Proposed Release of a 

Parasitoid (Tamarixia 

radiata Waterston) 

for the Biological Control 

of Asian Citrus Psyllid 

(Diaphorina citri 

Kuwayama) in the 

Continental 

United States 

Environmental Assessment

June 2010

United States

Department of 

Agriculture

Marketing and 

Regulatory 

Programs

Animal and 

Plant Health 

Inspection 

Service
Proposed Release of a 

Parasitoid (Tamarixia radiata

Waterston) for the Biological 

Control of Asian Citrus Psyllid 

(Diaphorina citri Kuwayma in 

the Continental 

United States

Environmental Assessment, 

June 2010

 

Agency Contact:

Shirley Wager-Page, Branch Chief

Pest Permitting

Plant Protection and Quarantine

Animal and Plant Health Inspection Service

U.S. Department of Agriculture

4700 River Road, Unit 133

Riverdale, MD 20737–1236

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recommendation or endorsement by the U.S. Department of Agriculture 

(USDA) over others not mentioned. USDA neither guarantees or warrants 

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solely to report factually on available data and to provide specific information.

This publication reports research involving pesticides. All uses of pesticides

must be registered by appropriate State and/or Federal agencies before they 

can be recommended.

CAUTION: Pesticides can be injurious to humans, domestic animals, 

desirable plants, and fish or other wildlife–if they are not handled or applied 

properly. Use all pesticides selectively and carefully. Follow recommended 

practices for the disposal of surplus pesticides and pesticide containers.
Table of Contents

I. Purpose and Need for the Proposed Action ........................ 1

II. Alternatives............................................................................. 2

III. Affected Environment ............................................................ 6

IV. Environmental Consequences .............................................. 7

V. Other Issues.......................................................................... 12

 

VI. Agencies and Organizations Consulted............................. 13

 

VII. References............................................................................ 14
1

I. Purpose and Need for the Proposed 

Action

The U.S. Department of Agriculture (USDA), Animal and Plant Health 

Inspection Service (APHIS), Plant Protection and Quarantine (PPQ) 

Permit Unit is proposing to issue permits for release of the insect

Tamarixia radiata (T. radiata) (Waterston) (Hymenoptera: Eulophidae). 

The agent would be used for the biological control of the Asian citrus 

psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), in the 

continental United States. Before permits are issued for release of T. 

radiata, APHIS needs to analyze the potential impacts of the release of 

this agent into the continental United States.

This environmental assessment1(EA) has been prepared, consistent with 

USDA–APHIS' National Environmental Policy Act of 1969 (NEPA) 

implementing procedures (Title 7 of the Code of Federal Regulations 

(CFR) part 372). It examines the potential effects on the quality of the 

human environment that may be associated with the release of T. radiata

to control infestations of ACP within the continental United States. This 

EA considers a ―no action‖ alternative and the potential effects of the 

proposed action.

The purpose for releasing T. radiata is to reduce the severity of 

infestations of ACP in the United States. ACP, a serious pest of citrus, 

was first discovered in Boynton Beach, Palm Beach County, Florida, in 

June 1998. By 2001, it had spread to 31 counties in Florida, primarily due 

to the movement of infested nursery plants. In 2001, ACP was 

accidentally introduced into Puerto Rico and the Rio Grande Valley of 

Texas. It was subsequently found in Hawaii in 2006, Guam in 2007, and 

in Alabama, Georgia, Louisiana, Mississippi, South Carolina, and 

California in 2008. ACP serves as a vector (disease transmitter) of 

Huanglongbing disease (HLB), also known as citrus greening disease, and 

is considered to be one of the most serious citrus diseases in the world. 

HLB is a bacterial disease caused by strains of the bacterial pathogen 

Candidatus Liberibacter asiaticus that attacks the vascular system of host 

plants. The pathogen is phloem-limited, inhibiting the food-conducting 

tissues of the host plant, and causes yellow shoots, blotchy mottling and 

chlorosis, reduced foliage, and tip dieback of citrus plants. HLB greatly 

reduces production, destroys the economic value of citrus fruit, and can 

kill trees. Once infected, there is no cure for a tree with HLB. In areas of 

 

1

Regulations implementing the National Environmental Policy Act of 1969 (42 United States Code 

4321 et seq.) provide that an environmental assessment “[shall include brief discussions of the need 

for the proposal, of alternatives as required by section 102(2)(E), of the environmental impacts of the 

proposed action and alternatives, and a listing of agencies and persons consulted” (40 CFR § 

1508.9). 
2

the world where HLB is established, citrus trees decline and die within a 

few years and may never produce usable fruit. HLB was first detected in 

the United States in Miami-Dade County, Florida, in 2005. Currently, in 

the United States, HLB is only known to be present in Florida, Louisiana, 

South Carolina, and Georgia.

