Jorge Fernandez-Cornejo, Seth Wechsler, 

Mike Livingston, and Lorraine Mitchell

Economic

Research

Service

Economic 

Research

Report

Number 162

February 2014

United States Department of Agriculture

Genetically Engineered Crops

in the United States
Economic Research Service 

www.ers.usda.gov

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Fernandez-Cornejo, Jorge, Seth Wechsler, Mike Livingston, and Lorraine Mitchell. 

Genetically Engineered Crops in the United States, ERR-162 U.S. Department of Agriculture, 

Economic Research Service, February 2014.

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United States Department of Agriculture

Economic 

Research 

Service

Economic

Research

Report

Number 162

February 2014

Abstract

More than 15 years after their first successful commercial introduction in the United 

States, genetically engineered (GE) seeds have been widely adopted by U.S. corn, 

soybean, and cotton farmers. Still, some questions persist regarding the potential benefits 

and risks of GE crops. The report finds that, although the pace of research and development (measured by the number of USDA-approved field tests) peaked in 2002, other 

measures show that biotech firms continue to develop new GE seed varieties at a rapid 

pace. Also, U.S. farmers continue to adopt GE seeds at a robust rate, and seed varieties 

with multiple (stacked) traits have increased at a very rapid rate. Insecticide use has 

decreased with the adoption of insect-resistant crops, and herbicide-tolerant crops have 

enabled the substitution of glyphosate for more toxic and persistent herbicides. However, 

overreliance on glyphosate and a reduction in the diversity of weed management practices 

have contributed to the evolution of glyphosate resistance in some weed species. 

Keywords: Genetically engineered crops, agricultural biotechnology, seed industry, 

research and development, adoption, crop yields, pesticide use, corn, soybeans, cotton

Acknowledgments

The authors wish to thank ERS colleagues Paul Heisey, Marca Weinberg, and Utpal 

Vasavada for their helpful comments provided on earlier drafts of this report. We 

also thank Michael Schechtman, USDA’s Agricultural Research Service, Office of 

Pest Management Policy; Neil Hoffman, USDA’s Animal and Plant Health Inspection 

Service; Mark Petry, USDA’s Foreign Agricultural Service; George Frisvold, University 

of Arizona; and Corinne Alexander, Purdue University. We also thank Dale Simms for 

editorial assistance and Cynthia A. Ray for graphics and layout, both ERS.

Jorge Fernandez-Cornejo, Seth Wechsler, 

Mike Livingston, and Lorraine Mitchell

Genetically Engineered Crops in the 

United States
ii

Genetically Engineered Crops in the United States, ERR-162

Economic Research Service/USDA

Contents

Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

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

From the Laboratory to the Field. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Field Releases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Determination of Non-Regulated Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

The Research and Development Pipeline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Adoption of GE Crops by U.S. Farmers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Farm-Level Economic Impacts of GE Crop Adoption. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Adoption, Net Returns, and Household Income . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Adoption and Pesticide Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Adoption and Conservation Tillage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Pest Resistance Management and GE Crops. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Insect Resistance to Bt Crops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Evolution of Glyphosate Resistance in Weeds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Consumer Demand for GE Products. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Willingness To Pay for GE and Non-GE Foods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Consumer Acceptance of GE Foods in High- and Low-Income Countries. . . . . . . . . . . . . . . . . 34

Effect of Information on the Desire of Consumers To Purchase GE Foods . . . . . . . . . . . . . . . . 38

Insect Resistance to Bt Crops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
www.ers.usda.gov

What Is the Issue?

Genetically engineered (GE) varieties with pest management traits became commercially available for major crops in 1996. More than 15 years later, adoption of these varieties by U.S. farmers 

is widespread and U.S. consumers eat many products derived from GE crops—including cornmeal, oils, and sugars—largely unaware that these products were derived from GE crops. Despite 

the rapid increase in the adoption of corn, soybean, and cotton GE varieties by U.S. farmers, 

questions persist regarding their economic and environmental impacts, the evolution of weed 

resistance, and consumer acceptance. 

What Did the Study Find?

This report examines issues related to three major stakeholders in agricultural biotechnology: GE 

seed suppliers and technology providers (biotech firms), farmers, and consumers.

GE seed suppliers/technology providers. The number of field releases for testing of GE varieties 

approved by USDA’s Animal and Plant Health Inspection Service (APHIS) is an important measure 

of research and development (R&D) activities in agricultural biotechnology. The number of releases 

grew from 4 in 1985 to 1,194 in 2002 and averaged around 800 per year thereafter. However, while 

the number of releases peaked in 2002, other measures of research and development activity—the 

number of sites per release and the number of gene constructs (ways that the gene of interest is packaged 

together with other elements)—have increased very rapidly since 2005. Also, releases of GE varieties 

with agronomic properties (like drought resistance) jumped from 1,043 in 2005 to 5,190 in 2013. 

As of September 2013, about 7,800 releases were approved for GE corn, more than 2,200 for GE 

soybeans, more than 1,100 for GE cotton, and about 900 for GE potatoes. Releases were approved 

for GE varieties with herbicide tolerance (6,772 releases), insect resistance (4,809), product 

quality such as flavor or nutrition (4,896), agronomic properties like drought resistance (5,190), 

and virus/fungal resistance (2,616). The institutions with the most authorized field releases 

include Monsanto with 6,782, Pioneer/DuPont with 1,405, Syngenta with 565, and USDA’s 

Agricultural Research Service with 370. As of September 2013, APHIS had received 145 petitions 

for deregulation (allowing GE seeds to be sold) and had approved 96 petitions: 30 for corn; 15 for 

cotton; 11 for tomatoes; 12 for soybeans; 8 for rapeseed/canola; 5 for potatoes; 3 for sugarbeets; 2 

each for papaya, rice, and squash; and 1 each for alfalfa, plum, rose, tobacco, flax, and chicory. 

Farmers. Three crops (corn, cotton, and soybeans) make up the bulk of the acres planted to GE 

crops. U.S. farmers planted about 169 million acres of these GE crops in 2013, or about half of 

total land used to grow crops. Herbicide-tolerant (HT) crops have traits that allow them to tolerate 

more effective herbicides, such as glyphosate, helping adopters control pervasive weeds more 

effectively. U.S. farmers used HT soybeans on 93 percent of all planted soybean acres in 2013. 

United States Department of Agriculture

A report summary from the Economic Research Service February 2014

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Jorge Fernandez-Cornejo, Seth Wechsler, 

Mike Livingston, and Lorraine Mitchell

Economic 

Research 

Service

Economic 

Research 

Report 

Number 162

February 2014

United States Department of Agriculture

Genetically Engineered Crops 

in the United States

Jorge Fernandez-Cornejo, Seth Wechsler, Mike Livingston, and Lorraine Mitchell

Genetically Engineered Crops in the United States
HT corn accounted for 85 percent of corn acreage in 2013, and HT cotton constituted 82 percent of cotton acreage. 

Farmers planted insect-resistant (Bt) cotton to control pests such as tobacco budworm, cotton bollworm, and pink bollworm on 75 percent of U.S. acreage in 2013. Bt corn—which controls the European corn borer, the corn rootworm, 

and the corn earworm—was planted on 76 percent of corn acres in 2013. 

The adoption of Bt crops increases yields by mitigating yield losses from insects. However, empirical evidence regarding 

the effect of HT crops on yields is mixed. Generally, stacked seeds (seeds with more than one GE trait) tend to have higher 

yields than conventional seeds or than seeds with only one GE trait. GE corn with stacked traits grew from 1 percent of corn 

acres in 2000 to 71 percent in 2013. Stacked seed varieties also accounted for 67 percent of cotton acres in 2013. 

Planting Bt cotton and Bt corn seed is associated with higher net returns when pest pressure is high. The extent to 

which HT adoption affects net returns is mixed and depends primarily on how much weed control costs are reduced 

and seed costs are increased. HT soybean adoption is associated with an increase in total household income because 

HT soybeans require less management and enable farmers to generate income via off-farm activities or by expanding 

their operations.

Farmers generally use less insecticide when they plant Bt corn and Bt cotton. Corn insecticide use by both GE seed 

adopters and nonadopters has decreased—only 9 percent of all U.S. corn farmers used insecticides in 2010. Insecticide 

use on corn farms declined from 0.21 pound per planted acre in 1995 to 0.02 pound in 2010. This is consistent with 

the steady decline in European corn borer populations over the last decade that has been shown to be a direct result of 

Bt adoption. The establishment of minimum refuge requirements (planting sufficient acres of the non-Bt crop near the 

Bt crop) has helped delay the evolution of Bt resistance. However, there are some indications that insect resistance is 

developing to some Bt traits in some areas.

The adoption of HT crops has enabled farmers to substitute glyphosate for more toxic and persistent herbicides. 

However, an overreliance on glyphosate and a reduction in the diversity of weed management practices adopted by 

crop producers have contributed to the evolution of glyphosate resistance in 14 weed species and biotypes in the 

United States. Best management practices (BMPs) to control weeds may help delay the evolution of resistance and 

sustain the efficacy of HT crops. BMPs include applying multiple herbicides with different modes of action, rotating 

crops, planting weed-free seed, scouting fields routinely, cleaning equipment to reduce the transmission of weeds to 

other fields, and maintaining field borders. 

The price of GE soybean and corn seeds grew by about 50 percent in real terms (adjusted for inflation) between 2001 

and 2010. The price of GE cotton seed grew even faster. The yield advantage of Bt corn and Bt cotton over conventional seed has become larger in recent years as new Bt traits have been incorporated and stacked traits have become 

available. Planting Bt cotton and Bt corn continues to be more profitable, as measured by net returns, than planting 

conventional seeds. 

Consumers. Consumer acceptance of foods with GE ingredients varies with product characteristics, geography, and 

the information that consumers are exposed to. Most studies in industrialized nations find that consumers are willing 

to pay a premium for foods that don’t contain GE ingredients. However, studies in developing countries yield more 

mixed results. Some studies, including some with a focus on GE ingredients with positive enhancements (such as 

nutrition), find consumers to be willing to try GE foods and even to pay a premium for them, while others find a willingness to pay a premium for non-GE foods. Most studies have shown that willingness-to-pay for non-GE foods is 

higher in the EU, where some retailers have policies limiting the use of GE ingredients. Non-GE foods are available in 

the United States, but there is evidence that such foods represent a small share of retail food markets.

How Was the Study Conducted? 

This report updates the ERS report titled The First Decade of Genetically Engineered Crops in the United States. To 

consider biotech seed firms, we use information from the literature and analyze USDA data on field testing approvals 

by APHIS for new GE varieties. To study farmers’ use of GE crops, we analyze USDA farm surveys, particularly 

the Agricultural Resource Management Survey (ARMS), and summarize the literature. To understand consumers’ 

perspectives, we summarize surveys of consumers’ attitudes from the literature.

www.ers.usda.gov
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Genetically Engineered Crops in the United States, ERR-162

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Genetically Engineered Crops in the 

United States 

Introduction

Genetic engineering is a key component of modern agricultural biotechnology.1 The first genetically 

engineered (GE) plant, a tomato, was developed in 1982 (USDA/ARS, 2012). By 1985, the USDA 

had approved four releases of GE organisms for field testing. Commercial use of major GE crops 

began in 1996.2

Genetically engineered crop traits have been classified into one of three generations (FernandezCornejo, 2004). The first generation features enhanced input traits such as herbicide tolerance, 

resistance to insects, and resistance to environmental stress (like drought). The second features 

value-added output traits such as nutrient-enhanced seeds for feed. The third generation of GE crops 

would include traits to allow production of pharmaceuticals and products beyond traditional food 

and fiber. 

While the first GE crop approved by USDA’s Animal and Plant Health Inspection Service (APHIS) 

and commercialized in 1994 was a crop with a strictly second-generation trait (FlavrSavr tomato), 

most GE crops planted in the United States have first-generation traits. All three generations of GE 

crop traits are in various stages of research and development.3

Most U.S. acres planted to GE crops have traits that provide herbicide tolerance (HT) and/or insect 

resistance. These seeds became commercially available in 1996. HT crops are able to tolerate 

certain highly effective herbicides, such as glyphosate, allowing adopters of these varieties to control 

pervasive weeds more effectively. Commercially available HT crops include soybeans, corn, cotton, 

canola, sugarbeets, and alfalfa. Insect-resistant or Bt crops contain a gene from the soil bacterium 

Bacillus thuringiensis (Bt) that produces a protein which is toxic to certain insects, protecting the 

plant over its entire life (Fernandez-Cornejo and McBride, 2002). Commercially available Bt crops 

include corn and cotton. 

1Genetic engineering is a technique used to alter genetic material (genes) of living cells. A gene is a segment of DNA 

that expresses a particular trait. It is a unit of heredity transmitted from generation to generation during reproduction 

(Zaid et al., 1999). DNA constitutes the genetic material of most known organisms.

2Plant biotechnology in general and genetic engineering in particular have significantly reduced the time needed to develop improved plant varieties, increasing the range and precision of characteristics incorporated into these new varieties 

(Fernandez-Cornejo, 2004). By allowing scientists to target single plant traits through genetic recombination techniques, 

plant biotechnology decreases the number of residual unwanted characteristics that often result from traditional plant 

breeding crosses, enabling breeders to develop desirable new varieties more rapidly.

3Several second-generation GE crops have been approved by APHIS: high-lysine corn, reduced-nicotine tobacco, higholeic acid soybean oil, stearidonic acid-producing soybeans, improved fatty acid-profile soybeans, altered-flower color 

roses (blue), oil profile-altered canola, and alpha amylase corn. Overall, nearly 20 percent of the approvals for deregulation (as of September 2013) are second-generation crops. 
2

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More than 15 years after commercial introduction, adoption of first-generation GE crop varieties by 

U.S. farmers has reached about 90 percent of the planted acres of corn, soybeans, and cotton. U.S. 

consumers eat many products derived from these crops—including cornmeal, oils, and sugars—

largely unaware of their GE origins. Despite the rapid increase in adoption rates for GE corn, 

soybean, and cotton varieties by U.S. farmers, some continue to raise questions regarding the potential benefits and risks of GE crops. 

