United States 

Department of 

Agriculture 

Marketing and 

Regulatory 

Programs 

Animal and 

Plant Health 

Inspection 

Service 

APHIS 

~ 

USDA 

~ 

Field Release of Aphelinus 

glycinis (Hymenoptera: 

Aphelinidae) for Biological 

Control of the Soybean 

Aphid, Aphis glycines 

(Hemiptera: Aphididae), in 

the Continental United 

States 

Environmental Assessment, 

March 2012 
Field Release of Aphelinus glycinis 

(Hymenoptera: Aphelinidae) for 

Biological Control of the Soybean 

Aphid, Aphis glycines (Hemiptera: 

Aphididae), in the Continental United 

States 

Environmental Assessment, 

March 2012 

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 

The U.S. Department of Agriculture (USDA) prohibits discrimination in all 

its programs and activities on the basis of race, color, national origin, sex, 

religion, age, disability, political beliefs, sexual orientation, and marital or 

family status. (Not all prohibited bases apply to all programs.) Persons 

with disabilities who require alternative means for communication of 

program information (Braille, large print, audiotape, etc.) should contact 

USDA's TARGET Center at (202) 720-2600 (voice and TDD). 

To file a complaint of discrimination, write USDA, Director, Office of Civil 

Rights, Room 326-W, Whitten Building, 1400 Independence Avenue, SW, 

Washington, DC 20250-9410 or call (202) 720-5964 (voice and TDD). 

USDA is an equal opportunity provider and employer. 

Mention of companies or commercial products in this report does not imply 

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

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

the standard of any product mentioned. Product names are mentioned 

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 

Ill. Affected Environment .............................................................. 5 

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

V. Other Issues ............................................................................ 11 

VI. Agencies, Organizations, and Individuals Consulted ......... 12 

VII. References ............................................................................. 13 

Appendix A ................................................................................... 22 

Appendix 8 ................................................................................... 24 
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) Pest 

Permitting Branch (PPB) is proposing to issue permits for release of the 

insect Aphelinus glycinis (Hymenoptera: Aphelinidae). The agent would 

be used by the applicant for biological control of soybean aphid, Aphis 

glycines (Hemiptera: Aphididae), in the continental United States. Before 

permits are issued for release of A. glycinis, the APHIS-PPQ PPB needs to 

analyze the potential impacts of the release of this organism 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 A. glycinis 

to control soybean aphid in the continental United States. This EA 

considers a "no action" alternative and the potential effects of the 

proposed action. 

The applicant's purpose for releasing A. glycinis is to reduce the severity 

of soybean damage from infestations of soybean aphid (A. glycines) in the 

continental United States. In 2000, the soybean aphid that is native to 

Asia, was found in North America and has now become a major pest, 

infesting 42 million acres in 2003 alone resulting in decreased soybean 

yields and greatly increased control costs (Ragsdale et al., 2011; Landis et 

al., 2008; Song and Swinton, 2009). The soybean aphid has invaded most 

soybean production regions in North America, including numerous U.S. 

states and three Canadian provinces since being found here in 2000 

(Ragsdale et al., 2004 ). 

Existing soybean aphid management options (discussed below) are 

expensive, temporary, or have non-target impacts. For these reasons, the 

applicant has a need to identify an effective, host-specific biological 

control organism and release it into the environment of the continental 

United States for the control of soybean aphid. 

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). 

1 
1. Chemical 

Control 

2. Host Plant 

Resistance 

II. Alternatives 

This section will explain the two alternatives available to the APHIS-PPQ 

PPB-no action (no issuance of permits) and issuance of permits for 

environmental release of A. glycinis in the continental United States. 

Although APHIS' alternatives are limited to a decision of whether to issue 

permits for release of A. glycinis, other methods available for control of 

soybean aphid in the United States are also described. These control 

methods are not decisions to be made by APHIS, and are likely to 

continue whether or not permits are issued for environmental release of A. 

glycinis. These are methods presently being used to control soybean aphid 

by growers in the United States. 

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

Under this third alternative, the APHIS-PPQ PPB would have issued 

permits for the field release of A. glycinis; however, the permits would 

contain special provisions or requirements concerning release procedures 

or mitigating measures, such as limited release of A. glycinis in the United 

States. No issues have been raised which would indicate that special 

provisions or requirements are necessary. 

A. No Action 

Under the no action alternative, the APHIS-PPQ PPB would not issue 

permits for the field release of A. glycinis for the control of soybean 

aphid-the release of this biological control agent would not take place. 

The following methods are presently being used to control soybean aphid 

in the United States; these methods will continue under the "no action" 

alternative and are likely to continue even if permits are issued for release 

of A. glycinis. Presently, control of soybean aphid in the United States is 

limited to chemical control, plant resistance, and biological control 

methods. 

Insecticide treatments are currently the most effective method to manage 

soybean aphids in North America. Foliar sprays of insecticides provide 

temporary suppression (7 to 14 days) of soybean aphid populations. 

Insecticides including esfenvalerate, dimethoate, chlorpyrifos, zetacypermethrin, methyl parathion, permethrin, and lambda cyhalothrin are 

or have been labeled for foliar application against soybean aphid (Ostlie, 

2002). Soybean seed treatments using the neonicotinoid insecticides 

imidacloprid and thiamethoxam for systemic control of soybean aphids 

can also be used (Pedersen and Lang, 2006; Magalhaes et al., 2009). 

Aphid-resistant soybean plants have been developed to reduce aphid 

populations. Host plant resistance works by inhibiting aphid growth and 

2 
3. Biological 

Control 

1. Aphelinus 

glycinis 

Taxonomic 

Information 

___________ , _____ ._,_,,, 

development and increasing plant tolerance to aphid feeding. 

Aphelinus certus is a parasitoid native to Asia. A parasitoid is an insect 

whose immature stages (larvae and pupae) live as parasites that eventually 

kill their hosts (typically other insects). Aphelinus certus has a broad host 

range, but is commonly found in soybean aphids in Asia, and has been 

found attacking soybean aphid in parts of North America (Heimpel et al., 

2010; Frewin et al., 2010). It appears to have been accidentally 

introduced into the United States, arriving around the time when soybean 

aphid invaded, and it may have been introduced with soybean aphid. 

High levels ofparasitism of soybean aphid by A. certus have been. 

observed in Quebec and Ontario, but the parasitoid is not as common 

elsewhere. 

A previously introduced strain ofthe European parasitoidAphelinus 

atriplicis was released against soybean aphid in 2002. This strain was first 

released in the western United States against the Russian wheat aphid 

(Hopper et al., 1998; Prokrym, 1998; Heraty et al., 2007) and was found to 

attack the soybean aphid as well (Wu et al., 2004). Although this strain of 

Aphelinus atriplicis was released in nine Minnesota sites in 2002 (Heimpel 

et al., 2004), it has not been recovered since then. Another Asian 

parasitoid, Binodoxys communis (Hymenoptera: Braconidae), was released 

in the United States beginning in 2007; unfortunately, it has not 

established (Ragsdale et al., 2011). 

B. Issue Permits for Environmental Release of 

A. glycinis. 

Under this alternative, the APHIS-PPQ PPB would evaluate application 

requests and issue permits for the field release of A. glycinis for the control 

of soybean aphid in the continental United States. These permits would 

contain no special provisions or requirements concerning release 

procedures or mitigating measures. 

Insect Taxonomy 

Order: 

Family: 

Genus: 

Species: 

Common name 

Hymenoptera 

Aphelinidae 

Aphelinus 

glycinis Hopper and Woolley 

none 

A paper describing A. glycinis has been accepted for publication in the 

Journal of Hymenoptera Research. Voucher specimens of A. glycinis are 

held at the USDA, Agricultural Research Service (ARS), Beneficial 

Insects Introduction Research Unit in Newark, Delaware; Texas A & M 

University, Department of Entomology; and the USDA-ARS, Systematic 

Entomology Laboratory at the Smithsonian National Museum of:Natural 

3 
2. Description 

and 

Biology of 

Aphelinis 

glycinis 

3. Geographic 

Range of 

Aphelinis 

glycinis 

History in Washington, DC. 

Aphelinus species are tiny (about 1 millimeter (mm) in length), stingless 

wasps. Like all parasitic wasps, the immature stages develop as 

parasitoids of arthropods where, in this case, feeding of the wasp larva 

inside the host aphid eventually kills the host aphid. Many species of 

Aphelinus have demonstrated their importance in the biological control of 

aphids (Hemiptera: Aphididae ). 

Aphelinus glycinis females prefer second to fourth instar (an immature 

developmental stage) aphid hosts for oviposition (egg laying), but will lay 

eggs in all stages, including winged adults. Females use an egg laying 

organ called an ovipositor to insert an egg into the aphid. The inserted egg 

hatches and the wasp larva feeds on the internal organs of the aphid host. 

At 20°C, the wasps develop from egg to pupa in about 14 days; third instar 

wasps kill their hosts but leave the aphid host external skeleton 

(exoskeleton) intact, causing it to harden and tum black, a process called 

mummification. Adult A. glycinis wasps emerge from the mummified 

aphid about one week after pupation, chewing a hole through the host 

exoskeleton to escape. Adult wasps eat plant nectar and honeydew (a 

sugary liquid secreted by aphids and other sap-feeding insects). Adult 

females also feed on aphids to obtain nutrients for egg production by 

piercing or "stinging" the aphids with their ovipositor and drinking the 

hemolymph (insect blood) from the wound, killing about 2 aphids per day 

by such feeding. Females emerge as adults with five to 15 mature eggs, 

but produce more eggs throughout their lives, maturing about 10 eggs per 

day. In the laboratory, adult wasps live for two to three weeks, but they 

are unlikely to survive this long in the field. 