In addition to transmitting Candidatus Liberibacter asiaticus, ACP can 

cause economic damage to citrus in groves and nurseries by direct feeding.

Both adults and nymphs feed on young foliage, depleting the sap and 

causing galling or curling of leaves. High populations feeding on a citrus 

shoot can kill the growing tip. 

In 1998, the proposed biological control organism T. radiata was imported 

from Taiwan and Vietnam into quarantine by Division of Plant Industry, 

Florida Department of Agriculture and Consumer Services. It was 

initially intentionally released into Florida in St. Lucie County on July 15, 

1999, and Palm Beach County on August 17, 1999 and has become 

established in Florida. It also spread to Puerto Rico and Texas via 

accidental introductions. However, the APHIS–PPQ Permit Unit has 

received permit applications requesting to release T. radiata into 

additional States where ACP has spread, such as California, and has also 

received permit applications for importation and release of T. radiata from 

sources other than Taiwan and Vietnam (i.e., Punjab, Pakistan) because 

they may be more climatically adapted to new release locations.

The applicant has a need to include a host specific biological control agent 

as an additional tool for controlling ACP populations in the continental 

United States, especially in natural areas and neighborhoods where 

insecticide applications to control ACP are not always feasible.

II. Alternatives

This section will explain the two alternatives available to the PPQ Permit 

Unit―no action and issuance of permits for expanded environmental 

release of T. radiata. Although the PPQ Permit Unit’s alternatives are 

limited to a decision on whether to issue permits for expanded release of 

T. radiata, other methods of control of ACP are described. These control 

methods are not decisions to be made by the PPQ Permit Unit, and their 

use will likely continue whether or not permits are issued for expanded 

environmental release of T. radiata. These are methods presently being 

used to control ACP by public and private concerns. For instance, the 

APHIS–PPQ, Citrus Health Response Program has undertaken measures 

to control the spread of ACP and HLB to uninfested areas of the United 

States since the introduction of HLB into the United States in 2005. This 
3

program was analyzed in an environmental assessment prepared by 

APHIS (USDA, APHIS, 2009) and it is incorporated by reference into this 

document. 

A third alternative was considered, but will not be analyzed further. 

Under this third alternative, the PPQ Permit Unit would have issued 

permits for the field release of T. radiata but the permits would contain 

special provisions or requirements concerning release procedures or 

mitigating measures. No issues have been raised that would indicate that 

special provisions or requirements are necessary.

A. No Action 

Under the no action alternative, the PPQ Permit Unit would not issue 

additional permits for the field release of T. radiata for the control of

ACP—further release of this biological control agent outside of Florida 

would not take place and permits for release of new, more climaticallyadapted strains would not be approved. Besides the APHIS–PPQ

program, control measures could be taken by other Federal or non-Federal 

entities; those actions would not be under APHIS’ control or funded by 

APHIS. Those additional methods of control are discussed in the ―ACP 

Control Methods‖ section below and will likely continue even if permits 

are issued for expanded release of T. radiata.

T. radiata was introduced into Florida in 1998 (Hoy and Nguyen, 2001). 

It was also detected in Texas, Mexico, and Puerto Rico where purposeful 

releases were not made. The insect may have moved to these locations on 

infested orange jasmine Murraya paniculata (L). Although T. radiata is 

already established in Florida, Puerto Rico, and Texas, under this 

alternative, the APHIS–PPQ Permit Unit would not issue permits for 

movement of T. radiata into new States and would not issue permits to 

release new strains of T. radiata into the United States that were collected 

from new sources in Asia. However, since T. radiata is established in 

Florida, Puerto Rico, and Texas, it will continue to be used in those areas. 

It is possible that T. radiata will naturally spread from Florida and Texas 

into other States. 

ACP Control Methods

Chemical control of ACP includes the use of foliar and/or systemic 

applications of the following insecticides: imidacloprid, thiamethoxam, 

dinotefuran, acetamiprid, aldicarb, abamectin, chlorpyrifos, deltamethrin, 

fenpropathrin, bifenthrin, cyfluthrin, carbaryl, dimethoate, phosmet, 

spinetoram, formetanate, diflubenzuron, and spirotetramat, kaolin, 

petroleum and horticultural mineral oils (UC IPM, 2009; Rogers et al., 

1. Chemical 

Control 
4

2009a; Rogers et al., 2009b). There are no chemical controls for HLB.