This report updates ERS’ 2006 report, The First Decade of Genetically Engineered Crops in the 

United States. As in the previous report, this report examines the three major stakeholders of agricultural biotechnology: GE seed suppliers and technology providers (biotech firms), farmers, and 

consumers. 
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From the Laboratory to the Field

Over the last century, private research and development (R&D) expenditures in the seed industry 

have increased rapidly both in absolute terms and relative to public expenditures, altering the focus 

of R&D and of the crops studied (Fernandez-Cornejo, 2004). Over the past two decades, technological innovation in the form of modern biotechnology and changes in property rights have enabled 

private-sector firms to capture more value from the seeds that they develop, and seed remains the 

most research-intensive of the agricultural input sectors to date (Heisey and Fuglie, 2012). 

While the rapid commercial success of GE varieties is the fulfillment of R&D efforts, earlier benchmarks include the number of releases for field testing of GE plant varieties approved by APHIS as 

well as the determination of nonregulated status (see box, “Regulatory Oversight”).

4 Field testing is 

a critical part of seed development (Fernandez-Cornejo and Caswell, 2006).

Field Releases

The number of field release permits and notifications issued by APHIS for GE organisms (mostly 

plant varieties) grew from 4 in 1985 to 1,194 in 2002 and then averaged around 800 per year (fig. 

1). The cumulative number (beginning in 1985 and ending in September 2013) of releases for field 

testing increased from 10,700 in 2005 to more than 17,000 in 2013. Field releases approved for corn 

increased from close to 5,000 in 2005 to 7,800 in 2013. Approved releases for GE varieties with 

herbicide tolerance traits increased from 3,587 in 2005 to 6,772 in 2013, insect resistance from 3,141 

to 4,909, and product quality such as flavor or nutrition from 2,314 to 4,896.

4Another indicator of R&D activity is the number of patents issued by the U.S. Patent and Trademark Office. More 

than 4,200 new agricultural biotech patents were issued between 1996 and 2000 (King and Heisey, 2003, 2004). 

Figure 1

Number of releases of genetically engineered (GE) organisms varieties approved by APHIS,

1985-2013* (Includes permits and notifications) 

*As of September 24, 2013.

Authorizations for field releases of GE organisms (mostly plant varieties) are issued by USDA’s Animal and Plant Health 

Inspection Service (APHIS) to allow technology providers to pursue field testing.

Source: Information Systems for Biotechnology (ISB, 2013). 

4 11 11 16 30 51 90

160

301

579

711

612

763

1,071

983

925

1,083

1,194

813

893

955

865

932

871

751

660

792

665

536

1985 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13
4

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However, these numbers do not fully indicate the amount of R&D activity. A permit or notification 

can include many release sites and authorize many different gene constructs (ways that the gene 

of interest is packaged with other elements, like promoters that allow gene expression) to be tested 

at each site.5 Thus, while the number of APHIS notifications and permits peaked in 2002, a more 

comprehensive measure of the amount of R&D activity in agricultural biotechnology—the number 

of authorized sites and authorized constructs—has increased very rapidly since 2005. For example, 

while the number of releases authorized in fiscal year (FY) 2012 was lower than in FY2005, the 

5A gene construct is the technical name used for a functional unit necessary for the transfer or the expression of a gene 

of interest (http://www.gmo-safety.eu/glossary/667.gene-construct.html). Typically, a construct comprises the gene or 

genes of interest, a marker gene (to facilitate detection inside the plant), and appropriate control sequences as a single 

package (FAO, 2001).

Regulatory Oversight

Before commercial introduction, genetically engineered (GE) crops must conform to standards set by State 

and Federal statutes (Fernandez-Cornejo and Caswell, 2006; USDA/APHIS, 2013). Under the Coordinated 

Framework for the Regulation of Biotechnology, Federal oversight is shared by the U.S. Department of Agriculture 

(USDA), the U.S. Environmental Protection Agency (EPA), and the U.S. Food and Drug Administration (FDA). 

USDA’s Animal and Plant Health Inspection Service (APHIS) plays a central role in regulating field testing of 

agricultural biotechnology products. Through either a notification or permit procedure, such products—which 

include certain genetically engineered plants, microorganisms, and invertebrates—are considered “regulated 

articles.” APHIS issues authorizations for field releases of those GE organisms (mostly GE plants) that are 

categorized as “regulated articles” under its regulations, to allow technology providers to pursue field testing. 

GE plants that meet six specific criteria described in the regulations undergo an administratively streamlined 

process, known as a notification. Under a notification, applicants provide information on the nature of the plant 

and introduced genes, descriptions of genetic modifications, size of the introduction, and origin and destinations 

for movement or the location of a field test. For GE plants that do not meet the criteria for a notification, an 

APHIS permit is required. This process involves a more comprehensive review. In addition to the data required 

for notification, permit applicants must describe how they will perform the test, including specific measures to 

reduce the risk of harm to other plants, so the tested organisms remain confined and do not persist after completion of the field test.

After years of field tests, an applicant may petition APHIS for a determination of nonregulated status in order to 

facilitate commercialization of the product. If, after extensive review, APHIS determines that the GE organism is 

unlikely to pose a plant pest risk, the organism is issued a “determination of nonregulated status.” At this point, 

the organism is no longer considered a regulated article and can be moved and planted without APHIS oversight 

under the biotechnology regulations (USDA/APHIS, 2012). 

If a plant is engineered to produce a substance that “prevents, destroys, repels, or mitigates a pest,” it is considered a pesticide and is subject to regulation by EPA (Federal Register, November 23, 1994). FDA regulates all 

food applications of crops, including those crops that are developed through the use of biotechnology, to ensure 

that foods derived from new plant varieties are safe to eat. A more complete description of the regulations of GE 

products may be found in USEPA, 2003; Belson, 2000; and USDA/APHIS, 2013). 

Though the current regulatory system is considered to be effective, USDA, EPA, and FDA update regulations as 

needed to address new trends and issues of the future. 
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number of authorized sites in FY2012 almost doubled those in FY2005 and the number of constructs 

increased more than 150-fold (table 1).6 

Most field releases have involved major crops, particularly corn, which had about 7,800 field releases 

approved as of September 2013. More than 2,200 field releases were approved for GE soybeans, 

more than 1,100 for GE cotton, and about 900 for GE potatoes (fig. 2). Releases approved between 

1985 and September 2013 included GE varieties with herbicide tolerance (6,772), insect resistance 

(4,809), product quality such as flavor or nutrition (4,896), agronomic properties (like drought 

resistance) (5190), and virus/fungal resistance (2,616) (fig. 3). A notable change in R&D activities 

6Within each location there can be multiple sites or fields where the trial will be carried out (Information Systems for 

Biotechnology, 2013).

Table 1

Number of releases, sites, and constructs authorized by APHIS for evaluation

Releases Authorized sites Authorized constructs

FY2012 767 9,133 469,202

FY2011 967 10,128 395,501

FY2010 754 6,626 297,422

FY2009 846 6,751 217,502

FY2008 948 7,744 125,365

FY2007 1,066 3,623 63,217

FY2006 974 4,327 18,532

FY2005 1011 4,939 3,042

FY2004 997 4,523 2,851

FY2003 824 2,910 2,650

FY2002 1,226 5,111 3,234

FY2001 1,190 5,831 3,208

FY2000 1,002 3,836 3,126

FY1999 1,068 4,134 3,502

FY1998 1,151 4,781 3,830

FY1997 782 3,427 2,650

FY1996 653 2,745 2,305

FY1995 734 3,690 2,666

FY1994 569 1,669 1,926

FY1993 341 455 870

FY1992 164 121 427

FY1991 90 10 226

FY1990 46 14 142

FY1989 32 12 74

A gene construct is the name used for a functional unit necessary for the transfer or the expression of a gene of interest 

(http://www.gmo-safety.eu/glossary/667.gene-construct.html). Typically, a construct comprises the gene or genes of 

interest, a marker gene (to facilitate detection inside the plant), and appropriate control sequences as a single package 

(Food and Agriculture Organization, 2001). A construct is a piece of DNA which functions as the vehicle or vector carrying the target gene into the recipient organism. It has several different regions.

Source: Unpublished USDA Animal and Plant Health Inspection Service database
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between 2005 and 2013, as measured by the field releases of GE varieties, is the five-fold jump in 

releases of GE varieties with agronomic properties (like drought resistance) from 1,043 in 2005 to 

5,190 in 2013 (fig. 3).

The top release permit-holding institutions include Monsanto (6,782 permits/notifications held), 

Pioneer/DuPont (1,405), Syngenta (565), and USDA/ARS (370) (fig. 4). 

Figure 2

Number of releases approved by APHIS: Top 10 crops (includes permits and notifications)* 

*As of September 24, 2013.

Authorizations for field releases of GE plant varieties are issued by USDA’s Animal and Plant Health Inspection Service 

(APHIS) to allow technology providers to pursue field testing.

Source: Information Systems for Biotechnology (ISB, 2013). 

7,778

2,225

1,104 904 688 485 452 427 310 294

Corn Soybeans Cotton Potato Tomato Wheat Alfalfa Tobacco Rapeseed Rice

Figure 3

Number of releases approved by APHIS by GE trait (includes permits and notifications)*

*As of September 24, 2013.

Authorizations for field releases of GE plant varieties are issued by USDA’s Animal and Plant Health Inspection Service 

(APHIS) to allow technology providers to pursue field testing. Counts refers to the actual number of approved release 

locations per phenotype category. http://www.aphis.usda.gov/biotechnology/status.shtml

Source: Information Systems for Biotechnology (ISB, 2013). 

Source: Information Systems for Biotechnology (ISB, 2013) 

Herbicide tolerance, 6,772 

Insect resistance, 4,809

Product quality, 4,896

Agronomic properties, 5,190

Other, 1,986

Marker gene, 1,892

Virus resistance, 1,425

Fungal resistance, 1,191 

Bacterial resistance, 224 Nematode resistance (NR), 149
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Determination of Nonregulated Status

Nonregulated status allows seed companies to commercialize the GE seeds that they have developed. After successful field testing, technology providers petition APHIS for a determination of 

non-regulated status. If, after review, APHIS determines that the organism (i.e., GE plant) is unlikely 

to pose a plant pest risk, the organism is deregulated (see box, “Regulatory Oversight”) and can be 

moved and planted without APHIS oversight. As of September 2013, APHIS had received 145 petitions for deregulation—compared with 103 petitions received in 2005—and had granted 96 (31 were 

withdrawn, 17 were pending, and 1 was incomplete) (Information Systems for Biotechnology, 2013). 

For corn, 30 petitions were granted nonregulated status; 15 were granted for cotton; 11 for tomatoes; 

12 for soybeans; 8 for canola/rapeseed; 5 for potatoes; 3 for sugarbeet; 2 each for papaya, rice, and 

squash; and 1 each for alfalfa, plum, rose, tobacco, flax, and chicory. By trait, as of September 2013, 

43 petitions were granted nonregulated status for herbicide tolerance, 31 for insect resistance, 17 for 

product quality, 9 for agronomic properties, 8 for virus resistance, and 2 for others.7

The Research and Development Pipeline

APHIS approval for field testing and determination of nonregulated status signals that the GE products are near commercial status. In addition to crops with improved pest management traits, APHIS 

approvals include crops with traits that provide viral/fungal resistance; favorable agronomic properties (resistance to cold, drought, frost, salinity, more efficient use of nitrogen, increased yield); 

enhanced product quality such as delayed ripening, flavor, and texture (fruits and vegetables); 

increased protein or carbohydrate content, fatty acid content or micronutrient content; modified 

starch, color (cotton, flowers), fiber properties (cotton) or gluten content (wheat); naturally decaffein7

A petition (as well as an approval) may include more than one trait or phenotype category. For example, a petition for 

corn may include one or more HT traits and one or more Bt traits.

Figure 4

Institutions having the most authorized permits and notifications (number held)

*As of September 24, 2013.

Authorizations for field releases of GE plant varieties are issued by USDA’s Animal and Plant Health Inspection Service 

(APHIS) to allow technology providers to pursue field testing.

Source: Information Systems for Biotechnology (ISB, 2013).

6,782

1,085 565 370 326 400 320 311 260 210

Monsanto Pioneer

(now part

of DuPont)

Syngenta USDA/ARS AgrEvo Dow

AgroSciences

DuPont ArborGen Bayer

CropScience

Seminis
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ated (coffee); nutraceuticals (added vitamins, iron, antioxidants such as beta-carotene); and pharmaceuticals (table 2).8 Additional information is found in the Pew Initiative (2001), Runge and Ryan 

(2004), Monsanto (2012), and Pioneer (2012).

8Pharmaceutical plant compounds produced are intended for pharmaceutical use and would need to be approved from 

at least one of the following agencies prior to commercialization: U.S. Food and Drug Administration (FDA) Center for 

Biologics Evaluation and Research (human biologics), FDA Center for Drug Evaluation and Research (human drugs), 

FDA Center for Veterinary Medicine (animal drugs), and USDA Center for Veterinary Biologics (animal biologics). 

None of the plants currently under permit produce pharmacologically active compounds.

Table 2

Biotech crops currently available and in development 

Input traits Output traits

Crop

Herbicide 

tolerance

Insect 

resistance

Virus/fungi, 

resistance

Agronomic 

properties11

Product 

quality14

Pharmaceuticals/

nutraceuticals17

Corn C C5 D C12 D D D

Soybeans C D D C15 D

Cotton C C6 D D

Potatoes W7 D D D D

Wheat C2 D

Other field crops1 C3 D4 D D D D D

Tomato, squash, 

melon, sweet corn C8 C9 D D C16 D D

Other vegetables D D

Papaya C10

Fruit trees D D

Other trees D13 D

Flowers D

1Includes barley, canola, peanuts, tobacco, rice, sugar beet, alfalfa, etc. 

2Monsanto discontinued breeding and field level research on its GE Roundup Ready wheat in 2004. 

3Canola, sugar beet, alfalfa. 4Barley, rice. 5Bt corn to control the corn borer commercially available since 1996; Bt corn 

for corn rootworm control commercially available since 2003; Bt corn to control the corn earworm commercially available 

since 2010; stacked versions of them also available. 

6Bt cotton to control the tobacco budworm, the bollworm, and the pink bollworm, commercially available since 1996. 

7Bt potatoes, containing built-in resistance to the Colorado potato beetle were commercially introduced in 1996 and 

withdrawn in 1999.

