1

United States Department of Agriculture

Animal and Plant Health Inspection Service

Plant Protection and Quarantine

Importation of Litchi (Litchi chinensis Sonn.) and 

Longan (Dimocarpus longan Lour.) fruits from 

Vietnam into the Continental United States

Risk Management Document

August 18, 2011

United States Department of Agriculture

Animal and Plant Health Inspection Service

Agency Contact: claudia.ferguson@aphis.usda.gov
2

I. Executive Summary:

The National Plant Protection Organization (NPPO) of Vietnam requested market access to 

export fresh litchi (Litchi chinensis) and longan (Dimocarpus longan) fruits to the continental 

United States. These fruits have not been exported from Vietnam to the United States before, so 

Vietnam provided detailed information on pests associated with this commodity in that country. 

Vietnam further proposed to treat the fruit with an APHIS approved generic irradiation treatment 

that would mitigate risks from most insect pests. Based on the pest information received and that 

the fruit would receive an APHIS approved irradiation treatment, APHIS determined that a pest 

list identifying all quarantine insect pests in Vietnam would be sufficient information to evaluate 

pathway risks from insects and that further assessment for the insect pests was not needed. This 

approach would also meet one of APHIS’ objectives behind the development of a generic 

irradiation treatment for most insect pests. 

APHIS’s Center for Plant Health Science and Technology (CPHST) developed a pest risk 

assessment (PRA) for litchi, longan and rambutan, originating from member countries of the 

ASEAN region comprising: Brunei, Cambodia, Indonesia, Laos, Malaysia, the Philippines, 

Thailand, and Vietnam (USDA, 2011). CPHST identified the quarantine pests that are likely to 

follow the pathway for these three commodities from each country. The PRA further analyzes the 

pathway risks from non-insect pests i.e. the pests that are not targeted by the irradiation 

treatment, and recommends measures that might be needed to mitigate risks from these noninsect pests. The PRA was based on (1) the information provided by member countries of the 

region, (2) published scientific literature and (3) pest interception records of the United States 

Department of Agriculture (Pest ID, 2009). 

Analysis of the pest lists for litchis and longans from Vietnam indicated that most pests likely to 

follow the pathway are insect pests and would be effectively neutralized1 with the irradiation 

generic dose of 400 Gy (USDA, 2006). Litchis and longans may also potentially serve as a 

pathway for a mite Aceria litchii and litchis may also serve as a pathway for a fungus, 

Phytophthora litchii. Both Aceria litchii and Phytophthora litchii are rated to have a medium

risk potential. Since irradiation is not an approved treatment for these pests, additional measures 

would be needed to mitigate their pathway risks. 

This risk management document outlines the phytosanitary measures that APHIS will require for

the importation of litchis and longans from Vietnam and documents the evidence used by APHIS 

to conclude that these measures will effectively prevent the introduction of quarantine pests into 

the continental United States. 

 

1 A pest is considered neutralized when it is killed, rendered sterile or its further development into becoming an adult 

is stopped.
3

II. Commodity wise analysis of quarantine pests and mitigation measures 

required

1. Litchis

A. Introduction

The PRA completed by CPHST identified 16 quarantine pests that could potentially follow the 

pathway of litchi fruit from Vietnam (USDA, 2011; Table 1). These include 14 insect pests, one 

mite and one fungus as follows:

Table 1. Quarantine pests likely to follow the pathway of fresh litchi fruit imported from 

Vietnam into the continental United States.

B. Risk Management Measures 

APHIS proposes to allow the importation of the fresh litchi fruit from Vietnam into the 

continental United States (except Florida) under the following conditions: 

(a) The fruit must be commercially produced and be part of a commercial consignment as 

defined in 7 CFR Section 319.56-2. The fruit must be grown in orchards registered with and 

monitored by the NPPO of Vietnam to ensure that fruits are produced free of disease caused 

by Phytophthora litchii. 