In addition to T. radiata, another parasitoid used for biological control of 

ACP is an encyrtid wasp, Diaphorencyrtus aligarhensis (D. aligarhensis). 

A parasitoid is an organism that spends a significant portion of its life 

history within a single host organism which it ultimately kills (and often 

consumes) in the process. T. radiata is more efficient at parasitizing ACP 

than D. aligarhensis (Tang, 1989). Both T. radiata and D. aligarhensis

were released into Florida (McFarland and Hoy, 2001) but with mixed 

results (Halbert and Manjunath, 2004). Only T. radiata has established in 

Florida (Michaud, 2002) but has exhibited a very low rate of parasitism of 

ACP (approximately 1 percent) (Michaud, 2004). However, more recent 

studies by Qureshi et al. (2009a; 2009b) found that rates of parasitism of 

ACP by T. radiata in Florida were variable, and averaged less than 20 

percent during spring and summer, but 39 percent in September and 56

percent in November in the central and southwest regions of Florida, 

respectively. These rates are lower than those observed on Reunion 

Island, Guadeloupe, or Puerto Rico, where significant suppression of ACP 

populations has been reported (Aubert and Quilici, 1984; Étienne et al. 

2001; Torres et al., 2006; Pluke et al., 2008). 

Native predators, such as spiders, coccinellids (lady beetles), lace wings, 

syrphids, and minute pirate bugs attack ACP (Quereshi et al., 2009b; UC 

IPM, 2009). Coccinellids are important predators of ACP in Florida 

(Michaud, 2002; 2004). 

B. Issue permits for expanded release of T. radiata

Under this alternative, the PPQ Permit Unit would issue permits for the 

expanded field release of T. radiata, including permits for new, more 

climatically-adapted or better performing strains, for the control of ACP 

wherever it occurs in the continental United States. These permits would 

contain no special provisions or requirements concerning release 

procedures or mitigating measures.

T. radiata (Hymenoptera: Chalcidoidae: Eulophidae) is a small, stingless 

wasp ectoparasite (an external parasitic organism). It was described as 

Tetrastichus radiata by Waterston (1922) from host materials—

Diaphorina citri—on lemon leaves collected in Lyallpur, Punjab 

(Pakistan).

The biology of T. radiata was studied in detail by Chu and Chien (1991), 

Chien et al. (1989), and Chien (1995). Females deposit eggs between the 

thorax and abdomen of immature ACP. The newly hatched T. radiata

larva sucks fluid from the site where it is attached externally to the ACP 

host, eventually killing it. By the time the T. radiata larva has matured, it 

2. Biological 

Control

1. Description 

of T. radiata

2. Life History of 

T. radiata
5

has sucked out the contents of the ACP, and the psyllid becomes

'mummified' and turns a dark brown color. The adult T. radiata parasitoid 

emerges from the top of the mummified ACP thorax, leaving a distinctive 

emergence hole. Under laboratory conditions, T. radiata females deposit 

166 to 300 eggs during their life span of 14 to 24 days. The development 

time from egg to adult is 12 days under a 25 °C and 14 hours of light:10 

hours of dark regime. T. radiata completes development at temperatures 

varying from 15 to 32 °C, with an optimum of 25 °C. The lowest 

developmental threshold is estimated to be 11 °C for all stages, from egg 

to adult.

Adult T. radiata females also kill psyllids by host feeding. Females insert 

their ovipositor (egg-laying organ) into the ACP, producing a hole, and 

then suck up the liquid that oozes out. Host feeding provides a source of 

protein that helps the female parasitoid produce more eggs. T. radiata

females also feed on honeydew (sticky waste product excreted by nymphs 

and adult psyllids after digesting phloem) excreted by the psyllids. A 

single T. radiata female is able to kill over 500 psyllids through the

combination of host feeding and parasitism (Nguyen, 2009). 

The native range of T. radiata includes Africa: Saudi Arabia (Bove, 1986), 

and Asia: India (Husain and Nath, 1927), China (Jiangxi and Fujian 

Provinces) (Tang, 1998; Tang and Aubert, 1990), Japan (Ryukyu 

Archipelago) (Kohno et al., 2002), Nepal (Lama et al., 1988), Pakistan 

(Waterson, 1922), Thailand (Morakote and Nanta, 1995), and Vietnam 

(Hoy et al., 1999).