Aphelinus species are weak fliers, searching primarily by walking 

(Fauvergue et al., 1995; Mason and Hopper, 1997). Another parasitoid in 

this genus, Aphelinus asychis, dispersed an average of 13 feet in one 

generation and 26 feet in three generations (Fauvergue and Hopper, 2009). 

However, these low distances were in fields with abundant hosts; they 

would have to disperse much further at the end of the growing season to 

track their hosts. 

Aphelinus glycinis was collected from parasitized soybean aphids on 

soybean in 2007 near Xiyuan, Liaoning Province, Peoples Republic of 

China, and is not known to occur elsewhere. However, this province has a 

climate that closely matches the climate in the northern midwest United 

States where the majority of soybean is grown and where soybean aphid 

has become a major pest. It is expected that A. glycinis will be limited to 

this region and perhaps the Canadian provinces of Ontario and Quebec. In 

this region, it is expected that it will be found in soybean fields infested 

with soybean aphid during the growing season and on Rhamnus species 

(buckthorns that are woody perennial shrubs/trees in forest understories 

4 
4. Impact of 

Aphelinis 

glycinis 

on Soybean 

Aphid 

1. Native and 

Worldwide 

Distribution 

2. Present 

Distribution in 

North America 

and crop borders) where soybean aphid overwinters. 

In the laboratory, an individual female A. glycinis wasp can parasitize or 

· kill by host feeding over 150 aphids during a lifetime of three weeks, but 

such long lifetimes are unlikely in the field. However, if females lived 

one week in the field they could parasitize and host feed on 40 to 50 

aphids, if aphids are sufficiently abundant. 

Ill. Affected Environment 

A. Soybean Aphid 

The soybean aphid is a host alternating species, which means it must 

disperse between two different types ofhost plants between summer and 

winter. Females reproduce asexually on soybean from June to September, 

producing winged and wingless forms. In September, winged males and 

parthenogenetic (a form of reproduction in which an unfertilized egg 

develops into a new individual) females migrate to their primary host 

plants, Rhamnus species, and the migratory females bear sexual, flightless 

females, which mate with the migratory males and lay overwintering eggs. 

In spring, parthenogenetic females hatch from these eggs, and several 

generations of females reproduce asexually on Rhamnus species before 

winged aphids move to soybean plants. Although soybean aphids are 

weak fliers, the rapid rate of spread of soybean aphid indicates a high rate 

of windborn dispersal. In the laboratory, soybean aphid has a high rate of 

population increase at 25°C, with a steep decline to a negative rate when 

temperatures are higher than 30°C (McCornack et al., 2004), which 

explains why it has not moved further south in the United States where 

temperatures are warmer. At 25°C, females can produce 73 offspring 

during their lifetime, with a generation time of 10 days. The combination 

of high dispersal rate and high reproductive rate mean that soybean aphid 

can rapidly reach damaging levels over wide regions, if not properly 

managed. 

B. Areas Affected by Soybean Aphid 

The soybean aphid is native to east Asia, found in eastern Russia, China, 

Japan, and Southeast Asia (Vietnam, Thailand, Indonesia, Malaysia, and 

the Philippines). It is also known from Kenya, and invaded Australia in 

2000. 

In North America, it is currently known from Ontario and Quebec in 

Canada, and from the following U.S. states: Arkansas, Connecticut, 

Delaware, Georgia, Indiana, Iowa, Illinois, Kansas, Kentucky, Louisiana, 

Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, 

Missouri, Nebraska, New Jersey, New York, North Dakota, Ohio, 

5 
3. Soybean 

Aphid 

Hosts 

1. Insects 

Related 

to 

Soybean 

Aphid 

2. Insects 

Related to 

Aphelinus 

glycinis 

Oklahoma, Pennsylvania, South Carolina, South Dakota, Tennessee, 

Virginia, West Virginia, and Wisconsin (Ragsdale et al., 2011). 

Soybean (Glycine max) is the summer host of soybean aphid while various 

buckthorn species (Rhamnus species) are the winter hosts. Several native 

and a few introduced species of Rhamnus occur in the United States. 

C. Insects Related to Soybean Aphid and A. glycinis 

in the United States 

Information regarding insects taxonomically related to soybean aphid is 

included because insect species which are closely related to it have the 

greatest potential to be attacked by A. glycinis. 

Of the 497 species identified in the genus Aphis, 119 are reported from 

North America (Eastop, 2006). Of these 119, 33 are also widely 

distributed throughout the world, but the remaining 86 species are likely 

native to North America. Fortunately, most native Aphis species are not 

closely related to soybean aphid (Aphis glycines), and A. glycinis does not 

parasitize Aphis species that are distantly related to soybean aphid. 

Among the species of Aphis present in North America which are closely 

related to the soybean aphid are the cotton aphid, Aphis gossypii, which is 

also native to Asia and a major agricultural pest, and the buckthorn-potato 

aphid, Aphis nasturtii, which is also thought to be native to Asia, and is a 

pest of potatoes in North America. 

Thirty-one species of Aphelinus are reported from North America; 

however, only about half of these species (14) are reported exclusively or 

almost exclusively from North America, and are likely native (see 

Appendix A). The remainingAphelinus species reported from North 

America were described elsewhere, are reported from one to several other 

continents, and therefore are unlikely to be native to North America. 

Several have been introduced for biological control of pest aphids (Hopper 

et al., 1998; Jackson et al., 1971; van den Bosch et al., 1959). 

Aphelinis glycinis is not expected to compete with native species of 

Aphelinus. Three native Aphelinus species have been reported as parasites 

of Aphis species, Aphelinus marlatti, A. nigritis, and A. semiflavus, but 

only A. semiflavus parasitizes a species closely related to the soybean 

aphid, being reported from the cotton aphid in the midwestern United 

States. Native parasitoid species are unlikely to switch to attack the 

soybean aphid, and such switches have not been observed (Lin and Ives, 

2003; Rutledge et al., 2004; Kaiser et al., 2007; Costamagna and Landis, 

2007; Noma and Brewer, 2008; Noma et al., 2010). The native Aphelinus 

species most closely related to A. glycinis are Aphelinus lapisligni, A. 

mali, A. prociphili, A. sanborniae, and A. siphonophorae which are in the 

mali complex to which A. glycinis belongs. However, their hosts are very 

6 
1. Impact of 

Soybean 

Aphid on the 

Environment 

2. Impact from 

the Use of 

Other Control 

Methods 

different from those parasitized by A. glycinis. 

IV. Environmental Consequences 

A. No Action 

a. Effect of soybean aphid on host plants 

Soybean aphids suck sap from plants. When aphid infestations are large, 

infested leaves are wilted or curled. Direct feeding damage from aphids 

may include plant stunting, reduced pod and seed counts, and yellowing of 

leaves. Soybean aphids are also able to transmit plant viruses such as 

alfalfa mosaic, soybean mosaic, and bean yellow mosaic, that can cause 

reduction in soybean yields. 

For soybean growers in the north central United States, soybean aphid is 

the first insect pest to consistently cause important losses over wide areas 

(Ragsdale et al., 2004), with yield decreases of up to 40 percent (Ragsdale 

et al., 2007). Because of the soybean aphid invasion, pest management 

practices of soybean producers have changed dramatically. In 2000, less 

than 0.1 percent of soybeans in the north central states were treated with 

insecticides; by 2006, over 13 percent of the soybeans in these states were 

treated with insecticides, indicating that soybean aphid has been 

responsible for a 130-fold increase in the use of insecticides (Ragsdale et 

al., 2011). Control of the soybean aphid currently relies on insecticide 

use, and millions of acres of soybeans have been sprayed since the 

invasion of this pest in the United States. This is a major disruption in the 

70 million acres where soybean is grown. 

The continued use of chemical control, plant resistance, and biological 

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

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

release of A. glycinis. 

a. Chemical Control 

Foliar applications may not sufficiently control soybean aphids and 

prevent yield loss, especially if large quantities of soybean aphids are 

surviving on lower leaves. Foliar sprays may also pose a threat to bees 

and aphid natural enemies such as lady beetle larvae and predatory 

bugs. 

Seed treatments of systemic insecticides such as imidacloprid do not last 

the entire growing season. In addition, seed treatment insecticides are 

applied at the beginning ofthe growing season before it is known if 

treatment for soybean aphid is even necessary. This can result in a 

7 
1. Impact of 

A. glycinis on 

Non-target 

Insects 

financial loss to growers if aphid populations would not have been high 

enough to cause economic damage. 

b. Plant Resistance 

Although plant resistance inhibits aphid growth and development and 

increases plant tolerance to aphid feeding, plant resistance in certain cases has 

been overcome by soybean aphids. 

c. Biological Control 

Two biological control organisms have previously been released against 

soybean aphid. However, neither A. atriplicis nor Binodoxys communis 

have established in the environment and are therefore not likely to control 

soybean aphid. 

These environmental consequences may occur even with the 

implementation of the biological control alternative, depending on the 

efficacy of A. glycinis to reduce soybean aphid infestations in the 

continental United States. 

B. Issue Permits for Environmental Release of A. 

glycinis 

a. Scientific Literature 

Aphelinus glycinis is new to science so there is no literature on its host 

range but it was determined to be part of the A. mali complex, a group 

within the genus Aphelinus that are closely related to each other. Other 

species in the A. mali complex tend to have narrow host ranges, although a 

few, including A. mali itself, are reported to have broad host ranges. 