8Sweet corn with insect resistance (to the corn earworm and European corn borer) was planted in anout 20,000 acres 

and sold in the fresh market in 2008 (NRC, 2010). 

9VR squash accounted for about 12 percent of the squash produced in in 2005 (NRC, 2010). 

10Responding to a devastating papaya virus epidemic in the mid-1990s, researchers at Cornell University and at the University of Hawaii developed two virus-resistant varieties of GE papaya. First commercial plantings were made in 1998. 

The new varieties were successful in resisting a viral epidemic and were planted on more than 30 percent of Hawaii’s 

papaya acreage in 1999. 

11Such as resistance to drought, frost, salinity; more efficient use of nitrogen.

12Drought tolerant corn approved for commercial use in 2011; expected to be introduced in 2012. 

13Modified lignin content. 

14Includes delayed ripening (fruits and vegetables with longer shelf life); protein content, carbohydrate content, fatty acid 

content, micronutrient content, oil content, modified starch content, flavor and texture (fruits and vegetables), color (cotton, flowers), fiber properties (cotton), gluten content (wheat), naturally decaffeinated (coffee), and low phytase. 

15High oleic soybeans. 

16FlavrSavr tomato genetically engineered to remain on the vine longer and ripen to full flavor after harvest was pulled 

out of the market because of harvesting and marketing problems. 

17Includes increased vitamin, iron, beta-carotene (antioxidant), lycopene (anti-cancer), amino acid content; low-calorie 

sugar; hypoallergenic crops; antibodies, vaccines. Industrial uses (such as specialty machine oils).

Sources: ISB (2013); Fernandez-Cornejo and Caswell (2006); National Research Council (2010); USDA Animal and 

Plant Health Inspection Service.
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Adoption of GE Crops by U.S. Farmers

When farmers adopt a new technology, they typically expect benefits like increased farm net returns, 

time savings (by making farming less effort intensive), or reduced exposure to chemicals. Net benefits are a function of farm characteristics and location, output and input prices, existing production 

systems, and farmer abilities and preferences. 

Judging by the widespread adoption of GE seeds, farmers have benefited from them. U.S. farmers 

planted about 169 million acres of GE corn, soybeans, and cotton in 2013 (table 3), accounting for 

almost half of the estimated total land used to grow all U.S. crops.

On a global scale, approximately 420 million acres of GE crops were planted in 28 countries in 

2012 ( International Service for the Acquisition of Agri-biotech Applications, 2012). U.S. acreage 

accounted for approximately 41 percent of acres planted with GE seed, Brazil accounted for 21 

percent, Argentina for 14 percent, Canada for 7 percent, India for 6 percent, and China, Paraguay, 

South Africa, and Pakistan each for roughly 2 percent. 

Commercially introduced in the United States in 1996, major GE crops were rapidly adopted. 

Planting of GE crops (measured in acres) increased by 68 percent between 2000 and 2005 and grew 

by 45 percent between 2005 and 2013. Three crops (corn, cotton, and soybeans) make up the bulk 

of U.S. acres planted to GE crops (table 3), mostly for herbicide tolerance (HT) and insect resistance 

(Bt). Including varieties with HT and/or Bt traits, GE crops accounted for 90 percent of all planted 

cotton acres, 93 percent of soybean acres, and 90 percent of corn acres in 2013. U.S. farmers have 

Table 3

Major genetically engineered crops, 2000-2013

GE corn GE soybeans GE cotton

Year Million acres 

planted

Percent of 

corn acres

Million acres 

planted

Percent of 

soybean acre

Million acres 

planted

Percent of 

cotton acres

2000 19.89 25 40.10 54 9.47 61

2001 19.68 26 50.37 68 10.88 69

2002 26.82 34 55.47 75 9.91 71

2003 31.44 40 59.46 81 9.84 73

2004 38.04 47 63.93 85 10.38 76

2005 42.53 52 62.67 87 11.25 79

2006 47.78 61 67.21 89 12.68 83

2007 68.27 73 58.91 91 9.42 87

2008 68.79 80 69.66 92 8.15 86

2009 73.42 85 70.48 91 8.05 88

2010 75.85 86 71.99 93 10.21 93

2011 81.21 88 70.46 94 13.25 90

2012 85.50 88 71.79 93 11.58 94

2013 87.64 90 72.29 93 9.23 90

Genetically engineered crops in this table include Bt crops that have insect-resistant traits or HT crops that have herbicide tolerance traits, or both. 

Sources: USDA Economic Research Service using data from from USDA/NASS Quick Stats and Fernandez-Cornejo 

(2013).
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tended to adopt HT seeds at higher levels than seeds with insect resistance (fig. 5). In part, this is 

because weeds are a pervasive problem.9 HT adoption was particularly rapid in soybeans, with U.S. 

farmers increasing their planting of HT soybeans from 54 percent of soybean acres in 2000 to 87 

percent in 2005 and 93 percent in 2013. HT cotton increased from 46 percent of cotton acres in 2000 

to 61 percent in 2005 and 82 percent in 2013. HT corn increased from 7 percent of corn acres in 

2000 to 26 percent in 2005 and 85 percent in 2013. Insect infestations tend to be more localized than 

weed infestations (fig. 6). Farmers planted Bt cotton (to control insects such as tobacco budworm, 

cotton bollworm, and pink bollworm) on 35 percent of the cotton acres in 2000, 52 percent in 2005, 

and 75 percent in 2013. Bt corn—commercially introduced to control the European corn borer in 

1996, the corn rootworm in 2003, and the corn earworm in 2010—was planted on 19 percent of corn 

acres in 2000, 35 percent in 2005, and 76 percent in 2013. 

Other GE crops commercially grown in the United States are HT canola, HT sugarbeets, HT alfalfa, 

virus-resistant papaya, and virus-resistant squash.10 In addition, other traits are being developed and 

tested, including cold/drought resistance and enhanced protein, oil, or vitamin content (see table 2).11

9Over 90 percent of U.S. acreage devoted to major crops has been treated with herbicides in recent decades (Osteen 

and Fernandez-Cornejo, 2012).

10Some other GE crops were only on the market for a limited amount of time. Bt potato varieties were introduced in 

1996, but withdrawn from the market after the 2001 season. FlavrSavr tomatoes, which were genetically engineered to 

remain on the vine longer and ripen to full flavor after harvest, were introduced in 1994, but withdrawn from the market 

after several years.

11Drought-tolerant corn was approved for commercial use in 2011 (Federal Register, 2011; Monsanto, 2012) and commercially introduced in 2012.

Figure 5

Adoption of genetically engineered crops in the United States

Bt crops have insect resistant traits; HT crops have herbicide tolerance traits.

Data for each crop category include varieties with both Bt and HT (stacked) traits. 

Source: U.S. Department of Agriculture (USDA), Economic Research Service (ERS). 2013. Adoption of Genetically 

Engineered Crops in the U.S. data product.

Percent acres planted

0

10

20

30

40

50

60

70

80

90

100

1996 98 2000 02 04 06 08 10 12

HT Soybeans

HT Cotton

Bt Cotton

Bt Corn

HT Corn
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Based on the Agricultural Resource Management Survey (see box, “ARMS Data”),12 farmers 

indicate that they adopted GE corn, cotton, and soybeans primarily to increase yields (fig. 7). Other 

popular reasons for adopting GE crops were to save management time, to facilitate other production 

practices (such as crop rotation and conservation tillage), and to reduce pesticide costs.

12USDA’s National Agricultural Statistics Service (NASS) and Economic Research Service (ERS) sponsor the Agricultural Resource Management Survey (ARMS). This survey includes a crop-specific survey of production practices 

(called ARMS Phase 2) for selected major corps each once every 5 years on a rotating basis. This survey was conducted 

in 2006 for soybeans, 2007 for cotton, and 2010 for corn. 

 

 

 

Figure 6

Percentage of U.S. corn farmers who adopted Bt seeds in 2010

Bt crops have insect-resistant traits.

Source: USDA, Economic Research Service using data from the 2010 Agricultural Resource Management Survey

(ARMS) Phase II corn survey.

0 - 33

33 - 66

66 - 100

The ARMS Data

The Agricultural Resource Management Survey (ARMS), sponsored by USDA’s National 

Agricultural Statistics Service (NASS) and the Economic Research Service (ERS), has a multiphase, multi-frame, stratified, probability-weighted design. In other words, farmers with preselected characteristics are administered the ARMS each year. After data collection, NASS 

generates probability weights to help ensure that the ARMS sample accurately represents the 

population of U.S. famers. 

The ARMS has three phases. Phase I, administered in the summer of the survey year, verifies 

that all respondents operate a farm or plant a specific crop. Phase II, administered in the fall or 

winter of the survey year, is a field-level survey that collects data on production practices and 

input use. Phase III, administered in the spring following the survey year, gathers data on debt, 

revenue, operating costs, and expenditures for the entire farm. 

Phase I and Phase III are annual surveys that are administered to all respondents. Phase II is a 

commodity-specific survey that is administered annually for a rotating selection of crops. For 

instance, the ARMS Phase II Corn survey was administered in 2005 and 2010. The Phase II 

Soybean survey was administered in 2006 and the cotton survey was administered in 2007.
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Farm-Level Economic Impacts of GE Crop Adoption

The impacts of GE crop adoption vary by crop and technology. Many studies have assessed the 

factors that influence adoption as well as the impacts of GE crops on yields, net returns, and pesticide use (table 4; Fernandez-Cornejo and McBride, 2002).

Over the first 15 years of commercial use, GE seeds have not been shown to increase yield potentials 

of the varieties.13 In fact, the yields of herbicide-tolerant or insect-resistant seeds may be occasionally lower than the yields of conventional varieties if the varieties used to carry the HT or Bt genes 

are not the highest yielding cultivars, as in the earlier years of adoption (Fernandez-Cornejo and 

Caswell, 2006; National Research Council, 2010).14 However, by protecting the plant from certain 

pests, GE crops can prevent yield losses to pests, allowing the plant to approach its yield potential. 

13Potential yield is defined as “the yield of an adapted cultivar when grown with the best management and without 

natural hazards such as hail, frost, or lodging, and without water, nutrient, or biotic stress limitations (water stress being 

eliminated by full irrigation or ample rainfall)” (Fischer and Edmeades, 2010). Farm level (actual or effective) yield is 

equal to potential yield minus the yield lost to pests or to other stresses. 

14Since Bt and HT traits protect yield rather than increase potential yield, it is possible that in some cases the Bt and 

HT traits are not introduced in the highest yielding germplasm. Over time, this so-called “yield drag” usually disappears 

(NRC, 2010, Ch 3). On the other hand, Shi et al. (2013) show that the opposite situation may arise if GE genes are added 

more frequently to “high quality” germplasm. They call this situation genetic selectivity bias. 

Figure 7

Farmers’ reasons for adopting genetically engineered crops

Bt crops have insect resistant traits; HT crops have herbicide tolerance traits.

Sources: USDA Economic Research Service using data from Agricultural Resource Management Survey (ARMS)

Phase II surveys: 2010 for corn, 2007 for cotton, and 2006 for soybeans.

Bt cotton 

 

79%

5%

12%

4%

Decrease pesticide input cost

Other

Increase yields

Save management time and 

make other practices easier

77%

6%

12%

5%

60% 20%

15%

5%

71%

7%

13%

9%

HT soybeans HT corn

77%

6%

10%

7%

Bt corn

HT cotton
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Table 4

Summary of selected studies on the effects of genetically engineered crops on yields, pesticide use, 

and net returns

Crop/researchers/date of publication Data source

Effects on

Yield Pesticide use Net returns

Herbicide-tolerant soybeans

Delannay et al., 1995 Experiments Same na na

Roberts et al., 1998 Experiments Increase Decrease Increase

Arnold et al., 1998 Experiments Increase na Increase

Marra et al., 1998 Survey Increase Decrease Increase

Reddy and Whiting, 2000 Experiments Same na Increase

Duffy, 2001 Survey Small decrease na Same

Fernandez-Cornejo et al., 20021 Survey Small increase Small increase Same

McBride & El-Osta, 20022 Survey na na Same

Bradley et al., 2004 Experiments Same na na

Marra et al., 2004 Survey Same na Increase

Herbicide-tolerant cotton

Vencill, 1996 Experiments Same na na

Keeling et al., 1996 Experiments Same na na

Goldman et al., 1998 Experiments Same na na

Culpepper and York, 1998 Experiments Same Decrease Same 

Fernandez-Cornejo et al., 20001 Survey Increase Same Increase 

Adhicari et al. 2000 Survey na na Increase

Herbicide-tolerant corn

Fernandez-Cornejo and Klotz-Ingram, 

1998

Survey Increase Decrease Same

Ferrell and Witt, 2002 Experiments Same na Small increase

McBride & El-Osta, 20022 Survey na na Increase

Parker et al., 2006 Experiments Same na na 

Bt cotton

Stark, 1997 Survey Increase Decrease Increase

Gibson et al., 1997 Survey Increase na Increase

ReJesus et al., 1997 Experiments Same na Increase

Bryant et al., 19993 Experiments Increase na Increase

Marra et al., 1998 Survey Increase Decrease Increase

Fernandez-Cornejo et al., 20001 Survey Increase Decrease Increase

Falck-Zepeda et al., 20001 Survey Increase na Increase

Cattaneo et al., 2006 Survey Increase Decrease na

Piggott and Marra, 2007 Experiments Increase na Increase

Bt corn

Rice and Pilcher, 19981 Survey Increase Decrease Depends on 

infestation

continued—
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The profitability of GE seeds for individual farmers depends largely on the value of the yield losses 

mitigated and the associated pesticide and seed costs.15 GE adoption tends to increase net returns if 

the value of yield losses mitigated plus the pesticide savings exceeds the additional GE seed costs. 

Adoption of Bt crops increases yields by mitigating yield losses to pests. Bt crops are particularly 

effective at mitigating yield losses. For example, before Bt corn was commercially introduced in 1996, 

the European corn borer was only partially controlled using chemical insecticides (Fernandez-Cornejo 

and Caswell, 2006). Chemical use was not always profitable, and timely application was difficult. 