According to Étienne and Aubert (1980), the biological control project 

using T. radiata in Reunion Island started in 1978. Reunion Island is 

located in the Indian Ocean, east of Madagascar, about 120 miles south 

west of Mauritius. Approximately 5,000 T. radiata adults originating 

from Punjab, Pakistan, were released in the field in 13 locations on 

Reunion Island. The population of ACP started to decrease significantly 

in 1980, and in 1982, T. radiata parasitism rates increased drastically to 

such levels that ACP disappeared from the citrus groves and maintained 

just a few residual populations on the ornamental Murraya paniculata, one 

of its preferred hosts (Aubert and Quilici, 1984; Étienne et al., 2001).

From surveys made on Reunion Island, it was determined that T. radiata

attacked 60 to 70 percent of ACP nymphs (Aubert, 1987). More than 25

years after release of T. radiata on Reunion Island, Aubert et al. (1996) 

concluded that the effort to control HLB was very successful. This was 

achieved by a combined effort of supplying certified disease-free trees and 

the highly successful biological control of ACP, the main vector of HLB. 

A similar program was also launched in Mauritius with the same success. 

While success on Reunion Island has been very high, use of the agent in 

Southeast Asia has been less successful, possibly because of the presence 

3. Native Range

of T. radiata

4. Impact of T. 

radiata on 

Asian Citrus 

Psyllid
6

of hyperparasites (in this case, a parasite that attacks T. radiata) causing 

mortality of T. radiata (Supriyanto and Whittle, 1991). 

T. radiata is established in Florida (Hoy and Nguyen, 2001) but parasitism 

rates reported in Florida (Tsai et al., 2002; Michaud, 2004; Qureshi et al.,

2009) have been lower than generally reported in Reunion Island, 

Guadeloupe, and Puerto Rico (Aubert and Quilici, 1984; Étienne et al. 

2001; Torres et al., 2006; Pluke et al., 2008).

III. Affected Environment

A. Asian Citrus Psyllid

ACP is an insect in the family Psyllidae. It is a pest of citrus and close 

relatives of citrus, and is the target of T. radiata. Psyllids resemble 

miniature cicadas and are sometimes called jumping plantlice. ACP 

damages plants through its feeding activities. New shoot growth that is 

heavily infested by ACP does not expand or develop normally, and is 

more susceptible to breaking off. While direct damage is serious, there is 

even greater concern as ACP is an efficient vector of the bacterium that 

causes HLB. 

ACP is found in tropical and subtropical Asia, Afghanistan, Saudi Arabia, 

Réunion, Mauritius, parts of South and Central America, Mexico, and the 

Caribbean. In the United States and its territories, this species is present in

all or parts of Alabama, California, Florida, Georgia, Guam, Hawaii, 

Louisiana, Mississippi, Puerto Rico, South Carolina, and Texas.

ACP is known to develop only on members of the plant family Rutaceae 

including the genera Aegle, Aelopsis, Afraegle, Atalantia, Balsamocitrus, 

Citropsis, Citrus, Clausena, Eretmocitrus, Fortunella, Limonia, Merrillia, 

Microcitrus, Murraya, Naringi, Pampurus, Poncirus, Severina, Swinglea, 

Toddalia, Vepris, and Zanthoxylum. Murraya paniculata (L.) Jack 

(orange jasmine) and Citrus spp. are the preferred hosts of ACP (Aubert, 

1987; Halbert and Manjunath, 2004; Yang et al., 2006).

B. North American Psyllid Species

Over 100 psyllid species occur on both native and introduced landscape 

plants in the United States. Several psyllid species are pests of crops such 

as pear, potato, and tomato. Each kind of psyllid feeds on only one plant 

species or closely related group of plants. Most psyllids native to the 

United States are relatively uncommon and rarely become pests. Psyllid 

species in North America could possibly be attacked by T. radiata; 
7

however, reports from the literature and host-specificity tests have 

indicated that T. radiata is specific to ACP (see discussion under chapter 

4, Environmental Consequences).

C. Citrus Resources in North America

Citrus resources in the United States are at risk from ACP and HLB. 

Production of citrus in the United States includes oranges, tangelos, 

tangerines, grapefruit, lemons, and limes mainly in the States of Florida, 

California, Texas, and Arizona. The United States was forecast to produce 

11.7 million tons of citrus in 2008–09, down from the 13-million ton crop 

produced in 2007–08 (USDA–ERS, 2009). The United States is one of 

the top citrus exporters in the world ranking first in grapefruit, third in 

oranges, fourth in lemons, and seventh in tangerines (USDA–FAS, 2009). 