However, broad host ranges in the literature for species in the genus 

Aphelinus are suspect because similar looking species have frequently 

been confused with one another, resulting in false host reports (Heraty et 

al., 2007). 

b. Host Specificity Testing 

Host specificity testing of A. glycinis was conducted in a quarantine 

facility (Hopper, 2010, appendix B). The ability to parasitize 13 aphid 

species in five different genera on nine different plant species occurring in 

eight families was tested (Table 1 ). These different kinds of aphids 

represent many of the aphids reported as hosts of the A. mali complex, of 

which A. glycinis is a member. Based on the aphid distributions in 

Blackman and Eastop (2006), many of these aphid species tested occur 

within the native geographic range of A. glycinis in Asia. 

8 
2. Uncertainties 

Regarding the 

Environmental 

Release of A. 

glycinis. 

In the laboratory experiments in quarantine, oviposition and host feeding 

by A. glycinis were restricted almost completely to species in the genus 

Aphis that are closely related to soybean aphid (see appendix B for more 

detailed study information). Furthermore, parasitoid stinging that did not 

lead to mummification or host feeding did not increase mortality of any 

aphid species. Handling times (the time needed in host handling and 

parasitization) were long so that ant-tended native aphids, such as A. 

monardae and A. oestlundi, are not expected to be at risk in the field 

Table 1. Aphid and host plant species used to test Aphelinus 

glycinis host specificity (Hopper, 201 0). 

Aphid species Plant species Plant family 

Myzus persicae Raphanus sativus Brassicaceae 

Diuraphis noxia Hordeum vulgare Poaceae 

Rhopalosiphum padi Hordeum vulgare Poaceae 

Rhopalosiphum maidis Hordeum vulgare Poaceae 

Schizaphis graminum Hordeum vulgare Poaceae 

Aphis rumicis Rumex altissimus Polygonaceae 

Aphis craccivora Vigna unguiculata Fabaceae 

Aphis glycines Glycine max Fabaceae 

Aphis gossypii Gossypium hirsutum Malvaceae 

Aphis monardae Monarda fistulosa Lamiaceae 

Aphis oestlundi Oenothera biennis Onagraceae 

Aphis asclepiadis Asclepias syriaca Apocynaceae 

Aphis nerii Asclepias syriaca Apocynaceae 

because ants would have time to chase away A. glycinis if it were to 

attempt to oviposit or host feed on these aphid species. 

Once a biological control agent such as A. glycinis is released into the 

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

from the target insect (soybean aphid) to attack nontarget insects, such as 

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

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

aphid species were to be attacked by A. glycinis, the resulting effects could 

be environmental impacts that may not be easily reversed. Biological 

control agents such as A. glycinis 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. 

In addition, these agents may not be successful in reducing soybean aphid 

populations in the continental United States. Approximately 12 percent of 

all parasitoid introductions have led to significant sustained control of the 

9 
, 3. Cumulative 

Impacts 

4. Endangered 

Soecies Act 

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 soybean aphid populations 

by A. glycinis 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 action alternative, depending on the efficacy of A. 

glycinis to reduce soybean aphid in the continental United States. 

"Cumulative impacts are defined as the impacts on the environment which 

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

present and reasonably foreseeable future actions regardless ofwhat 

agencies or person undertakes such other actions" ( 40 CFR 1508. 7). 

No other soybean aphid biological control organisms released in the 

United States have successfully established. Therefore, no competitive 

interactions would occur between A. glycinis and other biological control 

organisms. In addition, as discussed previously, A. glycinis is not 

expected to compete with native species of Aphelinus. However, the nonnative parasitoid Aphelinus certus has established in North America 

accidentally (Heimpel et al., 2010, Frewin et al., 2010). Because of its 

broad host range, A. certus was not considered for purposeful introduction 

against soybean aphid. The abundance of A. certus in the United States is 

unlikely to be affected by introduction of A. glycinis because A. glycinis 

does not attack many of the same host species used by A. certus. 

Aphelinus certus might interfere with establishment of A. glycinis, but 

given that these parasitoid species coexist in Asia, such interference is 

likely to be transitory. 

Release of A. glycinis is not expected to have any negative cumulative 

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

soybean aphids. Effective biological control of soybean aphid will have 

beneficial effects for soybean growers in the United States, and may result 

in a long-term, non-damaging method to assist in the control of soybean 

aphid and may reduce the use of insecticides on soybean. 

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. 

APHIS has determined that, based on the host specificity of A. glycinis, 

there will be no effect on any listed insect species or designated critical 

habitat in the continental United States. In host specificity testing, A. 

glycinis attacked only Aphis species in the Aphis gossypii/glycines 

10 
complex. No federally listed threatened or endangered insects belong to 

the aphid family, Aphididae (USFWS, 2012). No federally listed species 

are known to depend on or utilize soybean aphid. 

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 anticipated from the field release of 

A. glycinis and its 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, no disproportionate effects on children are 

anticipated as a consequence of the field release of A. glycinis. 

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 the affected states. APHIS 

continues to communicate with Indian tribal officials to ensure that they 

are well-informed and represented in policy and program decisions that 

may impact their agricultural interests, in accordance with EO 13175. 

11 
VI. Agencies, Organizations, and 

Individuals Consulted 

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

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

follow. 

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 

4700 River Road, Unit 133. 

Riverdale, MD 20737 

U.S. Department of Agriculture 

Agricultural Research Service 

Beneficial Insect Introductions Research Unit 

501 South Chapel Street 

Newark, DE 19713 

12 
VII. References 

Archer, T.L., Cate, R.H. and Eikenbary, R.D. 1974. Parasitoids collected 

from greenbugs and com leaf aphids in Oklahoma in 1972. Annals ofthe 

Entomological Society of America. 67: 11-14. 

Ashmead, W.H. 1888a. Descriptions of some new North American 

Chalcididae. III: Euderinae (Hymenoptera: Chalcidoidea). Canadian 

Entomologist. 20: 101-107. 

Ashmead, W.H. 1888b. Descriptions of some unknown parasitic 

Hymenoptera in the collection of the Kansas State Agricultural College, 

received from Prof. E.A. Popenoe. Bulletin of Kansas Agricultural 

Experiment Station, Manhattan. No.3 (appendix):v. 

Becker, G.G. 1918. Notes on the woolly aphis. Bulletin ofthe Arkansas 

Agricultural Experiment Station. 11: 245-255. 

Bilu, E., Hopper, K.R. and Coll, M. 2006. Host choice by Aphidius 

colemani: effects of plants, plant-aphid combinations and the presence of 

intraguild predators. Ecological Entomology. 31: 331-336. 

Blackman, R.L. and Eastop, V.F. 2006. Aphids of the world's herbaceous 

plants and shrubs. Volume 2: the aphids. Wiley and Sons, Ltd., West 

Sussex, U.K.· 

Bruner, L. 1894. Insect enemies of the apple tree and its fruit. Annual 

Report of the Nebraska State Horticultural Society. 2: 154-223. 

Bueno, R., Jr. and Stone, J.D. 1983. Phenology of a parasite ofthe 

blackmargined aphid in West Texas. Southwestern Entomologist. 8: 

73-79. 

Carver, M. 1980. A new species of Aphelinus Dalman (Hymenoptera: 

Chalcidoidea: Encyrtidae). Proceedings of the Entomological Society of 

Washington. 82: 536-540. 

Chau, A. and Mackauer, M. 2001. Preference of the aphid parasitoid 

Monoctonus paulensis (Hymenoptera: Braconidae, Aphidiinae) for 

different aphid species: Female choice and offspring survival. Biological 

Control. 20: 30-38. 

Costamagna, A.C. and Landis, D.A. 2007. Predators exert top-down 

control of soybean aphid across a gradient of agricultural management 

systems. Ecological Applications. 17: 639-639. 

Cresson, E.T. 1862. Catalogue ofthe described species ofNorth American 

13 
Hymenoptera. (Continued.) Proceedings of the Entomological Society of 

Philadelphia. 1: 227-238. 

Delong, D.M., and Jones, M.P. 1926. Control measures for the Houghton 

gooseberry aphis with special reference to plant resistance. Journal of 

Economic Entomology. 19:40-43. 

Driessen, G., Hemerik, L. and Boonstra, B. 1991. Host selection behaviour 

of the parasitoid Leptopilina clavipes, in relation to survival in hosts. 

Netherlands Journal of Zoology. 41: 99-111. 

Edelson, J.V. and Estes, P.M. 1987. Seasonal abundance and distribution 

of predators and parasites associated with Monelliopsis pecanis Bissell 

and Monellia caryella (Fitch) (Homoptera: Aphidae). Journal of 

Entomological Science. 22: 336-347. 

El-Sebae, A.H., Sherby, S.M. and Mansour, N.A. 1980. Gossypol 

suppresses development and inhibits protease and lipid-peroxidation 

activities of Spodoptera littoralis. Toxicology Letters. 51: 51. 

Fauvergue, X. and Hopper, K.R. 2009. French wasps in the New World: 

experimental biological control introductions reveal a demographic Allee 

effect. Population Ecology. 51: 385-397. 

Fauvergue, X., Hopper, K.R. and Antolin, M.F. 1995. Mate finding via a 

trail sex-pheromone by a parasitoid wasp. Proceedings of the National 

Academy of Sciences of the United States of America. 92: 900-904. 

Frewin, A.J., Xue, Y.E., Weisman, J.A., Broadbent, A.B., Schaafsma, 

A.W. and Hallett, R.H. 2010. Development and parasitism by Aphelinus 

certus (Hymenoptera: Aphelinidae), a parasitoid of Aphis glycines 

(Hemiptera: Aphididae ). Environmental Entomology. 39: 1570-1578. 

Gahan, A.B. 1924. Some new parasitic Hymenoptera with notes on several 

described forms. Proceedings of the United States National Museum. 65: 

9. 

