For this to be possible, a systematic data collection program has to be implemented.

• Conduct periodic data collection efforts (“blitzes”).

Carry out statistically sound data collection to answer 

specific questions. Consider regionwide coordination and 

sharing of resources with others in Asia-Pacific for carrying 

out blitzes. Share results regionwide.

• Foster collaboration between customs officials, agricultural officials, mail facility staff, and any other 

groups. With limited resources, all parties can benefit by sharing both resources and information.

• Monitor interisland trade via small vessels.

Any commodities that are reshipped to other islands 

should be monitored for the possible shipment of invasive 

species to reduce the risk of spread and establishment to 

additional locations.

Monitor areas on and near the perimeter of the ports 

regularly for introduced pests of particular interest (Robinson et al. 2008). To reduce costs, employ the help of amateur 

taxonomists, university students, and qualified volunteers. 
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GENERAL TECHNICAL REPORT PSW-GTR-250

Avoid attracting pests into the area (e.g., through lures, 

lights, others).

• Develop a strategy to ensure adequate inspection of 

SWPM on all agricultural and nonagricultural cargo.

Simply checking for treatment seals is not a sufficient 

inspection method. A certain percentage of SWPM should 

be randomly selected and thoroughly searched for pests, 

both on the surface and inside the wood. All pertinent information (type of cargo, origin of cargo, presence of treatment 

seal, types and number of pests found, and other) should be 

recorded and shared regionwide.

• Increase regionwide inspection and identification 

expertise on pests associated with SWPM.

Educate inspectors on how to look for pests on SWPM. 

Ensure that identifiers have the expertise and the necessary 

reference material to identify the pests that are found.

Regulations

• Require phytosanitary certificates for all imports of 

plant materials.

The certificate should include species and variety of 

imported plant, if applicable, and should certify that the 

material was pest free at the time of shipping based on 

specified inspection protocols and issued by appropriate 

officials. This includes both international and domestic 

sources of plant material.

• Preshipment pest inspections and treatments.

Prior to shipment from the country/state of origin, 

require that plant material be inspected for the presence of 

any invasive pest.

• Minimize pest contamination on containers by:

• Minimizing time of container storage outdoors.

• Avoiding container storage on soil and 

near vegetation.

• Avoiding night-time lighting of outdoor 

storage areas.

• Cleaning storage areas on a regular basis.

• Cleaning inside and outside of containers after 

and before each use.

• Make the declaration of SWPM mandatory for all 

imports regardless of commodity. 

The origin of SWPM usually cannot be determined. 

Having shippers identify the presence of SWPM may 

increase the effectiveness of inspection. This includes 

material as part of the shipment, as well as associated material, such as dunnage. Ensure that SWPM meets ISPM 15 

standard. Inspection of SWPM should include looking for 

actual pests, boring holes, boring dust and frass, staining, 

and other indicators of pest presence.

• Record information on propagative material 

imported by plant species, with information on variety, type of material (roots, cuttings, other), country 

of origin, growing and inspection practices followed, 

date of importation, and amount imported in consistent units.

Education/Public Awareness

• Emphasize a statewide public awareness campaign 

on invasive species focused on transport and introduction from overseas.

Hawai‘i has several active groups involved in invasive 

species management and public information distribution. 

The Hawai‘i Invasive Species Council provides policy-level 

direction, coordination, and planning among state departments, federal agencies, and international and local initiatives for the control and eradication of harmful invasive 

species infestations through five working groups, including 

a group for public awareness. The Coordinating Group 

on Alien Pest Species is composed primarily of management-level staff from every major agency and organization 

involved in invasive species work, including federal, state, 

county, and private entities. They, too, provide information 

to the public on invasive species. These groups need to be 

maintained and encouraged in their efforts to inform the 

public on the threats of invasive species 

• Develop voluntary codes of conduct for groups 

involved in the dispersion of and the prevention of 

the introduction of exotic species. 

Draft a voluntary code of conduct for nurseries and 

landscaping businesses to limit spread of any newly introduced invasive species. Draft a voluntary code of conduct 

for local governments, resorts, hotels, and other entities that 
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Risk and Pathway Assessment for the Introduction of Exotic Insects and Pathogens That Could Affect Hawai‘i’s Native Forests

engage in large-scale landscaping. Draft a voluntary code 

of conduct for botanical gardens and arboreta. Develop a 

certification process.

Acknowledgments

This report was initiated at the request of Paul Conrey, State 

Forester of Hawai‘i. The support and advice provided by 

Robert Hauff with Hawai‘i DOFAW were invaluable in the 

completion of this assessment.

Portions of this document were extracted from the 

Chilean Pest Risk Assessment (USDA FS1993), the 

Mexican Pest Risk Assessment (Tkacz et al. 1998), the 

South American Pest Risk Assessment (Kliejunas et al. 

2001), and the Australia Eucalypt Pest Risk Assessment 

(Kliejunas et al. 2003).

Two previous pest risk assessments provided 

important background and data for this report. The 

authors of this assessment take full responsibility for 

the contents, however.

Meissner, H.; Lemay, A.; Bertone, C.; Schwartzburg, 

K.; Ferguson, L.; Newton, L. 2009. Evaluation of 

pathways for exotic plant movement into and within the 

greater Caribbean region. Raleigh, NC: U.S. Department 

of Agriculture, Animal and Plant Health Inspection 

Service, Plant Protection and Quarantine. 267 p.

Culliney, T.W.; Meissner, H.E.; Lemay, A.V.; Neeley, 

A.D.; Garrett, L.J.; Spears, B.M.; Liquido, N.J. 

[N.d.]. Pathway analysis of invasive species introduction 

into the state of Hawai‘i. Unpublished document. On 

file with U.S. Department of Agriculture, Animal and 

Plant Health Inspection Service, Plant Protection and 

Quarantine, Raleigh, North Carolina 27606. 246 p.

Numerous individuals made valuable contributions to 

the success of this pest risk assessment project. Reviewers 

and contributors are identified in appendix 1.

Dr. John T. Kliejunas served as technical editor for this 

document and his services are appreciated. The efforts of 

Susan Frankel and editors at Pacific Northwest Research 

Station in producing a final product are also appreciated. 

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English Equivalents

When you know: Multiply by: To find

Micrometers (μm) 0.000039 Inches

Millimeters (mm) 0.039 Inches

Centimeters (cm) 0.394 Inches

Meters (m) 3.28 Feet

Kilometers (km) 0.6215 Miles

Hectares (ha) 2.47 Acres

Square kilometers (km2) 0.386 Square miles

Kilograms (kg) 0.0011 Tons

Metric ton 1.102 Tons

Celsius (°C) 1.8 °C + 32 Fahrenheit
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GENERAL TECHNICAL REPORT PSW-GTR-250

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Pacific Southwest Research Station

800 Buchanan Street

Albany, CA 94710