1 bio 4101: pesticides and the environment

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BIO 4101: Pesticides and the Environment BIO 4101: Pesticides and the Environment 1


!  Farmers have been genetically modifying plants for 1000s of years –  Artificial selection propagates bad

traits with the good –  Most recently, trying to eliminate

bad traits !  Modern technology allows for

the insertion of desirable genes into target organism genomes (recombinant DNA)


!  1) Agriculture –  A) resistance/tolerance to insects –  B) resistance/tolerance to herbicides –  C) resistance/tolerance to pathogens

!  2) Public Health –  Production of vaccines (ex. insulin) or protein products

(ex. Growth hormones) !  3) Forestry

–  Production of tree varieties resistant/tolerant to pathogens or of increased quality (ex. Lignin production, pollution tolerance)

!  4) Other –  Industrial biomaterials, environmental rehabilitation

organisms

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!  First products: bacterial gene insertions to create human protein products –  Insulin –  Growth hormones –  No societal resistance whatsoever

!  First products intended for human consumption:

–  Plants resistant to pesticides –  GMO tobacco in field studies

from 1986-1989


!  Why resistance against pesticides? !  Traits associated with yield (seed quality, early maturation,

nitrogen fixation etc.) are often multi-gene complexes, therefore molecular techniques are too complicated

!  Traits for resistance are often associated with only one gene in particular


!  Nutraceuticals –  Medicinal properties –  Added value

!  Transgenic animals –  Milk with added nutrition/medicines –  Less susceptible to disease –  Limit pollution from manure

!  Plants tolerant to wider range of conditions –  Dessication, salt, better PS

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!  Increase yield/decrease losses !  Decrease external costs !  Increase value of crops !  Reduce environmental damage !  Improve quality of life by eliminating

deleterious genes (ageing, cancers etc.)


!  1) Subjective –  Ethical, political, theistic, social,

economic… !  2) Rational/scientific

–  A) poses no danger upon consumption •  Ex. Human or animal food

–  B) poses no danger to the environment •  Ex. Perturb ecological processes •  Ex. Resistance


!  Much confusion, ignorance and disinformation exists

!  Most people lack the basic understanding required to discuss the topic – Ex. a UK poll demonstrated that 60% of

respondents did not realize that non-GMO tomatoes also contained genes

!  Other problem: there is no consensus on the definition of a GMO

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!  1) over the process –  Unnatural, ‘playing God’ –  Due to molecular homology we already

share most of our genes across very distant taxa… what’s one more?

–  Pork gene in a tomato •  Can it be eaten by jews/muslim? •  What if the gene already exists in tomatoes?

–  For non-food GMOs (insulin or cystic fibrosis enzyme from bacterial gene insertion and cloning) •  Most people are ok with this form of GMOs so

they are not inherently against the process itself

!  2) over the products (potential) –  Creating ‘monsters’ –  Haven’t yet seen any problems


!  Genetic modification = genetic engineering = recombinant DNA (rDNA) –  A series of technologies and processes –  Ex. Molecular analysis, gene

identification, gene extraction and cloning, gene splicing and gene transfer

–  Most people consider only the latter to be GM

–  We end up by creating an organism with novel traits (Canada’s regulation applies at that level)


!  In Canada, a GMO: –  All organisms with traits that do not exist in the natural

varieties (organism with novel traits) –  This applies to organisms created by traditional methods

of selection –  Most of our food (microbes, plants, animals) are currently

genetically different from their natural cousins

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!  As a function of their inherent properties –  Ex. Canada –  Control is based on the product, not the

process !  As a function of their mode of

production –  Ex. USA

!  As something completely different –  Ex. EU


!  Selection !  Crossings !  Emasculation

–  Prevent paternity in non-desirable plants

!  Genus crossings –  Ex. Triticale: wheat and rye

!  Haploid selection –  Forcing double haploid embryos to

develop


!  Mutant selection –  Expose plants to mutagens to see what is

created –  >1400 cultivars from several spp.

!  Somaclonal variation –  Provoke genetic changes during micro-

propagation in cultures !  Cell selection

–  Growth of cultured cells and mutants are selected for propagation

–  Selection for resistance is based on applying noxious chemicals or poisons to remove normal cells

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!  Risk: probability that something poses a danger

!  To public health: –  Increase in toxicity, allergens or

decrease in nutritional quality – Risk for toxicological profile is calculated

using a) biological activity of the product, b) the frequency, intensity and duration of exposure


!  1) Modification of the rhizosphere by gene transfer


!  2) Diffusion of GMOs into the environment –  Super-Weeds could become invasive –  In W Canada, natural populations of

Canola have become resistant to herbicides

–  Margin of security: artificial selection has weakened hardiness of agricultural crops

–  Herbicide resistance not really an issue in nature, other forms of tolerance could be problematic

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!  2) Diffusion of GMOs into the environment – Gene flow between GMO populations and

natives –  12/13 of the most important plant crops are

grown in proximity of their wild cousins (ex. wheat, rice, corn, soya, cotton, barley)

– How to control? •  Dispersal by pollinators, seeds…


!  2) Diffusion of GMOs into the environment –  Ex: Starlink Corn (B.t.) –  Protein product Cry9C (similar to

many allergens) –  Banned from human

consumption –  Approved pour industrial non-

food uses, animal feed and the production of grain

–  Contamination has been documented in food products (requires recalls, inquiries, compensations etc.)