Gerling, D.B. Roitberg, D. and Mackauer, M. 1990. Instar-specific 

defense of the pea aphid, Acyrthosiphon pisum: Influence on oviposition 

success of the parasite Aphelinus asychis (Hymenoptera: Aphelmidae). 

Journal of Insect Behavior. 3: 501-514. 

Gillette, C.P. and Taylor, E.P. 1908. A few orchard plant lice. Colorado 

Agricultural Experiment Station Bulletin. 133: 1-48. 

Girault, A.A. 1909. A new chalcidoid of the eulophid genus Aphelinus 

Dalman, parasitic on Schizoneura crataegi Oestlund. Psyche, Cambridge. 

14 
16: 29. 

Girault, A.A. 1911. A new aphid-infesting Aphelinus which is not black. 

Entomologist. 44: 178. 

Girault, A.A. 1916. Descriptions Hymenopterorum Chalcidiocorum 

variorum cum observationibus, ii. Entomological News. 27: 405. 

Girault, A.A. 1917. Descriptiones stellarum novarum. Private publication: 

1-18. 

Godfray, H.C. J. 1994. Parasitoids: Behavioral and Evolutionary Ecology. 

Princeton University Press, Princeton, New Jersey. 

Greathead, D., and Greathead, A.H. 1992. Biological control ofinsect 

pests by parasitoids and predators: the BIOCA T database. Biocontrol 

News and Information. 13: 61N-68N. 

Griswold, G.H. 1926. Notes on some feeding habits of two chalcid 

parasites. Annals ofthe Entomological Society of America. 19: 331. 

Griswold, G .H. 1927. Observations on the biology of a new geranium 

aphid (Macrosiphum cornelli Patch). Journal of Economic Entomology. 

20: 91-94. 

Haldeman, S.S. 1859. Eriophilus. Proceedings of the Boston Society of 

Natural History. 6: 402-403. 

Hartley, E.A. 1922. Some bionomics of Aphelinus semiflavus (Howard) 

chalcid parasite of aphids. Ohio Journal of Science. 22: 209-237. 

Heimpel, G.E., Frelich, L.E., Landis, D.A., Hopper, K.R., Hoelmer, K.A., 

Sezen, Z., Asplen, M.K. and Wu, K.M. 2010. European buckthorn and 

Asian soybean aphid as components of an extensive invasional meltdown 

in North America. Biological Invasions. 12: 2913-2931. 

Heimpel, G.E., Lee, J.C., Wu, Z.S., Weiser, L., Wackers, F. and Jervis, 

M.A. 2004. Gut sugar analysis in field-caught parasitoids: adapting 

methods originally developed for biting flies. International Journal of Pest 

Management. 50: 193-198. 

Helms, S.E., Connelly, S.J. and Hunter, M.D. 2004. Effects of variation 

among plant species on the interaction between a herbivore and its 

parasitoid. Ecological Entomology. 29: 44-51. 

Heraty, J.M., Woolley, J.B., Hopper, K.R., Hawks, D.L., Kim, J.W. and 

Buffington, M. 2007. Molecular phylogenetics and reproductive 

15 
incompatibility in a complex of cryptic species of aphid parasitoids. 

Molecular Phylogenetics and Evolution. 45: 480-493. 

Herting, B. 1972. Homoptera. A ·catalogue of parasites and predators of 

terrestrial arthropods. Section A. Host or Prey/Enemy. Commonwealth 

Agricultural Bureaux, Slough, England. 

Hopper, K.R. 2010. Petition for the Release of Aphelinus glycinis 

(Hymenoptera: Aphelinidae) for the Biological Control of the Soybean 

Aphid, Aphis glycines (Hemiptera: Aphididae). 32 pp. 

Hopper, K.R., Coutinot, D., Chen, K., Mercadier, G., Halbert, S.E., 

Kazmer, D.J., Miller, R.H., Pike, K.S. and Tanigoshi, L.K. 1998. 

Exploration for natural enemies to control Diuraphis noxia in the United 

States. In: A response model for an introduced pest- The Russian wheat 

aphid, (Quissenbery, S.S. and Peairs, F.B., eds.). pp. 166-182. Thomas 

Say Publications in Entomology: Proceedings. Entomological Society of 

America, Lanham, MD. 

Howard, L.O. 1881. Report of the parasites ofCoccidae in the collections 

ofthe U.S. Department of Agriculture Part III .. In: Report of the 

entomologist for 1880, (Comstock, J.H., ed.). pp. 350-372, plates 23,24. 

United States Department of Agriculture, Washington. 

Howard, L.O. 1895. Revision of the Aphelininae ofNorth America a 

subfamily of hymenopterous parasites of the family Chalcididae. 

Technical Series, Bureau of Entomology, United States Department of 

Agriculture. 1: 25. 

Howard, L.O. 1908. Upon the aphis feeding species of Aphelinus. 

Entomological News. 19: 365-367. 

Howard, L.O. 1914. Concerning some Aphelininae. Proceedings ofthe 

Entomological Society of Washington. 16: 80 

Howard, L.O. 1917. A new aphis-feedingAphelinus. Proceedings ofthe 

Biological Society of Washington. 30: 77. 

Jackson, H.B., Coles, L.W., Wood, E.A. and Eikenbary, R.D. 1970. 

Parasites reared from the greenbug and com leaf aphid in Oklahoma in 

1968 and 1969. Journal ofEconomic Entomology. 63: 733-736. 

Jackson, H.B., Rogers, C.E. and Eikenbary, R.D. 1971. Colonization and 

Release of Aphelinus asychis, an imported parasite of greenbug. Journal of 

Economic Entomology. 64: 1435-1438. 

Jaenike, J. 1978. On optimal oviposition behavior in phytophagous 

16 
insects. Theoretical Population Biology. 14: 350-356. 

Jervis, M.A., Ellers, J. and Harvey, J.A. 2008. Resource acquisition, 

allocation, and utilization in parasitoid reproductive strategies. Annual 

Review ofEntornology. 53: 361-385. 

Johnson, H.A., Rogers, L.L., Alkire, M.L., McCloud, T.G. and 

NcLaughlin, J.L. 1998. Bioactive rnonoterpenes from Monardafistulosa 

(Larniaceae ). Natural Product Letters. 11: 241-250. 

Kaiser, M.E., Norna, T., Brewer, M.J., Pike, K.S., Vockeroth, J.R. and 

Gairnari, S.D. 2007. Hymenopteran parasitoids and dipteran predators 

found using soybean aphid after its midwestern United States invasion. 

Annals of the Entomological Society of America. 100: 196-205. 

Kelly, E.O.G. 1917. The green-bug (Toxoptera graminum Rond.) 

outbreak of 1916. Journal of Economic Entomology. 10: 233-248. 

Kraaijeveld, A.R., Nowee, B. and Najern, R.W. 1995. Adaptive variation 

in host-selection behaviour of Asobara tabida, a parasitoid of Drosophila 

larvae. Functional Ecology. 9: 113-118. 

Kuhlmann, U., Schaffner, U., and Mason, P.G. 2005. Selection of nontarget species for host specificity testing of entornophagous biological 

control agents. In: International Symposium on Biological Control of 

Arthropods, September 12-16, 2005. Complied by Hoddle, M.S., United 

States Department of Agriculture, Forest Service, FHTET -2005-08, 

Morgantown, WV, USA, 566-583. 

Landis, D.A., Gardiner, M.M., van der Werf, W. and Swinton, S.M. 2008. 

Increasing com for biofuel production reduces biocontrol services in 

agricultural landscapes. Proceedings of the National Academy of Sciences 

ofthe United States of America. 105: 20552-20557. 

Lane, S.D., Mills, N.J., and Getz, W.M. 1999. The effects ofparasitoid 

fecundity and host taxon on the biological control of insect pests: the 

relationship between theory and data. Ecological Entomology. 

24:181-190. 

Lin, L.A. and Ives, A.R. 2003. The effect ofparasitoid host-size 

preference on host population growth rates: an example of Aphidius 

colemani and Aphis glycines. Ecological Entomology. 28: 542-550. 

Lohrenz, H.W. 1911. The woolly aphis, Schizoneura lanigera. Journal of 

Economic Entomology. 4: 162-170. 

Louda, S.M., Pemberton, R.W., Johnson, M.T., and Follett, P.A. 2003. 

17 
Nontarget effects-the Achilles' heel ofbiological control. Retrospective 

analyses to reduce risk associated with biological control introductions. 

Annual Review of Entomology. 48: 365-396. 

Magalhaes, L.C., Hunt, T.E., and Siegfried, B.D. 2009. Efficacy of 

neonicotinoid seed treatments to reduce soybean aphid populations under 

field and controlled conditions in Nebraska. J. Econ. Entomol. 102: 

187-195. 

Malcolm, S.B. 1989. Disruption of web structure and predatory behavior 

of a spider by plant-derived chemical defenses of an aposematic aphid. 

Journal ofChemical Ecology. 15: 1699-1716. 

Mason, P.G. and Hopper, K.R. 1997. Temperature dependence in 

locomotion of the parasitoid Aphelinus asychis (Hymenoptera: 

Aphelinidae) from geographical regions with different climates. 

Environmental Entomology. 26: 1416-1423. 

McCornack, B.P., Ragsdale, D.W. and Venette, R. C. 2004. Demography 

of soybean aphid (Homoptera: Aphididae) at summer temperatures. 

Journal ofEconomic Entomology. 97: 854-861. 