Arthropods

Acari: Eriophyidae Aceria litchii (Keifer) 

Diptera: Tephritidae Bactrocera cucurbitae (Coquillett)

Bactrocera dorsalis (Hendel)

Hemiptera: Coccidae Ceroplastes rubens Maskell

Coccus viridis (Green)

Hemiptera: Pseudococcidae Dysmicoccus neobrevipes Beardsley

Nipaecoccus viridis (Newstead) 

Paracoccus interceptus Lit 

Planococcus lilacinus (Cockerell) 

Planococcus litchi Cox

Planococcus minor (Maskell)

Pseudococcus cryptus Hempel 

Lepidoptera: Gelechiidae Conopomorpha sinensis Bradley

Lepidoptera: Pyralidae Conogethes punctiferalis (Guenée) 

Lepidoptera: Tortricidae Cryptophlebia ombrodelta (Lower)

Fungi

Oomycetes: Pythiales Phytophthora litchii (C.C. Chen ex W.H. Ko, H.S. 

Chang, H.J. Su, C.C. Chen & L.S. Leu) Voglmayr, 

Göker, Riethm. & Oberw
4

(b) The cartons containing the fruit must be stamped “Not for importation into or distribution in 

FL”.

(c) The fruit must be irradiated with a minimum absorbed dose of 400 Gy and follow the 

requirements of 7CFR parts 305 and 319. 

(d) Prior to departure from Vietnam: 

 If irradiation is applied outside the United States, each consignment of fruit must be 

inspected jointly by APHIS and Vietnam inspectors. Using a sampling procedure 

mutually agreed upon by APHIS and the NPPO, a representative sample of fruit must be 

drawn from each lot, inspected and found free from the fungus, Phytophthora litchii. A 

Phytosanitary Certificate (PC) issued by the NPPO of Vietnam must accompany each 

consignment certifying that the fruit received the required irradiation treatment with 400 

Gy as the minimum absorbed dose. The PC must also include an AD that the 

consignment was inspected by the Vietnam inspectors and found free from Phytophthora

litchii.

 If irradiation is to be applied upon arrival in the United States, each consignment of fruit 

must be inspected by Vietnam inspectors. Using a sampling procedure mutually agreed 

upon by APHIS and the NPPO, a representative sample of fruit must be drawn from each 

lot, inspected and found free from the fungus, Phytophthora litchii. A Phytosanitary

Certificate (PC) issued by the NPPO of Vietnam must accompany each consignment with 

an Additional Declaration (AD) that the consignment was inspected by the Vietnam 

inspectors and found free from Phytophthora litchii.

(e) Each consignment is subject to inspection at the U.S. ports-of-entry. 

C. Evidence for the Effective Removal of Pests of Concern from the Pathway

(i) Insect Pests:

Fourteen of the sixteen pests likely to follow the litchi pathway are insect pests. A minimum 

abosorbed dose of 400 Gy has been determined by APHIS regulations 7CFR305.9 to be adequate 

to neutralize all insect pests excluding adults and pupae in the order Lepidoptera. Of the fourteen 

insect pests likely to follow the pathway, three belong to the order Lepidoptera (Table 1). 

Although the generic irradiation treatment is not approved for Lepidopteran pupae and adults, 

those life stages are unlikely to be associated with the commodity. Due to their mobility, freeliving adults of Lepidoptera are unlikely to be in the pathway of commercially produced litchi 

fruits. As for the pupal stage, in most of the genera of concern (Conogethes, Conopomorpha, 

Cryptophlebia), the pupae are either associated with plant parts other than fruit or they occur 

externally on their host’s plant parts (CABI, 2007; Hwang and Hsieh, 1989; IPM DANIDA,

2003; Nair, 1975; Ooi et al., 2002; Underhill, 1943; van der Berg et al., 2001). Or, if the pupae 

occur inside the fruit or seed of their host plants, they would be associated with premature fruit 

drop and/or obvious damage and symptoms (CABI, 2007; Gupta et al., 2005; Singh et al., 2002; 

Waite and Hwang, 2002), thereby making it likely for the fruit to be culled during standard 

harvest or post-harvest handling and processing. Also, except for two interceptions of 

Conopomorpha in permit cargo with litchi fruit, inspectors at U.S. ports-of-entry have never 

intercepted pupae of the other Lepidoptera genera of concern associated with commercial fruit 
5

shipments of any type of fruit (PestID, 2009). This lack of interception is evidence of the low 

likelihood of any of the Lepidoptera pupae following the pathway of commercial fruit. The 

irradiation treatment, along with standard postharvest processes, therefore, will likely mitigate 

the risks from all the insects listed above. 

