Ecological impacts of genetically engineered crops:

a case study of the Farm Scale Evaluations

L. LaReesa Wolfenbarger

University of Nebraska

GEO Environmental Risks and GEO Environmental Risks and BenefitsBenefits

• Risks of invasivenessRisks of invasiveness• Non-target organism impactsNon-target organism impacts• New viral diseasesNew viral diseases• Reduced pesticide environmental impactReduced pesticide environmental impact• Reduced rate of land conversionReduced rate of land conversion• Soil conservationSoil conservation• PhytoremediationPhytoremediation

Source: Wolfenbarger & Phifer (2000) Science

Survival

Reproduction

Self-sustaining

Spread and persistence

Pollen flow

Hybrid formation

Hybrid survival

Hybrid reproduction

Gene introgression

Pathways to invasiveness

Introductionof plant

Pathways by which environmental impacts could occur

• Presence of transgenic crop or its transgene – plant above ground – roots – decomposing tissue – pollen drift – gene flow to wild relatives in

natural ecosystem

Pathways by which ecosystem effects could occur

• Changes in agricultural practices associated with adoption of a transgenic crop – Pesticide use patterns– Amount of agricultural land– Tillage practices– Crop diversity/rotation

Non-target data considered in latest EPA risk assessment for Bt crops*

• Larval and adult honeybee• Green lacewing*• Ladybird beetles• Parasitic Hymenoptera• Monarch butterfly*• Avian oral toxicity• Static renewal acute toxicity, Daphnia• Corn as food for farmed fish• Collembola• Earthworms

*Standard studies based on EPA Subdivision M and/or OPPTS 885 Guidelines

OVERALL

Very limited evidence for toxic effects*

Monarch butterflyMonarch butterfly

Risk assessment over a large geographic Risk assessment over a large geographic scalescale

Farm Scale Evaluations

• Test hypothesis that biodiversity will be the same in fields managed with GM crops compared to conventional counterparts

Farm Scale Evaluations:Why?

• By 1998 GE Herbicide tolerant crops have cleared most hurdles for commercialization

• BUT, concerns that GE Herbicide tolerant crops will reduce plant and invertebrate populations on which farmland wildlife depend

Farming in the UK

• Arable and pastoral farming

• 75% of surface area• Land use

continuous since 700 BC

Farmland is the environment

• Average farm size is 50 ha

• Lots of edge habitat• Wildlife depends on

fields and margins

Status of birds in the UK

Farm Scale Evaluations:Why?

• Concerns that GE Herbicide tolerant crops will reduce plant and invertebrate populations on which farmland wildlife depend

Design of the FSE

• Fields planted 1/2 GE, 1/2 Conventional• Approx 60 fields per crop• Four GE herbicide tolerant crops: beets, maize,

spring oilseed rape and winter rapeseed

Sites distributed over the UK

Design of the FSE

• Fields planted 1/2 GE, 1/2 Conventional• Approx 60 fields per crop• Four GE herbicide tolerant crops: beets,

maize, spring oilseed rape (canola) and winter rapeseed

• Measure biodiversity within fields and at margins

• Biodiversity: weeds, seeds and inverts

Habitats sampled

Why not measure birds?

• Plants and inverts respond directly to herbicide management

• Conclusion of no effect more robust

• Model effect on birds

Herbicide practices during FSE

GE crop

Fewer applications, later timing, weed cover variability

Herbicide practices: MaizeGE crop

More weed cover in GE half of field

Herbicide practices: Oilseed rape

More weed cover with conventional cropping

GE cropping: later, fewer

Results: 8 papers, >100 Tables and figures

Andow’s cheat

sheet for results

What do we do with

this?

Complications to maize interpretations?

• Atrazine banned in 2003

Largest differences due to crop and season

Status of birds in the UK

How was information from FSE used?

Policy results

• Advisory committee recommends ban on GE HT beets and oilseed and approval of GE HT maize

Recommendations to parliament

• oppose EU approval for the commercial cultivation of the GM beet and oilseed rape as grown in the FSE trials

• only allow the commercial cultivation of the GM maize in the FSE trials if restrictions are imposed on its EU marketing consent to limit herbicide use

March 2004

March 2005

• BayerCropScience withdraws its plans to cultivate its approved GE corn

• “…too many demands”

November 2005

• No GE crops grown in the UK• None expected before 2008• Approval for use of GE crops in feed is

occurring

And, the latest….

Swiss citizens are not prepared to sell their souls and convictions to satisfy their consumer tastes.

Le Matin on approval of a five-year ban on GM foods, 28 November 2005