Mizell, R.F., III and Schiffbauer, D.E. 1990. Effects of pesticides on 

pecan aphid predators Chrysoperla rufilabris (Neuroptera: Chrysopidae), 

Hippodamia convergens, Cycloneda sanguinea (L.), Olla v-nigrum 

(Coleoptera: Coccinellidae), and Aphelinus perpallidus (Hymenoptera: 

Encyrtidae). Journal of Economic Entomology. 83: 1806-1812. 

Mooney, K.A., Jones, P. and Agrawal, A.A. 2008. Coexisting congeners: 

demography, competition, and interactions with cardenolides for two 

milkweed-feeding aphids. Oikos. 117: 450-458. 

Noma, T. and Brewer, M. J. 2008. Seasonal abundance of resident 

parasitoids and predatory flies and corresponding soybean aphid densities, 

with comments on classical biological control of soybean aphid in the 

Midwest. Journal of Economic Entomology. 101: 278-287. 

Noma, T., Gratton, C., Colunca-Garcia, M., Brewer, M.J., Mueller, E.E., 

Wyckhuys, K.A.G., Heimpel, G.E. and O'Neal, M.E. 2010. Relationship 

of soybean aphid (Hemiptera: Aphididae) to soybean plant nutrients, 

landscape structure, and natural enemies. Environmental Entomology. 39: 

31-41. 

Ode, P.J., Hopper, K.R. and Coll, M. 2005. Oviposition vs. offspring 

fitness in Aphidius colemani parasitizing different aphid species. 

Entomologia Experimentalis et Applicata. 115: 303-310. 

18 
Oliver, K.M., Moran, N.A. and Hunter, M.S. 2005. Variation in 

resistance to parasitism in aphids is due to symbionts not host genotype. 

Proceedings of the National Academy of Sciences of the United States of 

America. 102: 12795-12800. 

Oliver, K.M., Russell, J.A., Moran, N.A. and Hunter, M.S. 2003. 

Facultative bacterial symbionts in aphids confer resistance to parasitic 

wasps. Proceedings of the National Academy of Sciences of the United 

States of America. 100: 1803-1807. 

Ostlie, K. 2002. Managing Soybean Aphid. 

http://www.soybeans.umn.edu/pdfs/SBAMgmtFact 2.pdf last accessed 

January 20, 2012. 

Pasteels, J.M. 1978. Apterous and brachypterous coccinellids at the end 

of the food-chain, Cionura erecta (Asclepiadaceae)- Aphis nerii. 

Entomologia Experimentalis et Applicata. 24: 379-384. 

Peck, 0. 1963. A catalogue ofthe Nearctic Chalcidoidea (Insecta; 

Hymenoptera). Canadian Entomologist (Supplement). 30: 267. 

Pedersen, P. and Lang, B. 2006. Use of insecticide seed treatments for 

managing soybean aphids. Integrated Crop Management. IC-496. 

http://www .ipm.iastate.edu/ipm/icm/200611-23/seedtreat.html last 

accessed January 30, 2012. 

Prokrym, D.A. 1998. Biological control ofDiuraphis noxia (Homoptera: 

Aphididae): implementation and evaluation of natural enemies. In: A 

response model for an introduced pest - The Russian wheat aphid. 

(Quissenberry, S.S. and Peairs, F.B., eds.). pp. 183-208. Entomological 

Society of America, Lanham, MD. 

Ragsdale, D.W., Landis, D.A., Brodeur, J., Heimpel, G.E. and Desneux, 

N. 2011. Ecology and management of soybean aphid in North America. 

Annual Review of Entomology. 56: 375-99. 

Ragsdale, D.W., McComack, B P., Venette, R.C., Potter, B.D., Macrae, 

LV., Hodgson, E.W., O'Neal, M.E., Johnson, K.D., O'Neil, R.J., Difonzo, 

C.D., Hunt, T.E., Glogoza, P.A. and Cullen, E.M. 2007. Economic 

threshold for soybean aphid (Hemiptera: Aphididae). Journal of 

Economic Entomology. 100: 1258-1267. 

Ragsdale, D.W., Voegtlin, D.J. and O'Neil, R.J. 2004. Soybean aphid 

biology in North America. Annals of the Entomological Society of 

America. 97: 204-208. 

Rogers, C.E., Starks, K.J., Jackson, H.B., Eikenbarry, R. and Starks, K.J. 

19 
1972. Host-parasitoid interaction of Aphis helianthi on sunflowers with 

introduced Aphelinus asychis, Ephedrus plagiator, and Praon gallicum, 

and native Aphelinus nigritus and Lysiphlebus testaceipes. Annals of the 

Entomological Society of America. 65: 38-41. 

Rothschild, M., von Euw, J.V. and Reichste. T. 1970. Cardiac glycosides 

in oleander aphid, Aphis nerii. Journal oflnsect Physiology. 16: 

1141-1145. 

Rutledge, C.E. and O'Neil, R.J. 2005. Orius insidiosus (Say) as a 

predator of the soybean aphid, Aphis glycines Matsumura. Biological 

Control. 33: 56-64. 

Rutledge, C.E., O'Neil, R.J., Fox, T.B. and Landis, D.A. 2004. Soybean 

aphid predators and their use in integrated pest management. Annals of the 

Entomological Society of America. 97: 240-248. 

Smith, 1923. Research Bulletin of the Idaho Agricultural Experiment 

Station. 2: 55-57. 

Song, F. and Swinton, S.M. 2009. Returns to integrated pest management 

research and outreach for soybean aphid. Journal of Economic 

Entomology. 102: 2116-2125. 

Sullivan, D.J. and van den Bosch, S. J. 1971. Field ecology of the 

primary parasites and hyperparasites of the potato aphid, Macrosiphum 

euphorbiae, in the east San Francisco Bay area. Annals of the 

Entomological Society of America. 64: 389-394. 

U.S. Fish and Wildlife Service. 2012. Environmental Online 

Conservation System. http://ecos.fws.gov/tess__public/ last accessed 

January 31,2012. 

USFWS-see U.S. Fish and Wildlife Service 

van Alphen, J .J .M. and Vet, L.E.M. 1986. An evolutionary approach to 

host finding and selection. In: Insect Parasitoids (Waage, J. and 

Greathead, D., eds.). pp. 23-61. Academic Press, London. 

van den Bosch, R., Schlinger, E.l., Dietrick, E.J., Hagen, K.S. and 

Holloway, J.K. 1959. The colonization and establishment of imported 

parasites ofthe spotted alfalfa aphid in California. Journal of Economic 

Entomology. 52: 136-41. 

Venette, R.C. and Ragsdale, D.W. 2004. Assessing the invasion by 

soybean aphid (Homoptera: Aphididae): Where will it end? Annals of the 

Entomological Society of America. 97: 219-226. 

20 
Warashina, T. and Noro, T. 2000. Cardenolide and oxypregnane 

glycosides from the root of Asclepias incarnata L. Chemical 

Pharmacology Bulletin. 48: 516-524. 

Watterson, G.P. and Stone, J.D. 1982. Parasites ofblackmargined aphids 

and their effect on aphid populations in far-West Texas. Environmental 

Entomology. 11: 667-669. 

Webster, F.M. 1909. Investigations of Toxoptera graminum and its 

parasites. Annals of the Entomological Society of America. 2: 67-87. 

Webster, F.M. and Phillips, W.J. 1912. The spring grain-aphis or 

"greenbug". In: USDA Bureau of Entomology Bulletin, Vol. 110 

(Agriculture, ed.). 153 pp. 

Wu, Z.S., Hopper, K.R., O'Neil, R.J., Voegtlin, D.J., Prokrym, D.R. and 

Heimpel, G.E. 2004. Reproductive compatibility and genetic variation 

between two strains of Aphelinus albipodus (Hymenoptera: Aphelinidae), 

a parasitoid of the soybean aphid, Aphis glycines (Homoptera: Aphididae). 

Biological Control. 31:311-319. 

Wyckhuys, K.A.G., Koch, R.L. and Heimpel, G.E. 2007. Physical and 

ant-mediated refuges from parasitism: Implications for non-target effects 

in biological control. Biological Control. 40: 306-313. 

Wyckhuys, K.A.G., Stone, L. Desneux, N. Hoelmer, K.A. Hopper, K.R. 

and Heimpel, G.E. 2008. Parasitism of the soybean aphid, Aphis glycines 

by Binodoxys communis: the role of aphid defensive behaviour and 

parasitoid reproductive performance. Bulletin of Entomological Research. 

98: 361-370. 

Zuparko, R.L. and Dahlsten, D.L. 1993. Survey of the parasitoids of the 

tuliptree aphid, Illinoia liriodendri (Hom: Aphididae ), in northern 

California. Entomophaga. 38: 31-40. 

Zuparko, R.L. and Dahlsten, D.L. 1995. Parasitoid complex of 

Eucallipterus tiliae (Homoptera: Drepanosiphidae) in northern California. 

Environmental Entomology. 24: 730-737. 