(ii) Mites:

 

The litchi mite, Aceria litchii, is found associated with litchi and longan only (USDA, 2007). 

The mite is primarily a pest of foliage and flower parts but is also sometime associated with the 

fruit. In severe cases, flowers may be completely destroyed and setting of fruit is prevented or the 

set fruit may be damaged cosmetically (Waite, 1999). Mites are external pests on the fruit, and 

because of the damage it causes on fruits, inspection and culling of the damaged fruit are 

considered effective in mitigating risk from such pests. Although it is unlikely that commercially

produced fruit is a pathway for the mite, because of its small size, shipments should be prohibited 

into Florida, where litchis are grown, as an added precaution. This is consistent with other import 

programs where shipments of litchis and/or longans are prohibited into Florida for the same pest. 

Shipments of litchi and/or longans from China, India, Thailand and Hawaii into the mainland 

U.S. with inspection for the pest over the past few years show no record of interception. 

(iii) Fungi:

Commercial litchi production areas where Phytophthora litchii is present and active will require 

fungicidal field treatments to reduce fruit drop. Having NPPO of Vietnam monitor fields where 

litchi is produced for export will ensure application of disease control measures. In nature the 

disease is confined to a single host (litchi), although under laboratory conditions, tomatoes, 

papayas and loofah (Luffa cylindrical) may also be infected (CABI, 2003). Most infected litchi 

fruit will be culled because trained harvesters, packinghouse personnel, and plant quarantine 

inspectors can easily detect the distinctive signs of the disease on fruit. Infected, nonsymptomatic fruit may go undetected, but the likelihood of introduction via the few fruit that may

escape detection is very low. It is highly unlikely that market fruit will be in a situation to 

introduce the disease because free water is required for the spores to infect a host. Additionally, 

there is no record of interception of this disease on litchis imported into the U.S. from other 

countries in regions where this pathogen is present. Therefore no measures are recommended for 

this pathogen beyond certification for freedom based on inspection (USDA 2007).

As part of the U.S. requirements (7 CFR 305.9) governing the use of irradiation as a 

phytosanitary treatment, APHIS and the NPPO of Vietnam must jointly develop an operational 

work plan (OWP). The work plan shall include details of activities including inspection of 

articles that NPPO must perform before the treatment or departure. Inspection of the fruit and 

freedom from pests not targeted by irradiation as declared on the PC will ensure that all pests of 

concern are removed from the pathway.
6

2. Longan

A. Introduction

The PRA completed by CPHST identified 17 quarantine pests that could follow the pathway of 

longan fruit from Vietnam (USDA, 2011; Table 2). All but one pest, a mite, are insect pests.

Table 2. Quarantine pests identified as likely to follow the pathway of fresh longan fruit 

imported from Vietnam into the continental United States

 

Arthropods

Acari: Eriophyidae Aceria litchii (Keifer) 

Diptera: Tephritidae Bactrocera dorsalis (Hendel)

Hemiptera: Coccidae Ceroplastes rubens Maskell

Coccus viridis (Green)

Drepanococcus chiton (Green)

Hemiptera: Pseudococcidae Dysmicoccus neobrevipes Beardsley

Exallomochlus hispidus (Morrison) 

Maconellicoccus hirsutus (Green)

Nipaecoccus viridis (Newstead) 

Paracoccus interceptus Lit 

Planococcus lilacinus (Cockerell) 

Planococcus litchi Cox

Planococcus minor (Maskell)

Pseudococcus cryptus Hempel 

Lepidoptera: Gelechiidae Conopomorpha sinensis Bradley

Lepidoptera: Pyralidae Conogethes punctiferalis (Guenée) 

Lepidoptera: Tortricidae Cryptophlebia ombrodelta (Lower)

B. Risk Management Measures 

APHIS proposes to allow the importation of the fresh longan fruit from Vietnam into the 

continental United States (except Florida) under the following conditions: 

(a) The fruit must be commercially produced and be part of a commercial consignment as 

defined in 7 CFR Section 319.56-2. 

(b) The cartons containing the fruit must be stamped “Not for importation into or distribution in 

FL”.