!  3) Risks of insects developing resistance to GMOs –  Many species already show B.t.

resistance in laboratory –  One case observed in nature:

Diamond-backed moth (Plutella xylostella) on crucifers in FLA and NY

!  Selection pressures are more intense because expression is continuous in GMOs

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!  Strategies to reduce the potential for resistance

– Mixed cultures – Non-GMO refugia

around GMO crops – EPA (2000): no more

than 80% of a crop can be GMO B.t.


!  4) Negative effects on biodiversity – Agriculture is already among the human activities

that leads to biodiversity losses – UNEP: biodiversity loss has been accelerating

since 1600, has reached 100x the natural rate – A) genetic homogenization of parental stocks – B) effects on non-target organisms and up the

food chain


!  Pleiotropic effects – Genes rarely act in isolation – Many interactions exist

between genes and the genome •  Ex. Regulators of the

expression of other genes (amplitude)

•  Ex. Initiators or terminators of the expression of other genes

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!  Reduction of pesticide use – Australia: noticed a reduction of 50% in 2 years

with B.t. cotton – USA (1998-1999): reduction of 21% with B.t.

cotton – USA: reduction of 10-30% with GMO soya – USA in general (FDA): pesticides were reduced in

7/12 regions, but not in the other 5/12


!  Why no reduction in 5/12 regions? – Herbicide resistant GMOs created to be specifically

used with a particular pesticide – Ex. Monsanto “Round-up Ready” plants can only

be used with glyphosate

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Target Species

Source: G Frisvold, University of Arizona

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!  Proposed at the Rio Earth Summit in 1992

!  Signed at the UN conference on the Environment and Sustainable Development

!  “if an action or policy has suspected risk of causing harm to the public or to the environment, in the absence of a scientific consensus that harm would not ensue, the burden of proof falls on those who would advocate taking the action.”


!  UN convention on biological diversity in Montréal in 1993

!  Strategies aimed a maintaining biological species and ecosystem diversity

!  Addition to the PP in order to include the risks associated with biotechnologies (GMOs)

!  PP and CP: international guidelines for the evaluation and standardization of food products


!  GMO creation is under rigorous and elaborate scrutiny at every step – Many more varieties are created by genetic

engineering than by conventional methods

– We have no idea what genes are created by mutation but we know exactly with gene transfer

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!  Different processes are often confused with one another –  Ex. Herbicide-resistant Canola

coming from Canada (GMO) are banned in the UK, but not those coming from Australia (conventional)

–  Ex. Whole organisms and derived products are often considered as equivalent - tomatoes (intact DNA) vs. paste (denatured DNA)

–  Some refined products contain no genes or protein products (oils, sugars etc.)


!  Have been growing experimentally for 35-40 years –  Thousands of generations of GMO plants

!  GMO products have been consumed by humans since 1994

!  No pronounced effect has been observed in public health or on ecosystem functioning to date

!  When unintended effects have been discovered, those strains have been scrapped –  Ex. Beans with nut gene


!  GMO plants must be exactly the same as cousin plant, except for GM

!  Must be considered “Substantially Equivalent” – Agricultural, environmental

and public health parameters

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GMO plants World cultivated surface (M ha) % of all GMOs

% of this plant’s production

globally

Soya 25,8 58,4 36

Corn 10,3 23,3 16

Cotton 5,3 12 11

Canola 2,8 6 7

Total 44,2 99,7 16



USA Canada UK Corn 12 15 1

Canola 7 15 5

Tomatoes 6 3 4

Cotton 5 5 0

Potatoes 4 4 0

Soya 3 1 1

Beets 2 0 0

Gourds 2 2 0

Radishes 1 0 0

Papaya 1 0 0

Linseed 1 1 0

Total 44 42 19

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Country 1999 2000 % change USA 28,7 30,3 +5,6

Argentina 6,7 10,0 +49,3

Canada 4,0 3,0 -25,0

China 0,3 0,5 +66,7

S Africa 0,1 0,1 +100

Australia 0,1 0,2 +100

Other <0,1 <0,1 -

Total 39,9 44,2 +10,8


Canada Ontario Quebec Wheat 20 695,3 1 222 116,9

Corn 7 550 4 750 2 800

Barley 11 103,3 387,5 485

Oats 2 838,3 74 210

Rye 201,5 54,6 3,2

Soya 2 040,1 1 660,1 380

Canola 4 788,8 31,3 10

Mixed Cereals 375,8 208,7 3,2


Sales R&D Syngenta (Swiss) 5 888 745

Monsanto (USA) 3 885 588

Aventis (France) 3 701 469

DuPont (USA) 2 511 1776

Dow (USA) 2 271 892

Bayer (Germany) 2 252 2208

BASF (Germany) 2 228 758

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!  Gouvernement du Québec. Conseil de la science et de la technologie. 2002. OGM et alimentation humaine: impactes et enjeux pour le Québec. 178p.

!  McHughen, A. 2000. Pandora’s picnic basket. Oxford University Press, NY. 277p.

1 bio 4101: pesticides and the environment

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