21 
s species described from North America and their species complexes, distributions, and reported hosts 

Species 

complex Reported distribution Reported hosts 

abdomina/is California (Howard, 1895) Acyrthosiphon pisum (Herting, 1972); Macrosiphum euphorbiae 

(Sullivan and van den Bosch, 1971 ); Illinoia liriodendri (Zuparko and 

abdomina/is 

asychis 

asychis 

mali 

mali mali 

mali mali 

varipes 

subgenus 

Mesidia 

subgenus 

Mesidia 

California (Gahan, 1924); New York (Griswold, 

1926) 

Colorado (Howard, 1908); Indiana (Hartley, 1922); 

Kansas, Oklahoma (Kelly, 1917); Minnesota, New 

Mexico (Webster and Phillips, 1912); New York 

(Griswold, 1927); Ohio (Girault, 1917) 

Kansas (Ashmead, 1888b); Ontario; Quebec (Peck, 

1963) 

Oregon (Howard, 1917); Idaho (Smith, 1923 ); 

Washington (Smith, 1923) 

Arkansas (Becker, 1918); Colorado (Gillette and 

Taylor, 1908); District of Columbia, Illinois, 

Missouri (Howard, 1881); Kansas (Lohrenz, 1911); 

Nebraska (Bruner, 1894); Pennsylvania (Cresson, 

1862) 

Iowa (Carver, 1980) 

Pennsylvania (Gahan, 1924); Ohio (Delong and 

Jones, 1926) 

Florida (Ashmead, 1888a); New Jersey (Peck, 

1963) 

South Carolina (Howard, 1908); Kansas, Minnesota 

(Webster and Phillips, 1912); New Mexico 

(Webster, 1909); Oklahoma (Jackson et al., 1970); 

Texas (Archer et al., 1974) 

California (Gahan, 1924) 

Illinois (Girault, 1911); Virginia (Girault, 1916); 

California (Zuparko and Dahlsten, 1995) 

Dahlsten, 1993) 

Acyrthosiphon malvae (Griswold, 1926); Acyrthosiphon 

pseudodirhodum (Griswold, 1927); Aulacorthum so/ani (Herting, 

1972); Macrosiphum euphorbiae (Gahan, 1924); Myzus persicae 

(Griswold, 1927) 

Acyrthosiphon pisum, Aphis gossypii, Cerusaphis viburnicola, 

Rhopalosiphum maidis, Macrosiphoniella sanborni, Macrosiphum 

avenae (Hartley, 1922); Aphis rumicis, Brevicoryne brassicae, 

Lipaphis pseudobrassicae, Sitobion avenae (Peck, 1963);Chaitophorus 

viminalis, Schizaphis graminum (Webster and Phillips, 1912); Myzus 

persicae (Howard, 1908); Myzaphis rosarum (Peck, 1963) 

Aphis sp. (Ashmead, 1888b); Myzus persicae (Herting, 1972) 

Brachycaudus helichrysi (Peck, 1963); Nearctaphis bakeri (Howard, 

1917) 

Eriosoma americanum (Girault, 1909); Eriosoma crataegi (Howard, 

1881); Eriosoma lanigerum (Haldeman, 1859) 

Prociphilus fraxinifolii (Carver, 1980) 

Sanborniajuniperi (Gahan, 1924); Nasonovia houghtonensis (Delong 

and Jones, 1926) 

Macrosiphum sp. (Ashmead, 1888a) 

Schizaphis graminum (Howard, 1908); Hysteroneura setariae 

(Webster and Phillips, 1912); Aphis helianthi (Rogers et al., 1972); 

Rhopalosiphum maidi (Jackson et al., 1970) 

Chaitophorus nigrae (Gahan, 1924) 

Chaitophorus sp. (Girault, 1911); Hysteroneura setariae (Girault, 

1916); Eucallipterus tiliae (Zuparko and Dahlsten, 1995) 

22 
subgenus 

Mesidia 

subgenus 

Mesidia 

Colorado (Howard, 1914) 

Iowa (Gahan, 1924); Alabama (Edelson and Estes, 

1987); California (Peck, 1963); Florida (Mizell and 

Schiffbauer, 1990); Texas (Watterson and Stone, 

1982) 

Diuraphis tritici (Howard, 1914) 

Chromaphis juglandicola (Peck, 1963); Melanocallis fumipennellus, 

Monellia costa/is (Peck, 1963); Monellia caryella (Bueno and Stone, 

1983); Monelliopsis pecanis (Edelson and Estes, 1987) 

23 
Appendix B. Host specificity tests for Aphelinis 

glycinis (Hopper, 201 0). 

In laboratory experiments in quarantine, attack by A. glycinis on the soybean aphid and nontarget aphid species was evaluated, as well as the mechanisms underlying differences in 

parasitism among aphid species. Parasitoids in the genus Aphelinus could kill aphids in three 

ways: oviposition which leads to aphid mummification, stinging (with or without oviposition) 

that leads to aphid death but no mummification, and host feeding. These experiments tested for 

each type of mortality. Parasitism of 13 aphid species in 5 genera in 2 tribes on 9 plant species in 

9 families was measured. These aphids span most of the phylogeny of aphids reported as hosts 

of the Aphelinus mali complex, of which A. glycinis is a member. Furthermore, these aphid-plant 

combinations provide contrasts of aphids in the same versus different genera on .the same versus 

different plants. Based on the aphid distributions in Blackman and Eastop (2006), many of these 

aphid species occur within the native geographic range of A. glycinis, so these aphids and this 

parasitoid are likely to have been in contact for at least 10,000 years. The exceptions are D. 

noxia, which is native to central to western Asia and Europe, and Aphis oestlundi and A. 

monardae, both native to North America. The goal was to explore the phylogenetic and host 

plant limits on parasitism as has been recommended for host specificity testing of entomphagous 

insects (Kuhlmann et al., 2005). Three rounds of testing were done: round one involved species 

in five aphid genera distributed across the phylogeny of known hosts of the A. mali complex; 

round two narrowed the testing to species in the genus Aphis but involved more species in this 

genus and included species native to North America; round three used aphid species from rounds 

one and two, but involved detailed direct observations of parasitoid and aphid behavior, as well 

as measurement of aphid suitability. 

Parasitism in 24 hour exposure of aphids on plant. Individual female parasitoids were exposed 

to one of 13 aphid species. One to five-day old females that had been with males and aphids 

since emergence were used and thus had the opportunity to mate, host-feed, and oviposit. 

Females were isolated from males and aphids for 24 hours before using them in experiments to 

ensure that the females had a full egg load. Each female parasitoid was placed in a cage (10 

centimeters (em) in diameter by 22 em tall) enclosing the foliage of a potted plant of the 

appropriate species with 100 aphids of mixed instars of a single species. Female parasitoids 

were removed after 24 hours and were used only once. 

Because these parasitoids can parasitize a maximum of 20 aphids in 24 hours, this abundance of 

aphids and period of exposure allowed parasitoids to use their full egg complement. 

Furthermore, the density of aphids, amount of plant material, and cage size meant that 

parasitoids were not limited by search rate. Parasitism scoring was delayed until the larval 

parasitoids had killed and mummified their hosts. Therefore, a combination of acceptance of 

hosts for oviposition and suitability of hosts for parasitoid development was measured. 

Female parasitoids had the choice of whether to oviposit or not in a particular host species. This 

is frequently the choice parasitoids make in the field. The idea was to measure parasitism in an 

environment that appears to harbor only one aphid species on only one plant species and where 

24 
female parasitoids re-encounter this combinationrepeatedly starting with a full egg complement. 

Ten days after exposure of aphids to parasitoids, any mummified aphids were collected and held 

for adult parasitoid emergence. After the adults emerged, the number of mummified aphids and 

the number and sex of adult parasitoids was recorded. Seven to 14 females on each of 13 aphid 

species were tested. 

After 24 hours exposure, the number of aphids mummified by A. glycinis varied with aphid 

species (F = 5.7 ; df= 12, 123; P < 0.0001; Fig. 1). Female parasitoids rarely or never 

parasitized aphids outside the genus Aphis; within the genus Aphis, female parasitoids produced 

mummified aphids on species phylogenetically close to A. glycines, such as A. gossypii, A. 

monardae, and A. oestlundi, but not on aphids that are more phylogenetically distant, such as A. 

asclepiadis, A. nerii, and A. rumicis. The low numbers of mummified aphids for A. asclepiadis 

and A. nerii may have resulted from their host plant, Asclepias syriaca, which is known to 

produce toxic secondary chemicals which aphids could sequester for their defense (Mooney et 

al., 2008; Warashina and Noro, 2000). Although the number of mummified aphids varied 

greatly among aphid species, the proportion of mummies from which adults emerged was high 

(0.93±0.02) and did not vary significantly among species that were parasitized. The proportion 

of females among parasitoid progeny varied with species (F = 2.89 ; df = 4, 42; P = 0.03), but 

only because A. gossypii produced a low proportion of females (0.11±0.06) compared to other 

species of Aphis (e.g. 0.46±0.1 0 for A. glycines) 

C/') 

"0 

:.c 

c. 

co 

10 Host plant species 

.......... 

"0 

Q) 

\;::::: 

.E ~ 

E ::J 

::J C/') 

E o 

"0 

-~ Q) 

Q) .... .~ ::J 

:!:: 0 

CJ).!: 

~~ CON 

c.-

-

9 D Glycine max 

8 D Gossypium hirsutum 

7 

! • Monarda fistulosa 

f • Oenothera biennis 

6 Asclepias syriaca 

5 • Vigna unguiculata 

4 

~ ! • Rumex altissimus 

• Hordeum vulgare 3 

• Raphanus sativus 

2 

0 

.... 

Q) 1 

.0 

E 

::J 

z 

0 

~ ~ # & ~ ~ ~ ~ ~ & ~ ~ e 6~ c:,~ ~o ~ .. §' ·-:..ttf. 0 ·~·P ~u ~ ~ttf. • ~-s o~ ·':!o.c,ttf. 

cy~ e;,oc:, o~~ oec:,~ ~e~ 't>-· fl}vv" ·'-s a_.~ <(--· fl}~ <;) .~ "e'C:J 

't>-· 't>-· ~ ~. fl}Cj c,\ 'i>- ,- <§ ~ "'." 't>-· ,. - 't>-· 't>-· S· ~· 

Aphid species 

Fig. 1. Number of aphids parasitized (mummified) of various aphid species exposed to Aphelinus 

glycines for 24 hours. Aphid species are ordered by phylogenetic distance from Aphis glycines. 