In 2006–07, the United States exported 851,000 tons of citrus with 

74 percent of the exports going to Japan, Canada, and Korea (USDA–

FAS, 2008). Florida, the leading citrus-producing State, has 576,577 total 

acres (bearing and nonbearing) devoted to commercial citrus production

(FASS, 2009a; FDOC, 2009). There were 271,281 total acres (bearing 

and nonbearing) of citrus in California in 2008 (USDA–NASS, 2008a). In 

the Lower Rio Grande Valley of Texas, there are roughly 27,300 bearing

acres of citrus and, in Arizona, approximately 21,800 bearing acres 

devoted to commercial citrus production (FASS, 2009b; USDA–NASS, 

2008b). 

Nursery operations that produce citrus trees, orange jasmine, curryleaf, 

and other ACP host plants will be adversely affected by ACP and HLB. 

For example, according to the 2007 Census of Agriculture, there were 

3,549 greenhouse, nursery, and floriculture operations in California, 

(USDA–NASS, 2009). In Hawaii, there were 1,393 greenhouse, nursery, 

and floriculture operations within the State (USDA–NASS, 2009). 

Eighteen commercial citrus operations accounted for 95 percent of the 

citrus nursery plants produced in Texas in 2008. Many more greenhouse, 

nursery, and floriculture operations occur in other States that are or could 

become infested with ACP and HLB. Many of these operations are 

identified by the Small Business Administration as small businesses.

IV. Environmental Consequences

A. No Action

ACP damages citrus by feeding on young foliage, depleting the sap, and 

causing galling or curling of leaves. High populations feeding on a citrus 

shoot can kill the growing tip. ACP also causes damage by excreting 

1. Impact of 

Spread of 

ACP and HLB

on Hosts of 

ACP and 

Citrus 

Resources 
8

honeydew that coats plant leaves, allowing the growth of sooty mold that 

reduces or inhibits sunlight penetration (Chien and Chu, 1996). However, 

the worst threat is that ACP is an efficient vector of the bacterium which

causes HLB. This is the most serious disease of citrus in the world, 

causing reduced production of fruit and eventual death of the trees. HLBinfected trees show a blotchy, mottled condition of the leaves which 

results in the development of yellow shoots, the characteristic symptom of 

the disease. Trees are stunted, decline, and bear very few lop-sided, poor 

quality fruit. The fruit produced by infected trees is not suitable for either 

the fresh market or juice processing due to the significant increase in 

acidity and bitter taste. The lack of effective control measures to prevent 

the spread of HLB from sites of infestation to other areas and counties 

could lead to higher production costs and an increase in shortages of citrus 

fruits and plants to the general economy. This would potentially result in 

increased costs for survey, detection, and treatment for the control of ACP 

and HLB as they spread to other areas and counties.

Commercial acreage of citrus in Florida has dropped to 576,577, the 

lowest level since USDA began tracking citrus acreage in 1966 (FLCM, 

2008). Commercial citrus acreage in Florida peaked in 1970 at more than 

941,000 acres (FLCM, 2008). As the industry commits millions of dollars 

to new research to find a cure for HLB, costs to growers are soaring 

because they are spending more on fertilizer, insecticides, and inspection 

to limit crop losses and further spread (FLCM, 2008).

Pesticide usage to control ACP has increased significantly in Florida, 

since the introduction of HLB, with 6 or more applications per year. 

Application and spray material costs have risen dramatically, as well, from 

pre-HLB levels of $100 and $80 per acre, up to $140 and $240 per acre 

post-HLB (Irey, 2008). Prior to this, ACP was considered a minor pest. 

However, growers must apply both systemic soil drench treatments along 

with multiple foliar sprays (especially to protect newly planted and young 

(4 to 8-year old) trees that are more vulnerable to ACP attack because they 

flush more frequently. This pattern is similar to what has occurred in 

Brazil, South Africa, and other countries where HLB has been introduced. 

In Brazil, foliar applications of insecticides have steadily increased from 

12 up to 24 per year, and soil treatments from 2 up to 4 per year. In an 

effort to reduce costs, pesticides with longer residual effects are being

substituted. Pesticides also are being applied aerially over large areas to 

achieve greater control of ACP. There are no effective alternatives that 

can be used for organic citrus production. 