(c) The fruit must be irradiated with a minimum absorbed dose of 400 Gy and follow the 

requirements of 7CFR parts 305 and 319. 

(d) Prior to departure from Vietnam: 

 If irradiation is applied outside the United States, each consignment of fruit must be 

inspected jointly by APHIS and Vietnam inspectors and accompanied by a Phytosanitary
7

Certificate (PC) issued by the NPPO of Vietnam certifying that the fruit received the 

required irradiation treatment with 400 Gy as the minimum absorbed dose. 

 If irradiation is to be applied upon arrival in the United States, each consignment of fruit 

must be inspected by Vietnam inspectors and accompanied by a Phytosanitary Certificate 

(PC) issued by the NPPO of Vietnam. 

(e) Each consignment is subject to inspection at the U.S. ports-of-entry. 

C. Evidence for the Effective Removal of Pests of Concern from the Pathway

(i) Insect Pests:

Sixteen of the seventeen pests likely to follow the longan pathway are insect pests. A 

minimum absorbed dose of 400 Gy has been determined by APHIS regulations 7CFR305.9 to be 

adequate to neutralize all insect pests excluding adults and pupae in the order Lepidoptera. Of 

the sixteen insect pests likely to follow the pathway, three belong to the order Lepidoptera 

(Table 2). Although the generic irradiation treatment is not approved for Lepidoptera pupae and 

adults, those life stages are unlikely to be associated with the commodity here. Due to their 

mobility, free-living adults of Lepidoptera are unlikely to be in the pathway of commercially

produced longan fruits. As for the pupal stage, the pupae in the three genera of concern 

(Conogethes, Conopomorpha, and Cryptophlebia), are either associated with plant parts other 

than fruit or they occur externally on their host’s plant parts (CABI, 2007; Hwang and Hsieh, 

1989; IPM DANIDA, 2003; Nair, 1975; Ooi et al., 2002; Underhill, 1943; van der Berg et al., 

2001). Or, if the pupae occur inside the fruit or seed of their host plants, they would be associated 

with premature fruit drop and/or obvious damage and symptoms (CABI, 2007; Gupta et al., 

2005; Singh et al., 2002; Waite and Hwang, 2002), thereby making it likely for the fruit to be 

culled during standard harvest or post-harvest handling and processing. Except for two 

interceptions of Conopomorpha in permit cargo with litchi fruit, inspectors at U.S. ports-of-entry

have never intercepted pupae of the other Lepidoptera genera of concern associated with 

commercial fruit shipments (of any type of fruit) (PestID, 2009). This lack of interception is 

evidence of the low likelihood of any of the Lepidoptera pupae following the pathway of 

commercial fruit. The irradiation treatment, along with standard postharvest processes, therefore, 

will likely mitigate the risks from all the insects listed above. 

 

(ii) Mites:

 

As explained under litchis, the litchi mite, Aceria litchii, is found associated with litchi and 

longan only (USDA, 2007). The mite is primarily a pest of foliage and flower parts but is also 

sometimes associated with the fruit. In severe cases, flowers may be completely destroyed and 

setting of fruit is prevented or the set fruit may be damaged cosmetically (Waite, 1999). Mites 

feed externally on the fruit and because of the damage mites causes on fruits, inspection and 

culling of the damaged fruit are considered effective in mitigating risk from such pests. 

Although it is unlikely that commercially produced fruit is a pathway for the mite, because of its 

small size, shipments should be prohibited into Florida, where litchis are grown, as an added 

precaution. This is consistent with other import programs where shipments of litchis and/or 

longans are prohibited into Florida for the same pest. Shipments of litchi and/or longans from 
8

China, India, Thailand and Hawaii into the mainland U.S. with inspection for the pest over the 

past few years show no record of interception. 

As part of the U.S. requirements (7CFR305.9) governing the use of irradiation as a phytosanitary

treatment, APHIS and the NPPO of Vietnam must jointly develop an operational work plan 

(OWP). The work plan shall include details of activities including inspection of articles that 

NPPO must perform before the treatment or departure. Phytosanitary inspection of the fruit will 

ensure that all pests of concern not targeted by irradiation are removed from the pathway.