Asterisks indicate level of difference from Aphis glycines: * * * P<O. 00 1 ; * * * * P<O. 000 1. Error bars are 

standard errors of means. 25 
Direct observation of parasitoid and aphid behavior. Behavior of parasitoids and aphids were 

directly observed to determine the factors affecting host use patterns from the experiment above, 

observing 18 to 21 female parasitoids exposed to each of 12 aphid species. A randomized 

complete-block design was used with each block done on a single day. Each female parasitoid 

was exposed to 10 second and third instar aphids on an excised leaf of the appropriate plant 

species in small arenas (10 millimeters (mm) in diameter by 4 mm in height). The arenas were 

formed using two microscope slides with vinyl foam weather-stripping glued to them; on one 

slide, the weather-stripping had a 10 mm diameter hole bored into it, exposing the slide surface 

through which observations were made. A freshly cut leaf from a plant was clamped between 

the slides (weather-stripping against the leaf) and the leaf petiole placed in 1 percent agar in a 

small vial to maintain turgor. Aphids were placed in the arenas about 0.5 hour before beginning 

observations to allow them to settle and begin feeding on the leaves. One-day old females were 

exposed to 3 second and third instar A. glycines for about 0.5 hour before being observed. 

The behaviors of each female parasitoid and the aphids with which she was enclosed were 

observed continuously for 25 minutes under a zoom binocular stereoscope at 10-30X 

magnification and these behaviors were recorded using an attached video camera and digital 

video tape recorder. Locations and sequences ofbehaviors were noted on maps of the arenas, 

and these locations and sequences were verified by reviewing the tape recordings. 

On encountering a potential host, A. glycinis females stop at about half their body length away 

from the aphid. Without touching the aphid, females sway from side to side several times with 

antennae extended (an approach). They tum 180° to face away from the aphid, extend their 

ovipositor, and insert it into the aphid (a sting). Females sometimes failed to contact the aphid 

with their ovipositor (a miss) and made several attempts to approach and sting the aphid. 

Besides ovipositing in an aphid, A. glycinis females may also paralyze them, make a wound with 

their ovipositor, and drink hemolymph from the wound (host-feeding). Female parasitoids 

paralyze and kill the aphids on which they feed and thus do not oviposit in them. 

The following data was recorded for aphids: whether an aphid was approached; if approached, 

the outcome of each encounter (stung, missed, host-fed); the duration of the longest sting, the 

duration of the encounter with longest sting from approach until the parasitoid leaves the aphid 

(handling time), and the presence of aphid defense behaviors (kicking, bucking, rotating around 

while retaining mouth parts in the leaf, walking away, and comicular secretion). From these 

data, the number of aphids approached, the numbers of aphids stung, and the numbers of aphids 

fed upon were tabulated. Aphid defense was calculated as the number of aphids defending 

themselves weighted by the frequencies of defensive behaviors (kicking, bucking, rotating, 

walking away, and comicular secretion) when approached by female parasitoids. For aphids that 

were not approached, whether they changed location from the beginning to the end of the 

observation period was recorded. Female parasitoids were removed after the observation period, 

their ovaries were dissected in Ringer's solution and mixed with neutral red stain, and the 

number of mature eggs was counted under 40-1 OOX magnification (neutral red does not pass the 

chorion of mature eggs and thus they remain unstained). 

If a female parasitoid stung one or more aphids, either all the aphids were dissected from a given 

26 
observation period to determine whether eggs were laid, or all aphids were transferred from a 

given observation period to the appropriate host plant species and were reared to determine 

whether parasitoid progeny survived to mummification and whether exposure to parasitoids 

otherwise affected aphid survival. Aphids were dissected in batches of five on glass microscope 

slides. Each batch was placed in a small drop of Ringer's solution and covered with a separate 

cover slip. Parasitoid eggs from the dissected aphids were counted at 40-1 OOX magnification. 

Aphids were dissected from half the replicates and aphids were reared from the other half of the 

replicates, yielding 10 replicates of dissected aphids and 1 0 replicates of reared aphids per aphid 

species that a female parasitoid stung. For aphid species that were not stung, these aphids were 

neither dissected nor reared after observation. 

Because sampling for eggs in aphids was destructive, the number of aphids with parasitoid eggs 

and the number that mummified could not be directly compared. Instead, Spearman's rank 

correlation coefficient (p) was used to test the relationship between the mean number of 

mummified aphids and the mean number of aphids in which parasitoids oviposited. 

In these short, direct, behavioral observations in small arenas, the behavior of female A. glycinis 

varied with aphid species, and the differences among species increased while the range of 

species involved in specific behaviors narrowed through the steps in parasitism (approach, sting, 

oviposition or host feeding, mummification, adult emergence). In particular, A. glycinis was 

limited to some, but not all species in the genus Aphis. 

The number of aphids approached varied with species (F = 13.9; df= 11, 222; P < 0.0001; Fig. 

2), primarily because three species, A. rumicis, D. noxia, and M persicae, were rarely 

approached, whereas in the genus Aphis (excluding A. rumicis ), about half the available aphids 

(5.3±0.5 to 6.5±0.6) were approached. 

The number of aphids stung varied with species (F = 13.2; df= 11, 221; P < 0.0001; Fig. 2). 

Aphids in the genus Aphis were stung 2-4 times more often than those outside this genus, with 

the exceptions of A. rumicis which was rarely stung and S. graminum which was stung almost as 

often as Aphis species. Aphid survival rate was not correlated with stings per aphid (Spearman's 

p = -0.11; P = 0.28; n = 1 02), indicating that parasitoid stings (other than those that resulted in 

mummified or host-fed aphids) did not cause aphid mortality. 

The number of aphids in which parasitoids oviposited varied strongly with species (F = 2.9; df = 

11, 129; P < 0.002; Fig. 2). Parasitoids rarely laid eggs in aphids outside the genus Aphis, and in 

the genus Aphis, parasitoids oviposited in 0. 7±0.3 to 1.9±0.4 aphids, again with the exception of 

A. rumicis which recejved no eggs. Egg load for the 1-2 day-old A. glycinis females used in this 

experiment was 11.2±0.3. Although 1 percent of the parasitoids carried 1-3 eggs, 95 percent 

carried more than five eggs (and 5 percent carried more than 16 eggs) so these females could 

have laid eggs in all the aphids they approached. However, the ratio of oviposition to approaches 

was 0.27±0.07 for A. glycines and varied from 0.12±0.05 for A. nerii to 0.37±0.07 for A. 

oestlundi among species in the genus Aphis (excluding A. rumicis ). This low ratio of 

ovipositions to approaches can be explained in part by host feeding. Females often host fed 

during observations, despite having been exposed to three A. glycines nymphs for 0.5 hour 

before observations. The number of aphids on which parasitoids host fed varied with species (F 

27 
= 5.1; df= 11, 221; P < 0.0001; Fig. 2). Parasitoids rarely fed on aphids outside the genus Aphis, 

and in the genus Aphis, parasitoids fed on 0.2±0.1 to 1.2±0.2 aphids. Both A. nerii and A. 

rumicis were fed on less often than A. glycines. Contrary to previous speculation that feeding 

host range should be broader than oviposition host range, the choice of aphids on which to host 

feed was essentially the same as the choice of aphids in which to oviposit (Fig. 3). 

For aphid species in which parasitoids oviposited, handling time varied among aphid species for 

encounters that might have involved oviposition (F = 2.2; df= 11, 550; P = 0.01). This handling 

time varied from 1.0±0.4 minutes for A. nerii to 2.4±0.3 minutes for A. glycines. For aphids on 

which parasitoids host fed, handling time varied from 8.1±0.7 minutes for A. gossypii to 

10.9±1.2 minutes for A. glycines, but no differences among aphid species were significant. 

Given these long handling times, it is unlikely that A. glycinis would be able to parasitize antdefended aphids, like A. monardae and A. oestlundi in the field (Wyckhuys et al., 2007). 

28 
-

~ ::::s 

(J) 

0 

0. 

>< 

Q) 

Q) 

........ 

:::J 

c 

E 

L{) 

N 

c 

-C/) 

""C 

..c 

0. 

co 

'+-

0 

s... 

Q) 

..c 

E 

::::s 

z 

8 

7 

6 

5 

4 

3 

2 

1 

0 

1.5 

1.0 

0.5 

0.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

/9" ~ Approached 

Jy/ ,~ / "" I 

y T ---.- • T \ 

,\ 

\ 

\ 

\ 

\ 

\ 

**** 

/}-!~t Hostfed 

Sf \ I ·· 

** • ..I. *** "t _........ "!\. /y............ **** 

'... 'I''-'"* --Y '--~ ~ 

Host plant species 

D Glycine max 

D Gossypium hirsutum 

• Monarda fistulosa 

• Oenothera biennis 

~ Asclepias syriaca 

• Vigna unguiculata 

- Rumex altissimus 

- Hordeum vulgare 

• Raphanus sativus 

0C;) R~ q,0 ~' ~~ ~0 . \_C:J ~' • ~,C:J ~ \'ll 0 cf' <:,~ '&?j ~·§' ~0 .~0 .,Nov ~'l> fli' ·~.S o"f- \V'l> 

~ & ~ ~ ~ ~ ~· ~ ~ ~ ~ ~ ~·cs ~·cs ~o r....o0 6flj ~· ~· r:Sflj Q -~·~ ~· r· ~· ~· ~· 

Aphid species 

Fig. 2. Number of aphids approached, stung, host-fed, oviposited, and mummified by Aphelinus glycines in 

25 minute observations. Asterisks above or below means indicate difference from Aphis glycines: ** P<O.O 1; 

***?<0.001:  ?<0.0001. Error bars are standard errors of means. 

29 
-

~ :::J 

(/) 

0 

a. 