Many farmers accepted expected yield losses of 0.4 to 3.2 bushels from this pest rather than incur the 

expense and uncertainty of chemical control (Hyde et al., 1999). After the introduction of Bt corn, 

adopters who had previously controlled corn borer infestations using insecticides lowered their pesticide costs and increased their yields. Adopters who had not previously treated European corn borer 

infestations with insecticides achieved only yield gains (and may have incurred higher seed costs). 

In addition to improvements in background germplasm, Bt corn yields have increased over time 

as new insect resistance traits have been incorporated into the seeds and multiple (stacked) traits 

have become available (Fernandez-Cornejo and Wechsler, 2012). For instance, upon commercial 

introduction in 1996, Bt corn seeds were only resistant to one type of pest: the European corn borer. 

Since then, resistance to corn rootworms (2003) and corn earworms (2010) has been introduced. 

15In this report, net returns are defined as per-acre revenues minus per-acre variable costs. Revenues per acre are equal 

to crop yields times crop price. Per-acre variable input costs include pesticide, seed and labor costs. Seed costs paid 

by adopters of GE varieties include a technology fee. This measure of net returns is used because most of the financial 

impacts of adopting GE crops result from changes in crop yields, chemical costs, and increased seed costs. This measure 

is estimated using field-level data and captures the greatest influence that GE crop adoption would have on farm financial 

performance as it also filters out the impact of other farm activities—such as livestock production (Fernandez-Cornejo 

and McBride, 2002). The econometric estimation involves estimating a restricted profit function (Fernandez-Cornejo and 

Wechsler, 2012) together with the associated supply function and input demand functions (hired labor is also included 

and wages are used as the numeraire).

Table 4

Summary of selected studies on the effects of genetically engineered crops on yields, pesticide use, 

and net returns

Crop/researchers/date of publication Data source

Effects on

Yield Pesticide use Net returns

Marra et al., 1998 Survey Increase Decrease Increase

Duffy, 20012 Survey Increase Na Same

Baute, Sears, and Schaafsma, 2002 Experiments Increase Na Depends on 

infestation

McBride & El-Osta, 20024 Survey Na Na Decrease

Pilcher et al., 20025 Survey Increase Decrease Na

Dillehay et al., 20046 Experiments Increase Na Na

Mitchell et al., 20047 Experiments Increase Na Depends on 

infestation

Fernandez-Cornejo and Li, 20058 Survey Increase Decrease Na

Mungai et al., 20059 Experiments Increase Na Na

Fang et al., 200710 Experiments Increase Na Na

na = not analyzed in the study; 1Results using 1997 data; 2Results using 1998 data; 3Results are for 1996 and 1998, results were different for 

1997 when the pest pressure was low; 4Results using 1998 data; 5Results using 1996-1998 data; 6Results using 2004-2006 data; 7Results using data from 1997-1999 ; 8Results using data from 2001; 9Results using data from 2002-2003, 10Results using data from 2002.

—continued
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Most experimental field tests and farm surveys show that Bt crops produce higher yields than conventional crops (table 4). Intuitively, Bt adopters are more likely to obtain higher yields than nonadopters 

by controlling insects and thus reducing yield losses to pests. The yield gain of Bt crops has become 

larger in recent years as new Bt traits have been incorporated into the seeds and multiple (stacked) 

traits have become available. For example, ARMS data show that the yield gain by Bt corn adopters 

relative to conventional varieties increased from 12.5 bushels per acre in 2001 to 16 bushels in 2005 

and 26 bushels in 2010 (table 5; Fernandez-Cornejo and Li, 2005).16 The geographical distributions of 

Bt adoption rates and average corn yields for 2010 are shown in figures 6 and 8, respectively.

While mean comparisons are illustrative, definitive conclusions about relative yields are possible 

only if the data are generated under experimental settings where factors other than adoption are 

controlled for by making them as similar as possible (Fernandez-Cornejo and McBride, 2002; NRC, 

2010).17 This is not the case with survey data.18 Bt use is not random. Surveyed farmers are not 

randomly assigned to a treatment group (adopters) and a control group (nonadopters). Consequently, 

adopters and nonadopters may be systematically different from one another (for example, in terms 

of management ability). If these differences affect both farm performance and Bt adoption, they will 

confound the analysis (Fernandez-Cornejo and McBride, 2002; Fernandez-Cornejo et al., 2002). 

This self-selection19 biases the statistical results unless it is corrected (Greene, 1997). Fernandez16The difference in means of corn yields between adopters and nonadopters is statistically significant for 2005 and 

2010 using either the delete-a-group jackknife procedure (Kott, 1998) or the standard statistical test.

17The panel members who wrote the NRC report were Y. Carriere, W. Cox, D. Ervin, J. Fernandez-Cornejo, 

R. Jussaume Jr., M. Marra, M. Owen, P. Raven, L. Wolfenbarger and D. Zilberman.

18Marra et al. (2002a) provides an extensive discussion of the various types of biases that can arise when comparing 

means not only in farm (and field) surveys but in experimental settings as well (see box 3 for a discussion of the bias that 

may be caused by the halo effect).

19Self-selection is a type of endogeneity (Maddala, 1983; Greene, 1997). Endogeneity arises when there is a correlation 

between the explanatory variable and the model’s residuals. If endogeneity is not accounted for (for instance, through the 

use of instrumental variable techniques), the results of the analysis will be biased. A common approach used to control 

for self-selection is sometimes called an instrumental variables approach. The model includes two stages. The first stage, 

which is referred to as the adoption decision model, is used to estimate the predicted values of the probability of adoption 

using a probit model. The second stage, or impact model, uses the predictions estimated in the first stage to estimate the 

impact of adopting Bt seeds on yields, seed demand, insecticide demand, and net returns.

Table 5

Bt corn adopters and non-adopters, 2005 and 2010 (Samnple means of selected variables)

Variable Unit Bt Non-Bt Difference Significance

2005

Yield Bushels/acre 155.1 138.6 16.6 ***

Insecticide use Pounds Ai/acre 0.05 0.09 -0.04 1

Corn price Dollars/bushel 1.95 2.01 -0.06 NS

2010

Yield Bushels/acre 159.2 132.7 26.5 ***

Insecticide use Pounds Ai/acre 0.02 0.02 0.00 NS

Corn price Dollars/bushel 5.39 5.40 -0.01 NS

*, **, and *** Indicates statistical significance at 10, 5, and 1 percent level, respectively.

NS = Not significant. 1Significant at the 5-percent level when using standard procedures but not significant (p value 0.15) 

when using the delete-a-group jacknife procedure to estimate variances (Kott, 1998). 

Source: USDA Economic Research Service using data from 2005 and 2010 Agricultural Resource Management Survey 

corn surveys.
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Cornejo and Wechsler (2012) specified an econometric model to estimate the impact of adoption that 

accounts for self-selection. Using this model, they found that a 10-percent increase in the probability 

of adopting Bt corn was associated with a 1.7-percent increase in yields in 2005, and in a new ERS 

analysis using 2010 survey data, they found a 2.3-percent increase in yields (table 6). Using a similar 

econometric method to analyze cotton data, ERS researchers found that a 10-percent increase in 

the probability of adopting Bt cotton was associated with a 2.1-percent increase in yields in 1997 

(Fernandez-Cornejo and McBride, 2002). 

The effect of HT seeds on yields is mixed. The evidence on the impact of HT seeds on soybean, 

corn, and cotton yields is mixed (table 4). Several researchers found no significant difference 

between the yields of adopters and nonadopters of HT; some found that HT adopters had higher 

yields, while others found that adopters had lower yields. For instance, an ERS study found that 

a 10-percent increase in the adoption of HT cotton led to a 1.7-percent increase in cotton yields. 

HT soybean adoption was associated with a statistically significant, but small, increase in yields: a 

10-percent increase in the probability of adopting HT soybeans was associated with a 0.3-percent 

increase in yields (Fernandez-Cornejo and McBride, 2002). 

ARMS results show that HT soybean yields were 5 bushels per acre (3 percent) higher than conventional soybean yields in 2006 (but only significantly different at the 10-percent level) (table 7). In the 

case of corn, ARMS results show that HT corn yields were similar to those of conventional corn in 

2010. However, unlike soybeans, the majority of corn (and cotton) producers in recent years use seed 

with stacked traits (figs. 9 and 10). Multiple stacked traits make evaluating the effect of individual 

GE traits on yields and profitability more complicated. 

Stacked-trait seeds tend to have higher yields. An analysis of ARMS corn data indicates that 

stacked seeds (seeds with several GE traits) have higher yields than conventional seeds or seeds with 

only one GE trait. For example, 2010 ARMS data show that conventional corn seeds had an average 

 

 

 

Figure 8

Average yields (in bushels per acre) for U.S. corn farmers in 2010

Source: USDA, Economic Research Service using data from 2010 Agricultural Resource Management Survey (ARMS)

Phase II corn survey.

0 - 49

50 - 149

150 - 260
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yield of 134 bushels per acre in 2010. By contrast, seeds with two types of herbicide tolerance 

(glyphosate and glufosinate) and three types of insect resistance (corn borer, corn rootworm, and 

corn earworm) had an average yield of 171 bushels per acre. These results are consistent with findings by Nolan and Santos (2012), who analyzed a rich dataset of experimental hybrid trials collected 

by the extension services of 10 universities in major corn-producing States from 1997 to 2009. 

Not surprisingly, adoption rates of stacked-seed varieties have increased quickly (figs. 9 and 10). 

Stacked corn seeds grew from 1 percent of the corn acres in 2000 to 9 percent in 2005 and 71 

percent in 2013, while stacked cotton seeds grew from 20 percent to 34 percent in 2005, and 67 

percent in 2013 (figs. 9-10). The most widely adopted GE corn varieties have both Bt and HT traits 

(table 8). Varieties with three or four traits are now common. 

GE seed prices are influenced by stacking and many other factors. The market price of seed 

incorporates the costs associated with seed development, production, marketing, and distribution 

(Fernandez-Cornejo, 2004). The price must reflect farmers’ willingness to pay while ensuring a profit 

margin after costs. Furthermore, the price depends on the competitiveness of the particular seed 

market, and the pricing behavior of those firms that hold large shares of the market (NRC, 2010). 

Table 7

HT soybean adopters and non-adopters, 2006 

Variable Units

HT 

adopters

Nonadopters Difference Significance

Yield Per acre yields, in bushels 45.6 40.6 5.0 *

Total herbicide use Pounds AI per acre 1.36 1.05 0.31 NS

Glyphosate use Pounds per acre 1.23 0.38 0.85 ***

Other herbicides use Pounds per acre 0.13 0.66 -0.53 **1

*, **, and *** Indicates statistical significance at 10-, 5-, and 1-percent level, respectively.

NS = Not significant.

1Significant at the 5-percent level when using standard procedures but not significant (p value = 0.14) when using the 

jacknife procedure to estimate variances (Kott, 1998).

HT crops have herbicide tolerance traits.

Source: Economic Research Service using data from 2006 Agricultural Resource Management Survey soybean survey.

Table 6

The Impact of adopting Bt corn: Elasticities 2005, 20101

Variable

Elasticity with respect to the probability of adoption

2005 2010

Net returns 0.17 0.23

Yield 0.17 0.23

Seed 0.1 0.21

Insecticide NS NS

1Elasticity measures the responsiveness of a variable (e.g., s, yield) to a change in another (e.g., adoption rate). It is unit 

free and always expressed in percentage terms.

Bt crops have insect-resistant traits

NS = Not significant.

Sources: 2005: Fernandez-Cornejo and Wechsler (2012). 2010: New analysis by Economic Research Service. (Model 

results using 2010 ARMS corn data. Model specification similar to that used by Fernandez-Cornejo and Wechsler, 2012). 
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In recent decades, private sector R&D costs have been rising with the application of new technologies, and much of the increase in seed prices has been associated with this trend (Krull et al., 1998). 

R&D costs vary among the different seed markets. For example, the corn seed market depends 

extensively on private sector R&D and passes these costs on to farmers. The wheat seed market 

Figure 9

Adoption of genetically engineered corn: growth of stacked traits, 2000-2013 

Bt crops have insect-resistant traits; HT crops have herbicide tolerance traits.

Source: U.S. Department of Agriculture (USDA), Economic Research Service (ERS). 2013. Adoption of Genetically 

Engineered Crops in the United States, data product.

Percent of acres planted

0

10

20

30

40

50

60

70

80

90

100

2000 01 02 03 04 05 06 07 08 09 10 11 12 13

Bt only

Stacked (Bt and HT)

HT only

0

10

20

30

40

50

60

70

80

90

100

2000 01 02 03 04 05 06 07 08 09 10 11 12 13

Bt only

Stacked (Bt and HT)

HT only

Figure 10

Adoption of genetically engineered cotton: growth of stacked traits, 2000-2013 

Bt crops have insect-resistant traits; HT crops have herbicide tolerance traits.

Source: U.S. Department of Agriculture (USDA), Economic Research Service (ERS). 2013. Adoption of Genetically 

Engineered Crops in the United States, data product.

Percent of acres planted
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depends largely on public sector research, which is largely cost free for farmers. There is no GE 

wheat commercially available.20

The real price index for seed rose nearly 30 percent faster than the average index of prices paid by 

U.S. farmers over 1996-2007 (NRC, 2010). The price of GE soybean and corn seeds grew by about 

20Monsanto discontinued breeding and field level research on its GE Roundup Ready wheat in 2004.