III. Conclusion

The phytosanitary requirements described above include treatment of litchi and longan fruit from 

Vietnam with irradiation using a minimum absorbed dose of 400 Gy and phytosanitary

inspections for pests not targeted by the irradiation treatment. The risk management document 

concludes that based on the evaluation of effectiveness of these measures directed against the 

pests of concern, APHIS finds that the safeguards of 7 CFR § 319.56 and the additional 

mitigations described here will result in the effective removal of the pests of concern identified 

by the PRA for the importation of fresh litchis and longans from Vietnam into the Continental 

United States.

IV. Authors:

Inder Paul S. Gadh, Ph.D.

Senior Risk Manager – Treatments

V. References: 

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(CABI), Wallingford, UK.

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(formerly Commonwealth Agricultural Bureau International) (CABI), Wallingford, UK.

Gupta, H. C. L., O. P. Ameta, and V. K. Chechani. 2005. Management of insect pests of 

horticultural crops. Agrotech Publishing Academy, Udaipur. 224 pp.

Hwang, J. S., and F. K. Hsieh. 1989. The bionomics of the cocoa pod borer, Conopomorpha 

cramerella (Snellen), in Taiwan. Plant Protection Bulletin Taipei 31(4):387-395.

IPM DANIDA. 2003. Durian fruit borer. IPM Thailand. Last accessed March 10, 2006,

http://www.ipmthailand.org/EN/Pests/Durian_fruit_borer.htm.

Nair, M. R. G. K. 1975. Insects and mites of crops in India. Indian Council of Agricultural 

Research New Delhi. 404 pp.

Ooi, P. A. C., A. Winotai, and J. E. Peña. 2002. Pests of minor tropical fruits. Pages 315-330 in

J. E. Peña, J. L. Sharp, and M. Wysoki, (eds.). Tropical fruit pests and pollinators: biology, 

economic importance, natural enemies and control. CAB International, Wallingford, U.K.
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PestID. 2009. Pest Identification Database (PestID). United States Department of Agriculture, 

Animal and Plant Health Inspection Service, Plant Protection and Quarantine. 

https://mokcs14.aphis.usda.gov/aqas/login.jsp. (Archived at PERAL).

Singh, Y. P., G. K. Singh, and K. Suresh. 2002. Occurrence of Dichocrocis punctiferalis Guen. 

(Lepidoptera: Pyralidae) on mango in Western U.P. Progressive Horticulture 34(1):130.

Underhill, G. W. 1943. Some insect pests of ornamental plants [Abstract]. Virginia Agric Expt 

Sta Bull 349:1-38.

USDA. 2006. USDA Treatments for Fruits and Vegetables. January 27, 2006 issue of Federal 

Register 71(18): 4451-4464.

USDA. 2007. Pest lists for fresh Litchi chinensis (lychee or litchi), Dimocarpus longan (longan), 

Mangifera indica (mango), Garcinia mangostana L. (mangosteen), Nephelium lappaceum L.

(rambutan), and Ananas comosus (pineapple) fruit from Thailand, US Department of 

Agriculture, Animal & Plant Health Inspection Service, Plant Protection & Quarantine, 

Center for Plant Health Science & Technology, NC .

USDA. 2011. Importation of Fresh Fruit of Litchi (Litchi chinensis), Longan (Dimocarpus 

longan), and Rambutan (Nephelium lappaceum) into the Continental United States from 

ASEAN Countries - A Qualitative, Pathway-initiated Pest Risk Assessment. USDA, APHIS, 

CPHST, 107 pp.

van den Berg, M. A., E. A. de Villiers, and P. H. Joubert. 2001. Pests and beneficial arthropods 

of tropical and non-citrus subtropical crops in South Africa. Institute for Tropical and 

Subtropical Crops, Nelspruit, South Africa. 525 pp.

Waite, G. K. 1999. New evidence further incrimates honey bees as vectors of lychee erinose mite 

Aceria litchi (Acari: Eriophiidae). Experimental and Applied Acarology 23(2): 145-147.

Waite, G. K., and J. S. Hwang. 2002. Pests of litchi and longan. Pages 331-359 in J. E. Peña, J. 

L. Sharp, and M. Wysoki, (eds.). Tropical fruit pests and pollinators: biology, economic 

importance, natural enemies and control. CABI Publishing, Wallingford, UK.