For nurseries in the United States that produce citrus trees, orange 

jasmine, and curryleaf, the effects of ACP and HLB will be adverse. For 

areas quarantined for HLB, nursery operations will suffer a complete loss 

of domestic market access. For areas quarantined only for ACP but not 
9

for HLB, nursery operations will incur costs associated with treatment 

prior to interstate movement of the articles, as well as the loss of market 

access to other citrus-producing States not currently affected with ACP. 

As an example of ACP quarantine costs, the Texas State entomologist has 

estimated the cost of treatments with soil drenches and foliar sprays due to 

the quarantine in Texas to be approximately $0.24 per plant. 

The continued use of chemical controls and previously released biological 

control agents at current levels would result if the no action alternative is 

chosen, and may continue even if permits are issued for expanded 

environmental release of T. radiata.

a. Chemical Control

The environmental consequences of many of the insecticides used for 

control of ACP were analyzed by APHIS (USDA–APHIS, 2009) and will 

not be discussed further in this document. However, an additional 

environmental consequence of the use of insecticides for control of ACP is 

a reduction in occurrence of natural predators of ACP, such as lady 

beetles, syrphids, and spiders. Following the discovery of HLB in Florida, 

many growers adopted intensive insecticide programs to control the 

psyllid (Rogers, 2008; Rogers et al., 2008). Most of the materials used to 

control ACP are broad-spectrum insecticides which disrupt not only native 

predators of ACP but also of other citrus pests. Research indicates that T. 

radiata is sensitive to a number of chemicals used in citrus (Hall and 

Nguyen, unpublished). 

b. Biological Control

Native predators and previously released biological control agents will 

remain in the environment and exert some level of control over ACP. 

However, these are not adequate to control ACP populations in the 

United States.

B. Issue permits for expanded release of T. radiata

Host specificity of T. radiata to ACP has been demonstrated through field 

observations and host specificity testing. Other nontarget psyllids are not 

expected to be attacked by T. radiata.

a. Scientific Literature

In scientific literature, the host records of T. radiata are listed in the 

Universal Chalcidoidea Database (http://www.nhm.ac.uk/researchcuration/research/projects/chalcidoids/ last accessed July 9, 2009), and 

2. Impact from 

the Use of 

Other Control 

Methods

1. Impact of 

T. radiata on 

Nontarget 

Psyllids
10

include Euphalerus citri, Psylla hyalina, Trioza erytreae and Trioza sp. E. 

citri is a synonym of D. citri. It is thought that Psylla hyalina and Trioza 

erytreae, as hosts of T. radiata, are likely mistaken reports (McDaniel and 

Morgan, 1972; Nguyen, unpublished data).

b. Host Specificity Testing

Researchers conducted host specificity testing using five native psyllid 

species—Glycaspis brimblecombei, Ceropsylla sideroxyli, Trioza 

magnoliae, Hereropsylla cubana, and Pachypsylla sp. (Nguyen et al., 

2009). Each cage that contained either the native psyllids or ACP was

inoculated with four females and two males of T. radiata from three

different source colonies—Northern Vietnam, Southern China, and

Pakistan. Three to six replications (cages) per each T. radiata colony were 

used for the test. In the tests, T. radiata did not parasitize any of the 

native psyllid species, only ACP. In addition, an Australian psyllid 

released into Florida for the biological control of melaleuca

(Boreiolycaspis melaleuca) was tested but was not parasitized by T. 

radiata. The researchers concluded that T. radiata is specific to ACP 

(Nguyen et al., 2009).

Once a biological control agent such as T. radiata is released into the 

environment and becomes established, there is a slight possibility it could 

move from the target insect (ACP) to attack nontarget insects, such as 

native psyllid species. Native species that are closely related to the target 

species are the most likely to be attacked (Louda et al., 2003). If other 

psyllid species were to be attacked by T. radiata, the resulting effects 

could be environmental impacts that may not be easily reversed. 

Biological control agents such as T. radiata generally spread without 

intervention by man. In principle, therefore, release of these parasitoids at 

even one site should be considered equivalent to release over the entire 

area in which potential hosts occur and in which the climate is suitable for 

reproduction and survival. For example, although not purposely released 

in Puerto Rico and Texas, T. radiata has been found there. 