Table 8

Adoption of genetically engineered varieties by U.S. corn producers, 2010

GE traits (percent adopters)

Seed Type Bt only HT only Bt/HT No GE

1. Genetically modified herbicide resistant seed variety (e.g. 

LIBERTYLINK; ROUNDUP READY CORN) 21.36

2. Non-genetically modified herbicide resistant seed variety 

(e.g. IMI-CORN) 3.48

3. Genetically-modified Bt variety for insect resistance to 

control the European Corn Borer (Bt-ECB) (e.g. YIELDGARD, 

YIELDGARD CORN BORER, HERCULEX I, NATUREGARD, 

KNOCKOUT) 7.12

4. Genetically modified Bt variety for insect resistance to control the corn rootworm (Bt-CRW) (e.g. YIELDGARD ROOTWORM, HERCULEX RW) 3.06

5. Stacked gene (trait) variety with both genetically modified 

Bt-ECB and Bt-CRW (e.g. YIELDGARD PLUS, HERCULEX 

XTRA) 3.81

6. Stacked gene variety with two genetically modified herbicide resistant traits (e.g. LIBERTYLINK + ROUNDUP READY) 3.73

7. Stacked gene variety with both genetically modified Bt-ECB

and herbicide resistant (e.g. YIELDGARD + ROUNDUP 

READY, YIELDGARD CORN BORER WITH ROUNDUP 

READY CORN 2, HERCULEX I + LIBERTYLINK) 9.77

8. Stacked gene variety with both genetically modified 

Bt-CRW and herbicide resistant (e.g. YIELDGARD ROOTWORM WITH ROUNDUP READY CORN 2, HERCULEX CW + 

ROUNDUP READY CORN ) 8.03

9. Triple stacked gene variety with genetically modified BtECB and Bt-CRW plus herbicide resistant traits (e.g. YIELDGARD PLUS WITH ROUNDUP READY CORN 2, HERCULEX 

XTRA + LIBERTYLINK) 25.91

10. Stacked gene varieties that, in addition to the ECB and the 

rootworm, can control the corn earworm

5.71

11. Multiple (more than three) trait stacked variety with several Bt traits and two herbicide resistant traits—glyphosate 

(Roundup) and glufosinate (Liberty) 1.24

12. None of the above 6.79

Total 13.99 25.08 50.66 10.26

Source: USDA Economic Research Service using data from 2010 Agricultural Resource Management 

Survey corn survey.
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50 percent in real terms (adjusted for inflation) between 2001 and 2010 (fig. 11). The price of GE 

cotton seed grew even faster (NRC, 2010). 

The increase in GE seed prices can be attributed in part to increasing price premiums over conventional seeds (which include technical fees) associated with the rising share of GE seeds with more 

than one trait and/or more than one mode of action for particular target pests (NRC, 2010). Another 

factor contributing to the increase in GE seed prices is the improvement in seed genetics (germplasm) (NRC, 2010). The rapid adoption of GE crops indicates that many farmers are willing to pay 

higher seed prices because of improved seed performance and the additional pest management traits 

embedded in the GE seed. 

Various studies of stacked GE seed varieties have found that stacked seeds are priced less than the 

sum of their component values (Stiegert et al., 2010). Shi et al. (2008, 2010) note that sub-additive 

pricing is consistent with “the presence of economies of scope in seed production.” Moreover, 

these scope economies are consistent with “synergies in R&D investment (treated as a fixed cost)” 

across stacked seeds that can contribute to reducing total cost (Shi et al., 2010). Shi et al. (2009) 

found that while increased concentration in the seed industry has contributed to higher seed prices, 

complementarity effects in production and distribution mitigate these effects. Kalaitzandonakes et 

al. (2010-11) conclude that, while estimation of market power and associated price markups is not 

straightforward, the U.S. seed industry show both “moderate market power” and dynamic market 

efficiency (as indicated by the balance between firm profits and investments in product quality and 

innovation) over their period of analysis (1997-2008).

Adoption, Net Returns, and Farm Household Income 

The impacts of GE crop adoption vary by crop and technology. Most studies show that adoption of 

Bt cotton and Bt corn is associated with increased net returns (table 4). However, some studies of 

Bt corn show that profitability is strongly dependent on pest infestation levels.21 The impact of HT 

seeds (for corn, cotton, and soybeans) on net returns depends on many factors.

Planting Bt cotton and Bt corn is often more profitable than planting conventional seeds. ERS 

researchers found that adoption of Bt cotton was positively associated with net producer returns in 

1997 (Fernandez-Cornejo and McBride, 2002). Using 2005 ARMS data, Fernandez-Cornejo and 

Wechsler (2012) found that a 10-percent increase in the probability of adopting Bt corn was associated with a 1.7-percent increase in net returns. In a new ERS analysis using 2010 ARMS data, we 

find that a 10-percent increase in the probability of adopting Bt corn was associated with 2.3-percent 

increase in net returns (table 6). Thus, there is essentially no change compared to earlier findings 

that planting Bt cotton and Bt corn is more profitable, as measured by net returns, than planting 

conventional seeds. 

The effect of HT seeds on net returns depends on many factors. A primary advantage of herbicide-tolerant crops over traditional crops is cost savings (Fernandez-Cornejo and McBride, 2002). 

Producers who plant HT crops expect to achieve at least the same output while lowering weed 

21Because pest pressure varies from one region to another, the economic benefits of Bt corn and consequently the rates 

of adoption vary regionally (fig. 6). Additionally, farmers must decide whether or not to use Bt corn before they know the 

severity of pest infestations, corn prices, or the price of insecticides. “Overadoption” may result from incorrect predictions (Fernandez-Cornejo and McBride, 2002). Alternately, farmers may be willing to adopt Bt seeds in order to reduce 

the risks associated with infestation levels that are higher than expected.
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control costs for chemicals and for mechanical methods, and minimizing the need for scouting. In 

return, producers pay more for HT seeds. 

An additional economic effect is that the substitution of glyphosate, used in most herbicide-tolerant 

programs, for other herbicides decreases the demand for (and thus the price of) other herbicides 

Figure 11

Prices of genetically engineered (GE) seed are higher than those of non-GE seed, soybeans

HT crops have herbicide tolerance traits.

Source: USDA Economic Research Service using data from USDA National Agricultural Statistics Service 

Agricultural Prices, various years.

2007 $ per bushel

Prices of genetically engineered (GE) seed are higher than those of non-GE seed, corn

2007 $ per bag (80,000 kernels)

0

50

100

150

200

250

300

2001 02 03 04 05 06 07 08 09 10

 GE corn

Non-GE

0

10

20

30

40

50

2001 02 03 04 05 06 07 08 09 10

HT soybeans

Conventional soybeans
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(Fernandez-Cornejo and McBride, 2002). Thus, the introduction of HT seeds may have lowered 

pesticide costs for both HT seed adopters and nonadopters. 

Finally, HT seed-based production programs allow growers to use one product to control a wide 

range of both broadleaf and grass weeds instead of using several herbicides to achieve adequate 

weed control. Herbicide-tolerant crops also complement ongoing trends toward post-emergence 

weed control, the adoption of conservation tillage practices, and the use of narrow row spacing. The 

simplicity and flexibility of weed control programs for HT seeds require less management attention, 

freeing valuable management time for other activities (Fernandez-Cornejo and McBride, 2002). 

HT seed has a mixed effect on net returns. The evidence on the impact of HT seeds (for corn, 

cotton, and soybeans) on net returns is mixed (table 4). Several researchers (Fernandez-Cornejo 

and McBride, 2002; Bernard et al., 2004; Marra et al., 2002) found that the adoption of herbicidetolerant cotton has a positive impact on net returns. For example, Fernandez-Cornejo and McBride 

(2002) found that the elasticity of net returns with respect to the probability of adoption of herbicidetolerant cotton was +0.18.22 Bernard et al. (2004) found that adopting HT soybeans improved profits 

on Delaware farms. However, Fernandez-Cornejo et al. (2002) and McBride and El-Osta (2002) 

found no significant difference between the net returns of adopters and nonadopters of HT soybeans. 

Bullock and Nitsi (2001) found that HT soybean farmers are less profitable than their conventional 

counterparts. Overall, the empirical evidence on the impact of adopting herbicide-tolerant soybeans 

on net returns is inconclusive (NRC, 2010).23

The fact that several researchers found no significant differences between the net returns of adopters 

and nonadopters of HT crops (particularly HT soybeans) despite the rapid adoption of these crops 

suggests that many adopters may derive nonmonetary benefits from HT adoption. In particular, 

weed control for HT soybeans may be simpler, freeing up management time for leisure, enterprise 

growth, or off-farm income-generating activities.

HT crop adoption increases farm household income and has non-pecuniary benefits. ERS 

research shows that HT adoption is associated with higher off-farm household income for U.S. 

soybean farmers, most likely because time savings are used to generate income via off-farm employment (Fernandez-Cornejo et al., 2005). ERS researchers found that a 10-percent increase in the 

probability of adopting HT soybeans is associated with a 16-percent increase in off-farm household 

income. Household income from onfarm sources is not significantly associated with adoption of HT 

technology (Fernandez-Cornejo et al, 2007). These findings corroborate the notion that technology 

adoption is influenced by (or influences) the tradeoff between household/operator time spent in 

onfarm and off-farm activities. More recently, Gardner et al. (2009) confirm that genetically engineered crops lead to household labor savings in U.S. crop (corn and cotton) production. Using corn 

and soybean data, Marra and Piggott (2006) demonstrate that there are non-pecuniary benefits to 

GE crop adoption and show that farmers adopting GE crops place a monetary value on the convenience, flexibility, and increased worker safety associated with growing HT crops. 

22Elasticity measures the responsiveness of a variable (e.g., net returns) to a change in another (e.g., adoption rate). It is 

unit free and is expressed in percentage terms.

23Given the high rates of adoption of HT soybeans (more than 90 percent in recent years), econometric studies using 

recent data are problematic because of the small size of the sample of nonadopters and the likelihood that there may be 

other factors influencing the decision not to adopt (e.g., organic farming) of that small group. This may lead to a stronger 

selection bias compared to studies using data from earlier years.
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Adoption and Pesticide Use

Many studies based on field tests and farm surveys have examined the extent to which GE crop 

adoption affects pesticide (insecticide and herbicide) use, and most results show a reduction in 

pesticide use (table 4). A National Research Council study (2010) concurred that GE crops lead to 

reduced pesticide use and /or lower toxicity compared to conventional crops. 

Insecticide use decreases with the adoption of Bt crops. Generally, Bt adoption is associated with 

lower insecticide use (table 4). Pounds of insecticide (per planted acre) applied to corn and cotton 

crops have declined over the course of the last 15 years (fig. 12). (Results for cotton in 1999-2001 

were distorted because of the high application rates of the insecticide Malathion during the boll 

weevil eradication program.)

Insecticide use on corn farms declined most years and had an overall drop from 0.21 pound per corn 

planted acre of corn in 1995 (the year before Bt corn was commercially introduced) to 0.06 in 2005 

and 0.02 pound in 2010 (fig. 12). Insecticide use has declined for both Bt adopters and nonadopters 

in recent years. According to ARMS data, only 9 percent of all U.S. corn farmers applied insecticides in 2010.

Econometric studies by ERS researchers have also found that, except for recent years, Bt crop 

adoption led to decreases in insecticide use, controlling for other factors. For example, FernandezCornejo et al. (2003) show that the adoption of Bt cotton in the Southeast region (which had higher 

rates of Bt adoption) was associated with lower insecticide use on cotton in 1997. After controlling 

for other factors, a 10-percent increase in Bt corn adoption was associated with a decrease in insecticide use of 4.1 percent in 2001 (Fernandez-Cornejo and Li, 2005). However, Bt corn adoption was 

not significantly related to insecticide use in more recent years using 2005 data (Fernandez-Cornejo 

and Wechsler, 2012), as well as in a new ERS analysis using 2010 survey data (table 6). 

Figure 12

Insecticide use in corn and cotton production, 1995-2010

Source: USDA Economic Research Service using data from USDA National Agricultural Statistics Service 

Agricultural Chemical Usage reports.

Cotton, pounds per planted acre Corn, pounds per planted acre

0

0.05

0.10

0.15

0.20

0.25

0.30

0

0.50

1.00

1.50

2.00

2.50

3.00

1995 96 97 98 99 2000 01 02 03 04 05 06 07 08 09 10

Cotton insecticides

(left axis) 

Corn insecticides

(right axis) 
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Taken together, these results suggest that insect infestation levels on corn were lower in recent years 

than in earlier years and are consistent with findings by Hutchinson et al. (2010) that European 

corn borer populations have steadily declined over the last decade. Moreover, several researchers 

have shown that areawide suppression of certain insects such as the European corn borer and the 

pink bollworm are associated with the use of Bt corn and Bt cotton, respectively (see box, “Bt Crop 

Adoption and Areawide Pest Suppression”). 

Adoption of HT crops has mixed impact on herbicide use. Herbicide use on cotton and soybean 

acres (measured in pounds per planted acre) declined slightly in the first years following introduction of HT seeds in 1996, but increased modestly in later years (fig. 14a). Herbicide use on soybean 

farms has been mostly constant since 1996, but increased slightly starting in 2002 and peaked in 

2006. Herbicide use on corn fell from about 2.6 pounds per acre in the early years of HT corn adoption to less than 2 pounds per acre in 2002 but increased moderately in recent years. Herbicide use 

on corn by HT adopters increased from around 1.5 pounds per planted acre in both 2001 and 2005 

to more than 2.0 pounds per planted acre in 2010, whereas herbicide use by nonadopters did not 

change much (fig. 14b). HT adoption likely reduced herbicide use initially, but herbicide resistance 

among weed populations may have induced farmers to raise application rates in recent years, thus 

offsetting some of the economic and environmental advantages of HT corn adoption regarding 

herbicide use.24

The main effect of HT crop adoption on herbicide use is the substitution of glyphosate for more 

toxic herbicides. Despite the mixed but relatively minor effect HT crop adoption has had on overall 

herbicide usage, most researchers agree (NRC, 2010) that the main effect of HT crop adoption is 

the substitution of glyphosate for more traditional herbicides. Because glyphosate is significantly 

24Adoption of conservation tillage by HT adopters may have also confounded these comparisons.

Figure 13

Insecticide use in corn farms: adopters and non-adopters of Bt corn, 2001-2010

Bt crops have insect-resistant traits.

Source: USDA Economic Research Service using data from 2001, 2005, and 2010 ARMS Phase II corn surveys. 

Pounds per planted acre

0

0.02

0.04

0.06

0.08

0.10

0.12

2000 2005 2010

Bt adopters

Non-adopters
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less toxic and less persistent than traditional herbicides (WHO, 1994; NRC, 2010),25 the net impact 

of HT crop adoption is an improvement in environmental quality and a reduction in the health 

risks associated with herbicide use (even if there are slight increases in the total pounds of herbicide applied).26 However, glyphosate resistance among weed populations in recent years may have 

induced farmers to raise application rates. Thus, weed resistance may be offsetting some of the 

economic and environmental advantages of HT crop adoption regarding herbicide use. Moreover, 

herbicide toxicity may soon be negatively affected (compared to glyphosate) by the introduction 

(estimated for 2014) of crops tolerant to the herbicides dicamba and 2,4-D. 