>< 

Q) 

Q) 

......., 

::J 

c:: 

E 

L{) 

N 

c:: 

.......... 

(/) 

"'C 

..c 

a. 

ro 

....... 

0 

s.... 

Q) 

.c 

E 

:::J 

z 

8 

7 

6 

5 

4 

3 

2 

1 

0 

1.5 

1.0 

0.5 

0.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

..r9, ~ Approached 

;y..r ,~ / "" I 

y T ---..- • T \ 

,\ 

\ 

\ 

\ 

\ 

\ 

** ** 

/}-!~-t Hostfed 

Sf \ I ·· 

** ... ..I. *** "t _....... T' /y ""- ..-   

'... "P~· ... --Y '+--7 ~ 

Host plant species 

D Glycine max 

D Gossypium hirsutum 

• Monarda fistulosa 

• Oenothera biennis 

~ Asclepias syriaca 

• Vigna unguiculata 

• Rumex altissimus 

• Hordeum vulgare 

• Raphanus sativus 

0~ R~ '1>0 ~' ~~ -&'~> • \.~ ~' • ~,~ ~ \'~> 0 cf' ~~ '!..~ ~ .. §' ~0 .~0 .,Nov ~f(f. qf- ·~..S o"f- \_vf(f. 

~ & ~ ~ ~ ~ ~· ~ ~ ~ ~ ~ \>-'~ \>-'~ ~0 ..... .00 6-f(j. \>-' ~· cyf(j. Q ~l...~ \>-' f. \>-' C.,· ~· 

Aphid species 

Fig. 2. Number of aphids approached, stung, host-fed, oviposited, and mummified by Aphelinus glycines in 

25 minute observations. Asterisks above or below means indicate difference from Aphis glycines: **  P<O.Ol; 

***P<O.OOl:  ?<0.0001. Error bars are standard errors of means. 

29 
1.5 

""0 0 A. glycines 

/ 

~ 0 A. gossypii / 

/ 

• A. monardae I +"' 

en 

• 0 A. oestlundi 1.0 

• A. nerii ...c 

/ en / / 

• A. craccivora ""0 / / / 

• ...c A. rumicis / / 

+ R. padi c.. / 

ro / 

+ R. maidis "- 0.5 

• S. graminum (J) 

... D. noxia 

..c / 

E 

;:, ~ M. persicae 

z 

0.0 

0.0 0.5 1.0 1.5 2.0 2.5 

Number aphids oviposited 

Fig. 3. Host-feeding versus oviposition in aphids by Aphelinus glycines. Error bars are standard 

errors of means. Solid line is least-squared regression; dotted lines are 95% confidence intervals for 

regression. 

The number of mummified aphids varied with species (F= 3.3; df= 11, 131; P = 0.0006; Fig. 2). 

Aphelinus glycinis produced more mummies on A. glycines (1.6±0.5) than on all other species 

except A. oestlundi. Few or no mummies were produced on species in genera other than Aphis 

or on A. rumicis, which is not surprising, given the low rate of oviposition in these species. 

Furthermore, few mummies were produced on A. gossypii, A. monardae, and A. nerii as well, 

although female parasitoids oviposited as often in these species as in A. glycines. The proportion 

of adults which emerged from mummified aphids was high (0.95±0.05) and did not vary with 

species. 

Aphid behavioral defense varied with species (F = 28 .0; df = 11, 182; P < 0.0001; Fig. 4 ). Aphis 

craccivora and S. graminum defended themselves more than A. glycines, but A. oestlundi 

defended themselves less than A. glycines. In the genus Aphis, the proportion of aphids that 

parasitoids stung that either received an egg or were host-fed varied from 0.62±0.11 for A. 

glycines through 0.24±0.08 for A. craccivora to 0.03± 0.03 for A. rumicis, and this proportion 

was not correlated with the level of aphid behavioral defense. Handling time increased with 

amount of aphid behavioral defense (F = 8.83; df=l, 559; P = 0.003), and the Aphis species that 

defended itself most, A. craccivora, did receive relatively low numbers of eggs. Nonetheless, 

oviposition was determined primarily by detection and acceptance of aphids by parasitoids and 

was little affected by aphid behavioral defenses. Thus, while aphid defensive behavior may 

mediate host specificity of parasitoids, parasitoids are able to circumvent these defenses in the 

species that are hosts. The effectiveness of defensive behavior varies with aphid instar (Gerling 

et al. 1990; Wyckhuys et al. 2008) and thus the high suitability aphid species may be inaccessible 

30 

-··· .. ~.___,,.......,,,.,, ... , ......... 
** ** 20 j 

f 

18 

- 161 Q) 

..... 

** 

:::J 

C/) 14 

+ 

Q) 0 C/) 0.. 12 c >< 

+ 

~ Q) 

f 

Q) Q) 10 

9 

"0 .... 

** *** 

:::J 

+ f + 

"0 c 8 

2 + 

+ 

E 

0.. E 

6 <( 1.{) 

  

C\1 

• 

c 4 ._.. 

2 

0 

s ~ 0 & ~ . ,\6~0 ss~~ '~}of(} ~·§' ~0'" .~o'0 ~6,s ~0o' ~~,s . ~~~ ~ ~ ~ ~ ~ & ~ ~ ~ ~ ~ ~ ~ ? ~ ~ ~ ~ ~· ~ ~· ~· 

~0 0 ~0 ·').uf(} 

~· 0\Cj 

~·~ 

Aphid species 

Fig. 4. Defense by aphids approached by female Aphelinus glycines. Defense was measured as the number of 

aphids defending themselves weighted by the frequencies of defensive behaviors (kicking, bucking, rotating, 

walking away, and comicular secretion) when approached by female parasitoids in 25 minute observations. Error 

bars are standard errors of means. Asterisks indicate difference in aphid defense from Aphis glycines: P<0.05; **  

P<O.Ol; ***P<O.OOI; ****P<O.OOOl. 

in later instars. Aphid parasitoids may have behaviors adapted to efficiently approach some 

aphid species but not others, leading to behavioral specialization on these species. 

Oviposition by A. glycinis in an aphid species was correlated with progeny survival in that 

species (Spearman's p = 0.59; P = 0.04; n =12; Fig. 5) , so our results were consistent with the 

preference-performance hypothesis (Jaenike, 1978) and results from other parasitoid species 

(Ode et al., 2005; van Alphen and Vet, 1986; Driessen et al., 1991; Kraaijeveld et al., 1995; Chau 

and Mackauer, 2001; Bilu et al., 2006). However, the correlation is weak because several aphid 

species in which parasitoids oviposited were poor hosts for parasitoid development. Host-plant 

chemistry explains some ofthis lack of suitability. Aphids are known to sequester secondary 

metabolites when feeding on toxic plants (Mooney et al., 2008) and these compounds can be 

detrimental to aphid natural enemies (Helms et al., 2004). Aphelinus glycinis mummified few 

aphids of species on milkweed, which suggests that milkweed toxins limited the suitability of 

aphids on milkweed. Milkweed synthesizes cardenolides which are sequestered by aphids 

(Mooney et al., 2008), and these cardenolides affect the fitness of various aphid natural enemies 

31 
2.5 0 A. glycines 

"0 0 A. gossypii 

(]) 

;:;:::: 

. E 2.0 • A. monardae 

• A. oestlundi 

E • A. nerii 

:::::1 

E 1.5 

en • A. craccivora 

• A. rumicis 

"0 

:.c 

a. 

Cil 1.0 

-0 

.... 

(]) 

0.5 ..0 

E 

:::::1 

z 

• R. padi 

• R. maidis 

• S. graminum 

• D. noxia 

~ M. persicae 

+, ¢ ,, + L...__l0.0 '!=--' 

0.0 0.5 1.0 1.5 2.0 2.5 

Number of aphids oviposited 

Fig. 5. Aphid species preference (oviposition) versus performance (aphid mummification= survival 

through third instar) in Aphelinus glycines. Error bars are standard errors of means. 

(Pasteels, 1978; Malcolm, 1989 ). In particular, the low suitability of A. nerii may have resulted 

from its ability to sequester toxic host-plant allelochemicals (Rothschild et al., 1970; Malcolm, 

1989; Malcolm, 1989). Low suitability on milkweed-feeding aphids may also result from other 

chemical defenses such as the steroidal pregnane glycosides (Warashina and Noro, 2000). 

Aphelinus glycinis also mummified few Aphis gossypii on Gossypium hirsutum and A. monardae 

on Monarda fistula, and both of these plants produce defensive chemicals (Elsebae et al., 1980; 

Johnson et al., 1998) that these aphids could sequester. However, little is known about whether 

these aphids sequester these chemicals or whether the chemicals affect parasitoids. 

Another potential source of resistance to immature parasitoids in aphids are bacterial 

endosymbionts like Hamiltonella defensa, which interferes with successful development of 

Aphidius ervi in the pea aphid Acyrthosiphon pisum (Oliver et al., 2003). Hamiltonella defensa 

has been found in A. craccivora (Oliver et al., 2005), and was present at the start of our 

experiments on A. glycinis. However, the A. craccivora culture lost its H defensa without 

change in the suitability, indicating that H defensa did not defend against A. glycinis. 

In the absence of effects of endosymbionts or plant secondary metabolites, mortality of 

parasitoids in some aphid species (A. craccivora and R. maidis) may have resulted from low 

nutritional quality for parasitoid development. Parasitoid larvae have nutritional needs that are 

strongly stage-specific, as a result of the complex pathways of nutritional physiology associated 

with the parasitic lifestyle (Godfray, 1994; Jervis et al., 2008). 

32 

j