In addition, these agents may not be successful in reducing ACP

populations in the continental United States. Approximately 12 percent of 

all parasitoid introductions have led to significant sustained control of the 

target pests, but the majority of introductions have failed to provide 

control of the pest (Greathead and Greathead, 1992) either because 

introduction did not lead to establishment or establishment did not lead to 

control (Lane et al., 1999). Actual impacts on ACP populations by T. 

radiata will not be known until after release occurs and post-release 

monitoring has been conducted. The environmental consequences 

discussed under the no action alternative may occur even with the 

implementation of the biological control alternative, depending on the 

2. Uncertainties 

Regarding the 

Environmental 

Release of T. 

radiata
11

efficacy of T. radiata to reduce ACP populations in the continental United 

States.

―Cumulative impacts are defined as the impact on the environment which 

results from the incremental impact of the action when added to other past, 

present and reasonably foreseeable future actions regardless of what 

agencies or person undertakes such other actions‖ (40 CFR 1508.7).

USDA–APHIS has undertaken measures to control the artificial spread of 

ACP and HLB to uninfested areas of the United States since the 

introduction of HLB in 2005. On September 16, 2005, APHIS issued a 

Federal Order designating all or parts of 10 affected counties in Florida as 

quarantined areas, and imposed restrictions on the interstate movement of 

all ACP and HLB host material from these areas. Since then, it has been 

necessary to update the restrictions and expand the ACP and/or HLB

quarantine areas with subsequent Federal Orders due to the continuing 

spread of both ACP and HLB. APHIS has issued a total of 12 Federal 

Orders to impose restrictions on the interstate movement of ACP and HLB

host plant material from quarantined areas. APHIS is developing an 

interim rule that would replace the most recent Federal Order for ACP and 

HLB. It would codify some of the provisions of the Order, clarify others, 

and add provisions that APHIS has determined to be necessary since the 

issuance of the last Federal Order so as to prevent the spread of ACP and 

HLB to uninfested areas of the United States.

California Department of Food and Agriculture (CDFA) is working to 

eradicate ACP from the two infested counties in that State and prevent 

spread into new counties. Since August 28, 2008, CDFA has detected 

populations of ACP in portions of San Diego, Imperial, Orange, and Los 

Angeles Counties, and has implemented an aggressive control and 

quarantine program to protect California from this invasive pest, including 

survey activities for the pest. 

Release of T. radiata is not expected to have any negative cumulative 

impacts in the continental United States because of its host specificity to 

ACP. Effective biological control of ACP would have beneficial effects 

for ACP and HLB management programs, and may result in a long-term, 

non-damaging method to assist in the control of ACP and HLB, and 

prevent their spread into other areas potentially at risk from invasion.

Section 7 of the Endangered Species Act (ESA) and ESA’s implementing 

regulations require Federal agencies to ensure that their actions are not 

likely to jeopardize the continued existence of federally listed threatened 

and endangered species, or result in the destruction or adverse 

modification of critical habitat. 

4. Endangered 

Species Act

3. Cumulative 

Impacts
12

APHIS has determined that, based on the host specificity of T. radiata, 

there will be no effect on any listed insect in the continental United States. 

In host specificity testing, the biological control organism attacked only 

ACP. No federally listed threatened or endangered insects belong to the 

family Psyllidae (FWS–TESS, 2009). In addition, no listed species is 

dependent on ACP as a food source. Although certain federally listed 

plants occur in the family Rutaceae and may serve as hosts of ACP, 

release of T. radiata will not benefit any of these species because all occur 

outside of the continental United States. T. radiata will only be released 

within the continental United States.

V. Other Issues

Consistent with Executive Order (EO) 12898, ―Federal Actions to Address 

Environmental Justice in Minority Populations and Low-income 

Populations,‖ APHIS considered the potential for disproportionately high 

and adverse human health or environmental effects on any minority 

populations and low-income populations. There are no adverse 

environmental or human health effects from the field release of T. radiata,

and their release will not have disproportionate adverse effects to any 

minority or low-income populations. 

Consistent with EO 13045, ―Protection of Children From Environmental 

Health Risks and Safety Risks,‖ APHIS considered the potential for 

disproportionately high and adverse environmental health and safety risks 

to children. No circumstances that would trigger the need for special 

environmental reviews are involved in implementing the preferred 

alternative. Therefore, it is expected that no disproportionate effects on 

children are anticipated as a consequence of the field release of T. radiata.

EO 13175, ―Consultation and Coordination with Indian Tribal 

Governments,‖ was issued to ensure that there would be ―meaningful 

consultation and collaboration with tribal officials in the development of 

Federal policies that have tribal implications....‖

Consistent with EO 13175, APHIS sent letters of notification and requests 

for comment and consultation on the proposed action to tribes in 

California, Arizona, and Texas. APHIS will continue to consult and 

collaborate with Indian tribal officials to ensure that they are wellinformed and represented in policy and program decisions that may impact 

their agricultural interests, in accordance with EO 13175.
13

VI. Agencies and Organizations Consulted

This EA was prepared and reviewed by APHIS. The addresses of 

participating APHIS units, cooperators, and consultants (as applicable) 

follow.