25However, recent publications have raised questions regarding the toxicity of glyphosate. Seralini et al. (2012) claim 

that GE corn and low levels of glyphosate herbicide formulations at concentrations well below officially-set safe limits 

induce severe adverse health effects, such as tumors, in rats. But a review of the study by the European Food Safety 

Authority (EFSA, 2012) concluded the Seralini et al. study as reported in the publication “is inadequately designed, 

analyzed and reported” and is “of insufficient scientific quality for safety assessments. As a result, the EFSA states that 

“conclusions cannot be drawn on the difference in tumour incidence between treatment groups on the basis of the design, 

the analysis and the results as reported.” In a separate study, Mesnage et al. (2012) find that while toxicity of glyphosate 

has been safety tested on mammals, another ingredient used in commercial formulations used as adjuvant is toxic. More 

recently, Samsel and Sanoff (2013) claim that “glyphosate enhances the damaging effects of other foodborne chemical 

residues and environmental toxins.” 

26HT crops also simplify the management of pesticide application (Carpenter and Gianessi, 1999). There is a greater 

window over which the herbicides can be applied (glyphosate can be effective on older plants). This makes it much easier 

to manage weather-related delays to the herbicide application schedule. Use of glyphosate also may reduce the need for 

aerial applications that are sometimes needed when it is too wet to enter the field. 

Bt Crop Adoption and Areawide Pest Suppression

Hutchinson et al. (2010) show that areawide suppression of the European corn borer is associated with Bt corn use. They estimate that the cumulative benefits of Bt adoption over 14 years 

exceed $6 billion for corn growers in Illinois, Minnesota, Wisconsin, Iowa, and Nebraska. 

Non-adopters captured $4.3 billion of these benefits because they reap the rewards associated 

with low infestation rates without paying a premium for insect-resistant seeds.

Carrière et al. (2003) conducted a 10-year study in 15 regions across Arizona and showed that 

Bt cotton suppressed a major pest, the pink bollworm, “independent of demographic effects 

of weather and variation among regions.” Pink bollworm population density declined only in 

regions where Bt cotton was abundant. Such long-term suppression has not been observed with 

insecticide sprays, suggesting that deployment of Bt crops may also contribute to reducing the 

need for insecticide sprays.

Earlier, Marra et al. (2002a) considered the side-by-side trials of Bt and conventional varieties. 

They discuss the bias caused by the “halo effect” that arises from the insect suppression of the 

Bt crops spilling over onto the conventional treatments, thus increasing the yield of the conventional crop relative to what it would be if the conventional crop were grown in isolation. This 

effect biases downward the yield difference between the Bt and conventional varieties.

Based on data from 36 sites in 6 provinces of northern China over 1990-2010, Lu et al. 

(2012) found that there was an increase in beneficial insects (such as ladybirds and lacewings) and a decrease in pests (aphids) associated with the widespread use of Bt cotton 

reducing insecticide sprays.
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Adoption and Conservation Tillage

Conservation tillage (including no-till, ridge-till, and mulch-till) is known to provide environmental 

benefits (USDA’s ERS/NRCS, 1998; NRC, 2010). By leaving substantial amounts of crop residue (at 

least 30 percent) covering the soil surface after planting, conservation tillage reduces soil erosion by 

Figure 14a

Herbicide use in cotton, corn, and soybeans, 1995-2010

HT crops have herbicide tolerance traits.

Source: USDA Economic Research Service using data from 2001, 2005, and 2010 ARMS Phase II corn surveys. 

Pounds per planted acre

Figure 14b

Herbicide use on corn: HT adopters and nonadopters, 2001-2010

Pounds per planted acre

0

0.50

1.00

1.50

2.00

2.50

3.00

1995 96 97 98 99 2000 01 02 03 04 05 06 07 08 09 10

Cotton herbicides

Corn herbicides

Soybean herbicides 

Data for herbicide use for soybeans in 2007 and 2008 are from proprietary data.

Source: USDA/NASS Agricultural Chemical Usage reports and USDA/NASS Quickstats. 

0

0.50

1.00

1.50

2.00

2.50

2000 2005 2010

HT adopters

Nonadopters
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wind and water, increases water retention, and reduces soil degradation and water/chemical runoff. 

In addition, conservation tillage reduces the carbon footprint of agriculture.

Adopters of HT crops practice conservation tillage more than growers of conventional varieties. 

Since the 1980s, the adoption of conservation tillage practices by U.S. farmers has been facilitated 

by the availability of post-emergent herbicides that can be applied over a crop during the growing 

season. Post-emergent herbicides are especially beneficial in no-till production systems because 

these herbicides control weeds without tilling the soil. HT crops have helped spread no-till farming 

further since they often allow a more effective system than just using other post-emergent herbicides 

(Fernandez-Cornejo and Caswell, 2006). 

According to USDA survey data, 60 percent of HT soybean planted acres used conservation tillage 

practices in 1997 versus 40 percent of conventional soybean acres (Fernandez-Cornejo and Caswell, 

2006). By 2006, approximately 86 percent of HT soybean planted acres were under conservation 

tillage compared to only 36 percent of conventional soybean acres (fig. 15).

Differences in the use of no-till specifically are just as pronounced. While approximately 45 percent 

of HT soybean acres were cultivated using no-till technologies in 2006, only 5 percent of the 

acres planted with conventional seeds were cultivated using no-till techniques.27 Cotton and corn 

data exhibit similar though less pronounced patterns. Thirty-two percent of HT cotton acres were 

planted using conservation tillage in 2007, compared to 17 percent of conventional cotton acres (fig. 

16). Thirty-three percent of HT corn acres were planted using no-till in 2005, versus 19 percent of 

conventional corn acres (fig. 17).

27No-till systems are often considered the most effective of all conservation tillage systems. They leave 100 percent of 

crop residues on the soil surface and the soil is undisturbed from harvest to planting, resulting in the highest percentage 

of surface being covered by crop residues, minimizing soil loss and water runoff (Janssen and Hill, 1994). 

Figure 15

Adopters of herbicide-tolerant crops used conservation tillage more than did growers of 

conventional varieties: soybeans, 2006

Conservation tillage includes no-till, ridge-till and mulch-till. 

Source: USDA Economic Research Service using data from 2006 ARMS Phase II soybean survey.

Percent of acres

0

20

40

60

80

100

HT Conventional varieties

Conventional tillage practices

Other conservation tillage practices

(excludes no-till)

 No-till
28

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These trends suggest that HT crop adoption may encourage soil conservation practices. In addition, a 

review of several econometric studies point to a two-way causal relationship between the adoption of 

HT crops and conservation tillage (NRC, 2010). This implies that the adoption of herbicide-tolerant 

crops indirectly benefits the environment.

0

20

40

60

80

100

HT Conventional varieties

Figure 16

Adopters of herbicide-tolerant crops used conservation tillage more than did growers 

of conventional varieties: cotton, 2007

Conservation tillage includes no-till, ridge-till and mulch-till.

Source: USDA Economic Research Service using data from 2007 ARMS Phase II cotton survey.

Percent of acres

Conventional tillage practices

Other conservation tillage practices

(excludes no-till)

 No-till

0

20

40

60

80

100

HT Conventional varieties

Figure 17

Adopters of herbicide-tolerant crops used conservation tillage more than did growers 

of conventional varieties: corn, 2005

Conservation tillage includes no-till, ridge-till and mulch-till. 

Source: USDA Economic Research Service using data from 2005 ARMS Phase II corn survey.

Percent of acres

Conventional tillage practices

Other conservation tillage practices

(excludes no-till)

 No-till
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Pest Resistance Management and GE Crops

Pesticide resistance evolution occurs when pesticide use favors the survival of pests naturally resistant to the pesticide. Over time, these resistant pests become predominant in the pest population (see 

box, “Economics of Resistance Management”). Developers of Bt crops and other researchers recognized early on that insect resistance to Bt toxins could develop. Measures to delay the onset of such 

resistance (such as refuges) were taken and, so far, the emergence of insect resistance to Bt crops has 

been low and of “little economic and agronomic significance” (NRC, 2010), but there are some indications that insect resistance is developing to some Bt traits in some areas.28 Also, since many users 

of HT crops rely solely on glyphosate to control weeds, resistance to this herbicide was anticipated 

by some researchers. Thus far, overreliance on glyphosate and a reduction in the diversity of weed 

management practices adopted by crop producers have contributed to the evolution of glyphosate 

resistance in 14 weed species and biotypes in the United States.

Insect Resistance to Bt Crops 

Prior to the availability of Bt crops, entomologists and other scientists successfully argued that 

mandatory refuge requirements—planting sufficient acres of the non-Bt crop near the Bt crop—were 

needed to reduce the rate at which targeted insect pests evolved resistance. Such refuges slow the 

rate at which Bt resistance evolves by allowing target insects that are susceptible to the Bt toxin to 

survive and reproduce. To be effective, the refuge must be positioned appropriately and be large 

enough to ensure that insects that survive on the Bt acres mate with insects that survive on the 

non-Bt acres. Such interbreeding increases the chances that their progeny are susceptible, having 

inherited Bt resistance as a recessive trait.29

The U.S. Environmental Protection Agency (EPA) instituted mandatory refuge requirements as a 

condition of the registration of Bt corn and Bt cotton varieties for commercial use in the United 

States. This was the first time regulations were used to manage resistance to a pest control technology. Bt crop growers were required to sign a contract with their technology provider to comply 

with minimum refuge requirements, and technology providers were required to monitor and 

enforce grower compliance. An analysis of more than a decade of monitoring data suggests that the 

minimum refuge requirement, as well as natural refuges that also serve as hosts for target insect 

pests, has helped delay the evolution of Bt resistance (Tabashnik et al., 2008). 

28There is some indication of emergence of Bt-resistant corn rootworm in some parts of the Corn Belt http://www.

bloomberg.com/news/2012-09-04/-mounting-evidence-of-bug-resistant-corn-seen-by-epa.html. http://bulletin.ipm.

illinois.edu/article.php?id=1704. There is also anecdotal evidence that resistance is a contributing factor to increasing 

corn insecticide sales in 2012 and 2013 (I. Berry; WSJ, May 21, 2013). Tabashnik et al. (2013) recently analyzed 77 studies carried out in 5 continents from 1996 to 2012. They find that “although most pest populations remained susceptible, 

reduced efficacy of Bt crops caused by field-evolved resistance has been reported now for some populations of 5 of 13 

major pest species examined, compared with resistant populations of only one pest species in 2005.” They conclude that 

“the increase in documented cases of resistance likely reflects increases in the area planted to Bt crops, the cumulative 

duration of pest exposure to Bt crops, the number of pest populations exposed and improved monitoring efforts.” They 

also conclude that while “regulations in the United States and elsewhere mandate refuges of non-Bt host plants for some 

Bt crops, farmer compliance is not uniformly high and the required refuge percentages may not always be large enough 

to achieve the desired delays in evolution of resistance. Both in theory and practice, using Bt crops in combination with 

other tactics as part of integrated pest management may be especially effective for delaying pest resistance.”

29A dominant trait will be expressed in progeny if at least one of the parents has the gene for that trait. A recessive trait 

will be inherited if both parents have the gene for that trait. (Hedrick, 2000). 
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Economics of Resistance Management

When a pest population is confined to an individual farming operation, many of the benefits 

and costs associated with the farmer’s pest control decisions accrue to and are borne by the 

farmer. In this hypothetical scenario, economic theory suggests that the pest population will 

be maintained at an economically efficient or socially optimal level.1 However, when the pest 

moves from farm to farm, the pest control decisions made by any given farmer will affect 

the net returns accruing to that farmer, as well as those accruing to nearby farmers, although 

to a lesser extent. Because the effects of any farmer’s control decisions on the regional pest 

population are practically negligible and because the benefits and costs associated with those 

effects are not borne by any given farmer (are not fully internalized), those effects might not 

be accounted for in the farmer’s control decision. Because regional pest population dynamics 

are determined collectively by the decisions made by each farmer in the region, however, 

economic theory suggests that the pest population will not be maintained at a socially optimal 

level (Feder and Regev 1975).

This situation is referred to in the economics literature as a stock externality, an economic 

environment in which an individual ignores the impact of a decision that affects the level of 

a resource that is used by others (Gordon, 1954). In the presence of a stock externality, the 

resource might not be managed in a socially optimal manner. When the resource is a mobile 

pest population, Feder and Regev (1975) show how the introduction of a marginal user cost on 

pesticides, via a tax or a subsidy depending on the characteristics of the problem, can improve 

social welfare by ensuring that all of the net returns to pesticide use accrue to each user. The 

marginal user cost for a pesticide is the marginal expected present value of economic and 

environmental costs associated with the use of the pesticide, including impacts on regional 

pest population dynamics, impacts on the regional population dynamics of beneficial organisms that prey on the pest, and the evolution of resistance in the regional pest population to the 

pesticide, as well as the health effects associated with the accumulation of toxic pesticide residues and water/air pollution.

Pesticide resistance evolution is a process of artificial selection in which pesticide use favors 

the survival of particular insects and weeds and other pests resistant to the pesticide so that 

the frequency of resistant individuals in the population increases over time. In the presence of 

a mobile pest, farmers might not account for the effects of their pesticide use decisions on the 

evolution of resistance nor for the effects on regional pest population dynamics (Miranowski 

and Carlson, 1986). Hueth and Regev (1974) suggest that the institution of a tax equal to the 

marginal user cost could improve social welfare by ensuring that the costs associated with 

resistance are incorporated by farmers. Regev et al. (1983) examine such a tax in another 

theoretical analysis; however, noting the difficulty of applying the tax in practice, they suggest 

pesticide-use restrictions as an alternative.

