Environmental issues associated with modern biotechnology

1. Environmental issues associated with modern biotechnology By: Dr. Dorington O. Ogoyi Dept of Biochemistry, University of Nairobi

3. ENVIROMENTAL BENEFITS • Reduced use of chemicals hence more friendly to the ecosystem • Promote land conservation from higher yields • Sustains more beneficial organisms in the environment • Protection of biodiversity due to land conservation and reduced usage of hasher pesticides that are toxic to many more species.

4. ENVIROMENTAL CONCERNS • gene flow between the transgenic plants and their sexually compatible relatives, • changes in levels of weediness or invasiveness of the GM crops or their wild relatives; • horizontal transfer of engineered traits to other species, • non-target effects and • development of pest resistance or new secondary pests.

5. Genetically Modified Crops and Gene Flow • Gene flow: transfer and incorporation of genes from one population into another through pollen or seed movement • Pollen movement is not by itself an environmental concern, unless the GM crop can successfully hybridize with a relative. • Hybridization occurs frequently between crops plants and their sexually compatible relatives (both crops and wild species)

6. GM-Gene flow • For hybridization: Plant species must 1) be sexually compatible, 2) close enough for the pollen to be moved between plants by wind or vectors such as insects or birds, and 3) be in flower at the same time • Similar to their non GM, GM crops will probably hybridize with their sexually compatible species

7. GM-gene flow • Hybridization between GM crops and their compatible relatives may or may not have environmental consequences. • The impact of transgenes on natural populations is determined by the combination of the trait expressed by the gene itself and the invasiveness of the recipient species

8. Changes in Levels of Weediness or Invasiveness • Weeds “wild plants that interfere with human objectives”; and a wild plant as “plants that grow and reproduce without being deliberately planted

9. Levels of weediness/invasiveness • Concerns have been raised that; • transgenic crops themselves could become weeds and invade agricultural or natural ecosystems, • the engineered traits could be introduced into wild relatives via hybridization and increase the competitive ability and the weediness of those wild plants or their hybrid derivatives.

10. Levels of weediness/invasiveness • Many of the GM crops developed (cotton, maize and soybean) have been selected for thousands years by humans on agronomic sites and have lost many of their weedy characters. • Thus, GM crops are not more likely to become weeds than their non-GM counterparts

11. Levels of weediness/invasiveness • Concerns herbicide tolerance genes turning into uncontrollable weeds; particularly if several crops of the same species and tolerant to different herbicides are grown in close proximity. • Multiple hybridizations may result in multi-herbicide resistant hybrids which are difficult to eradicate

12. Levels of weediness/invasiveness • The emergence of herbicide resistance in weed species could add to farm management burdens, but it will not impact on the natural environment where herbicides are not applied.

13. Horizontal Transfer of Engineered Traits to Other Species • “A stable transfer of genetic material from one organism to another without reproduction or human intervention”. • This phenomenon can occur between bacteria and is considered a significant source of genome variation

14. Horizontal Transfer of Engineered Traits to Other Species • Concern: engineered traits could be transferred to non-target organisms thereby threaten environmental and animal safety • horizontal gene transfer from GM plants to other organisms is, at most, an extremely rare phenomena and to date no environmental harm has been reported.

15. GM Crops and Biodiversity • Biodiversity: “the variability among living organisms from all sources, including, among others, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part”

16. GM Crops and Biodiversity • Wide spread of GM crops could adversely affect the levels of natural diversity through: • replacement of traditional varieties (land races), • hybridizations between GM crops and land races or wild relatives, particularly in “centers of diversity” • interactions with non-target organisms. • Land races and centers of diversity are of particular importance both to farmers and plant breeders as sources of food and storehouses for genetic diversity to improve crop varieties.

17. GM Crops and Biodiversity • Hybridization between GM crops and wild relatives could reduce genetic variability: • a native population could go extinct due to high levels of pollen flow from a much larger commercial field, • selectively advantageous crop genes could replace native ones through hybridization

18. GM Crops and Biodiversity • The risk of altering native levels of genetic diversity via pollen flow is not unique to GM crops and is associated with the large scale cultivation of any new crop species. • The presence of the transgene is the only difference associated with the GM crops • While traditional varieties have been replaced in some areas by commercial varieties, traditional varieties have been maintained in many others.

19. Impact on Non-Target Organisms • Non-target organisms; any organisms that may be adversely affected by the GM crops that were not the intended targets.

20. Non target organisms • Non-target organisms Classification: • pollinators and natural enemies of pest and the wider category of beneficial species, • soil organisms, • non-target herbivores, • endangered and other species of conservation concern, • species which contribute to local biodiversity.”

21. Non target organisms • Potential direct and indirect effects: • Direct effects are due to toxicity through ingestion by the non-target organisms of a toxin produced by the GM plant, • Indirect effects occur via multi-trophic food chains, involving, for example, organisms not directly consuming the GM plant but feeding on other insects associated with the transgenic plants.

22. Non target organisms • Of the GM crops currently on the market, Bt crops are those with potential for non-target impacts; so the effects of Bt proteins have been extensively evaluated. • Results from a number of those studies have been summarized by OECD (2007) in a consensus document. • The broad concensus: that few non-target organisms are negatively impacted by exposure to Bt proteins.

23. Other Agro-Ecological Impacts Resistance to Bt Toxins • The widespread cultivation of pest-resistant GM crops might lead to resistance developing in the targeted pests. This is, of course, a risk to product performance, not the environment.

24. Resistance to Bt Toxins • Management strategies to delay the evolution of resistance in pest populations; • high doses of the pesticidal protein expressed by the transgenic plant, • A refuge that is planted alongside the transgenic crop field. • Introduction multiple toxin producing genes with different mechanism of action

25. Resistance to Bt Toxins • the evolution of resistance must be continually addressed. • The emergence of resistance will impact primarily on the control of pests in farmers’ fields and • may cause a return to control strategies currently employed in non GM crops fields which are less friendly to the environment.

26. Resistant Weeds to Glyphosate Herbicide • In recent years, glyphosate resistant weeds have also been reported in some countries • In the USA for instance, corn and soybean growers recently reported on weeds that had developed resistance to Roundup • Losing the use of glyphosate would be a critical issue if it brought back the use of herbicides that are less friendly to the environment.

27. Herbicide resistance • Management strategies have been developed to delay the development of resistance: • rotating the use of different herbicides • using “stacked” GM plants that have tolerance to more than one herbicide. • However, gene flow from stacked plants to native relatives could lead to the development of multi-resistant weeds • This raises agricultural concerns; however it is not an environmental issue as herbicides are not spayed in natural environments

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