Florida Department of Agriculture and Consumer Services

Division of Plant Industry

P.O. Box 147100

Gainesville, FL 32601

U.S. Department of Agriculture

Animal and Plant Health Inspection Service

Policy and Program Development 

Environmental and Risk Analysis Services

4700 River Road, Unit 149

Riverdale, MD 20737

U.S. Department of Agriculture

Animal and Plant Health Inspection Service

Plant Protection and Quarantine 

Registrations, Identification, Permits, and Plant Safeguarding 

River Road, Unit 133

Riverdale, MD 20737
14

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Hoy, M.A., and Nguyen, R., 2001. Classical biological control of Asian 

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17

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Decision and Finding of No Significant Impact 


for 


Proposed Release of a Parasitoid (Tamarixia radiata Waterston) 


for the Biological Control of Asian Citrus Psyllid (Diaphorina citri Kuwayama) in the 


Continental United States 


June 2010 


The U.S. Department of Agriculture (USDA), Animal and Plant Health Inspection Service 

(APHIS), Plant Protection and Quarantine (PPQ) Permit Unit, is proposing to issue permits for 

release of an insect, Tamarixia radiata Waterston (Hymenoptera: Eulophidae) in the continental 

United States. The agent would be used by the applicant for the biological control of Asian 

citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). Before permits are issued for 

release of T. radiata, APHIS must analyze the potential impacts of the release of this organism 

into the continental United States. APHIS has prepared an environmental assessment (EA) that 

analyzes the potential environmental consequences of this action. The EA is available from: 

U.S. Department of Agriculture 


Animal and Plant Health inspection Service 


Plant Protection and Quarantine 


Registrations, Identification, Permits, and Plant Safeguarding 


4700 River Road, Unit 133 


Riverdale, MD 20737 


hLtp://www.aphis.usda. gov/plant healthlealindex.shtml 


The EA analyzed the following two alternatives in response to a request for permits authorizing 

environmental release of T. radiata: (1) no action, and (2) issue permits for the release of T. 

radiata for biological control of Asian citrus psyllid. A third alternative, to issue permits with 

special provisions or requirements concerning release procedures or mitigating measures, was 

considered. However, this alternative was dismissed because no issues were raised that indicated 

that special provisions or requirements were necessary. The No Action alternative, as described 

in the EA, would likely result in the continued use at the current level of chemical and biological 

control methods for the management of Asian citrus psyllid. These control methods described 

are not alternatives for decisions to be made by the Permit Unit, but are presently being used to 

control Asian citrus psyllid in the United States and may continue regardless of permit issuance 

for field release of T. radiata. Notice of the EA was made available in the Federal Register on 

May 20,2010 for a 30-day public comment period. Four comments were received on the EA, all 

in favor of the release of T. radiata. 

I have decided to authorize the APHIS-PPQ Permit Unit to issue permits for the environmental 

release of T. radiata. The reasons for my decision are: 

• 	 This biological control agent is sufficiently host specific and poses little, if any, threat to 

the biological resources, including non-target psyUid species, of the continental United 

States. 
• 	 The release will have no effect on federally listed threatened and endangered species or 

their habitats in the continental United States. 

• 	 T. radiata poses no threat to the health of humans or wild or domestic animals. 

• 	 No negative cumulative impacts are expected from rel ease of T. radia{o. 

• 	 There are no disproportionate adverse effects to minorities, low-income populations, or 

children in accordance with Executive Order 12898 "Federal Actions to Address 

Environmental Justice in Minority Populations and Low-income Populations" and 

Executive Order 13045, "Protection of Children from Environmental Health Risks and 

Safety Risks." 

• 	 While there is not total assurance that the release of T. radiata into the environment will 

be reversible, there is no evidence that this organism will cause any adverse 

environmental effects. 

An environmental impact statement (EIS) must be prepared if implementation of the proposed 

action may significantly affect the quality of the human environment. r have determined that 

there would be no significant impact to the human environment from the implementation of any 

of the action alternatives and , therefore, no EIS needs to be prepared. 

Date 

Director 

Registrations, Identification, Permits, and Plant Safeguarding 

Plant Health Programs 

APHIS, Plant Protection and Quarantine