1For the purposes of this discussion, we are ignoring the costs associated with the accumulation of toxic pesticide residues, leaching of pesticides into surface and groundwater resources, and pesticide drift.
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Refuge requirements depend on economic factors. Hurley et al. (2001) and Livingston et al. (2004) 

examine the characteristics of economically efficient refuge requirements for U.S. corn and cotton 

producers, respectively, for the single-toxin Bt corn and Bt cotton varieties. Both studies demonstrate 

that economic returns might be improved over the long run if corn and cotton producers comply 

with refuge requirements because of forestalling the onset of Bt resistance. The size of the economically efficient refuge requirement, however, was shown to depend on the length of the time horizon, 

the discount rate, and resistance evolution to conventional insecticides used to control target insect 

pests in the refuge acres. The refuge’s ideal size was also shown to be extremely sensitive to how 

dominant the inherited Bt resistance trait is. Larger refuges are required to maintain susceptibility 

to Bt in target pest populations for longer time periods and when Bt resistance is inherited as a more 

dominant genetic trait by the target insect species.

Livingston et al. (2007) provide empirical support for the relaxation of mandatory refuge requirements for farmers who plant cotton varieties that express multiple Bt toxins in areas that have 

sufficient sources of unstructured refuge.30 These varieties control the target pest species much 

more effectively than single-toxin varieties. Also, most U.S. cotton is grown in areas with sufficient 

sources of unstructured refuge—including both cultivated and uncultivated crops and plants that 

serve as alternative hosts for the target insect pest species, particularly the cotton bollworm and the 

tobacco budworm—effectively eliminating the need for a structured (or minimum) refuge requirement. Cotton growers in Arizona, California, New Mexico, and west Texas are still required to plant 

minimum, structured refuges.

Refuge requirements are reduced for multiple-toxin Bt cotton varieties in some areas. EPA has 

eliminated the minimum refuge requirement for certain Bt cotton varieties that express multiple 

toxins in areas that appear to have sufficient unstructured refuge, but not for Bt corn varieties 

that express multiple toxins. The latter are less toxic to an important target pest known as the 

western corn rootworm, which might inherit Bt resistance as a partially dominant trait. Recently, 

western corn rootworm larvae were collected from Iowa Bt cornfields that showed evidence of root 

damage, and laboratory assays later confirmed that their progeny were less susceptible to Bt toxins 

(Gassmann et al., 2011). This has raised concerns about regulatory compliance and a continued need 

for minimum refuge requirements for Bt corn growers.

Evolution of Glyphosate Resistance in Weeds

The herbicide glyphosate is more environmentally benign than the herbicides that it replaces. 

Glyphosate controls a wide array of weeds and is used on most of the HT corn, soybeans, and cotton 

grown in the United States. Glyphosate has been the most heavily used pesticide in the United States 

since 2001 (Grube et al., 2011), due in part to the popularity of HT crops and the steady decline in 

its price following the expiration of glyphosate’s patent in 2000 (Duke and Powles, 2008).31

Because the pollen and seeds of many different weed species can disperse between farms in the 

atmosphere and in conjunction with the movement of animals and farm equipment, economic incentives for adopting best management practices (BMPs) that maintain the effectiveness of glyphosate 

30According to Andow et al. (2008), “a structured refuge is one that is planted near Bt cotton deliberately and an unstructured refuge relies on the other crops already grown as part of the local cropping system and where Bt is not used.”

31Impending expiration of glyphosate patent protection in 2000 and the availability of generic glyphosate herbicides 

have led to a decrease in its price since 1998. 
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over time are reduced (Miranowski and Carlson, 1986).32 The economic and biological impacts 

associated with any farmer’s pesticide-use decisions will accrue not only to that farmer, but to other 

nearby farmers as well. Unless resistance management is coordinated across farms, economic incentives for farmers to account for the effects of their decisions on resistance are reduced, even on 

their own farms. This is because the effectiveness and longrun economic benefits of using BMPs to 

manage resistance depend on the level of adoption by nearby farmers, while the short-run costs of 

BMP adoption are borne solely by the adopters.33 In this setting, resistance can evolve at an economically inefficient rate because market-based economic incentives are insufficient to promote an efficient level of BMP adoption (Hueth and Regev, 1974; Feder and Regev, 1975).

This reduction in economic incentives to adopt BMPs and the economic and environmental benefits associated with the HT crop-glyphosate combination have contributed to an overreliance on 

glyphosate and a concomitant reduction in the diversity of weed management practices by U.S. 

crop producers. This, in turn, has contributed to the evolution of glyphosate resistance in some 

weed species and a shift in weed composition in fields, favoring weeds that are naturally resistant to 

glyphosate. This leads to higher management costs, reduced yields and profits, and increased use of 

less environmentally benign herbicides. Glyphosate resistance is currently documented in 14 U.S. 

weed species (Heap, 2012), and the potential exists for much more acreage to be affected (Frisvold 

et al., 2009; Shaw et al., 2011).34

Because no new major herbicide chemistry has been made commercially available in the last 20 

years, and because few new ones are expected to be available soon (Harker et al., 2012), many plant 

scientists believe that slowing the rate of glyphosate resistance and the spread of glyphosate-resistant 

(GR) weeds are among the most important problems facing U.S. crop producers (NRC, 2010, 2012). 

In addition, private and public programs seeking to promote the adoption of BMPs are in their 

infancy and do not address the reduced incentives to adopt BMPs caused by the ability of weed 

seeds to disperse between farms—the programs do not discourage the use of weed management 

practices that contribute to resistance. 

Best management practices (BMP) may help sustain the efficacy of HT crops. Because weeds 

tend to inherit resistance to glyphosate as a dominant trait, the mandatory refuge requirement, which 

has been successful in sustaining the efficacy of Bt crops, might not be a viable option for HT crops 

(NRC, 2010). Depending on the weed, several BMPs, which are relatively difficult to monitor and 

enforce, might be required. These include using at least one other herbicide (particularly a residual 

herbicide that takes longer to decompose and thus stays in the soil longer), rotating crops, increasing 

the intensity of tillage, cleaning equipment between use in different fields to prevent the spread of 

weed seeds and pollen, and optimizing application by using the application rate recommended on 

the herbicide label and applying herbicides at the appropriate time and uniformly throughout the 

field. Some of these practices have been associated with increased weed management costs (Hurley 

et al., 2009), and many farmers, perhaps due partly to the incentive problems described above, are 

32Dauer et al. (2009) provide empirical evidence that horseweeds, one of the more important glyphosate-resistant weed 

species, can disperse between farms.

33BMPs include applying multiple herbicides with different modes of action at the recommended rates and developmental stages for the target weeds in the field, increasing the intensity of tillage to reduce the fraction of seeds that 

germinate, planting weed-free crop seed, scouting fields routinely, cleaning equipment to reduce the rate of introducing 

weeds to other fields, and preventing weed introductions by maintaining field borders (Norsworthy et al., 2012).

34Glyphosate resistance in weed species and biotypes in the United States is also due to glyphosate use in tree 

orchards, on roadsides, and on non-HT crops, where it is used before crops are planted and after they are harvested.
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only adopting BMPs in the presence of glyphosate-resistant weeds, as opposed to adopting preventative approaches.35

Another approach currently being promoted by technology providers is the use of HT crops that are 

tolerant to two herbicides. However, the commercial availability of these types of crops does not 

address the incentive problem caused by the ability of weeds to disperse between farms. At least 

one HT crop provider is issuing rebates to growers who plant specific HT crop varieties, use glyphosate herbicides manufactured by that HT crop technology provider, and agree to use pre-emergent, 

residual herbicides.36 The rebate program promotes the use of glyphosate in combination with other 

herbicides, which mitigates resistance; however, the program does not fully address the reduced 

incentive to adopt BMPs caused by the ability of weed seeds and pollen to disperse between farms.

USDA’s NRCS recently initiated the Integrated Pest Management (IPM) Herbicide Resistance Weed 

Conservation Plan, which specifies guidelines for monitoring, recordkeeping, IPM, and conservation that satisfy criteria for soil, water, and air quality. Under the program, USDA pays farmers 75 

percent of the cost of developing activity plans, which contain the minimum components needed to 

apply for cost-sharing assistance under the Environmental Quality Incentives Program (EQIP). This 

program can help promote the adoption of BMPs. However, in the absence of widespread adoption 

of BMPs, farmer participation might be insufficient to manage the evolution of glyphosate resistance 

in a manner that is optimal for crop producers.

35Many farmers incorrectly assume there is no need to adopt BMPs because new herbicides will be available in the 

future (Norsworthy et al. 2012). In addition, the benefits of using BMPs occur in the future and are uncertain, as opposed 

to the certain increase in production costs.

36More information about this program is available at https://www.roundupreadyplus.com/Pages/Home.aspx. 
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Consumer Demand for GE Products

The successful marketing of crops produced via genetic engineering is contingent on consumer 

acceptance of these products (or products containing GE ingredients). Some consumers, including 

those in the European Union, have indicated a reluctance to consume GE products. In other countries, including the United States, expression of consumer concern is less widespread. Researchers 

studying markets in high-income nations often find that consumers are willing to pay a premium 

for non-GE products,37 but recent studies have found that some consumers in developing countries, 

and others interested in second-generation traits like enhanced nutrition content, are more willing to 

consider GE foods. Information and types of GE technology may also affect consumer response to 

GE foods. In some countries, retailers have developed particular policies for GE ingredients in the 

foods they sell under their own brand names. 

Willingness-to-Pay for GE and Non-GE Foods 

Researchers have used a variety of methodologies to determine how much consumers are willing to 

pay for GE foods and how much they are willing to pay to avoid them (table 9). Some studies use the 

contingent valuation method, in which consumers are asked how much they would pay for non-GE 

foods. Other studies use experimental auctions, in which participants bid with actual money. 

Consumers’ responses on a survey, however, may differ from what they are actually willing to spend 

while shopping (Lusk, 2003). Meta-analyses of surveys indicate that when consumers are asked 

how much they value a good hypothetically, the values differ from what they actually will pay in 

a market setting, with the size of the difference dependent on such factors as whether consumers 

are asked how much they are willing to accept or willing to pay, the magnitude of the hypothetical 

price, the type of auction used or choices offered, and the type of good being evaluated (Murphy et 

al., 2005; List and Gallet, 2001). Murphy et al. (2005) found that models where respondents were 

asked to choose among alternatives, as opposed to developing their own, were associated with less 

hypothetical bias. On average, consumers tend to overstate what they would pay for goods, although 

in a significant minority of cases, they understated what they would pay. The willingness-to-pay 

values therefore may only approximate what consumers will actually pay. 

Mather et al. (2011), combining surveys with market methodology, found that when consumers 

in five EU countries plus New Zealand were surveyed, they selected organic over conventional or 

GE fruit.38 However, when actual fruit stalls were set up offering three different varieties of fruit, 

consumers in Sweden, New Zealand, and Germany bought more of the GE varieties, also labeled 

“spray-free,” but only when they were offered at a 15-percent discount.

Consumer Acceptance of GE Foods in High- and Low-Income 

Countries

Research on consumer acceptance of GE foods in high-income countries such as the United States, 

UK, and Canada finds that consumers are willing to pay a premium for non-GE foods 

37Non-GE foods can be more expensive if they cost more to produce, or if marketing streams must be kept separate.

38Consumers who asked about the GE fruit were told that it contained genes that caused it to produce a natural insecticide. GE fruit is not commercially available in these countries, and consumers who expressed surprise about this were 

told the fruit may have come from an experimental orchard (Mather et al., 2011). 
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Table 9

Studies in which consumers were willing to pay a premium for non-GE food 

Country Good Study Willingness to pay premium [1]

United States Potatoes 

and corn

Bernard and Bernard, 

2010

In experimental nth price auction, found positive 

premium for non-GE food

United States Various Huffman, 2010

In experimental nth price auction, found 15-percent 

discount for GE food, but difference was only statistically significant for one of three foods

United States Tomatoes Bukenya and 

Wright,2007

Surveyed Alabama consumers willing to pay a $0.39 

or 19-21 percent premium for non-GE tomatoes

United States

Vegetable 

oil, tortilla 

chips, and 

potatoes

Huffman et al., 2007 Found consumers willing to pay 14 percent less for 

GE foods

United States Vegetable 

oil Tegene et al., 2003 In experimental auctions, consumers willing to pay 14 percent more for non-GE food

United States Potatoes Loureiro and Hine, 

2002

Customers willing to pay 5 percent more for non-GE 

food

United Kingdom All foods Burton et al.,2001 Customers indicated willingness to increase food 

budgets by 26-129 percent to avoid GE foods

United States, France, 

Germany, United Kingdom

Beef fed 

with GE 

feed

Lusk et al., 2003

U.S. consumers willing to pay $2.83 and $3.31 per 

lb. to avoid biotech; European consumers $4.86 to 

$11.01

United States, United Kingdom Breakfast 

cereal

Moon and Balasubramanian, 2001

Found 56 percent of UK consumers willing to pay a 

premium to avoid GE food, compared to 37 percent 

of U.S. consumers.

United Kingdom Various Moon et al., 2007

Found that consumers were willing to pay a 20-percent premium for non-GE products and willing to 

accept a discount of 23 percent for GE foods

UK, Belgium, France, 

Germany, New Zealand, 

Sweden

Fruit Mather et al., 2011

Found that surveyed consumers offered organic, 

conventional, or GM fruit stated that they wanted 

organic, but the same consumers at roadside stalls 

bought GM (labeled spray-free and offered at a 15- 

percent discount) 15-43 percent of the time

Germany Canola Hartl and Herrmann, 

2009

In an online survey, found that the GE version must 

be discounted by over 100 percent

Romania

Potatoes, 

Sunflower 

oil

Curtis and Moeltner, 

2007

Found that so few of surveyed Romanians were willing to purchase GE foods that a premium could not 

be calculated

Sweden Beef, 

chicken Carlsson et al., 2007

Found that consumers were willing to pay 30 SEK/kg 

extra for chicken and 32.5 SEK/kg for beef fed feed 

not produced using GE ingredients

continued—
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(Bernard and Bernard, 2010; Huffman, 2010; Hartl and Herrmann, 2009; Volinskiy et al., 

2009; Bukenya and Wright, 2007; Moon et al. 2007; Huffman et al., 2007; Carlsson et al., 2007; 

Tegene et al., 2003; Loureiro and Hine, 2002; Burton et al., 2001; Lusk et al., 2003; Moon and 

Balasubramanian, 2001). Other research studies have identified concerns about GE foods (Bernard 

et al., 2007; Komirenko et al., 2010). 

Lusk et al. (2005) found that much of the variation in premia for non-GE foods across studies can 

be explained by a number of factors, including whether the study was done in Europe, whether the 

research surveyed shoppers, whether the survey took place in person, whether the consumers were 

asked to give hypothetical values for willingness-to-pay, whether they were asked for values for 

GE or non-GE foods, what type of product was considered, and whether consumers were told the 

product would provide them with a direct benefit. 

Table 9

Studies in which consumers were willing to pay a premium for non-GE food 

Country Good Study Willingness to pay premium [1]

Norway, United States, 

Japan, Taiwan

Vegetable 

oil Chern et al., 2002

For non-GE vegetable oil, Norwegian students were 

willing to pay $1.51 (55-69 percent premium) per 

liter. U.S. students were willing to pay $1.13 (50-62 

percent premium), Japanese students were willing to 

pay $0.88 (33-40 percent premium), and Taiwanese 

students were willing to pay $0.45 (17-21 percent 

premium)

Norway Bread Grimsrud, et al., 2004

Consumers required discounts of 37 to 63 percent to 

buy GE bread; one-fourth were willing to buy with no 

discount

Australia Beer Burton and Pearse, 

2002

Younger Australian consumers would pay $A 0.72 

less and older consumers $A 0.40 less for beer made 

with GE barley

Canada Canola Volinskiy et al, 2009

In a shopping experiment, found that consumers 

would pay Canadian $0.45 (20-30 percent) premium 

for non-GE canola

Canada West et al., 2002 83 percent of consumers ascribed a lower value to 

several GE food products

China Vegetable 

oil Hu et al., 2006

Consumers would consume GE product with a 

14-percent discount after hearing basic or positive 

information, and a 66-percent discount after hearing 

negative information

China Soybean oil 

and rice Lin et al., 2006 Consumers on average would pay a 52-percent 

premium for non-biotech foods

France Biscuits Noussair, et al., 2004

35 percent of consumers were unwilling to purchase 

GE foods, and 42 percent were willing to purchase 

them if they were less expensive

United States Various Rousu et al., 2004

Consumers reduced their demand by an average of 

7-13 percent for each food product having 1-percent 

and 5-percent tolerance levels for GE material relative to food not produced using GE ingredients

[1] Lusk et al., 2005 contains a more exhaustive review of the literature prior to 2005.

—continued
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More recent research on consumer willingness-to-pay for GE foods has focused on consumers in 

developing countries and has yielded different results than in wealthier nations (table 10). Several 

authors found that consumers are willing to pay a slight premium for GE foods in India (Krishna 

and Qaim, 2008; Anand et al., 2007), Kenya (Kimenju and De Groote, 2008), and China (Li et 

al., 2002). The few studies that have considered second generation attributes like nutrition have 

also found willingness-to-pay a premium for GE foods in India and Brazil (Anand et al., 2007; 

Gonzalez et al., 2009a). However, these findings are not universal across all developing countries. 

Hu et al. (2006) found that, on average, consumers in Nanjing would consume GE vegetable oil at a 

discount of 14 percent if presented with basic information or positive information and would require 

a discount of 66 percent if presented with negative information. Lin et al. (2006) also found that 

Chinese consumers would pay an average premium of 52 percent for non-GE foods. In addition, 

in Romania, a lower income country that is also in the EU, Curtis and Moeltner (2007) could not 

calculate a premium for non-GE goods over GE goods since too few in their survey of Romanians 

were willing to purchase GE goods. A cluster analysis of Brazilian stakeholders in the debate over 

Table 10

Studies in which consumers were willing to pay a premium for genetically engineered (GE) food 

or GE food with enhanced characteristics

Country Good Study Willingness to pay premium [1]

United States Good Huffman, 2010 Found that consumers would pay a 19- to 26-percent [2] premium for a product 

with intragenic addition of vitamins over a plain labeled product

United States Golden 

Rice Lusk, 2003 Customers willing to pay $0.93 for GE “golden rice” with added vitamin A, $0.65-0.75 for regular rice

Germany Canola

Hartl and 

Herrmann, 

2009

In an online survey, also found that consumers were willing to pay 1.37 Euros/

half-liter extra for GE oil with Omega3’s and 0.80 euros per half-liter for GE oil 

with cholesterol-reducing compounds, which reduced but didn’t eliminate the 

GE discount

Italy Bocatelli and 

Moro, 2001

Consumers willing to pay a positive amount for GE attributes; 66 percent did 

not require a premium to consume GE foods

China Rice Li et al., 2002

80 percent of consumers did not require a premium to purchase GE rice and 

on average were willing to pay a 38-percent premium for GE rice and a 16-percent premium for GE soy oil

Brazil

Vitamin 

A fortified 

cassava 

Gonzalez et al., 

2009

Found surveyed consumers willing to pay 64-70 percent more for GE VitaminA fortified cassava

India Bt vegetables

Krishna and 

Qaim, 2008

Found surveyed consumers willing to pay 1.5 percent premium for GE Bt 

(pest resistant ) vegetables

India Wheat Anand et al., 

2007

Found that if given no info, consumers will pay a 7-percent premium for GE 

foods; positive info leads to a 10-percent premium, negative info leads to a 

negative 139-percent premium (discount) for GE foods, and positive info on 

heart-healthy characteristics leads to a 23-percent premium for GE foods

Kenya Maize 

meal

Kimenju and 

De Groote, 

2008

Consumers surveyed in 2003 would pay a 13.8-percent premium for GE food

[1] Lusk et al., 2005 contains a more exhaustive review of the literature prior to 2005.

[2] Across all information treatments.
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GE foods found that while many respondents perceived little or no risk from GE foods, some were 

skeptical of the benefits (Gonzalez et al., 2009b). 

Some studies found that consumers, on average, would pay a premium for the non-GE version of the 

product while some would be willing to purchase GE foods without a premium (Lin et al., 2006). 

Bukenya and Wright (2007) found that younger consumers were willing to pay a premium for GE 

versions of the product.

More research is beginning to focus on second-generation attributes. Many of the currently marketed 

varieties of GE foods come from crops that have been engineered to decrease yield losses to pests 

and/or reduce costs of production (first generation). Second-generation attributes refer to genetically 

engineered characteristics of the foods themselves, such as extra vitamins that might make the food 

more attractive to consumers. Lusk et al. (2005) examined the literature up until 2005 and found 

that benefits to the consumer were significant in explaining the size of the premium consumers 

would pay for a non-GE food. Huffman (2010) found that U.S. consumers were willing to pay a 

premium for vitamin-enhanced GE food, as did Lusk (2003). Gonzalez et al. (2009) and Anand et 

al. (2007) found the same thing for consumers in Brazil and India. With an online survey of German 

consumers, Hartl and Herrmann (2009) found that GE enhancement of the Omega-3 content of 

foods or the addition of cholesterol-fighting compounds reduced the discount that GE foods had 

to offer relative to non-GE products. Boccaletti and Moro (2000) found that a sample of Italian 

consumers were willing to pay more for GE foods with improved nutritional qualities and lower 

pesticide use. 

A new area of research has been the contrast between intragenic and transgenic goods. Intragenic 

goods are created by transferring genes from a plant of the same species, but of a different variety, 

as opposed to transferring a gene from another species or type of plant. Huffman (2010), using 

experimental auctions, found that consumers discounted GE foods, but were willing to pay a 

premium for intragenic foods that had enhanced vitamin content versus a plain-labeled product. 

The difference between the premia for intragenic- and transgenic-enhanced vitamins, however, was 

not statistically significant unless pro-biotech information was given to consumers. A survey of 

stakeholders in the potato industry (Toevs et al., 2011) found that certain categories of stakeholders 

(women, Canadians) were optimistic about intragenic potato varieties. More research remains to be 

done to determine whether consumers as a whole will find intragenic foods more acceptable than 

transgenic foods.

Effect of Information on the Desire of Consumers To Purchase 

GE Foods 

Several studies have also considered the impact of information on the desire of consumers to 

purchase GE foods, and the results have varied. Huffman (2010), Huffman et al. (2007), Hu et al. 

(2006), and Tegene et al. (2003) found that positive information regarding biotechnology increased 

the willingness-to-pay for GE foods, while negative information reduced it. Onyango et al. (2004) 

found that those given both positive and negative information were less willing to buy GE foods than 

those given only positive information. Martinez-Poveda et al. (2009) found that previous knowledge of GE technology reduces the effects of negative information on the perception of GE foods, 

but could increase concern for health. Boccaletti and Moro (2000) found that previous knowledge 

increased the willingness-to-pay for positive GE attributes, while Lusk (2003) found that lack of 

previous knowledge increased willingness-to-pay. 
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Other studies have found that consumers value certain types of information. Hu et al. (2009) argued 

that those choosing to access information about GE foods may be different types of consumers 

than those who don’t access information about GE foods. They found that consumers who voluntarily access general information on GE foods are more likely to buy them, while those who access 

environmental information related to GE foods are less likely to buy them. Rousu and Lusk (2009) 

found that providing consumers with information on the environment was more likely to change 

consumer purchasing behavior with respect to GE foods, while information on the beneficial impact 

of GE foods in developing countries created more value for the consumer.

Evidence From Retail Settings

Market settings offer examples of retailers’ efforts to consider consumer preferences for GE foods. 

Some retailers do not have policies that explicitly address GE foods. Other retailers, mostly in the 

EU, have explicit policies stating that GE ingredients will not be used in their brand name food products.39 Some companies have even introduced lines of meat and eggs from animals not fed on GE 

feed (Agriculture and Agri-food Canada, 2007; ASDA, 2011; Carrefour, 2011b; ECCC, 2008; Tesco, 

2011; SHAFE, 2011). 

Lusk et al. (2005) found that consumers in Europe were willing to pay more for non-GE foods 

than consumers in other regions. Thus, we might expect to see more responsiveness on the part of 

European retailers, and indeed some of them have developed auditing procedures for their suppliers 

(Tesco, 2011). Store visits by researchers in 10 EU countries found few (between 1 and 27) products 

with GE ingredients in grocery stores in 7 of the countries (King’s College, 2008). The results of 

Mather et al. (2011) suggest that there may be circumstances under which consumers in a few EU 

countries would purchase GE foods. 

A market exists for non-GE products in the United States, as some U.S. retailers do offer non-GE 

products, and U.S. consumers wishing to avoid GE ingredients may also purchase organic products. 

However, the share of this market in the United States is still small compared to the widespread 

marketing of non-GE goods in the EU. For example, the four largest retail chains in the UK40 all 

indicate on their websites that their own-brand products do not include biotech ingredients (Tesco 

website, 2011; ASDA website, 2011; Sainsbury’s website, 2013; Wm Morrison website, 2013). They 

also have tried developing brands of meat from animals fed non-GE feed, but some of the chains 

have been unable to source enough feed to maintain production (Tesco Food News, 2013; Wm 

Morrison website, 2013). In contrast, of the four largest U.S. grocery retail chains,41 two make no 

mention of GE foods on their websites or corporate responsibility reports, one indicates that non-GE 

ingredients are not yet defined, and one will make one of its inhouse product lines non-GE in the 

coming year (Walmart, 2013a; Walmart, 2013b; Kroger, 2013a, Kroger, 2013b; Publix website, 

2013; Safeway/Vons website, 2013). Thus, U.S. supermarkets do not perceive the same advantage 

from marketing non-GE goods that the UK retailers do. 

39The supermarket chain Whole Foods has announced a labeling policy that will be implemented by 2018 to indicate if 

their products contain GE ingredients (http://media.wholefoodsmarket.com/news/whole-foods-market-commits-to-fullgmo-transparency). ERS researchers discuss the economic issues related to food labeling, including GE foods (Golan et 

al., 2001). 

40Tesco, ASDA, Sainsbury’s, and William Morrison.

41WalMart, Kroger, Safeway, and Publix.
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Further evidence comes from new product introductions in the United States. Of the 7,637 new food 

or food supplement products introduced between February 12, 2010, and February 11, 2011, as documented by the Datamonitor database, 2.6 percent advertise42 that they do not include GE ingredients, 

8 percent advertise that they are organic, and another 2.8 percent indicate that they at least have 

some organic or non-GE ingredients (Datamonitor, 2010-2011). Organic acreage of corn and soy, 

two potential sources of verified non-GE ingredients for U.S. food producers, remain a small share 

of the total acreage, with organic soy constituting 0.17 percent of total U.S. production and organic 

corn constituting 0.26 percent of total U.S. production in 2011 (USDA-ERS, 2013). 

Whether patterns of consumer approval have changed over time is not clear. International Food 

Information Council (FIC) polls seem to indicate that the percentage with favorable opinions of 

GE foods in the United States fell between 2003 and 2008, but it has recently risen somewhat. In 

terms of the more rigorous studies cited in this report, even in the United States and in the United 

Kingdom, for which we cite several studies from different time periods, the temporal patterns are 

not clear enough to draw definite conclusions.

42Via labels or promotional material. The current website was sometimes consulted if the claim was ambiguous.
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Conclusion

A large majority of U.S. farmers have adopted GE seeds for corn, soybeans, and cotton since their 

commercial introduction over 15 years ago. Despite the higher prices of GE seeds compared to 

conventional seed, farmers realize economic benefits from growing GE crops through higher crop 

yields, and/or lower pesticide costs, and management time savings.

Farmers will continue to use GE seeds as long as these seeds benefit them. However, it is not clear 

that first-generation GE seeds will benefit farmers indefinitely. With the help of refuges, the emergence of insect resistance to Bt crops has been low and of little economic significance over the first 

15 years, but there are some indications that insect resistance is developing to some Bt traits in some 

areas and resistance to the herbicide glyphosate has already evolved in certain weed populations. 

Best management practices can help delay the evolution of resistance and sustain the efficacy of HT 

crops.

An important issue beyond the scope of this report is the coexistence of crop production systems. 

According to the USDA Advisory Committee on Biotechnology and 21st Century Agriculture—

AC21 (2012), coexistence is defined as the “concurrent cultivation of crops produced through 

diverse agricultural systems including traditionally produced, organic, identity preserved, and 

genetically engineered crops.” USDA supports all these crop production systems and wants each 

to be “as successful as possible providing products to markets in the United States and abroad.”43

ERS is collecting data and conducting a study on several aspects of the economics of coexistence of 

organic, non-GE, and GE crops. 

43http://www.aphis.usda.gov/newsroom/2013/09/ac21.shtml)
42

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